Research Report Preliminary study of disfluency in school-aged children with autism

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1 INT J LANG COMMUN DISORD, JANUARY FEBRUARY 2014, VOL. 49, NO. 1, Research Report Preliminary study of disfluency in school-aged children with autism Kathleen Scaler Scott, JohnA.Tetnowski, James R. Flaitz and J. Scott Yaruss Misericordia University, Department of Speech Language Pathology, Dallas, PA, USA University of Louisiana at Lafayette, Department of Communicative Disorders, Lafayette, LA, USA University of Pittsburgh, Communication Science and Disorders, School of Health and Rehabilitation Sciences, Pittsburgh, PA, USA (Received January 2013; accepted June 2013) Abstract Background: In recent years, there has been increased identification of disfluencies in individuals with autism, but limited examination of disfluencies in the school-age range of this population. We currently lack information about whether the disfluencies of children with autism represent concomitant stuttering, normal disfluency, excessive normal disfluency, or some form of disfluency unique to the school-age population of children with autism. Aims: This paper explores the nature of disfluencies in school-aged children with autism in comparison with matched children who stutter and controls. It explores stuttering-like disfluencies, non-stuttering-like disfluencies and word-final disfluencies. Methods & Procedures: This study compared disfluency patterns in 11 school-aged children with Asperger s syndrome (AS), 11 matched children who stutter (CWS), and 11 matched children with no diagnosis (ND). Analyses were based on speech samples collected during an expository discourse task. Outcomes & Results: Results reveal statistically significant differences between children with AS and CWS and between children with AS and those with ND for the percentage of words containing stuttering-like disfluencies. In the AS group, four out of 11 (36%) met the common diagnostic criteria for a fluency disorder. Disfluencies in the AS group differed qualitatively and quantitatively from the CWS, and included a larger distribution of word-final disfluencies. Conclusions & Implications: This study provides initial data regarding patterns of disfluency in school-aged children with AS that, with careful consideration and the cautious application of all findings, can assist therapists in making more evidence-based diagnostic decisions. Findings offer evidence that when working with children with AS, disfluencies both similar and dissimilar to those of CWS may be identified in at least a subset of those with AS. Therefore, children with AS should be screened for fluency disorders during their initial evaluation and treated if it is determined that the fluency disorder negatively impacts the effectiveness of communication. Keywords: autism, school-aged children, Asperger s syndrome, stuttering, dysfluency. What this paper adds? Shriberg et al. (2001) found disfluent speech in a study of individuals with Asperger s syndrome and high-functioning autism (average age of 20.7 years). Studies involving samples of eight or fewer individuals on the autism spectrum have identified disfluencies in preschool children, one school-aged child, teens and adults. Before this study, information was lacking about whether the disfluencies of children with autism represent concomitant stuttering, normal disfluency, excessive normal disfluency or some form of disfluency unique to the autism population. Findings offer evidence that when working with children with autism, disfluencies both similar and dissimilar to those of CWS may be identified in at least a subset of those with autism. Clinical implications suggest that stuttering, cluttering and atypical disfluencies should all be ruled out when assessing those on the autism spectrum, and that expository discourse may be a useful context for taxing school-aged children who stutter to elicit disfluencies during evaluation. Address correspondence to: Kathleen Scaler Scott, Misericordia University, Department of Speech Language Pathology, 301 Lake Street, Dallas, PA 18612, USA; kscott@misericordia.edu International Journal of Language & Communication Disorders ISSN print/issn online C 2013 Royal College of Speech and Language Therapists DOI: /

2 76 Kathleen Scaler Scott et al. Introduction Asperger s syndrome (AS) is a diagnostic classification that falls within the autism spectrum. It was a former specific diagnostic category within the autism spectrum (American Psychiatric Association 2000), which recently was merged within the larger diagnostic category of autism (American Psychiatric Association 2013). Children on the autism spectrum struggle with social communication and interaction. Similar to some children who stutter (CWS), despite average cognition and receptive and expressive language on standardized testing, children with AS have other communication challenges that cause them to struggle with overall effective communication (Koning and Magill-Evans 2001, Shriberg et al. 2001, Tager-Flusberg 1994). Among the communication challenges experienced by many children and adults on the autism spectrum are difficulties with speech production, including disorders in the areas of articulation, stress, resonance, phrasing, prosody and fluency (Paul et al. 2005, Shriberg et al. 2001). In