Child Language Research Center

Department of Speech Pathology and Audiology, The University of Iowa
with support from the National Institute on Deafness and Other Communication Disorders

We are a collaboration of researchers studying the causes and consequences of developmenal language disorders.

The epidemiology of Specific Language Impairment
This seminal investigation set diagnostic criteria and defined the incidence of Specific Language Impairment by testing the language skills of over 7,000 Midwestern kindergarteners.

Abstract and funding information
Abstract: A study was conducted to estimate the prevalence of specific language impairment (SLI) in monolingual, English-speaking, kindergarten children; determine the proportion of subtypes of SLI; and examine the association of SLI with background factors in the child. A sample of 7,256 children stratified by rural, suburban and urban areas were screened. Children who failed the screening and selected controls were administered a diagnostic battery (N = 1,984). The estimated prevalence rate of SLI in this sample was 8.36 percent. Prevalence rates for rural, suburban, and urban strata were 8.4 percent, 6.8 percent, and 8.2 percent respectively. Receptive impairments occurred in 20 percent of the rural, 32 percent of the suburban, and 31 percent of the urban children with SLI. Expressive impairments occurred in 39 percent of the rural, 32 percent of the suburban, and 30 percent of the urban children. Expressive/receptive problems occurred in 39 percent of the rural, 26 percent of the suburban and 36 percent of the urban children with SLI. Of those with SLI in the rural setting, 25 percent also presented phonological impairments. These problems occurred in 28 percent of suburban children with SLI and 24 percent in urban settings. Of those with SLI in the rural, suburban, and urban settings, 65 percent, 54 percent, and 59 percent, respectively, were males. Of those with SLI living in in rural, suburban and urban settings, 20 percent, 18 percent, and 26 percent, had been or were receiving speech/language therapy.

Parents were interviewed to obtain information on risk factors associated with SLI. Several variables concerning parental background were found to be associated with SLI and these were found to be more often associated with an urban setting.

Principal investigator: J. Bruce Tomblin, Ph.D.

Funding source: National Institute on Deafness and Other Communication Disorders N01-DC12107

Funding dates: May 1991 to 1994

Description of work
Overview of Epidemiology Study of SLI
Children with Specific Language Impairment (SLI) have unexpected and unexplained difficulties learning and using spoken language. Although these difficulties are most apparent during the preschool and early school years, evidence now exists that these problems are usually present well into adulthood and are probably present throughout the person's life. Associated with difficulties in spoken language, first evident during early childhood, are impairments in reading and writing. As a result, those individuals presenting this condition are at high risk for academic difficulties. Despite life long academic, social and occupational consequences on those affected, there is little information about the prevalence of this condition or factors that place persons at risk for SLI. The few studies that do exist suffer from small sample sizes, poor sampling design and inadequate diagnostic procedures; furthermore none of these studies have been performed in the United States. The NIDCD, through a contract with The University of Iowa, has conducted an epidemiologic study of SLI in 5-year-old children based upon a sample of more than 7,256 children in the states of Iowa and Illinois. This study was designed to address the following issues:

1. Review existing literature on the epidemiology of SLI and related disorders.

2. Establish a definition of specific language disorder that is consistent with current research and clinical practice. In accordance with this definition, develop an explicit criterion for the diagnosis of specific language disorder.

3. Estimate, based upon this definition, the preva1ence of specific language impairment in five-year-old children each of three community environments in the United States: urban, suburban, and rural. Furthermore, estimate this prevalence rate in both males and females within these strata.

4. Characterize for each stratum the percentage of children with SLI who had primarily receptive primarily expressive, and receptive-expressive SLI. Also, determine the proportion of children with SLI within these strata who had concomitant phonological disorder.

5. Evaluate potential risk factors for specific language disorder.

6. Determine the history of clinical intervention for those children within each stratum.

Method
Three regions of the state of Iowa and one from Illinois, each centering upon a metropolitan area constituting an SMA (Standard Metropolitan Area) were used to obtain subjects from each of these strata.

Specifically these metropolitan areas were Waterloo/Cedar Falls/Cedar Rapids (IA), the Iowa-Illinois Quad Cities (Davenport/Bettendorf, IA, Moline, Rock Island, IL, and Des Moines, IA.). Within each of the strata and sampling region, all children who were age eligible for kindergarten during the study year (between 5 and 6 years old on September 15) were equally likely to be sampled. A stratified-cluster sampling method was used where the cluster unit was the attendance zone for a public school within one of the three community strata. The schools within each sampling region and strata were randomly selected and all kindergarten children attending the school were included in the study kindergarten children attending the school were included in the study. Using this sampling scheme over 7,000 children were sampled for participation in this study.

A two-stage assessment procedure was used to obtain the data needed to address the questions concerned with prevalence and risk for SLI. In the first stage, a brief language screening test was administered to all kindergarten children attending the schools sampled. The second stage of the assessment consisted of a diagnostic examination for SLI, administered to each child who failed. The screening test, as well as any child who had passed the screen and was randomly sampled from the same strata and community as the screening failure. The diagnostic examination consisted of a set of language measures, phonological measures, two subtests of the Wechsler Preschool and Primary Scale of Intelligence-R (Wechsler, 1989), and a pure tone hearing test. Additional information about the child's language background, history of speech and language intervention, and performance on pre-reading tasks was also obtained. In order to obtain information bearing on risk factors placing children at risk for SLI, the parents of each child who was found to present SLI, as well as 4 normal-control subjects per SLI child, were then contacted by Ames Statistical Laboratory. A 45-minute telephone questionnaire was administered to obtain background information pertaining to potential risk factors for SLI.

RESULTS
Summary & Introduction
The results in this summary will be collapsed over the residential stratification variable.

Screening Phase
Over the duration of the study, 7,844 children were eligible to participate, 626 of these children were not screened for one of three reasons: (1) they were non-English speaking or were from homes in which English was a second language, (2) they presented with unequivocal exclusionary conditions such as blindness or deafness, or (3) their parents did not wish them to participate. Of the 7,218 children who were screened, 1,933 failed the screening and 5,285 passed the screening. Of the 1,933 children who failed the screening, 1,835 were monolingual English speakers. Of the 5,285 children who passed the screening, 5,159 were monolingual English speakers. Thus, among monolingual English speakers 73.9% passed and 26.1% failed the screen.

Diagnostic Phase
Of the 3,877 children selected for the diagnostic (1,933 screening failures and 1,944 screening passes), 2,084 were given permission by their parent's to participate in the study. Of these children, 75 were reported by their parents to speak a second language. The rest of the 2,009 children constituted the final monolingual English speaker sample. The screening status for 901 of these monolingual English speakers was fail and for the rest (1,108) it was pass. However, 49 (39 of them had failed screening and the rest, 10, had passed) of these 2,009 monolingual English speakers were reported to have exclusionary conditions such as autism, head injury, mental retardation, etc. Although these children were not administered the diagnostic protocol, they were included in the denominator for calculating the prevalence of SLI. The diagnostic results of the remaining 1,960 children who were administered the diagnostic protocol showed that 1,479 had normal language status, 31 failed the hearing criteria, 215 presented language impairment but also failed the non-verbal cognitive criterion and 216 qualified as SLI by presenting a language impairment in the context of normal non-verbal IQ, normal hearing and no other exclusionary conditions.

Prevalence of SLI
The data above provided the raw frequencies necessary to compute the prevalence of SLI. Due to the nature of the study design in which all screening failures, and a partial sample of screening passes were diagnosed, the sample of children who received the diagnostic protocol were not a representative sample of all the monolingual English speaking children sampled and screened. Therefore, the prevalence could not be determined by simply dividing the number of SLI children by the number diagnosed. Instead, it was necessary to determine the prevalence of SLI in the screening failure group and the screen pass group separately and then to combine these based upon the differential rate of screening pass and failure. Among the screening pass children, 2.8% (31 of 108) were found to be SLI, whereas 20.5 % (185 of 901) of the screening failures were found to be SLI. The prevalence rate of SLI in the total screened population was then obtained by weighting 2.8% by the proportion of children passing the screen (.738) and likewise weighting the 23.4% by the proportion of children failing the screen (.262). The prevalence rate of SLI in the total population was thus estimated to be 7.42%.

Risk Factors
A 180 item questionnaire was administered to 228 parents of children with SLI and the parents of 860 children with normal hearing, intellectual, and language status. This questionnaire provided information on: parental background; maternal prenatal and perinatal health, parental exposure to tobacco, alcohol, and other drugs; family history of speech, language and learning problems; and several features of the child rearing environment. In addition, there were several items that provided extended insight into certain behavioral co-morbidities of SLI.
The principal risk factors for SLI were concentrated the background of the parents. In comparison with the parents of the control children, the parents of children with SLI, especially those in the urban setting, were less educated, younger, and had greater rates of learning problems, especially learning disorders in the mothers and speech and learning disorder in the fathers. The parents of the children with SLI were also more likely to smoke tobacco during and after the study child's birth than the parents of the control children. Finally, children who were read to infrequently, and/or had little opportunity to verbally share experiences or feelings were also at greater risk for SLI. When these risk factors were analyzed by strata, it was found that these risk factors were more often associated with SLI in the urban setting.

SLI DATA Sharing Project
In short, the project releases the large quantity of data collected in the Specific Language Impairment (SLI) Epidemiologic study. The National Institute on Deafness and Other Communication Disorders (NIDCD) created this outreach as a means to fully utilize research data gathered with its support.

Because of the NIDCD's generous funding, the data set is available without charge.

Those interested in this data set are likely child language researchers, particularly new or aspiring investigators who may not yet have support to carry out a large study such as this; those who need to boost their population sample size; or those interested in using the data for pilot studies. These data may also be used by professors interested in developing an educational exercise for their students.

Before requesting the data set, you should:
1. Read the description of the project to gain a general understanding of the goals and outcomes of the study.

2. Carefully read the lists of published articles and poster presentations to learn the analyses and conclusions presented/published by the CLRC. You would not wish - of course - to waste time by duplicating work already presented by the original research team.

3. Understand how the SLI data were collected.

SLI EPIDEMIOLOGIC STUDY: SUBJECTS AND SAMPLING

The target for this study was a stratified cluster sample of 6,000 kindergarten children who were monolingual speakers. The sample was stratified by residential setting and clustered according to school building. Rather than choosing a single urban, suburban and rural area, the sample was drawn from various regions of the states of Iowa and Illinois. These regions were centered on large metropolitan areas that will hereafter be referred to as "population centers." Each population center was selected for the ability to contribute an urban sample, with the surrounding areas contributing the suburban and rural samples. Several population centers reduced potential bias in participant characteristics associated with a single geographic area. The four selected population centers were Des Moines, Cedar Rapids, Waterloo/Cedar Falls, and the "Quad Cities" that straddle the Mississippi River. The Quad Cities are Davenport, IA, Bettendorf, IA, Moline, IL and Rock Island, IL.

Although Iowa is considered overall to be a rural, farming state, the use of population centers provided the desired urban, suburban and rural residential strata. The selected population centers were the largest in the state. Des Moines, the capital and largest city, had a 1990 city population of 191,000 and a metropolitan area population of 338,000. The second largest city in Iowa is Cedar Rapids, with a 1990 city population of 110,000 and a metropolitan area population of 170,000. Davenport had a 1990 city population of 103,000 and a metropolitan area population of 384,000. Waterloo/Cedar Falls together had a population of 100,388.

In summary, the population centers selected provided a suitable sample for the study of SLI in monolingual English speaking children. The general population in the areas sampled provided the linguistic homogeneity desired to reduce the chances that the identified language deficits were confused with cultural and regional differences.

Strata General Definition
The targeted 6,000 kindergarten children were equally distributed into three residential strata: urban, suburban and rural settings. This stratified sampling was specified by the NIDCD contract, and allowed the sampling of children across a spectrum of living and demographic conditions. To achieve this stratified sampling, the attendance zones of the school buildings from the four population centers were drawn and designated as being predominately urban, suburban or rural. Subsequent to the study, each individual child was assigned to a stratum according to that child's home address, thus allowing for a more accurate assignment of residential strata.

The U.S. Census Bureau specifically defines urban and rural areas, however suburban areas are defined by default, relative to the definitions of urban and rural areas (Census of Population and Housing, 1990). Based on the U.S. Census Bureau 1990 definitions, "urban" is defined in terms of territory, population, and housing units, and are considered to be places of 2,500 or more persons living in incorporated or unincorporated areas included in urbanized areas. An urbanized area comprises one or more places ('central places') and the adjacent densely settled surrounding territory ('urban fringe') that together have a minimum of 50,000 persons. The urban fringe generally consists of contiguous territory having a density of at least 1,000 persons per square mile.

The urban fringe also includes outlying territory of such density, connected to the urban area or fringe, and either within 1.5 road miles of the urban core, or within 5 road miles of the core but separated by water or other undevelopable territory (Census of Population and Housing, 1990).

"Rural" is defined by the U.S. Census Bureau (1990) as territory, population, and housing units not classified as urban. Rural areas may be divided into "places of less than 2,500" and "not in places," a category that is comprised of rural areas outside incorporated and census designated places and the rural portions of extended cities.

A general rule to determine strata for this study was developed by the investigators based on the two variables of population density and distance from the urban center. Areas designated as being "urban" were within 2 miles of the center business district. "Urban" also included areas that were between 2-3 miles of the center business district if the population density was 3,000 or more people per square mile. "Suburban" designation was assigned to areas having a population density greater than 2,000 persons per square mile and that did not qualify as being urban. "Rural" was considered to be areas with a population density less than 2,000 persons per square mile.

Because of the influence of the Mississippi River on the geographic layout of Rock Island, IL, the following definitions of residential strata for that population center were based solely on population density: Urban was considered to be greater than 3,000 people per square mile, suburban was between 2,000 and 3,000 people per square mile, and rural was designated as areas having less than 2,000 people per square mile.

Sampling of Elementary Schools
The method of sampling was a stratified cluster sample of school buildings located in the selected population centers. This sampling was accomplished by first contacting in writing the superintendent of each school district in the selected population centers. Along with a written explanation of the study was an invitation to participate during the course of this 2-year study. Receipt of a district superintendent's consent to participate served as permission to contact all of the principals of the school buildings in that district. A total of 41 districts were contacted; 21 (51.22%) superintendents consented to participate, 15 (36.59%) superintendents refused participation, and no response was elicited from 5 (12.19%) districts. It should be noted that only public school districts were sampled; there was no sampling of private schools or children being home schooled.

As was described above, each participating school building was assigned a residential stratum (urban, suburban, rural) based on their attendance zones. Once the individual school buildings were sorted by population center and residential strata, buildings within each stratum were assigned a number. Using a random number table, buildings were selected to obtain a minimum total sample of 1,000 students in each of the three strata across all population centers. For example, for the testing conducted during Field Year 1, a minimum of 333 children were selected from each rural, suburban and urban strata in each of the population centers of Des Moines, Waterloo/Cedar Falls, and the Quad Cities. (Cedar Rapids provided us with primarily an urban sample to supplement the urban sample from Waterloo/Cedar Falls population center). This procedure was repeated for Field Year 2. Therefore, because of the random sampling, some school buildings did not participate in this study; some were selected to participate in only one year of the study; and some school buildings were selected to participate in both years of the field testing. Because the population of Iowa does not contain a substantial number of African Americans, this sampling strategy was modified to over sample the urban strata, since this stratum contained the largest proportion of African Americans.