terms of fluency of speech, qualitative and descriptive studies have identified disfluency patterns in individuals with autism spectrum disorders (ASDs), both at the linguistic level (i.e. cohesiveness of message) and at the level of speech (i.e. fluency of production of speech sounds and syllables). Repetitions of parts of words, syntactical structures and lexical items were identified by Dobbinson et al. (1998) in the conversational patterns of a 28-year-old woman diagnosed with autism and mental retardation. Simmons and Baltaxe (1975) described speech patterns that could be characterized as stuttering-like (i.e. repetitions of sounds or syllables, prolongations of sound, blockage of sound from moving forward) and non-stuttering-like (i.e. repetitions of phrases, revisions of thought, use of interjections or filler words) disfluencies (Ambrose and Yairi 1999, Yairi and Ambrose 1992) in the speech of seven adolescents diagnosed with autism with at least average intelligence quotient (IQ) scores. Shriberg et al. (2001) were the first to confirm disfluent speech within the specific diagnostic category of AS. They examined the speech fluency of 15 individuals with AS and 15 individuals with high-functioning autism, as compared with 53 age-matched controls. Participants ranged in age from 10 to 50 years. Results indicated that 67% of the individuals with AS and 40% of the individuals with high-functioning autism had inappropriate or nonfluent phrasing, including sound, syllable, or word repetitions and single-word revisions on more than 20% of their utterances. More detailed disfluency analyses in studies with small sample sizes have revealed stutteringlike, non-stuttering-like, and atypical disfluencies in children and adults on the autism spectrum. Disfluencies were identified in studies of eight preschoolers on the autism spectrum (Plexico et al. 2010), one schoolaged child with AS (Sisskin 2006, Tetnowski et al. 2012), two teens on the autism spectrum (Hietala and Spillers 2005), one teen with AS (Sisskin 2006), and two young adults with AS (Scott et al. 2006). Atypical disfluencies were identified in each of these studies. In addition to presenting with stuttering and non-stuttering-like disfluencies, seven out of eight children in the Plexico et al. (2010) study exhibited atypical disfluencies, defined by the authors as between syllable insertions, within word breaks, final sound and syllable repetitions, and final sound prolongations (p. 48). Hietala and Spillers (2005) observed patterns of disfluencies in two teens diagnosed within the category of ASDs. In speech samples, both teens exhibited what the authors termed abnormal disfluencies, defined as final-syllable repetitions (e.g. football-ball ), rhyme repetitions (e.g. cat-at ), and disrhythmic phonation. The authors defined this disrhythmic phonation as an atypical pause within a word. In addition to the abnormal disfluencies, one participant also exhibited non-stuttering-like disfluencies, including single-syllable whole-word repetitions, revisions and filler words. More typical stuttering-like disfluencies, including part-word repetitions and blocks, as well as non-stuttering-like disfluencies including phrase repetitions and interjections, were also identified in two cases of young adults with AS (Scott et al. 2006). Both participants demonstrated at least some awareness of their disfluencies. In her study of two individuals with AS, Sisskin (2006) described two cases of students with AS, one aged 7 and the other aged 17, who both exhibited stuttering-like disfluencies, including part and whole-word repetitions and blocks; and non-stuttering like disfluencies, including phrase repetitions, revisions and interjections. Sisskin reported that the majority of disfluencies observed in the school-aged child and teen studied were either mid-syllable insertions or word-final disfluencies. Sisskin defined mid-syllable insertions as a short exhalation resembling the production of /h/, e.g. way-hay and word-final disfluencies as repetitions in which the repetition forms a rhyme by omitting the initial consonant(s) or syllable of the target word (p. 13) (e.g. train-ain ). Lake et al. (2011) compared the frequency of filled pauses, silent pauses, repetitions and revisions in 13 adults on the autism spectrum and 13 controls. All participants had average IQ and four of those in the autism group were diagnosed with AS. Results indicated increased silent pause and disfluent repetitions and fewer filled pauses and revisions among the adults with autism as compared with controls. While word-final disfluencies are not a pronounced characteristic of developmental stuttering they have been observed in populations within diagnostic categories other than stuttering, such as children and adults with neurological insults (Ardila and Lopez 1986, Bijleveld

3 Disfluency in autism 77 et al. 1994, Lebrun and Leleux 1985, Lebrun and van Borsel 1990, Rosenfield et al. 1991, Stansfield 1995, van Borsel et al. 1996, 2005). These patterns have also been observed in children with no diagnosis. Mowrer (1987) reported on a child with no other speech or language issues who was referred at 2 years, 10 months of age with 82% of his part-word repetitions in the final position. McAllister and Kingston (2005) reported on two school-age boys who presented with average intelligence and no known neurological issues. In a disfluency analysis, the authors indicated that both boys presented with interjections, single and multi-word repetitions, revisions, and incomplete phrases. Both boys also presented with initial part-word repetitions, broken words and final part-word repetitions. Neither boy presented with blocks, and one presented with prolongations. The two types of disfluency that occurred with the highest frequency for both boys were final part-word repetitions and revisions, with final-part word repetitions occurring with the highest frequency in one of the two boys. Disfluency is just one of many possible communication difficulties for a child on the autism spectrum. Given the number of communication issues a speech language pathologist (SLP) needs to address with students with ASDs, it would be easy to place disfluency low on the priority list. Most SLPs would likely agree, however, that pragmatic language is a high priority treatment goal for a child with autism (Prizant et al. 2003). If one considers factors related to disfluency that may exacerbate weak pragmatic communication skills, such as secondary behaviours (e.g. lack of eye contact) or lack of clarity in communication due to excessive revisions, the importance of understanding disfluency in this population becomes more evident. Without a true understanding of the role disfluency plays in effective communication for children with autism, we cannot say for certain what impact the speech characteristic may or may not have upon an individual s overall communication effectiveness. Specifically, for a child with AS, who by definition has no difficulties with formal language, it may be easy for fluency issues to be missed upon initial screening of speech language disorders. There are some normative data that compare the disfluencies of CWS and have no other diagnosis with those of children who do not stutter and have no other diagnosis (Ambrose and Yairi 1999, Haynes and Hood 1977, Yairi 1981, Yairi and Lewis 1984). These normative data show increased frequency of stuttering-like disfluencies in CWS. There are also some data that have identified excessive disfluency, especially non-stuttering-like disfluencies, in children with diagnosed language disorders (Hall 1977, 1996, Hall et al. 1993, van Borsel and Tetnowski 2007). There is also one study that compares the speech prosody characteristics of CWS, children with no diagnosis and children with autism (Fosnot and Jun 1999) and the aforementioned Lake et al. (2011) study comparing disfluencies in adults with autism with controls. There are no data that compare the speech fluency of school-aged children with autism with schoolaged children with no other diagnosis who do and do not stutter. Although the Shriberg et al. (2001) study does include an age range beginning at 10 years of age, average age of the group of participants with AS was 20.7 years. Additionally, this study did not include more than a descriptive analysis of disfluency types. We currently lack information about whether the disfluencies of children with AS represent concomitant stuttering, normal disfluency, excessive normal disfluency, or some form of disfluency unique to the AS population. This gap in the literature poses a problem for accurate diagnosis. For example, a child with AS and outward disfluencies may be perceived as having concomitant stuttering by one diagnostician, normal disfluency by another and excessive normal disfluency by another. Each diagnosis carries with it treatment implications: stuttering is treated with strategies for minimizing or modifying speech disruptions, normal disfluency is not treated at all, and excessive normal disfluency may be treated as a language or self-monitoring issue. Finding out whether children with AS have disfluencies that differ from or are similar to children with no diagnosis or CWS would help differentiate whether the disfluencies observed in children with AS are a unique and distinguishing feature of the speech of children with AS, or whether they are more prone to have a concomitant stuttering disorder. This information would provide a foundation for a more evidence-based diagnosis. Expository discourse represents a taxing linguistic context that is both relevant to school communication expectations (Nelson 1998, Rupp 2000) and provides a context rich with potential for eliciting disfluencies for study. This context has yet to be studied in CWS and children with AS. Following the logic that frequency of disfluencies increase as formulation demands increase, all children should demonstrate more non-stutteringlike disfluencies in a taxing context such as expository discourse than can be elicited in a less taxing context, such as conversation. Watkins et al. (1999) concluded that given that spontaneous language samples have not revealed any specific linguistic differences in preschool/early school-age CWS, a future avenue of recommended research should be examining language that involves on-line processing. Examination of disfluency patterns for cognitively taxing discourse tasks such as expository discourse would provide a rich context for observation of fluency during an on-line processing task. Such a study also would allow for observation of the potential impact of this type of task upon the disfluencies of CWS versus children without stuttering.