Table 1 presents the number of children who were sampled over the course of the study as age-eligible participants according to the study site and strata.

Table 1. Distribution of Participants by Strata and Study Site

Center	Rural	Suburban	Urban	Total
Des Moines	655	789	754	2,198
Waterloo/C.R.	888	665	957	2,510
Quad Cities	814	695	1001	2,510

SLI EPIDEMIOLOGIC STUDY: TEST INSTRUMENTS

Screening Phase Screening Instrument
The screening procedure only involved language performance. Children were not screened for hearing, nonverbal intelligence, or pervasive developmental disorder, the exclusionary criteria for SLI.

A language screening test was developed that had a very high predictive relationship with the diagnostic outcome. The screening tool consisted of 40 items from the "Test of Language Development-2:Primary" (Newcomer & Hammill, 1988). This screening instrument was administered to each child individually and took approximately 10 minutes to complete.

Screening Data Coding
All data were entered directly onto computerized scan forms by the examiner during the screening. The University of Iowa Testing Services department then scanned these forms and transferred the data onto computer disk for analysis. See Chapter IV for the procedures used to assign the screening outcomes of pass or fail.

Diagnostic Phase: Diagnostic Battery
The goal of the diagnostic testing phase was to identify those children who would serve as SLI cases or control subjects. The diagnostic battery included hearing, language, speech, cognitive, and pre-reading tasks, and gross motor observations. Because the examiners who had conducted the screening also administered the diagnostic tests, the children had become familiar with the examiners. Thus, introductory warm-up sessions were unnecessary. Testing was administered in a standardized manner. All children participated individually, and diagnostic testing took approximately 2 hours to complete. The diagnostic battery was completely administered during one testing session; when this was not possible due to scheduling reasons, the testing was completed within a week of its initiation. However, individual tests, such as the TOLD-2:P and WPPSI, were always administered in their entirety during a single session. The order of administration of the diagnostic tests was held constant when possible. Within individual tests, the same presentation order of subtests was maintained across examiners. The examiners provided written comments regarding the testing situation and impressions of the child's performance to supplement the objective measures.

The measures included in the diagnostic battery follow, along with a general discussion of the testing procedures.

Audiometric Testing
Because a hearing loss was an exclusionary criterion for the diagnosis of SLI, audiometric testing was performed. The purpose of the audiometric testing was to determine if the child had a persistent hearing loss that was suggestive of sensori-neural or conductive origins. Therefore, both pure tone audiometric screenings and acoustic omittance/impedance audiometry were conducted.

Pure tone screening was conducted for 500, 1, 2, and 4 kHz at 20 dB (American Speech-Language-Hearing Association, 1985). If the child failed the pure tone screening in an ear, pure tone thresholds were obtained and a visual inspection of the ear canal was done. Tympanometry was then done with four measures taken: Static Admittance (y A passing range was .22 to .81); Ear Canal Volume (Vea passing range was .42 to .97); Tympanometric Width (Gradient passing range was 59 to 151); and Tympanometric Peak Pressure (TPP passing range was -139 to + 11). If anyone of the four measures was failed in an ear, the child was considered to have failed the tympanometry testing for that ear.

If a child failed the pure tone screening bilaterally, no further procedures were done at that time, and the child was retested, usually after a period of two weeks. If the child failed the pure tone screening unilaterally, the diagnostic testing was continued at that time.

For the children who failed the pure tone testing unilaterally or bilaterally at the first screening, a letter was sent to the parents/guardians to notify them of the potential hearing problem and to suggest the appropriate audiologic or medical follow-up as based on the results of tympanometry (see Follow-up Procedures). If the child failed the second screening bilaterally, that child was disqualified from further testing. Regardless of whether the child failed the second screening unilaterally or bilaterally, a second follow-up letter was sent to the parents to notify them of the audiometric testing results.

Cognitive Testing
Because nonverbal cognitive ability was an exclusionary criterion for the diagnosis of SLl, nonverbal cognitive testing was performed. The Block Design and Picture Completion subtests of the "Wechsler Preschool and Primary Scale of Intelligence-Revised" (WPPSI; Wechsler, 1989) were administered. These subtests were chosen for two reasons: 1) of all the WPPSl performance subtests, these two were reported to be most highly correlated with full performance scale score (Block Design I = .59, Picture Completion I = .60), and 2) they afford an objective scoring method. These two performance subtests have been reported in the literature as a short form of the WPPSI Performance scale (LoBello, 1991). Further, these are easily administered and scored, and provide important criteria to assure inter-examiner reliability across the multiple field examiners.

The scaled score for each subtest was reported. The two scaled scores were summed, and a score of 16 or greater was selected for passing decisions. This summed score reflects a performance intelligence score greater than 85.

Diagnostic Language Testing
Language testing was conducted to identify the SLI cases and control subjects. Subtests of the "Test of Language Development-2:P" (TOLD-2:P; Newcomer & Hammill, 1988) was supplemented with a narrative story task (Culatta, Page, & Ellis, 1983). These tests were selected because they assessed multiple aspects of comprehension and production, and provided normative data that allowed the calculation of standard scores.

Further, these language measures were easily administered, and enabled development of scoring guidelines for reliable scoring across the multiple field examiners. The 5 TOLD-2:P subtests that were administered were Picture Vocabulary (PV), Oral Vocabulary (OV), Grammatic Understanding (GU), Sentence Imitation (SI), and Grammatic Completion (GC). The Word Articulation (W A) subtest was administered, however these results did not contribute to the language diagnosis. The subtests of the TOLD-2:P were administered according to the manual. Detailed scoring guidelines were developed to assure consistency within and across examiners during the field testing. Raw scores for each subtest were converted to standard scores based upon local norms.

Narrative Story Task
The Narrative Story task involved the retelling and comprehension of a short story about a birthday party. The examiner would read the story, and then ask the child to retell it. A maximum of three general recall were provided if the child needed prompting. The reported score was number of story events mentioned out of a possible 21.

The number-of-events-retold score was supplemented by the examiner's rating of the child's completeness and organization of recall. Completeness of recall was rated on the basis of whether or not all major components of the story were included in the retelling. To be considered complete, the child needed to include (1) Setting and problem (it was the boy's birthday, he wanted a puppy, his mom said "no"); (2) Complicating problem (the boy had a party and received presents, but did not get a puppy); and (3) Resolution (the boy was surprised and he got a puppy).

The organization of recall was rated on the basis of whether or not the main components of the story were retold in the correct sequential order, regardless of whether or not it was complete. Examiners rated organization of recall with a "yes" or "no." If the child retold no events or only one event, the organization of recall rating was scored "not applicable."

Following the child's retelling of the story, the examiner asked the child 10 questions to measure comprehension and memory of the story. The score reported was the total number of questions correctly answered out of a possible 10. The raw scores obtained for events mentioned during the retelling and for the comprehension questions were standardized.

Reading/Reading Readiness Tasks
Reading Readiness was a variable of interest for the risk factor study. However, rather than probe the parents about Reading Readiness (such as asking about reading in the home and the child's exposure to reading), measure was obtained. The Letter Identification subtest of the "Woodcock Reading Mastery Tests-Revised" (Woodcock, 1987), the "Word-Sound Deletion Task" (Catts, 1991), and the "Random Animals-Colors Task" (Catts, 1991) were used to measure pre-reading skills.

Letter Identification
The Letter Identification subtest is a measure of Reading Readiness. This test measures the child's ability to identify verbally letters written in several forms and scripts (such as upper or lowercase; roman, italic, and bold types; cursive and printed characters). Administration and scoring of this subtest was in accordance with the manual.

Normative data for each month of the academic year are provided in the manual so that scores obtained from children who are tested later in the year are adjusted to control for learning that has occurred during the year. As specified by the manual, raw scores were first converted into a "W" score. A difference score was then calculated by subtracting from the W score a reference value based on the month that the child was tested. The difference score was then converted into a standard score, which is the reported score.

Reliability information for the Letter Identification subtest shows that the split-half reliability coefficient for Grade 1 is of r= .94. The standard error of measure for the W scores as reported in the manual for 1st grade scores is 4 W scale units.

Word-Sound Deletion
The Word-Sound Deletion task (Catts, 1991) is a sound segmentation, phonological awareness task. In this task, the child was required to delete the initial phoneme or syllable from a word and repeat only the remaining phoneme or syllable. Three example items, all compound words, were demonstrated using pictures. For example, the directions were "Say 'baseball"' as pictures of "base" and "ball" were shown. Then, with the first picture covered, the child was asked "Now say 'baseball' without the 'base'." If the child did not respond correctly, the correct answer was provided for the demonstration items.

When the child showed an understanding of the task, the testing began. The directions were the same for each of the 21 test items, however, the pictured stimuli were discontinued. The stimuli consisted of compound words, two syllable words, and monosyllabic words. The sound sequence remaining as the correct response was always a high frequency word. One repetition of an item was provided if needed, and testing was discontinued when 6 consecutive items were incorrectly answered. The reported score was the raw score, and the maximum raw score was 21.

Random Animal-Colors
The Random Animal-Colors task measured rapid naming ability, a skill which has been reported to be a measure of phonetic coding ability (Catts, 1991). The Random Animal-Colors task involved showing the child an 11.5" x 17.5" page that contained images of 24 animals. These 24 animals were 1 of 3 randomly selected animals (a pig, a horse, and a cow) that were colored in 1 of 3 randomly selected colors (blue, red, or black). These colored animals were arranged in random order in 4 rows of 6 items each. The child was first given as much practice as needed to identify the animals and colors, and several demonstration items were provided to allow the child to practice responding with "adj+noun" responses. If the child did not know his/her colors or animals, this task was not administered. The examiner instructed the child to "name these as fast as you can" in sequential order.

The reported score for this task was the total time required for the child to name all of the colored animals, measured with a stopwatch. Thus, a lower total time score reflects better performance. A tally of incorrect responses was kept for this task.

The Word-Sound Deletion and Random Animals-Colors tasks were reported by Catts (1991) to be the best combination of predictors of reading group membership for a group of kindergartners that was comprised of 41 SLI and 30 control subjects. Catts reported that these tasks together enabled them correctly to classify 82.9% of the children in their study.

Iowa Severity Rating Scale
The Iowa Severity Rating Scale (ISRS; Jeffrey & Freilinger, 1986) was developed for use by speech-language pathologists working in the Iowa Public School system. The purpose of the ISRS measure in this study was to supplement the standardized measures of speech and language with a clinically significant measure, and to obtain an informal measure of voice and fluency.

The ISRS is a 5-point severity rating scale of speech, language, voice and fluency skills. The ratings are on a continuum, where 0 indicates adequate skills and 4 indicates a disorder. There are specified published criteria to guide the rating made by the speech-language pathologist, and these guidelines were used during this study (Jeffrey & Freilinger, 1986). Minimal additional guidelines were established for use during the Field Study because the examiners' subjective impressions were desired. Four guidelines were used:

(1) Articulation: The Word Articulation subtest of the TOLD-2:P was supplemented by the ISRS Articulation rating made by the examiner. A rating of "1" indicated developmental s, r, l problems. Because certain phonemes (initial k, m, v, n) are not sampled by the Word Articulation subtest, there was in some cases a discrepancy between the WA results and articulation severity rating.

(2) Language: The language severity rating was determined by the speech-language pathologist based on observation of the child in informal interactions as well as during the standardized language testing. In some cases, the TOLD-2:P raw scores were converted to standard scores by the examiners, and this information was considered when making the severity rating for language, as specified by the ISRS manual. If the examiner did not have sufficient information to make a language severity rating, a language sample was elicited. For children with low performance scores on the WPPSI, the language severity rating was made commensurate with cognitive ability.

(3) Voice: The only guidelines provided to supplement the manual were that mild hypernasality was rated as a "2," and moderate hypernasality was rated as a "3."

(4) Fluency: Ratings were made in accordance with the ISRS manual for fluency.

Motor skills
Two gross measures of motor skills were obtained: gait, and handedness. The examiner observed the child walking to the examining room, and noted if there were any obvious gross motor problems when walking. The child was also asked to write her/his name, and the examiner made note of which hand the child used.

Diagnostic Data Entry and Diagnosis
The diagnostic data were coded using a data entry program. To minimize coding errors, the data were entered using a two-pass method. Data were first entered and then verified during a second entry of these same data. Thus, data were entered at two different times and usually by two different people. The data entry program also had range checking for data having a minimum low and maximum high value.

Diagnostic outcomes were determined based on language performance as well as hearing and nonverbal cognitive performance. Based on the diagnostic results, the children were assigned to one of five diagnostic categories: (1) specific language impaired (SLI; failed language testing but passed hearing and nonverbal cognitive testing); (2) control (C; passed all language, hearing, and nonverbal cognitive testing); (3) language impaired (LI; failed the language testing and nonverbal cognitive testing, but passed hearing testing); (4) cognitive failure (CF; pass language and hearing testing, but failed nonverbal cognitive testing); and (5) hearing failure (HF; failed both hearing screenings and did not continue for further testing).

RISK FACTOR SURVEY
Development of the Risk Factor Survey
A major research question in this study was concerned with identifying risk factors for SLI. In order to address this question, information was obtained from the parents of SLI children and non-SLI controls regarding a wide range of exposures to potential risk factors. This information was obtained through a telephone survey that lasted approximately 50 minutes.

The candidate risk factors were selected after a literature review of risk factors and language impairment. A pilot survey was developed to obtain information regarding these risk factors, and was administered to 6 parents. Several modifications were made based on the pilot. A data coding manual for the final Risk Factor Survey is contained in Appendix I. The general categories of risk factors selected for this study are:

1. Parent exposure, prior to the study child's birth, to:
a. toxins
b. drugs
c. infectious diseases
d. alcohol and tobacco
e. autoimmune diseases and allergies
f. communication and learning problems
g. psychological & psychiatric disorders

2. Mother's pregnancy and delivery of the study child:
a. Mother's health during pregnancy and medical treatments
b. Term of pregnancy
c. Number of pregnancies prior to study child's birth
d. General nature of delivery

3. The study child's health & development
a. Autoimmune diseases and allergies
b. Otitis media
c. Speech/language/learning problems

4. Factors associated with the study child's rearing environment
a. Occupational and educational background of parents
b. Family income
c. Number of adults serving as parents in home during child's life
d. Presence of routine activities involving language interactions with the study child
e. Number of siblings and their spacing
f. Study child's attendance in day-care and preschool programs.

Risk Factor Survey Administration
The names of the parents who were to receive the Risk Factor Survey were sent from the lab at the University of Iowa to the Statistical Laboratory at Iowa State University (ISU), a subcontractor on this contract. The lab at the University of Iowa contacted these parents by letter to notify them that they had been selected to receive the Risk Factor Survey. The lab sent a list of chemicals for the parents' reference during the telephone call. Trained professional interviewers at the ISU Statistical Laboratory then called the parents to arrange a mutually convenient time to administer the survey. The interviewer usually administered the survey during one call. The parents almost always received the telephone survey prior to receiving any information regarding the outcome of their child.