4 78 Kathleen Scaler Scott et al. The purpose of this study was to examine whether there is a significant difference in the frequency and types of disfluencies exhibited by school-aged children with AS, CWS and those with no diagnosis (ND) during an expository discourse task. Since word-final disfluencies have been noted more in populations within a diagnostic category other than stuttering (Ardila and Lopez 1986, Bijleveld et al. 1994, Lebrun and Leleux 1985, Lebrun and van Borsel 1990, Rosenfield et al. 1991, Stansfield 1995, Tetnowski et al. 2012, van Borsel et al. 1996, 2005, Cosyns et al. 2010), and since some of these atypical disfluencies have been identified in previous studies of individuals with ASDs (Hietala and Spillers 2005, Plexico et al. 2010, Scott et al. 2006, Sisskin 2006, Tetnowski et al. 2012), the frequency of wordfinal disfluencies among these three populations was also examined. The following research questions were examined: Is there a significant difference in the percentage of words containing disfluencies between children with AS, CWS and those with ND during an expository discourse task? Is there a significant difference in the percentage of words containing each type of disfluency (i.e. stuttering and non-stuttering-like) between children with AS, CWS and those with ND during an expository discourse task? Is there a significant difference in the percentage of words containing word-final disfluencies between children with AS, CWS and those with ND during an expository discourse task? Material and methods Participants The total sample consisted of 33 males in grades 4 7 who were included in one of three different groups. There were three groups of 11 that were matched for grade level and sex: Children with a diagnosis of AS. Children with a diagnosis of stuttering (CWS). Children with no diagnosis (ND). Females were recruited for this study, but only one matched set was able to be obtained. Because an equal number of male and female participants were unable to be obtained for this study, the one-matched-set of females was excluded in order to ensure a more homogenous participant group. Adequate sample size, as determined through a priori power analysis based upon the GPOWER program (Erdfelder et al. 1996) and reviews of similar studies (Boscolo et al. 2002, Scott and Windsor 2000), was determined to be per group to obtain a large effect size (d = 0.80) at a power of Unfortunately, obtaining adequate sample sizes for disorders of (relatively) low prevalence such as stuttering and AS proved to be especially challenging in the current study, where participants were recruited within a narrow 4-year grade range (i.e. grades 4 8) and were closely matched according to several criteria. As data collection ensued, it became clear that it would not be possible to achieve the target sample size. When all available data had been obtained, power calculation was repeated to establish what impact the reduced sample size would have on the power of the study s design. Re-calculation established that the power of the study design to detect differences associated with the desired effect size (0.40) had fallen from 0.80 to Despite that decrease, it was decided that the design would have sufficient power to detect larger differences (if they were present), and so analysis proceeded, with an appreciation that the sample size might limit the ability of the study to detect those smaller differences, if they existed. This study was designed to control for influence of both age and grade level experience with expository discourse upon the speech sample obtained. Students were matched first by grade level, as grade level experience would impact experience with and exposure to expository discourse (Rupp 2000). There is precedent for grade-level matching in studies of school-aged children (van Houtte and Jarvis 1995). The mean grade level of the groups was 5.2 (SD = 1.2). Additionally, students who repeated a grade were excluded from this study to ensure homogeneity in the age of each group. The mean age of the children with AS was 11 years, 3 months (SD = 1 year, 2 months). The mean age of the CWS was 11 years, 0 months (SD = 1 year, 1 month). The mean age of the children with ND was 11 years, 3 months (SD = 1 year, 1 month). There were no significant differences between the groups in terms of age (F(2, 30) = 0.176, p = 0.839). As parental education level has been found to influence language production (Dollaghan et al. 1999, Entwisle and Astone 1994, Hauser 1994, Hoff and Tian 2005), and therefore has the potential to influence length and/or syntactic complexity in expository discourse, participants were also matched by maternal level of education. Levels of education were categorized with values of 1 for those with a high-school diploma with or without coursework short of a 4-year college degree, and two for those with a 4-year college degree, with or without post-baccalaureate education. In each group 27% of mothers fell into category 1 and 73% into category 2 since groups were matched exactly by level of maternal education. Based upon the informal assessment of an SLP with 15 years of experience in the

5 Disfluency in autism 79 assessment and treatment of child language disorders, no frank language disorders were observed in any study participants. Participants were recruited through various stuttering and AS support groups, as well as through referrals from speech language pathologists (SLPs), educational administrators, and other professionals (e.g. psychologists, neuropsychologists) within several states throughout the northeastern and southern United States. None of the participants demonstrated emotional or behavioural issues that precluded their cooperation with study procedures. Classification and inclusion criteria Children with AS Children with AS met the following inclusion criteria: (1) the child received a diagnosis of AS from a professional qualified to make that diagnosis, specifically a neuropsychologist, developmental paediatrician, neurologist or psychiatrist (Filipek et al. 1999); and (2) no change had occurred in diagnosis. Supporting documentation of at least average IQ was obtained for each child with AS. Report card grades were not used to classify the AS group because in this population grades are often not an accurate representation of academic potential due to attention and social concerns that may be associated with AS (Perry 2004). Because this study involved an exploration of fluency within the AS population, there were no exclusionary criteria for stuttering or other fluency issues within this group. Two participants in the AS group exhibited mild articulation difficulties. One exhibited an f/th substitution, while the other presented with distortion of rhotic /r/. Neither articulation impairment hindered accurate transcription of utterances by either the primary investigator or secondary coders. Neither had received treatment to address these specific articulation issues. CWS CWS met the following inclusion criteria: (1) the child and parent reported stuttering difficulty; (2) the child received an overall score of at least 6 (a severity equivalent of at least very mild ) on the Stuttering Severity Instrument, Third Edition (SSI-3; Riley, 1994); and (3) the child was enrolled in regular education classes and performing at grade-level expectations, according to report card numerical scores of 70s or higher or letter grades of C s or better within the prior year. Report card grades were used to rule out potential indicators of undiagnosed learning or emotional difficulties (Baker et al. 2006, Hill and Wigfield 1984). Additionally, to strengthen the validity of diagnosis, stuttering diagnosis was confirmed by an SLP and board-recognized specialist in fluency disorders with 20 years of experience in the field of fluency disorders. Stuttering ranged in severity from very mild to very severe, with a mean SSI-3 total overall score of (range = ). Children with ND Children with ND met the following inclusion criteria: (1) the child received a score of 5 or lower on the SSI-3 (less than the severity equivalent of very mild stuttering ); (2) no concerns were reported by the child, parent or other professional regarding stuttering or fluency of speech; (3) the child was enrolled in regular education classes and performing at grade-level expectations, according to report card numerical scores of 70s or higher, or letter grades of C s or better within the prior year; and (4) the child had no history of stuttering, cluttering or other fluency disorders per parent report. Additionally, lack of stuttering or other fluency diagnosis was confirmed by an SLP and board-recognized specialist in fluency disorders. Procedures Speaking and testing tasks All children were asked to engage in conversation with the primary investigator, to complete a monologue on a topic of their choice and to read one short passage from the SSI-3. The SSI-3 score confirmed group placement for the CWS and ND children. It also served to delineate any patterns of stuttering observed in the group of children with AS. During conversation the CWS and any children with AS who presented with stuttering were asked about their stuttering symptoms and their feelings and reactions to them. In order to gather a sample of each child s speech within the context of expository discourse, each participant was shown a 20-min educational video developed for students in grades 4 8. The film Weathering and Erosion (Discovery Education 2002) was selected based upon its representation of expository structure (Nelson 1998, Scott and Windsor 2000), including an introduction, transitions and conclusion, and elements of description, illustration and sequence. Previous studies (Liles 1993, Scott and Windsor 2000) and pilot work for the current study determined that a 15-min video was an appropriate minimum length for eliciting a verbal summary of adequate length for speech fluency analysis. Each participant watched the video. After watching the video, the following instructions were given: For this part, you re going to tell me about the video. You re going to try to tell me as completely as you can. You re going to try to talk for about five minutes. Some