A supplementary information booklet was developed to aid the telephone interviewers and to assure standardized administration of the survey. This booklet explained terms used in the survey, as well as general instructions for the interviewer, on a question-by-question basis. All interviewers were blind regarding the diagnostic outcome of the study child.

Once your application form has been received and approved, a CD with the full data set and instructions for its useage will be mailed to you

2. to protect the confidentiality of the study subjects by making no efforts to discover their identities (and to further ensure their privacy, we encourage presentation of only aggregate forms of data);

3. to acknowledge in any publication, poster or other presentation the original data sources as follows:

"Acknowledgement is given to original grant #N01-DC-1-2107 and supplement #3 P50 DC002746-08S1 from the National Institute on Deafness and Other Communication Disorders, a division of the National Institutes of Health";

4. to supply the CLRC with a copy of any publication produced from the data set as follows:

CLRC Epidemiologic Study
3 Wendell Johnson Speech & Hearing Center
The University of Iowa
Iowa City IA 52242

5. to take responsibility for the above conditions on behalf of his or her students if the requestor uses the data for teaching purposes.

(Submit the following information to Dr. J. Bruce Tomblin via Email: j-tomblin@uiowa.edu: Title, First name, Last name, Department, Institution, Institution Address, (if no institutional affiliation, use home address), Country, Zip or postal code, Telephone, Fax, Email. Type of user, and a brief description of how you plan to use these data).

Remember: by submitting this request, you agree to the fair use conditions as previously described.

Statistics tutorials
Accuracy in reporting prevalence of child language impairments

SLI prevalence exercise: Specific Language Impairment is diagnosed by scores on several tests. Virtually discover how varying criteria changes the SLI incidence rate. (Note: this link takes you to a new browser window. Flash 5.0 is required to make the animation work.)

Weighting methodology: While nearly 7,000 kindergarteners were originally screened for SLI, a smaller subset continues to be tested periodically for language development. Because the children with SLI are of most interest to researchers, this group is over-sampled. This exercise gives a step-by-step explanation of how mathematical weighting can be used to extrapolate findings to state the prevalence of SLI among all children. (Note: this link takes you to a new browser window.)

Regression to the mean: Studying an asymmetrical sample (in this case, children identified with SLI based on low test scores of language ability) over time has an inherent tendency to produce erroneous results. Step-by-step text and animations demonstrate how these errors can occur and what’s needed to produce accurate results. (Note: this link takes you to a new browser window. Flash 5.0 is required to make the animation work.)

Published articles
Hammer, C.S., Tomblin, J.B., Zhang, X. and Weiss, A. (2001). The relationship between parenting behaviors, demographic factors, and specific language impairment in children. International Journal of Language Communication Disorders 36(2), 185-205.

Lubbker, B., & Tomblin, J. B. (1998). The epidemiology of language disorders, Topics in Language Disorders, 19, 1-26.

Records, N.L., Tomblin, J.B. and Freese, P. (1992). Quality of life in adults with histories of specific language impairment. American Journal of Speech-Language Pathology, 1, 44-53.

Scheffner, Hammer, C. Pennock-Roman, M., Rzasa, S., & Tomblin, J. B. (2002). An analysis of the Test of Language Development-Primary for item bias. American Journal of Speech-Language Pathology, 11, 274-284.

Shriberg, L.D., Tomblin, J.B. and McSweeny, J.L. (1999). Prevalence of speech delay in 6-year-old children and comorbidity with language impairment. Journal of Speech, Language, and Hearing Research, 42, 1461-1481.

Tomblin, J. B., & Pandich, J. (1999). What can we learn from children with exceptional language development? Lessons from children with specific language impairment. Trends in Cognitive Science 3,283-285.

Tomblin, J. B. & Zhang, X. (1999). Are children with SLI a unique group of language learners? In H.Tager-Flusberg (Ed.), Neurodevelopmental Disorders: Contributions to a New Framework from the Cognitive Neurosciences.

Tomblin, J. B., Records, N. L., Buckwalter, P., Zhang, X., Smith, E., & O'Brien, M. (1997). The prevalence of specific language impairment in kindergarten children. Journal of Speech Language Hearing Research, 40, 1245-1260.

Tomblin, J. B., Smith, E., & Zhang, X. (1997). Epidemiology of specific language impairment: Prenatal and perinatal risk factors. Journal of Communication Disorders, 30, 325-344.

Tomblin, J. B., Records, N., & Zhang, X. (1996). A system for the diagnosis of specific language impairment in kindergarten children. Journal of Speech and Hearing Research, 39,1284-1294.

Tomblin, J. B. (1996). Epidemiological patterns of specific language impairment. In M. Gopnik (Ed.), Biological Basis of Language. London: Oxford University Press.

Zhang, X., & Tomblin, J. B. (1999). Can children with language impairment be accurately identified using temporal processing measures? A simulation study. Brain and Language, 65, 395-403.

Hewitt, L., Hammer, C., Yont, K., Tomblin, J. B., Cogburn, A. (2001). Language sample analysis measures for children with SLI in first grade. Poster presented at the 22nd Annual Symposium on Research in Child Language Disorders, Madison, WI.

Pandich, J.and Tomblin, J.B. (1999). Educational and Occupational Outcomes of Adults with Learning Disabilities. Presented at the Symposium on Research in Child Language Disorders, Madison, WI.

Records, N.L., Smith, E.M., and Tomblin, J.B. (1994). Preliminary Report: Risk Factors of SLI, Presented at the Annual Convention of the American Speech-Language-Hearing Association, New Orleans, LA.

Shriberg, L.D. and Tomblin, J.B. (1999). Prevalence of speech delay and comorbidity with language impairment. Poster presented at the Third International Symposium on Speech and Language Impairments From Theory to Practice, York, United Kingdom.

Shriberg, L.D. and Tomblin, J.B. (1999). Prevalence of Speech Delay and Comorbidity with Language Impairment. Presented at the AFASIC Third International Symposium, University of York, United Kingdom.

Shriberg, L.D. (1999). Emerging profiles for five phonological disorders. Paper presented at the Annual Child Phonology Conference, Bangor, Wales.

Shriberg, L.D. (1999). Epidemiologic and diagnostic profiles for five developmental phonological disorders. Paper presented at the Annual Convention of the American Speech Language Hearing Association, San Francisco, CA.

Smith, E., Zhang, X., Records, N., J. Tomblin, P. Buckwalter and O'Brien, M. (1999). SLI in Kindergarten Children: Prevalence and Risk Factors. Presentation at the Annual Convention of the American Speech-Language-Hearing Association, Seattle, Washington.

Tomblin, J. B. (2001). An Epidemologic Perspective of Childhood Apraxia of Speech. Invited talk at the 2002 Symposium on Childhood Apraxia of Speech. Scottsdale, AZ.

Tomblin, J.B. (1999). Epidemiology and familial transmission of specific language impairment. Paper presented at the Annual Meeting of the American Association for the Advancement of Science, Anaheim, CA.

Tomblin, J.B., Shriberg, L. and McSweeny, J. (1998). Prevalence of Speech Delay in Kindergarten-Age Children. Paper presented at the Annual Convention of the American Speech-Language-Hearing Association, San Antonio, TX.

Tomblin, J.B., Zhang, X., and Catts, H. (1998). The Place of Nonverbal Intelligence in Diagnosis of SLI. Presentation at the Annual Convention of the American Speech-Language-Hearing Association, San Antonio, TX.

Tomblin, J.B. and Zhang, X. (1998). The Place of Nonverbal Intelligence in the Diagnosis of SLI. Presented at the Annual Convention of the American Speech-Language-Hearing Association, San Antonio, TX.

Tomblin, J.B. (1998). Issues Concerned with Economic and Social Realities of Communication Disorders and Differences. Invited paper presented at the NIDCD Conference on the Social and Economic Realities of Communication Disorders and Differences, Bethesda, MD.

Tomblin, J.B. (1996). The Big Picture of SLI: Epidemiology of SLI. Invited paper presented at the Symposium on Research in Child Language Disorders.

Tomblin, J.B., N.L. Records and Zhang, X. (1994). Subtype Profiles of Specific Language Disorders. Presented at the Annual Convention of the American Speech-Language-Hearing Association, New Orleans, LA.

Zhang, X., Tomblin, J.B. and Records, N. (1994). Path Analysis of Risk Factors of SLI. Paper presented at the Symposium on Research in Child Language Disorders.

Longitudinal study of children with SLI
This current study follows the children identified as having SLI as kindergartners, along with a control group, to determine long-term language outcomes and patterns of language growth through age 16.

Abstract
The Collaboration on Specific Language Impairment (previously called "Midwest Collaboration on Specific Language Impairment") is a consortium of institutions focusing on SLI. It focuses on issues dealing with the diagnosis, etiology, and outcomes of children with developmental language impairment, particularly Specific Language Impairment (SLI). SLI is a developmental language impairment that is not associated with developmental disorders such as mental retardation or autism or sensory disorders such as deafness. Although these difficulties are most apparent during the pre-school and early school years, evidence suggests that these problems can persists well into adult life. Impairments in reading and writing often are associated with SLI and individuals with this problem often have life long academic and occupational difficulties.

Projects are underway to continue cross sectional and longitudinal studies of children with and without language impairment: causes, course and outcomes of language impairment from elementary through high school. Collectively, these issues center on when we should consider a child to have language impairment and why. One project addresses questions concerning the course of language impairment in children, determining long-term language outcomes and patterns of language growth, using the same participants from ages 5 through 16. We intend also to identify predictors of individual differences in these language growth patterns. A second project examines the relationship between information processing, speed and capacity, and language status. A key question in this project probes the extent to which individual differences in language performance are associated with general cognitive mechanisms specific to language. A third project examines reading disorder (RD) and the relationship of RD to spoken language impairment. This project emphasizes the study of RD in children with and without language impairment. It attends especially to the role of processing capacity on reading and listening components.

Principal investigator: J. Bruce Tomblin, Ph.D.

Funding source: National Institute on Deafness and Other Communication Disorders #1-P50-DC02746/2-P50-DC02746

Funding dates: July 1995 to June 2000/August 2001 to July 2006

Description of work
Our objective within this longitudinal study has been to advance our understanding of the nature of spoken language impairment in general, with a particular emphasis on Specific Language Impairment (SLI). This research has been concerned with three related issues.

Individual Differences in Language Acquisition
The first domain begins with the obvious: Children differ with respect to their capacity to acquire language. Thus, there are individual differences among children in the rate, and possibly the kind of language acquisition. This research program examines these individual differences in language acquisition across development. Therefore, we will be able to measure individual differences in growth rates and patterns of growth across several domains of spoken and written language.

Individual differences are necessary conditions for any notion of abnormal function; however, we contend that individual differences by themselves do not constitute impairment. Furthermore, the nature of the individual differences - whether they are qualitative or quantitative differences are often assumed to provide evidence of disease. However, eye color and blood types are qualitative forms of individual differences that are not construed to be disease. In order for some form of individual differences to be viewed as an impairment it is necessary for these differences to impact negatively on the person's life.

Social/Functional Costs
If we are to claim that children with certain language skills present language impairment it is necessary for us to show that there are negative outcomes associated with these language skills. Thus, a second domain of the proposed research recognizes that language enables individuals in our society to meet many of the demands society places upon them. Failure to meet these demands, due to limitations in language proficiency leads to undesirable outcomes in life function. One of the most prominent impairments is reading. We are continuing to examine this relationship between spoken and written language. In so doing, we hope to provide better explanations regarding the contributions of spoken language to reading disorders, and furthermore, to provide a means to evaluate diagnostic standards for spoken language disorder.

Causation
The third domain of our research recognizes a need to examine prominent theories concerned with the causes of those individual differences that comprise language impairment. We recognize that the etiology of language impairment is likely complex and varied. Thus, the adequacy of explanatory accounts of SLI may be influenced by the manner in which the diagnosis is made and thus there may be subtypes of SLI that can be revealed when important causal factors are examined in association with different clinical manifestations including differential patterns of growth. Within the research proposed are several studies designed to examine prominent theoretical explanations of SLI that derive from cognitive psychology. These theoretical accounts of SLI predict that the language deficits of these children can be found in limitations in general purpose cognitive systems that are particularly crucial, but not unique to language development. These systems concern limited capacities in memory and attention and/or speed of information processing. An alternate account of SLI has been that these language problems are rooted in language specific cognitive systems.

Our research program is also providing important insights into the role of language as a causal agent for reading impairment and also the effect of reading on later spoken language. Thus, within the limits of an observational design, we will be examining the relationship between spoken language and reading as potential reciprocal determinants. The direction of this influence is likely to shift across development such that spoken language at school entry may affect later reading development.

Longitudinal Study Description
Cohort Characteristics. The longitudinal cohort that has provided the participants for this research was obtained from a large sample of kindergarten-age children who participated in a cross-sectional epidemiologic study of SLI. A description of the sampling methods for the original cross-sectional sample can be found in Tomblin, et al. (1997) and the methods for selection of the longitudinal sample is provided in Tomblin, Zhang, & Buckwalter (2000). The members of this cohort, who initially consisted of 604 children, had been diagnosed with respect to language impairment when they were in kindergarten. These children were then re-evaluated two, four, eight and now ten years after kindergarten. Figure 1 provides sample size, age and the years in which these children participated at each observation. This figure shows that the observation interval covered a two-year time span. This is due to the fact that the participants were initially sampled over a two-year time period thus at any time, the total cohort covers a two-year age range. This allows us to distribute the burden of data collection for any interval over a two-year time period.

(Figure: Ages and calendar years when cohort members were observed. Values at each observation year represent number of children in the two cohorts.)

The last complete data set was obtained at Year Eight and thus we do not have summary data for Year Ten at this time.

Measures Obtained During First 10 Years. During the course of this longitudinal study the members of this cohort have been systematically observed in order to document their listening, speaking, reading, and writing development. Additionally, we have obtained information from parents and teachers concerning their academic, behavioral, mental and physical health. During the current year we are also obtaining self-report information. The data we have gathered characterize the development of our cohort children between kindergarten and 10th grade. This database is substantial, containing over 2,215 variables. In addition to data that pertains to the children in the cohort, the parents have provided data concerning themselves, their rearing practices, and certain home characteristics. The teachers have also provided data concerning the nature of the classroom and curriculum.

Published articles
Catts, H., Gillispie, M., Leonard, L., Kail, R., & Miller, C. (in press). The role of speed of processing, rapid naming, and phonological awareness in reading achievement. Journal of Learning Disabilities.

Catts, H.W., Hogan, T.P., & Fey, M. (in press). Subgrouping poor readers on the basis of reading-related abilities. Journal of Learning Disabilities.

Catts, H.W., Fey, M.E., Tomblin, J.B., & Zhang, Z. (in press). A longitudinal investigation of reading outcomes in children with language impairments. Journal of Speech, Language, and Hearing Research.

Catts, H.W., Fey, ME, Zhang, X., & Tomblin, J.B. (2001). Estimating risk for future reading difficulties in kindergarten children: A research-based model and its clinical implications. Language, Speech, and Hearing Services in Schools. 32(1), 38-50.

Catts, H., Fey, ME, & Proctor-Williams, K. (2000). The relationship between language and reading: Preliminary results from a longitudinal investigation. Logopedics, Phoniatrics, Vocology.

Catts, H. & Kamhi, A. (1999). Classifying reading disabilities. In H. Catts & A. Kamhi (Eds.). Language and Reading Disabilities. Needham Heights, MA: Allyn & Bacon.

Catts, H. & Kamhi, A. (1999). Defining reading disabilities. In H. Catts & A. Kamhi (Eds.). Language and Reading Disabilities. Needham Heights, MA: Allyn & Bacon.

Catts, H. & Kamhi, H. (1999) (Eds.). Language and reading disabilities. Needham Heights, MA: Allyn & Bacon.

Catts, H., Fey, M., Tomblin, J. B., & Zhang, X. (1999). Language basis of reading and reading disabilities: Evidence from a longitudinal investigation. Journal of Scientific Study of Reading, 3, 331-361.

Catts, H. (1997). Early identification of reading disabilities. Language, Speech, and Hearing Services in Schools, 28, 86-89.

Ellis Weismer, S., Plante, E., Jones, M., & Tomblin, J.B. (In review). A functional resonance imaging investigation of verbal working memory in adolescents with specific language impairment. Manuscript submitted for publication.

Ellis Weismer, S. (2004). Memory and processing capacity. In R. Kent (Ed.), MIT Encyclopedia of Communication Disorders . Boston: MIT Press.

Ellis Weismer, S., & Thordardottir, E.T. (2002). Cognition and language. In P. Accardo, A. Capute, & B. Rogers (Eds.), Disorders of Language Development (pp. 21-37). Timonium, MD: York Press, Inc.

Ellis Weismer, S., Tomblin, J.B., Zhang, X., Buckwalter, P., Chynoweth, J. G. & Jones, M. (2000). Nonword repetition performance in school-age children with and without language impairment. Journal of Speech, Language, and Hearing Research, 43, 865-878.

Ellis Weismer, S. (2000). Language intervention for children with developmental language delay. In D. Bishop & L. Leonard (Eds.), Speech and language impairments: From theory to practice, 157-176. Psychology Press.

Ellis Weismer, S., Evans, J., & Hesketh, L.J. (1999). An examination of verbal working memory capacity in children with specific language impairment. Journal of Speech, Language, and Hearing Research, 42, 1249-1260.

Kamhi, A. & Catts, H. (in press). The language basis of reading: Implications of classification and treatment of children with reading disabilities. In Bulter, K.&Silliman, E. (Eds.) Speaking, Reading, and Writing in Children with Language and Learning Disabilities: New Paradigms in Research and Practice.

Larrivee, L. & Catts, H. (1999). Word recognition problems in children with expressive phonological disorders. American Journal of Speech-Language Pathology.

Miller, C.A., Kail, R., Leonard, L.B., & Tomblin, J.B. (2001). Speed of processing in children with specific language impairment. Journal of Speech, Language, and Hearing Research, 44(2), 416-433.

Rice, M.L. (in press). A unified model of specific and general language delay: Grammatical tense as a clinical marker of unexpected variation. To appear in Y. Levy & J. Schaeffer (Eds.), Language competence across populations: Toward a definition of SLI. Mahwah, NJ: Lawrence Erlbaum.

Tomblin, J. B., Zhang, X., Buckwalter, P., & O’Brien, M. (2003). The stability of primary language disorder: four years after kindergarten diagnosis. Journal of Speech, Language, and Hearing Research, 46, 1283-1296.

Tomblin, J. B., Hafeman, L. L., & O' Brien, M., (2003). Autism and autistic behaviors in siblings of children with language impairment. International Journal of Language and Communication Disorders. 38 , 235-250.

Tomblin, J.B., Zhang, X., Weiss, A., Catts, H., Ellis Weismer, S. (2004). Dimensions of individual differences in communication skills among primary grade children. In M.L. Rice and S.F. Warren (Eds.), Developmental Language Disorders: From Phenotypes to Etiologies. Lawrence Erlbaum Associates, NJ: Mahwah.

Tomblin, J. B., Zhang, X., Buckwalter, P. and Catts, H. (2000). The association of reading disability, behavioral disorders and Language Impairment among second grade children, Journal of Child Psychology and Psychiatry 41(4), 473-482.

Tomblin, J. B., Hammer, C., & Zhang, X. (1998). The association of parental tobacco use and specific language impairment. International Journal of Language and Communication Disorders, 33, 357-368.

Zhang, X. and Tomblin, J.B., (2000). The Association of Intervention Receipt with Speech-Language Profiles and Social Demographic Variables. American Journal of Speech-Language Pathology, 9(4), 345-357.

Posters
Betz, S.K., Rice, M.L., Tomblin, J.B., & Chen, S. (2002). Grammatical reconstructions and tense errors made by children with SLI during imitation tasks. Poster presented at IX International Congress for the Study of Child Language and the Symposium on Research in Child Language Disorders, Madison, WI.

Betz, S.K., Rice, M.L., Tomblin, J.B., & Chen, S.D. (2001). Tense errors made by children with SLI during imitation tasks. Poster presented at the American Speech-Language-Hearing Association convention, New Orleans, LA.

Catts, H. & Hogan, T. (2002). At what grades should we assess phonological awareness? Poster presented at the Annual Convention of the American Speech-Language-Hearing Association, Atlanta, GA.

Catts, H. & Hogan, T. (2002). The fourth grade slump: Late emerging poor readers. Poster presented at the annual conference of the Society for the Scientific Study of Reading, Chicago IL.

Catts, H. & Gillispie, M. (2001). The role of speed of processing, rapid naming, and phonological awareness in reading achievement. Poster presented at the annual conference of the Society for the Scientific Study of Reading, Boulder, CO.

Catts, H., Fey, M., Tomblin, J.B., & Zhang, X. (2001) Fourth grade reading outcomes in kindergarten children with language impairments. Poster presented at the annual conference of the Society for Research in Child Language Disorders. Madison, WI.

Catts, H. and Gillispie, M. (2000). Are poor readers just slow? Poster presented at the Society for the Scientific Study of Reading, Stockholm, Sweden.

Catts, H., Fey, M.E., Zhang, X., and Tomblin, J.B. (2000). Generalized vs. specific slowing in poor readers. Poster presented at the Symposium on Research in Child Language Disorders, Madison, WI.

Catts, H. Fey, M.E., Zhang, X., and Tomblin, J.B. (2000). Estimating risk for reading difficulties in kindergarten children. Poster presented at the Symposium on Research in Child Language Disorders, Madison, WI.

Catts, H., Fey, M., Tomblin, J.B., and Zhang, X. (1999). Reading Outcomes in children with language impairments. Poster presented at the annual conference of American Speech-Language-hearing Association, San Francisco, CA.

Catts, H., Fey, M., Zhang, X., and Tomblin, J.B. (1998). The Relationship Between Language Abilities and Reading Achievement. Poster presented at the Annual Convention of the American Speech-Language-Hearing Association, San Antonio, TX.

Catts, H., Fey, M.E., and Tomblin, J.B. (1997). Semantic-Syntactic Deficits in Poor Readers. Poster presented at the Annual Convention of the American Speech-Language-Hearing Association, Boston, MA.
Ellis Weismer, S. and Thordardottir, E. (1999, April). Verbal Working Memory Abilities of School-Age Children with and without Language Impairment. Poster presented at the biennial meeting of the Society for Research in Child Development, Albuquerque, New Mexico.

Ellis Weismer, S., Tomblin, J.B., Zhang, X., Gaura, J., Buckwalter, P., and Jones, M. (1999). Nonword Repetition Performance in Second Graders with and without Language Impairment. Presented at the Symposium on Research in Child Language Disorders, Madison, WI.

Fey, M.E., Catts, H., and Proctor-Williams, K. (2000). Narrative generation by school-age children with typical & impaired language. Poster presented at annual conference of the American Speech-Language-Hearing Association, Washington, DC.

Kail, R.V. and Miller, C.A., (2003). Developmental stability in speed of information processing. Poster presented at the biennial meeting of the Cognitive Development Society, Park City, UT.

Kail, R.V. and Miller, C.A. (2003). Developmental change in speed of processing: Longitudinal data. Poster presented at the annual meeting of the Midwestern Psychological Association, Chicago, IL.

Miller, C.A., Leonard, L.B., and Kail, R.V. (2003). A longitudinal study of response time in children with and without language impairment. Poster presented at the biennial meeting of the Society for Research in Child Development, Tampa, FL.

Miller, C., Tomblin, J. B., Zhang, X., Kail, R., Leonard, L. (2001). Speed of processing as a predictor of language performance. Poster presented at the annual convention of the American Speech-Language-Hearing Association, New Orleans, LA.

Miller, C., Kail, R., and Leonard, L. (1998). Speed of Processing and Specific Language Impairment. Presentation at the Symposium on Research in Child Language Disorders, University of Wisconsin-Madison.

Rice, M. and Tomblin, J.B. (1999). Child Indices of Language Impairment: Grammatical Tense Compared to Conventional Testing. Presented at the Symposium on Research in Child Language Disorders, Madison, WI.

Tomblin, J.B., Burroughs, E., and Buckwalter, P. (2000). Aspects of social behavior in children with SLI. Poster presented at the Annual Convention of the American Speech-Language-Hearing Association, Washington, DC.

Tomblin, J.B., Burroughs, E., and Zhang, X. (2000). Iowa Tests of Basic Skills Performance in 4th Graders with SLI. Poster presented at the Annual Convention of the American-Speech-Language-Hearing Association, Washington, DC.

Tomblin, J.B., Zhang, X., Buckwalter, P., and O'Brien, M. (1999). Measurement Error Creates Decrement of Performance IQ in Children with SLI. Presented at the Symposium on Research in Child Language Disorders, Madison, WI.

Presentations
Catts, H. & Fey, M. (2002, November). Causal and correlative links between spoken and written language difficulties in children. Paper presented at the annual conference of the American Speech- Language-Hearing Association, New Orleans.

Catts, H. & Fey, M. (2002, July). Reading outcomes of children with SLI vs. NLI. Paper presented in symposium at the joint conference of the Society for Research in Child Language Disorders and the International Congress for the Study of Child Language, Madison, WI.

Catts, H. (2001, October). Language impairments and reading disabilities. Presentation at the annual meeting of the International Dyslexia Association, Albuquerque, NM.

Catts, H., Fey, M. Zhang, X., Tomblin, J. B. (2001). The Association of fourth grade reading outcomes with patterns of earlier language growth in children with language impairment, Annual Symposium on Research in Child Language Disorders, Madison, WI.

Catts, H. (2000). Reading Disabilities: Back to the future. Keynote address at the 9th symposium on literacy and disabilities, Cary, NC.

Catts, H., Fey, M.E., Zhang, X., and Tomblin, J.B. (2000). Predicting reading disabilities in kindergarten children. Presented at the 21st Annual Symposium on Research in Child Language Disorders, Madison, WI.

Catts, H. (2000). Who are poor readers. Invited presentation as part of special research symposium at the annual conference of the International Dyslexia Association, Washington, DC.

Catts, H. (1999). Early identification of reading disabilities. Open presentation in the Department of Education, University of Iceland, Reykjavik, Iceland.

Catts, H. (1999). The relationship between language and reading. Paper presented at conference entitled "Beyond Phonological processing: Other language and cognitive processing deficits in dyslexia," Lund University, Lund, Sweden.

Catts, H. (1998). Language basis of reading disabilities. Evidence from a longitudinal study. Invited lecture presented at the conference on Early Cognition and Learning Disabilities. University of Jyvaskyla, Jyvaskyla, Finland.

Catts, H., Fey M., Zhang, X., and Tomblin, J.B. (1998). Subtypes of reading disabilities: an alternative to IQ-achievement discrepancy. Paper presented at the Annual Meeting of the Society for the Scientific Study of Reading, San Diego, CA.

Catts, H. (1998). Language basis of reading disabilities. Evidence from a longitudinal study. Invited lecture presented at the Conference on Early Cognition and learning Disabilities, University of Jyvaskyla, Jyvaskyla, Finland.

Catts, H., Fey, M., Tomblin, B., and Zhang, X. (1997). Language deficits in reading disabilities. Paper presented at the annual meeting of the Society for the Scientific Study of Reading, Chicago, IL.

Catts, H., Fey, M., Tomblin, J.B., and Zhang, X. (1997). Language deficits in reading disabilities. Paper presented at the annual meeting of the Society for the Scientific Study of Reading, Chicago, IL.

Ellis Weismer, S. (2004, March). How specific is specific language impairment?: Evidence for limitations in working memory capacity. Invited talk to the Department of Speech and Hearing Sciences, University of Iowa, Iowa City, IA.

Ellis Weismer, S., Plante, E., & Jones, M. (2003, February). Capacity limitations in children with SLI: An fMRI study. Poster presented at the International Neuropsychological Society, Honolulu, HI.

Ellis Weismer, S. (2002, October). Language processing and working memory in specific language impairment. Invited research colloquium presented to the Program in Audiology and Speech Sciences, University of British Columbia, Vancouver, CA.

Ellis Weismer, S. (2002, July). A functional MRI study of language processing and verbal working memory in adolescents with specific language impairment. Talk presented as part of the symposium on the Application of Neuroimaging in language research at the joint conference of the International Congress for the Study of Child Language and the Symposium on Research in Child Language Disorders, Madison, WI.

Ellis Weismer, S. (2002, July). Processing limitations in specific and nonspecific language impairment. Talk presented as part of the symposium on Language-Nonverbal IQ Discrepancies in Children with SLI at the joint conference of the International Congress for the Study of Child Language and the Symposium on Research in Child Language Disorders, Madison, WI.

Ellis Weismer, S. (2001). Cognition and language: Separate or equal? Invited talk, The Spectrum or Developmental Disabilities XXIII Disorders of Language Development, 23rd Annual Program, Johns Hopkins, Baltimore, MD.

Ellis Weismer, S. and Evans, J. (2000). Tutorial on specific language impairment. Invited presentation, Department of Psychology, University of Wisconsin-Madison.

Ellis Weismer, S. (2000, June). Processing capacity limitations in developmental language disorder. Invited presentation, School of Human Development, University of Texas, Dallas, TX.

Ellis Weismer, S. (2000, February). Processing capacity limitations in specific language impairment. Colloquium presentation, Department of Psychology, University of Wisconsin-Madison.

Ellis Weismer, S., Tomblin, J.B., Zhang, X., Guara, J., Buckwalter, P., & Jones, M. (1999, November). Deficits in nonword repetition by children with language impairment. Poster presented at the annual convention of the American Speech-Language-Hearing Association, San Francisco.

Ellis Weismer, S. (1999, June) Cognitive deficits: Do they matter? Invited panel discussant at the 20th annual Symposium on Research in Child Language Disorders, Madison, WI.

Ellis Weismer, S., and Thoraddottir, E.T. (1998). Limitations in Linguistic Processing by Children with Specific Language Impairment. Presentation at the Symposium on Research in Child Language Disorders, University of Wisconsin-Madison.

Ellis Weismer, S. and Thordardottir, E.T. (1998). Linguistic processing limitations in school-age children with specific language impairment. Poster presented at the annual convention of the American Speech-Language-Hearing Association, San Antonio, TX.

Ellis Weismer, S., Evans, J., and Hesketh, L. (1997). Verbal Working Memory in Specific Language Impairment. Presentation at the Symposium on Research in Child Language Disorders, University of Wisconsin-Madison.

Fey, M.E., Catts, H., and K. Proctor-Williams, K. (2000). Narrative generation by school-age children with typical and impaired language. Presented at the convention of the American Speech-Language-Hearing Association, Washington, DC.

Fey, M.E. (2000). Identifying and managing children at risk for early reading difficulties. Presented at the 2000 Conference of the New Mexico Speech-Language-Hearing Association, Albuquerque. Also administered at the 2000 Conference of the Colorado Speech-Language-Hearing Association, Denver.

Fey, M.E. (2000). Literacy-based approaches to early speech and language assessment and intervention. Invited workshop presented at the Annual Meeting of the Arizona Speech-Language-Hearing Association, Tucson.

Fey, M.E. (2000). The speech-language pathologist and early reading disorders. Invited address presented at the Annual Meeting of the Southwest Branch of the International Dyslexia Association, Albuquerque, NM.

Fey, M.E. (1999). The speech-language pathologist and early reading disorders. Invited address presented at the Kansas Speech and Hearing Association Convention. Overland Park, KS.

Fey, M.E. (1999). Putting phonological awareness into perspective in speech-language pathology. Keynote address presented at the National conference of Speech Pathology Australia. Sydney, Australia

Fey, M.E. (1999). A new procedure for sampling, analyzing, and interpreting children's oral and written stories. Workshop presented at the National conference of Speech Pathology Australia. Sydney, Australia.

Fey, M. and Catts, H. (1998). Can the Language Basis of Reading Disability be Reduced to Problems in Phonological Awareness? Evidence from a Longitudinal Investigation. Presentation at the Symposium on Research in Child Language Disorders, University of Wisconsin-Madison.

Hafeman, L. and Tomblin, J.B. (1999). Autism behaviors in the siblings of children with specific language impairment. Paper presented at the VII World Congress of Psychiatric Genetics, Monerey, CA.

Redmond, S. and Rice, M. (1998). The Detection of Irregular Verb Violations by Children with and without Specific Language Impairment. Presentation at the Symposium on Research in Child Language Disorders, University of Wisconsin-Madison.

Rice, M.L. and Wexler, K. (2000). What she saying: SLI children's judgments of questions. Paper presented at the Boston University Conference on Language Development, Boston.

Rice, M.L. (2000). Language disorders in children: New findings. Seminar presented at the American Speech-Language Hearing Association annual conference, Washington, DC.

Tomblin, J. B., Rice, M., Miller, C., Ellis Weismer, S., Leonard, L., Catts, H. (2002). Language-nonverbal IQ discrepancies in children with SLI. Symposium presented at the Joint Conference of the IX International Congress for the study of Child Language and the Symposium on Research in Child Language Disorders, Madison, WI.

Tomblin, J. B. (2001). Issues in the Diagnosis of SLI. The Relationship of Genes, Environments, and Developmental Language Disorders: Research for the Twenty-first Century. Merrill Center for Advanced Study.

Tomblin, J. B. (2001). An Outcomes Approach to the Diagnosis and Treatment of SLI Carrefour en dysphasie. Invited seminar at a meeting of the Ordre des orthophonistes et audiologistes du Québec.

Tomblin, J. B., & Zhang, X. (2001). Characterizing language growth from kindergarten to fourth grade. Poster presented at the 22nd Annual Symposium on Research in Child Language Disorders, Madison, WI.

Tomblin, J.B. and Zhang, X. (1997). Stability of Developmental Language Disorders. Paper presented at the Annual Convention of the American Speech-Language-Hearing Association, Boston, MA.

Tomblin, J.B. and Zhang, X. (1997). Statistical Expectation for Recovery Rate for SLI. Paper presented at the Symposium on Research in Child Language Disorders.

Weiss, A., Ellis Weismer, S., Tomblin, J.B., and Buckwalter, P. (1998). The Demographics of Speech-Language Treatment for a Cohort of Second Graders., Presentation at the Symposium on Research in Child Language Disorders, University of Wisconsin-Madison.

Weiss, A., Ellis Weismer, S., Tomblin, J.B., & Buckwalter, P. (1998, November). Speech-language treatment demographics for a second grade cohort. Poster presented at the annual convention of the American Speech-Language-Hearing Associate, San Antonio, TX.

Zhang, X., Tomblin, J.B., and Buckwalter, P. (1997). Stability of Diagnoses of Developmental Language Disorders. Presentation at the Annual Convention of the American Speech-Language-Hearing Association, Boston, MA.

Rice, M.L. (2002). Identifying young children with language impairments: Measurement issues. Presentation at the ASHA Conference for Speech-Language Pathologists in Schools, Nashville, TN.

Rice, M.L. (2002). Children with specific language impairment: Progress toward a grammatical phenotype. Paper presented to the Center for Research on Atypical Development and Learning, Georgia State University, Atlanta, GA.

Rice, M.L., Wexler, K. & Francois, J. (2001). SLI children's delayed acquisition of passive. Paper presented at the BU Conference on Language Development, Boston.

Tomblin, J.B. and Zhang, X. (2004). Implicit learning in adolescents with and without Specific Language Impairment. Symposium on Research in Child Language Disorders, Madison, WI.

Zhang, X. and Tomblin, J.B. (2004). Lack of individual difference in the language growth rate from kindergarten to eighth grade. Symposium on Research in Child Language Disorders, Madison, WI.

Genetics influences on child language development
Increasing evidence points to a strong genetic component in language development. A long-range goal is to identify one or more of the specific genes or locations involved in language acquisition.

Abstract: There is increasing evidence that language development has a strong underlying genetic component. Our understanding of language acquisition in young children, as well as a variety of twin and family-based studies support a genetic component, both for normal language acquisition and its impaired state, which in one form is called Specific Language Impairment (SLI). We now have the ability to test very large numbers of individuals using both candidate genes or anonymous DNA markers using several different genetic strategies. The final product of this proposal should be the identification of one or more of the specific genes or locations involved in language development. It will provide important tools that will allow us to not only better understand the biology of language development but to identify at a very early state in life those children most at risk for language impairment.

Principal investigator: J. Bruce Tomblin, Ph.D.

Funding source: National Institute on Deafness and Other Communication Disorders #1 R01 DC05067-01

Funding dates: July 2002 to March 2004

Description of work
Our research into the genetics of developmental language impairment (LI) began in the late 1980s with research showing that language problems run in families. Our initial work asked if parental reports of speech and language problems were more common in children who had language problems than among children who did not have such problems. We found that there was an elevated rate of parental reported language problems in the near relatives of children with LI (Tomblin, 1989).

We followed this study with another study in which we directly tested the language skills of family members of individuals with LI. Again, we found that LI was common in these families, particularly among the fathers and brothers of the LI family member (Tomblin, 1994; Tomblin, 1996).

Having determined that LI did run in families, we conducted a study of LI in twins to determine if the familial characteristic of LI was based in genetic factors of the family or the environmental factors. Our twin research demonstrated that it was both genetic and environmental, but that genes were playing a strong role (Tomblin, 1996; Tomblin & Buckwalter, 1998).

These findings then led us to begin to look for specific genes that might be related to LI. To date we have not located a gene, however, we have found that a gene (FOXP2) that has been associated with LI in one family is not likely to contribute to LI in very many children. However, we did find evidence that a gene near FOXP2 may play a role in language development (O'Brien E.K., Zhang, Nishimura, Tomblin, & Murray, 2003; Tomblin, 1996; Tomblin et al., 1998).

Future work
We are currently submitting a research proposal to the NIH asking for funds to continue our research on the genetics of language impairment. This work will involve following recent findings from our lab and others regarding genes or genetic loci that appear to be associated with individual differences in language development. We are currently working with the members of the TB family to learn more about the speech, language, and cognitive features of individuals with a genetic defect involving FOXP2. We are beginning to see strong evidence that some of the cognitive features of this genetic condition may involve implicit learning. We believe that implicit learning may be associated with difficulties in grammatical abilities. This work with the TB family will help guide some of our work with the families who have been participating in our longitudinal study. With additional funding, we will perform genome wide linkage studies using phenotypic information that we have gotten from the children in our longitudinal study along with their siblings. We also hope to return to these family members in order to obtain more measures of language and cognitive abilities now that they will all be adults.

Reference list
O'Brien E.K., Zhang, X., Nishimura, C., Tomblin, J. B., & Murray, J. C. (2003). Association of specific language impairment (SLI) to the region of 7q31. American Journal of Human Genetics, 72, 1536-1543.

Tomblin, J. B. (1994). Family and twin studies of language impairment. In San Francisco, CA.

Tomblin, J. B. (1996). Genetic and environmental contributions to the risk for specific language impairment. In M.Rice (Ed.), Genetics of Specific Language Impairment (pp. 191-210). Baltimore, MD: Brooks.

Tomblin, J. B. & Buckwalter, P. (1998). The heritability of poor language achievement among twins. Journal of Speech and Hearing Research, 41, 188-199.

Tomblin, J. B. (1989). Familial concentration of developmental language impairment. Journal of Speech and Hearing Disorders, 54, 287-295.

Published articles and book chapters
O’Brien, E. K., Zhang, X., Nishimura, C., Tomblin, J. B., & Murray, J. C. (2003). Association of SLI to the region of 7q31. American Journal of Human Genetics, 72, 1536-1543.

Tomblin, J. B. (2003). Genetics and Language. Encyclopedia of the Human Genome. London: Nature Publishing Group.

Tomblin, J. B., & Buckwalter, P. A. (1998). The estimated heritability of language impairment using a twin design. Journal of Speech Language Hearing Research, 41, 188-199.

Tomblin, J. B., Nishimura, C., Zhang, X. and Murray, J. (1998). Association of developmental language impairment with loci at 7q31. The American Journal of Human Genetics, 63, A312.

Tomblin, J. B. (1996). Genetic and environmental contributions to the risk for specific language impairment. In M. Rice (Ed.), Genetics of Specific Language Impairment. Baltimore, MD: Brooks.

Tomblin, J.B., Freese, P. and Records, N.L. (1992). Diagnosing specific language impairment in adults. Journal of Speech and Hearing Research, 35, 832-843.

Zhang, X. & Wang, K. (2003). Bivariate linkage analysis of cholesterol and triglyceride levels in Framingham heart study. BMC Genetics, 4(Suppl I):S62.

Tomblin, J.B., Nishimura, C. Zhang, X., and Murray, J. (1998). Association of Developmental Language Impairment with Loci at 7q31. Poster presented at the Annual Meeting of the American Society of Human Genetics, Denver, CO.

Tomblin, J.B. and Murray, J. (1997). Molecular Genetic Studies of Developmental Language Disorders. Invited paper presented at the NID Workshop on Research Opportunities in Molecular Biology and Genetics in Voice, Speech and Language.

Tomblin, J.B. and Buckwalter, P. (1994). Preliminary Results of a Twin Study of SLI. Paper presented at the Symposium on Research in Child Language Disorders, Madison, WI.

Zhang, X. & Wang, K. (2002). Bivariate Linkage Analysis of Cholesterol and Triglyceride Levels in Framingham Heart Study? Poster presented at the Genetic Analysis Workshop 13, New Orleans, LA.

Language and genes: A tutorial
By J. Bruce Tomblin, Ph.D.

This article appears in Nature Encyclopedia of the Human Genome, copyright 2003 Macmillan Publishers Ltd., Nature Publishing Group, www.ehgonline.net

The development of spoken language involves the acquisition of a complex system of knowledge that is generally believed to depend on biological systems that are genetically influenced.

Introduction
The universal capacity of humans to acquire and use a complex language system for social interaction is often cited as that which makes them unique among animals. Despite the superficial differences across human languages, linguists believe that all human languages conform to a common set of abstract features involving the use of a finite set of words that are systematically combined according abstract grammatical principles to allow for the expression of a nearly limitless variety of messages. Despite that abstractness of languages, human infants and toddlers show remarkable abilities to rapidly acquire this complex system with little intentional tutoring by their parents.

These features of species specificity, species universality and rapid unaided development have provided the foundations for the claims that language, and most specifically grammar, is innate (Chomsky, 1988; Pinker, 1994). Within such a nativist account, it is claimed that the genome codes for neural systems that provide human infants with knowledge of critical universal features of all human languages. This genetically endowed knowledge allows children to rapidly exploit the linguistic experience in order to acquire knowledge of the particular language of their community. An alternative to linguistic nativism, comes from those who believe that species specificity, universality and rapid development could arise from an assemblage of biologically and potentially genetically influenced cognitive systems that are important, but not dedicated, to language (Bates, 1994; Elman et al., 12996; Tomasello, 1998). Thus, most contemporary views of language predict that the capacity for language in humans is, at least in part, dependent upon neural systems that are genetically influenced. There are considerable differences, however, with regard to the kinds of hypothesized systems these genes may affect.

It has been within this theoretical context that the research on genetics and language has been conducted. An additional motivation for this research comes from clinical interests in the etiology of impairments of language development. Thus, much of the research on genetics and language pertains to explanations of individual differences in children's development of language.

Heritability of Spoken Language Development and Disorders
Much of the empirical work concerning genes and language has addressed the question of the heritability of individual differences in spoken language using the twin method. The twins in this research have either been sampled from the general population and thus represent the full range of normal language development or they were sampled because at least one twin had poor or impaired language development.

Typically developing children
There has been a modest amount of research concerning the heritability of various aspects of language among normally developing twins. Vocabulary represents that aspect of language concerned with words and their meanings and in these studies is reflected in estimates of vocabulary size or degree of development. Studies examining the heritability of vocabulary development have typically shown that monozygotic twins (MZ) were more similar to each other with respect to vocabulary development than dyzgotic twins (DZ). Heritability estimates for vocabulary vary considerably, with higher levels of heritability found in older twins that younger twins (Stromswold, 2001). Among those studies of children over 3 years of age, levels of heritability in the range of 0.40-0.60 were typical, whereas values well below 0.40 have been common under the age of three. Grammar refers to a system that governs the arrangement of words in sentences in order that they convey a role in the sentence, such as the subject or object, and it is this aspects of language that linguistic nativism argues is most likely to be innate. Children systematically acquire grammatical skills beginning with rudimentary grammatical patterns that progressively approximate the mature adult grammar of their language. This level of grammatical development has been compared among twins in a small number of studies. In most cases, the MZ twins were more similar with respect to grammatical development that the DZ twins. Estimates of heritability varied considerably but were often over 0.30. Thus, the rate of vocabulary and grammar development in normally developing twins is likely to be moderately to strongly influenced by genetic sources. There does not appear to be evidence showing that grammatical ability is under greater genetic influence that vocabulary; however, there are suggestions that measures of language expression result in higher heritabilities than measures of language reception (Young et al., 2001). Furthermore, an analysis of the cross-twin vocabulary-grammar covariance has indicated that the genetic heritability of these two aspects of language is likely to be due to the same genes (Dale et al., 2000).

Adoption studies provide an alternate method for estimating the extent of a genetic effect on a trait such as language. One large-scale longitudinal adoption study, the Colorado Adoption Study, examined language in adopted children and their biological and adoptive parents and siblings. Heritability estimates for verbal development in these studies were usually found to be above 0.40 and increased to 0.64 when the adopted children reached adolescence (Alarcon et al., 1998; Cardon et al., 1993; Thompson and Plomin, 1988).

Children who are particularly slow in the development of spoken language despite normal hearing, linguistic experience and intellect have been described as having childhood dysphasia or specific language impairment (SLI). Owing to considerable evidence that SLI aggregates in families, several studies have used twinships where at least one twin is affected to examine for heritability of language impairment. It has been estimated from these studies that the concordance rate for MZ twins is around 0.84 and 0.43 for DZ twins (Stromswold, 2001). Some of these studies used quantitative measures of language development and thus heritability estimates for poor language development could be computed using the extremes method of DeFries and Fulker to compute group differences heritability (h2g). The heritability estimates in these twinships are typically above 0.60, particularly when the children with SLI were restricted to children whose language achievement was in the lowest 5% of their age group (Dale et al., 1999). Thus, poor language development appears to have a substantial genetic etiology. The heritability levels in twinships with SLI were typically higher than that found for children with normal language status, suggesting that there may be unique sources of genetic etiology for poor language achievement beyond that which results in variability of language development among normal learners.

Specificity of Genetic Effects on Language and Cognition
Before it is possible to claim that there are genes specifically dedicated to language, it is necessary to show that the genetic influence found for language in these twin and adoption studies is not shared with non-language cognitive skills. It is common to find that language and nonverbal skills are moderately correlated, which could justify the claim that the genetic basis of language is actually reflective of the genetic influence on more generalized intellectual abilities. Several of the same studies concerned with language heritability have used multivariate methods to determine the extent to which language and non-language traits have shared genetic roots - that are genetically correlated. Using both twin and adoptive family sets, these studies have shown very high levels of genetic correlation between verbal and nonverbal skills (Alarcon et al., 1999). One recent study of twins focused on the comorbidity between poor vocabulary and poor nonverbal cognitive development and found evidence in support of a common set of genes influencing both poor nonverbal cognition and poor vocabulary development (Purcell et al., 2001). Thus, there is considerable evidence that argues against genes having language-specific effects. Several studies of young twins, however, indicate that this conclusion may need to be qualified. In these studies, data from twins under 3 years of age provided evidence of unique genetic effects on language (Dale et al., 2000; Price et al., 2000). Furthermore, a longitudinal study has demonstrated a shift from a unique genetic influence on language at around age two to a shared genetic influence on language and non-language development at age three (Young et al., 2001). Thus, there may be a specific genetic contribution for early stages of language development that diminishes at older ages.

Molecular Genetic Studies of Language Disorder
Evidence that several genes or loci can have an impact on language development comes from the large number of genetic syndromes with associated mental retardation. Most, if not all, genetic syndromes of mental retardation involve deficits of language development. For instance, considerable research on the language development of children with Down syndrome has shown that these individuals have greater difficulties with language development than nonverbal cognitive development (Chapman, 1995). The only mental retardation syndrome that has been described as having preserved language in the context of general intellectual deficits has been Williams syndromes (WS), where reports of normal or near-normal development of grammar and speech sound skills are not uncommon (Bellugi et al., 1994). Despite these reports, other have noted that depressed language skills are typical among WS individuals (Bates et al., 2001). The large number of different genetic loci associated with mental retardation attest to the likelihood that there are several means by which genetic factors can perturb the development of brain in ways that will affect language. If there are genes that have a particular effect on language, it has been hoped that it may be possible to identify them through the study of SLI.

The twin studies cited earlier, showing that SLI is genetically influenced, have provided an impetus to search for genes that have particular or predominant effects on language. This interest was intensified by reports concerning one large multigenerational family (KE family) with a high rate of speech and language impairment. The speech and language deficits of the affected members of this kindred have, in some cases, emphasized specific grammatical difficulties in these individuals (Gopnik, 1990). However, most accounts have also indicated that these family members were impaired with respect to a wide range of speech, language and even nonverbal development (Vargha-Khadem et al., 1995). In particular, these affected family members have been described as having dyspraxia of speech, which is considered to be a motor speech impairment. A genome-wide search of the KE family by researchers at Oxford showed linkage to two markers on the long arm of chromosome 7 in the region of 7q31 (Fisher et al., 1998). The gene mutation accounting for the speech and language impairment in this family was identified as FOXP2 (Lai et al., 2001). Sequencing of this gene showed that it contains a forkhead box binding domain and the mutation results in the protein product having an arginine-to-histidine substitution in this domain. One other case of an unrelated individual with a translocation involving a breakpoint in this gene was reported by the same laboratory, however, they did not find evidence of association or instances of mutations of the FOXP2 gene among a larger set of SLI probands (Lai et al., 2000; Newbury et al., 2002). Thus, although FOXP2 appears to affect neural systems important for normal speech and language development, the extent to which it can lead to deficits that only involve language is not clear and it also does not appear to account for most cases of SLI.

The same laboratory that located the FOXP2 gene has also performed the only genome-wide scan for SLI in sib-pairs (The SLI Consortium, 2002). This scan resulted in loci on chromosomes 16q and 19q showing linkage to quantitative verbal measures, but it is noteworthy that they did not find linkage to the region of the FOXP2 mutation in 7q31. The chromosome 16q locus was linked to a measure of phonological working memory requiring remembering and repeating nonsense words. Previous word has shown that the phonological memory is a sensitive indicator of SLI and may be am important cognitive skill for language development (Ellis Weismer et al., 1999). The language trait linked to the chromosome 19q was one that represented the children's ability to express words and sentences.

It is not unreasonable to expect to find linkage of language to additional regions of the genome. Spoken language development has been shown to be very important for successful reading development. A large effort toward identifying genetic linkage to reading and reading disorder has been made during the past two decades with several replicated linkages found particularly in 6p21 region of chromosome 6. Given the close relationship between reading and spoken language, these findings may have important implications to the genetics of language.

Cochlear Implant users and language
Do the speech, language and reading skills of children with cochlear implants exceed those of age-mates with various levels of hearing loss?

Abstract
Research has shown that children with implants are reaching levels of speech and language development above levels obtained by profoundly deaf children. These levels of development also may be greater than those found in some children with moderate to severe hearing losses. Unfortunately, little is known about speech and language development among such children with moderate to severe hearing losses. With regard to these hearing aid users, we hypothesize that there will be a relationship between speech, language, reading, and aided and unaided audibility index scores among children with moderate to severe hearing losses. Furthermore, we predict that school-age children with cochlear implants will achieve levels of speech, language, and reading that surpass their age-mates with severe hearing losses and associated low audibility levels.

The speech, language and reading achievement levels of a large sample of children between 8 and 12 years of age, who have moderate to severe hearing losses, and who use hearing aids will be examined. The relationship between levels of audibility and communication performance will be determined. The same measures of speech, language, and reading in children with cochlear implants matched on age will be associated with performance of the hearing aid users to determine equivalent levels of audibility.

Principal investigator: J. Bruce Tomblin, Ph.D.
Project Director:: Bruce Gantz, M.D.

Funding source: National Institute on Deafness and Other Communication Disorders #5-P50-DC00242-17

Funding dates: September 1985 to May 2006

Two additional longitudinal studies are proposed that will test whether there are constraints on development that can be shown among children with cochlear implants.

One study will follow children implanted between 12- and 36-months old for 24 months. During this time period we plan to monitor their speech, language, and auditory perceptual development in order to determine if earlier implantation affects growth rates and 24-month, post-stimulation, achievement levels.

The second longitudinal study concerns children and adolescents with at least 10 years of implant experience. We plan to examine growth in speech and language from 5 to at least 10 years post-stimulation; we will also examine achievement at 10 years post-stimulation to determine if there are limits to long-term growth. We will also examine the extent to which long-term achievement levels approach levels found in normal-hearing adolescents and adults. The benefits of implantation on speech production and language development also result in a prediction that there will be subsequent gains in reading and general scholastic achievement among these children. Early reading achievement in second grade and later reading and scholastic achievement in 10th grade will be examined in two cross-sectional studies. Finally, achievement levels of speech and language development among implant users appears to exceed that found in many children with more acoustic hearing who wear hearing aids. A cross-sectional design will compare school-age implant users with age-mates who are hearing aid users. It is predicted that implant users will have better speech and language than hearing aid users with low audibility levels.

Future goals
We plan to continue to investigate the processes behind achievement within children who have cochlear implants. This includes investigating the extent to which these children are able to develop a phonological code for processing the English language and then to determine how well they are able to use this information for speech, language and literacy achievement.

Green, G.E., Scott, D.A., McDonald, J.M., Teagle, H.F.B., Tomblin, J.B., Spencer, L.J., Woodworth, G.G., Knutson, J.F., Gantz, B.J., Sheffield, V.C., and Smith, R.J.H. (2002). Performance of cochlear implant recipients with GJB2-related deafness. American Journal of Medical Genetics, 109:167-170.

Moore, J.A., & Bass-Ringdahl, S.M. (2002). Role of infant vocal development in candidacy for and efficacy of cochlear implantation. Annals of Otology, Rhinology, & Laryngology - Supplement 189, 111, 52-5.

Spencer, L.J. & Bass-Ringdahl, S. (in press). An evolution of communication modalities: very young cochlear implant users who transitioned from sign to speech during the first years of use. International Congress Series, Invited papers of the 8th Cochlear Implant Conference, Indianapolis, USA, (ICS 1273). Elsevier.

Spencer, L.J., Gantz, B.J., and Knutson, J.F. (2004). Outcomes and achievement of students who grew up with access to cochlear implants. Laryngoscope, 114:1576-1581.

Spencer, L.J., Barker, B.A., and Tomblin, J.B. (2003). Exploring the language and literacy outcomes of pediatric cochlear implant users. Ear and Hearing, 24, 236-247.

Spencer, L.J., Tye-Murray, N., and Tomblin, J.B. (1998). The Production of English Inflectional Morphology, Speech Production and Listening Performance in Children with Cochlear Implants. Ear and Hearing, 19(4), 310-318.

Tomblin, J.B., Barker, BA, Spencer, L.J., Zhang, X., & Gantz, B.J. (submitted to JSLHR). The effect of age at cochlear implant stimulation on expressive language growth in infants and toddlers.

Posters/Presentations
Barker, B. A. & Bass-Ringdahl, S. M. (2004, May). The effect of audibility on audio-visual speech perception in very young cochlear implant recipients. Poster presented at the 8th International Cochlear Implant Conference, Indianapolis, IN.

Barker, B. A., & Tomblin, J. B. (2002, September). Assessing speech perception skills in pediatric cochlear implant users via the Split-Screen Preferential Looking Procedure. Poster session presented at the 7th International Cochlear Implant Conference, Manchester, England.

Tomblin, J. B., Spencer, L. J., & Barker, B. A. (2002, July). The effect of age of cochlear implantation on language growth in infants and toddlers. Poster session presented at the 23rd Annual Symposium on Research in Child Language Disorders, Madison, WI. Paper also presented at the 7th International Cochlear Implant Conference, Manchester, England.

PowerPoint Presentations
Barker B. A., & Tomblin, J. B. (2003, April). Comparing bimodal perception skills in infant hearing-aid and cochlear-implant users. Paper presented at the 9th Symposium on Cochlear Implants in Children, Washington, D.C.

Barker, B. A., & Tomblin, J. B. (2003, November). Comparing bimodal perception skills in infant hearing-aid and cochlear-implant users. Paper presented at the Annual American Speech-Language-Hearing Association Convention, Chicago, IL.

Spencer, L.J. (2003, April). The First Class: Educational Outcomes and Achievement Test Results from Students Who Grew Up Wearing Cochlear Implants. Paper presented at the 9th Symposium for Cochlear Implants in Children Conference, Washington, DC.

Green, G.E., Scott, D.A., McDonald, J.M., Teagle, H.F.B., Tomblin, J.B., Spencer, L.J., Woodworth, G.G., Knutson, J.F., Gantz, B.J., Sheffield, V.C., and Smith, R.J.H. (2002). Performance of cochlear implant recipients with GJB2-related deafness. American Journal of Medical Genetics, 109:167-170.

Moore, J.A., & Bass-Ringdahl, S.M. (2002). Role of infant vocal development in candidacy for and efficacy of cochlear implantation. Annals of Otology, Rhinology, & Laryngology - Supplement 189, 111, 52-5.

Spencer, L.J. & Bass-Ringdahl, S. (in press). An evolution of communication modalities: very young cochlear implant users who transitioned from sign to speech during the first years of use. International Congress Series, Invited papers of the 8th Cochlear Implant Conference, Indianapolis, USA, (ICS 1273). Elsevier.

Spencer, L.J., Gantz, B.J., and Knutson, J.F. (2004). Outcomes and achievement of students who grew up with access to cochlear implants. Laryngoscope, 114:1576-1581.

Spencer, L.J., Barker, B.A., and Tomblin, J.B. (2003). Exploring the language and literacy outcomes of pediatric cochlear implant users. Ear and Hearing, 24, 236-247.

Spencer, L.J., Tye-Murray, N., and Tomblin, J.B. (1998). The Production of English Inflectional Morphology, Speech Production and Listening Performance in Children with Cochlear Implants. Ear and Hearing, 19(4), 310-318.

Tomblin, J.B., Barker, BA, Spencer, L.J., Zhang, X., & Gantz, B.J. (submitted to JSLHR). The effect of age at cochlear implant stimulation on expressive language growth in infants and toddlers.

Posters/Presentations
Barker, B. A. & Bass-Ringdahl, S. M. (2004, May). The effect of audibility on audio-visual speech perception in very young cochlear implant recipients. Poster presented at the 8th International Cochlear Implant Conference, Indianapolis, IN.

Barker, B. A., & Tomblin, J. B. (2002, September). Assessing speech perception skills in pediatric cochlear implant users via the Split-Screen Preferential Looking Procedure. Poster session presented at the 7th International Cochlear Implant Conference, Manchester, England.

Tomblin, J. B., Spencer, L. J., & Barker, B. A. (2002, July). The effect of age of cochlear implantation on language growth in infants and toddlers. Poster session presented at the 23rd Annual Symposium on Research in Child Language Disorders, Madison, WI. Paper also presented at the 7th International Cochlear Implant Conference, Manchester, England.

PowerPoint Presentations
Barker B. A., & Tomblin, J. B. (2003, April). Comparing bimodal perception skills in infant hearing-aid and cochlear-implant users. Paper presented at the 9th Symposium on Cochlear Implants in Children, Washington, D.C.

Barker, B. A., & Tomblin, J. B. (2003, November). Comparing bimodal perception skills in infant hearing-aid and cochlear-implant users. Paper presented at the Annual American Speech-Language-Hearing Association Convention, Chicago, IL.

Spencer, L.J. (2003, April). The First Class: Educational Outcomes and Achievement Test Results from Students Who Grew Up Wearing Cochlear Implants. Paper presented at the 9th Symposium for Cochlear Implants in Children Conference, Washington, DC.

Audio clips of CI users
The following four children were fitted with cochlear implants. As you listen to audio samples of their speech over time, you will likely note that language progression of children implanted with these devices is far from predictable. Research continues to try to better understand the processes behind achievement.

Child 1 received a set of cochlear implants at 18 months of age.
<audio sample 1> At 10 months of age, s/he is wearing hearing aids. Note that this child is in the pre-cannonical stage, exhibiting vowel prolongations.
<audio sample 2> Now at 12 months post implantation, (20 months of age), s/he produces cannonical babble and first words.
<audio sample 3> At 5 years of age, Child 1 exhibits intelligible speech.

Child 2 has made great strides since receiving his cochlear implant at three years of age.
<audio sample 4> At 36 months post-implant, he is 6 years old.
<audio sample 5> When this child reached 10 years of age, he had worn his CI for 84 months.
<audio sample 6 > By 120 months post-implant, Child 2 is 13 years old, and his speech has become understandable to most listeners.

Child 3 was 3 years old at time of implantation.
<audio sample 7 > Just prior to implantation, the child is imitating consonant vowel sequences with just fair accuracy.
<audio sample 8 > In this audio sample, the child is now 5 years old (24 months post-implant) and is able to imitate short sentences. You will note that the child produces consonant-vowel-consonant combinations but tends to delete final sounds and has several substitutions.
<audio sample 9 > At 72 months after implantation, he is now age 9 and very intelligible. You are able to note that sounds are complete and there are few, if any, articulation errors.
<audio sample 10> Now at 11 years post implantation and age 14, you will hear a fully mature voice that has undergone pubescent voice change. Intelligibility is high.

Child 4 was 4 years old at implant surgery. Listen to the audio samples to hear how this child's language progressed differently than that of Child 3.
<audio sample 11> Child 4 at 5 years of age (12 months after surgical intervention). Intelligibility is low, with many omissions of consonant clusters, and substitution errors.
<audio sample 12> Now two years post implantation at age 6, there is some improvement in intelligibility, yet some consonant substitutions and deletions remain.
<audio sample 13> At age 10, this child is 48 months post implantation. There is a marked increase in intelligibility with fewer consonant errors, yet substitutions are noted in consonant blends.
<audio sample 14> Six years post implantation (at age 12), note subtle changes. Residual consonant substitutions can be heard, for example d/g, t/s, d/voiced th.
<audio sample 15> The final sample is 96 months post implantation, and at age 14, intelligibility is very high. Only subtle consonantal errors are noted, with some slight prosodic differences present.

Published articles
Barker, B. A., & Tomblin, J. B. (2004). Comparing bimodal perception skills in infant hearing aid and cochlear implant users. Archives of Otolaryngology-Head & Neck Surgery, 130, 582-586.

Green, G.E., Scott, D.A., McDonald, J.M., Teagle, H.F.B., Tomblin, J.B., Spencer, L.J., Woodworth, G.G., Knutson, J.F., Gantz, B.J., Sheffield, V.C., and Smith, R.J.H. (2002). Performance of cochlear implant recipients with GJB2-related deafness. American Journal of Medical Genetics, 109:167-170.

Moore, J.A., & Bass-Ringdahl, S.M. (2002). Role of infant vocal development in candidacy for and efficacy of cochlear implantation. Annals of Otology, Rhinology, & Laryngology - Supplement 189, 111, 52-5.

Spencer, L.J. & Bass-Ringdahl, S. (in press). An evolution of communication modalities: very young cochlear implant users who transitioned from sign to speech during the first years of use. International Congress Series, Invited papers of the 8th Cochlear Implant Conference, Indianapolis, USA, (ICS 1273). Elsevier.

Spencer, L.J., Gantz, B.J., and Knutson, J.F. (2004). Outcomes and achievement of students who grew up with access to cochlear implants. Laryngoscope, 114:1576-1581.

Spencer, L.J., Barker, B.A., and Tomblin, J.B. (2003). Exploring the language and literacy outcomes of pediatric cochlear implant users. Ear and Hearing, 24, 236-247.

Spencer, L.J., Tye-Murray, N., and Tomblin, J.B. (1998). The Production of English Inflectional Morphology, Speech Production and Listening Performance in Children with Cochlear Implants. Ear and Hearing, 19(4), 310-318.

Tomblin, J.B., Barker, BA, Spencer, L.J., Zhang, X., & Gantz, B.J. (submitted to JSLHR). The effect of age at cochlear implant stimulation on expressive language growth in infants and toddlers.

Posters/Presentations
Barker, B. A. & Bass-Ringdahl, S. M. (2004, May). The effect of audibility on audio-visual speech perception in very young cochlear implant recipients. Poster presented at the 8th International Cochlear Implant Conference, Indianapolis, IN.

Barker, B. A., & Tomblin, J. B. (2002, September). Assessing speech perception skills in pediatric cochlear implant users via the Split-Screen Preferential Looking Procedure. Poster session presented at the 7th International Cochlear Implant Conference, Manchester, England.

Tomblin, J. B., Spencer, L. J., & Barker, B. A. (2002, July). The effect of age of cochlear implantation on language growth in infants and toddlers. Poster session presented at the 23rd Annual Symposium on Research in Child Language Disorders, Madison, WI. Paper also presented at the 7th International Cochlear Implant Conference, Manchester, England.

PowerPoint Presentations
Barker B. A., & Tomblin, J. B. (2003, April). Comparing bimodal perception skills in infant hearing-aid and cochlear-implant users. Paper presented at the 9th Symposium on Cochlear Implants in Children, Washington, D.C.

Barker, B. A., & Tomblin, J. B. (2003, November). Comparing bimodal perception skills in infant hearing-aid and cochlear-implant users. Paper presented at the Annual American Speech-Language-Hearing Association Convention, Chicago, IL.

Spencer, L.J. (2003, April). The First Class: Educational Outcomes and Achievement Test Results from Students Who Grew Up Wearing Cochlear Implants. Paper presented at the 9th Symposium for Cochlear Implants in Children Conference, Washington, DC.

Iowa's Department of Otolaryngology Cochlear Implant Center
The link, http://www.uihealthcare.com/depts/med/otolaryngology/iacic/index.html, will take you to UIHC's website.

Research overview
The research conducted within the CLRC laboratories is concerned with understanding the causes and outcomes of developmental speech and language disorders. Currently this work has been focused on two clinical populations.

One population consists of those who have poor language development despite normal sensory, nonverbal intellectual and social affective status. These children have been referred to as specific language impaired (SLI). The laboratory has been following a large cohort of children with and without SLI since they entered kindergarten 10 years ago. Repeated assessments of language, reading, behavior, and school performance have been conducted in order to document long-term outcomes.

Additionally, studies have been conducted regarding several cognitive, neurological, and genetic characteristics of these children. Research methods employed in this work have spanned molecular genetics, brain imaging (fMRI and electrophysiological), cognitive psychological designs, connectionist modeling, and epidemiologic studies.

A second population being studied consists of children who have hearing losses. The focus of this work is on those children with severe to profound hearing impairment who have received cochlear implants. This research has asked about long-term speech, language, and reading outcomes of these children and factors that impact on the individual differences in these outcomes. Research methods employed in this work consist of speech and language measures and -- because many of these children are infants -- the methods have included contemporary infant paradigms that exploit looking responses associated with linguistic stimuli (preferential looking, head-turn preference).

This research is being supported by several grants from the National Institute on Deafness and Other Communication Disorders.

Contact information
Child Language Research Center
Room 3, Wendell Johnson Speech and Hearing Center
Department of Speech Pathology and Audiology
The University of Iowa, 250 Hawkins Drive
Iowa City, Iowa 52242

Telephone 800/551-5601

Technical snafus? Email julie-ostrem@uiowa.edu

Project team biographies
The greatest strengths of the CLRC are the experience and energy of its staff. The CLRC project team represents nine educational institutions and academic backgrounds as diverse as genetics, child psychiatry, statistics, education, psychology and communication disorders. What links the team, however, is the deep motivation to better understand the causes and the effects of children's language difficulties.

CLRC on-site staff
Bruce Tomblin is the CLRC Director and the DC Spriestersbach Distinguished Professor in Liberal Arts and Sciences at the University of Iowa.
His research and teaching have long been in the area of children's language development and disorders. In recent years, his research has been concerned with the development and the genetic influence on the occurrence of certain forms of children's language problems. Much of this research has been supported by NIH research grants and contracts. He earned a bachelor's degree in psychology from the University of La Verne, a master's degree in speech from the University of Redlands, and a doctoral degree in communicative disorders from the University of Wisconsin, Madison. He is a fellow of the American Speech Language and Hearing Association and the Iowa Speech and Hearing Association. He holds a certificate of clinical competence in speech-language pathology from ASHA and is a licensed speech language pathologist in the state of Iowa. Email: j-tomblin@uiowa.edu

Xuyang Zhang is an associate research scientist at the CLRC. He's responsible for managing and analyzing the enormous amounts of data from the study subjects: children with and without SLI. He earned a bachelor's degree in psychology from Beijing Normal University and his master's and doctoral degrees in educational psychology from Capital Normal University, China. He also completed a master's degree in biostatistics and a doctoral degree in speech and hearing science, both from The University of Iowa. Email:xuyang-zhang@uiowa.edu

Jeff Murray collaborates on the genetics studies of the CLRC, investigating the genetic contribution to language acquisition. He is professor of pediatrics and biological sciences at The University of Iowa. He was director of the Cooperative Human Linkage Center, a Human Genome Center based at the University of Iowa, and director of the Craniofacial Anomalies Research Center in the Departments of Pediatrics, Biological Sciences, Otolaryngology, and Physiology at Iowa. Dr. Murray earned a bachelor's degree in biology from M.I.T. and a medical degree from Tufts Medical School in 1978. Following a pediatric residency at the Boston Floating Hospital, Dr. Murray did a medical genetics fellowship at the University of Washington. Email: jeff-murray@uiowa.edu

Marlea O'Brien is the program coordinator of the CLRC. She has held this role for over twelve years, and is the key point of contact for the various projects and activities of the CLRC. Marlea's responsibilities include oversight of field research activities and staff; management of the financial and grants processes; internal and external reporting of CLRC activities; and serving as liaison for families, school personnel, and investigators. In short, she creates the best possible environment for CLRC work and staff to keep moving forward. Email: marlea-obrien@uiowa.edu

Connie Ferguson is a speech-language pathologist and a field examiner for the Child Language Research Center. In addition to testing Des Moines, Iowa, research subjects, she is responsible for refining protocols, maintaining the integrity of the administration of the protocols, and training other field examiners. She earned a master's degree in speech pathology from Central Missouri State University. She has worked as a field examiner with Dr. Tomblin on several of his research studies since 1991. Prior to joining the CLRC, she served as a speech-language pathologist in the public schools for several years. Email: connie-ferguson@uiowa.edu

Juanita Limas is a CLRC field examiner who collects data on children in the Cedar Rapids and Des Moines, Iowa, communities.
She earned a bachelor's degree from The University of Iowa, and she has previously worked with the CLRC, taking time off to serve as a Peace Corps health volunteer in Nicaragua from 2000 - 2002. Emai: juanita-limas@uiowa.edu

Amy Schminke is a field examiner in the Waterloo/Cedar Falls, Iowa, area for the Child Language Research Center. She earned a bachelor's degree in elementary education/special education from Wartburg College and a master's degree in special education from the University of North Dakota. Amy has a field examiner with the CLRC since 1997. Previously, she worked in the public school systems in Iowa, Michigan, and Minnesota as a special education/elementary education teacher. Email: amy-schminke@uiowa.edu

Marcia St. Clair is a field examiner in the (Iowa-Illinois) Quad Cities area for the Child Language Research Center. Marcia has been working as a field examiner with the Child Language Research Center since 1998. She earned a bachelor's degree in elementary education from the University of Northern Iowa. Prior to joining the CLRC team, she worked in the public school systems in Iowa and Illinois as an elementary education teacher and reading tutor. Email: marcia-stclair@uiowa.edu

Wendy Fick began work as a research assistant at the CLRC in 2001. Her duties include entering and verifying data, insuring data accuracy and security, and disseminating data to appropriate investigators. She also conducts event-related potential recordings on subjects in a dedicated setting at the Child Language Research Center. She earned a bachelor's degree from The University of Iowa, and prior to joining the CLRC, worked as a research assistant for the speech physiology lab in Iowa's Department of Speech Pathology and Audiology. Email: wendy-fick@uiowa.edu

Julie Ostrem divides her time weaving websites for the CLRC and the Voice Academy, an NIDCD-funded site for the vocal health of teachers. She joined the CLRC team in 2003 to program and market the SLI Data Sharing project and to give a facelift to the CLRC site. To do these tasks, she draws on her bachelor's degree in journalism from Iowa State University and a master's degree in business administration from The University of Iowa. She never tires of the challenge of communicating knowledge from scientific research into useful forms to those who need it on a day-to-day basis. Email: julie-ostrem@uiowa.edu

Off-site investigators
Mabel Rice is a co-investigator on the project "Collaboration on Specific Language Impairment." She has both research and clinical experience with children who have specific language impairment (SLI). Her current research addresses several aspects of SLI: morphosyntactic markers, genetic etiology, social and academic consequences, lexical learning, and preschool language intervention. She is the Fred and Virginia Merrill Distinguished Professor of Advanced Studies, and directs three programs in the Schiefelbusch Institute for Life Span Studies. These are: The Child Language Doctoral Program, the Merrill Advanced Studies Center, and the Center for Biobehavioral Neurosciences in Communication Disorders. She also maintains an active research lab at the University of Kansas, and carries out collaborative studies at international levels. She is a fellow of the American Speech, Language, and Hearing Association and a fellow of the American Psychological Association. Email: mabel@ku.edu

Susan Ellis Weismer is a co-investigator on the project "Collaboration on Specific Language Impairment." Her research focuses on factors underlying specific language impairment and on intervention approaches for facilitating language learning.She is a professor in the Department of Communicative Disorders at the University of Wisconsin, Madison and coordinator of the Cognitive and Communication Processes Unit at the Waisman Center, where she directs the Language Processes Laboratory and the Early Language Learning Project. Email: ellisweismer@wisc.edu

Laurence Leonard is a co-investigator on the project "Collaboration on Specific Language Impairment." His academic interests center on the morphosyntactic, phonological, and semantic manifestations of childhood language disorders. Much of his work involves cross-linguistic studies of children with specific language impairment. He is the Rachel E. Stark Distinguished Professor in the Department of Audiology and Speech Sciences at Purdue University, where he directs the Child Language Research Lab. He earned a bachelor's degree in psychology and a master's degree in speech-language pathology from the University of South Florida and a doctoral degree in speech-language pathology and psycholinguistics from the University of Pittsburgh. His book, Children with Specific Language Impairment, was published in 1997 by MIT Press. Email: xdxl@purdue.edu

Hugh Catts is a co-investigator on the CLRC project called "Collaboration on Specific Language Impairment." His research focuses on the relationship between oral and written language disorders. He is a professor in the Department of Speech-Language-Hearing: Sciences and Disorders, University of Kansas. He earned his doctoral degree from the University of Florida and completed postdoctoral training at Johns Hopkins University. Dr. Catts is author of the book, "Language and Reading Disabilities." Email: catts@ku.edu

Christine Weber-Fox conducts research that focuses on how our brains function during the processing of language. She's particularly interested in how the nerve systems might be different for people who are bilingual, those who stutter, and children with language problems. She is an assistant professor in the Department of Audiology and Speech Sciences at Purdue University. Prior to her appointment, she earned master's and doctoral degrees from Purdue University. She also completed a postdoctoral fellowship at the Salk Institute in the area of cognitive neuroscience. Email: weberfox@purdue.edu

Carol Miller is a research associate on the project "Collaboration on Specific Language Impairment." Her primary research interests are normal and disordered first language acquisition, with particular interests in the acquisition of verb meanings, and in the relationships between typical and atypical language development. She earned a bachelor's degree in psychology from Michigan State University and a doctoral degree from the University of Pennsylvania in 1994. From 1994 to 1996, she completed a postdoctoral fellowship in the lab of Larry Leonard, and she continued there as a research associate before accepting an assistant professor position at Pennsylvania State University. Email: cam47@psu.edu

Marilyn Nippold is an investigator on the project "Collaboration on Specific Language Impairment." Her teaching and research interests include school-age language development and disorders, literacy, and stuttering. She is a professor and chair of the Communication Disorders and Sciences Program at the University of Oregon's College of Education. An ASHA Fellow, she earned a bachelor's degree from the University of California Los Angeles, a master's degree from California State Long Beach, and a doctoral degree from Purdue University. Email: nippold@oregon.uoregon.edu

Off-site consultants
Joseph Beitchman is a consultant with the CLRC, contributing his research interest studying the interface between childhood speech and language impairment and psychiatric disorders. He is professor and head of the Division of Child Psychiatry at the University of Toronto, TD Bank Financial Group Chair in Child and Adolescent Psychiatry, psychiatrist in chief at the Hospital for Sick Children and clinical head of child psychiatry at the Center for Addiction and Mental Health. He is also a senior scientist in the Research Institute at The Hospital For Sick Children. Email: joe_beitchman@camh.net

David Francis is a consultant for the CLRC. He collaborates in research on reading and reading disabilities, attention problems, developmental consequences of brain injuries and birth defects, and adolescent alcohol abuse. He is a professor of quantitative methods in the Department of Psychology, University of Houston, where he earned his doctoral degree in clinical neuropsychology. He is a fellow of Division Five (Measurement, Evaluation, and Statistics) of the American Psychology Association and has served as a consulting editor to six psychology journals. He is also a founding partner of FSD Data Services, Inc., a contract research services firm based in Houston, Texas. Email: dfrancis@uh.edu

Hollis Scarborough, a CLRC consultant, is a developmental psychologist whose primary research focus is the relationship between spoken and written language from the preschool years through adulthood. Her published work includes reviews and empirical studies of the preschool antecedents of reading disabilities, the prediction of reading achievement, the assessment of children's language abilities, and related topics. She is a senior research scientist at Haskins Laboratories and holds faculty appointments at the City University of New York and at Bryn Mawr College. She earned a bachelor's degree at New York University and master's and doctoral degrees in psychology from New York University. Email hscarborough@prodigy.net

Cochlear Implant on-site staff
Sandie Bass-Ringdahl is an investigator with the CLRC and an assistant professor in the Department of Speech Pathology and Audiology, The University of Iowa. Her research interests include the early speech development of infants and toddlers who are deaf or hard of hearing as well as early identification and aural (re)habilitation of hearing impairment. She earned her bachelor's degree in speech pathology and audiology from The University of Florida and a master's degree in audiology from Louisiana State University. She completed her clinical fellowship in audiology at the Baton Rouge Speech and Hearing Foundation and the V.A. Medical Center in New Orleans. She earned her doctoral degree in speech and hearing science at The University of Iowa in 2002. Before accepting her current academic position, she worked with Iowa's Early Hearing Detection and Intervention Program as well as the University of Iowa Hospitals and Clinics' Cochlear Implant Team in the Department of Otolaryngology. Email:
sandie-bass-ringdahl@uiowa.edu

Brittan Barker is a research assistant on the children's cochlear implant team. Her primary research interest is the link between speech perception and language acquisition in hearing-impaired infants, with particular interests in the role of talker variability in speech perception and how
such variability facilitates learning. She earned a bachelor's degree in psychology from Louisiana State University and a master's degree in cognitive psychology from the University of Iowa in 1999. She is currently a doctoral candidate in speech and hearing science at the University of Iowa. Email: brittan-barker@uiowa.edu

Linda Spencer contributes to the CLRC her interest in the language development of children with cochlear implants. She has worked as a staff speech-language pathologist in hospital and school settings and has been a Research Assistant III at the University of Iowa Hospitals and Clinics for 10 years. She maintains the database, designs studies, and collaborates in writing grant applications and additionally supervises students in training in the Speech Pathology and Audiology Department at the University of Iowa. She earned her bachelor's degree in speech and hearing science and her master's degree in speech pathology at the University of Iowa. She has developed specific research interests in the relationship of phonology, language skills and reading in children with normal hearing and in children with hearing loss and plans to pursue this line of research in her dissertation work. Email: linda-spencer@uiowa.edu

Frequently asked questions
What is the CLRC is trying to study?
In its simplest form, we are trying to learn how children's spoken language abilities affect their lives and what sorts of things cause some children to be better at spoken language than others. By learning if and when spoken language ability results in undesirable life circumstances, we can better establish which children need our clinical efforts. By understanding what factors contribute to poor spoken language ability, we will be better able to know what to do to help resolve the problem.

How exactly do the CLRC researchers do this?
A major thrust is the longitudinal observational study. We started by selecting children with a wide range of spoken language abilities as they entered school. Within this sample, however, we included a large group of children with poor language abilities because these children are the most informative for our purposes. We have then followed these children through school and gathered a range of data: academic performance, social development, and behavioral and health status. The academic performance was obtained from tests administered to the children. The behavioral and social data were obtained from parents and teachers. Now that the children are young adults, we are also gathering data on their views of themselves with regard to these areas of performance. As we have been following the children, we have also been looking at a number of possible explanations for the poor language. Many of these have focused on the children's ability to process complex information efficiently; however, we are also looking at genetic factors and studies that track brain activity during certain critical tasks.

If I am in the study, does it mean I have SLI?
No. More of the people in this study do not have SLI than do. Furthermore, it is our view that we really do not know what SLI is. Our SLI diagnosis at this point is a hypothesis we are testing. When we are done, we expect to change our view and finetune our diagnosis of SLI based on what we discover.

Will I get treatment for my SLI?
Our study is not directed at providing treatment. Treatment is available in the schools, and we do provide parents with information on the children's performance in order that they may decide to seek treatment.

Is SLI a common problem?
We believe it is. Our initial work indicated that a little over 7 percent of children have this condition. We may find that we need to change our diagnostic standard, and therefore, the incidence rate may change. However, it is unlikely to change substantially.

If one child in a family has SLI, does that mean there is a greater chance the siblings will have it?
SLI is like a lot of health problems that have been studied recently. Family members of children with SLI are more likely to also have signs of SLI. The best estimates are that about 25 percent of the siblings are at risk for SLI as well. The data also suggest that this shared family risk for SLI comes from both sharing genes and sharing the environment.

Do the researchers feel the study has been successful?
Yes! We have already learned much about the nature of outcomes of children with poor spoken language skills. At the same time, the study is not complete. We need to know how these children do as young adults entering society. We have learned that school is very challenging. Possibly, school is a special place in which these children do particularly poorly, but once out in the "real world" they will thrive. If this is true, we have to learn how to help these children through school giving them the best education possible, but also without generating harm. We may find, however, that school is not so different from the "real world" and these children face many of the same challenges as they move into a society that is increasingly a society based heavily on communication.

What are the results so far?
We have learned a lot, so it is difficult to summarize. These are the main points.

First, we have found that a child's spoken language status relative to those of other children remains remarkably stable during the school years. In other words, children who start school with poor language skills are very likely to remain poor throughout the school years, and likewise, those with very good skills continue with very good skills. Surprisingly, we have also found that all children from the poorest to the best all seem to progress at the same rate. Thus, nobody is falling behind or catching up. These results are unexpected and should stimulate some important theoretical work.

Next, we have found that there is a very strong relationship between later reading success or failure and initial language ability. These findings are not surprising, and other research had shown this. What we are now seeing, however, is that these initial spoken language skills become increasingly important for providing the base for reading comprehension in the later years. Initially, a great deal of reading performance is determined by how well children can read words. By eighth grade, however, reading performance is much more related with how well children can understand the meanings in sentences and passages when they hear them. Children with SLI have difficulties with this skill.

We also find that children with poor listening and speaking skills are likely to have problems with most areas of academic performance. Furthermore, when they face these school challenges, some of these children also have behavioral problems at home and in the classroom.

With regard to our work on what causes SLI, we continue to find evidence that these children are limited in their memory and information processing abilities. When they hear complex words or sentences that require a good deal of mental processing, they do poorly. They also seem to do poorly on processing tasks that don't require speech or language at all.

What are things parents and teachers can do to help a child with SLI?
We are finding that identifying these children early is probably important. One of the principal problems these children face is reading difficulties. Intervention prior to entering school or as soon as the child enters school is important to reduce these reading problems. Parents and teachers need to provide these children with opportunities to engage in active listening situations. Hearing stories read to the child and then being asked to talk about what was heard is useful. During the early preschool years, it appears that parents need to provide a type of language exposure to these children often described as "responsive." (Responsive language means that you talk about what the child has said or done, and thus, is in response to the child's actions rather than talk that is intended to direct the child.)

CLRC history
The Child Language Research Center began in 1993 when funding was awarded to Dr. Bruce Tomblin and his colleagues by the National Institute on Deafness and Other Communication Disorders. In the decade prior to this, a new term, Specific Language Impairment (SLI), had emerged to describe the condition that occurs when young children don't seem to acquire language skills that come easily to their peers. By 1993, the NIH was interested in learning more about the basic epidemiologic features of SLI.

Epidemiologic study: The NIDCD awarded a contract to Tomblin to determine the prevalence and risk factors for SLI. In collaboration with epidemiologists, a study was designed to sample a large number of children who were entering school and identify among them the children with SLI. In order to do this, it was first necessary to develop diagnostic standards and measurement tools to screen for SLI. This work was published in 1996 (Tomblin, Records, & Zhang, 1996). The study called for examining SLI within the context of children living in urban, suburban, and rural strata. Therefore, three areas of Iowa were targeted that contained cities of more than 100,000 people.

More than 7,000 Midwestern kindergartners were then sampled and screened for poor language. Nearly 2,000 were then given more extensive diagnostic tests for SLI. This resulted in a final study that reported the prevalence of SLI (Tomblin et al., 1997).

The team also collected social, economic and health information about many of these children's backgrounds to see what risk factors might be associated with SLI. These data revealed that most of the risk factors pertained to characteristics of the parents' backgrounds and behaviors (Tomblin, Smith, & Zhang, 1997).

While the SLI epidemiologic study added significantly to science's understanding of human language development, it also provided the opportunity to learn a great deal about SLI in a sample of children who represented a random sample of such children. Most research on clinical conditions employs people who are receiving clinical services. It is well known that such clinical samples are actually not representative of all those who have a given condition. A longitudinal study that examined how these children develop and what happens to these children was compelling.

Longitudinal study: In light of the value of a longitudinal study of SLI, the CLRC applied for and received NIDCD funds to follow these children. The longitudinal study sampled more than 600 children from the kindergarten study to follow. About half of these children were identified as having a language impairment, while the remaining half served as the control group.

Now in high school, the research group continues to collect data, and thus, final conclusions are cannot be made yet. However, Tomblin and his colleagues' suspicions about the pervasiveness of language difficulties seem to be well founded.

For example, investigators can predict - with 80 percent accuracy - that a child with oral language difficulties at kindergarten will show problems reading in second grade. Overall, academic development, especially in reading and writing, suffers in children with language difficulties.

Behavioral problems also seem to accompany SLI. These children are likely frustrated by the inability to communicate well, which in turn, can lead to behavior and discipline problems.

Genetic studies: Early in our research, one risk factor began to stand out. There seemed to be more speech, language, and reading problems in the families of children with SLI than in families of controls. These observations led to funded research projects that examined the extent to which this familial characteristic was due to genetic factors and how much was environmental. This work resulted in findings that, as in many cases, it was both (Tomblin & Buckwalter, 1998). The fact that genes may contribute to a child's predisposition for SLI resulted in our teaming up with Dr. Jeff Murray and his research team at Iowa's College of Medicine. We have used the children in the longitudinal study to determine if genes that are already known to influence learning are associated with SLI.

As we seek additional information, however, we realize the study of the genetic aspect of language development and disorders is complex. It appears that no one gene is responsible for language development. Rather, it is likely that several genes influence the development of language - and when non-genetic factors are added to the mix - the full picture of language development may take years to fully understand.

The CLRC team also collaborates with other researchers, including experts in the area of language of children with cochlear implants, reading disabilities, and other language development problems.

Until the language development is fully understood, however, parents can take a proactive role by frequently talking with and reading to their young children. This enrichment during a child's early years can only benefit an individual's language skills.

Reference List
Tomblin, J. B. & Buckwalter, P. (1998). The heritability of poor language achievement among twins. Journal of Speech and Hearing Research, 41, 188-199.

Tomblin, J. B., Records, N. L., Buckwalter, P., Zhang, X., Smith, E., & O'Brien, M. (1997). The prevalence of specific language impairment in kindergarten children. Journal of Speech Language Hearing Research., 40, 1245-1260.

Tomblin, J. B., Records, N. L., & Zhang, X. (1996). A system for the diagnosis of specific language impairment in kindergarten children. Journal of Speech & Hearing Research, 39, 1284-94.

Tomblin, J. B., Smith, E., & Zhang, X. (1997). Epidemiology of specific language impairment: Prenatal and perinatal risk factors. Journal of Communication Disorders, 30, 325-344.

Thanks
On behalf of all who benefit from CLRC research, we thank again our hundreds of research subjects, their families and their educators. We extend our sincere best wishes to all in the years ahead. Thank you!

And, we express our gratitude to the National Institute on Deafness and Other Communication Disorders — a division of the National Institutes of Health — for generous support and ongoing research funding.

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