6 80 Kathleen Scaler Scott et al. of that time you may be thinking, and that s just fine. Anything they told you about or showed you on the video, or anything you heard about or saw on the video is fair to talk about. Whenever you are ready you can start. The primary investigator provided neutral comments throughout the child s summary (e.g. Yes, Mmm-hmm ). Each participant was provided with verbal reminders that there was more time left. If the child stopped significantly before 5 min had passed, the primary investigator cued the child with You re doing a great job. You still have some time left. Take some time to think. See if there is anything else you can tell me about what you saw or they told you in the video. If after this cue the child still was unable to think of anything to add, the examiner used an open-ended question cue to facilitate expansion upon specific topics already mentioned. No cueing was provided to elicit information about topics the student did not already mention spontaneously. Furthermore, no closed-ended questions were used to elicit additional information from any participants. All responses were videotaped for analysis. A digital video camera (Canon ZR 800) with external microphone (Shure PG58) was used to record the samples. Data coding The primary investigator orthographically transcribed each expository discourse sample verbatim. Procedures for counting words for fluency analysis followed the methods of Yaruss (1997a, 1997b). Transcripts were used to calculate the following dependent variables for each participant. Frequency of disfluency: this variable was calculated by dividing the total number of disfluencies by the total number of words to obtain percentage of words containing disfluencies (hereafter described as total words disfluent, TWD) for each participant. Type of disfluency: this variable was calculated by first obtaining the total number of stutteringlike disfluencies and non-stuttering-like disfluencies for each participant, and dividing each by the total number of words, to obtain percentage of words containing each of the two disfluency categories. Following the conventions of Yairi and Ambrose (1992) and Ambrose and Yairi (1999), non-stuttering-like disfluencies are defined for this paper as phrase repetitions, revisions, interjections, multi-syllable whole-word repetitions, and single-syllable whole-word repetitions without tension. Stuttering-like disfluencies are defined for this paper as part-word repetitions, single-syllable whole-word repetitions with tension, prolongations, and blocks/tense pauses. Per cent of words with word-final disfluencies: this variable was calculated by totalling the number of word-final disfluencies within each sample and dividing this by the total number of words to obtain the percentage of words containing wordfinal disfluencies for each participant. Word-final disfluencies were defined for this study as partword repetitions of final sounds or syllables of words (e.g. chair-air, light-t ) or prolongations of final sounds of words (e.g. thissss ). Measurement reliability Both inter- and intra-judge reliability measures were calculated for all dependent variables. The primary investigator, an SLP with 15 years of experience and a boardrecognized fluency specialist, trained a second coder (a first-year doctoral student specializing in fluency disorders) who was not aware of the study s research questions or hypotheses, nor to the diagnosis of any participant. The second coder re-transcribed 10% of each of the 33 transcripts and identified frequency, type and word-final disfluencies for these samples. The inter-class correlation coefficient for percentage of words containing disfluencies was 0.98 (95% CI = ). The ICC for percentage of words containing non-stuttering-like disfluencies was 0.98 (95% CI = ). The ICC for percentage of words containing stuttering-like disfluencies was 0.93 (95% CI = ). The ICC for percentage of words containing word-final disfluencies was 0.82 (95% CI = ). To determine intra-judge reliability, the primary investigator re-transcribed and re-calculated dependent variable measures for 10% of each of the 33 transcripts, 2 weeks after initial transcription, following the previously outlined procedures. The inter-class correlation coefficient for percentage of words containing disfluencies was 0.99 (95% CI = ). The ICC for percentage of words containing non-stuttering-like disfluencies was 0.99 (95% CI = ). The ICC for percentage of words containing stuttering-like disfluencies was 0.99 (95% CI = ). The ICC for percentage of words containing word-final disfluencies was 1.00 (95% CI = ). Strong intra- and inter-judge reliability for all variables indicated that the primary investigator s coding was sufficiently consistent to be used for all analyses. Data analysis Because of concern regarding possible violations of assumptions of parametric procedures, disfluency analyses were run following non-parametric procedures.

7 Disfluency in autism 81 A series of Kruskal Wallis tests were used to test for differences between the groups for TWD and for percentage of words containing non-stuttering-like disfluencies, stuttering-like disfluencies and word-final disfluencies. Mann Whitney U-tests were run as non-parametric post-hoc analyses when significant main effects were found. Main and post-hoc comparisons were performed at the individual α = level to maintain an overall α = 0.05 across three comparisons. Results Frequency of disfluency A Kruskal Wallis test was conducted to evaluate differences among the three participant groups for the total percentage of words containing disfluencies. The test, which was corrected for tied ranks, was significant χ 2 (2) = 11.20, p = To establish the effect size associated with the observed group differences, partial eta squared was calculated. For this analysis, adjusted partial eta squared was 0.258, which can be viewed as a large effect (as per adjustments of Cohen s d to partial eta squared; Cohen 1988). A Mann Whitney test was used to test the hypothesis that the distribution of disfluencies for all three groups was equal. The distributions of TWD in the group of children with AS was not significantly different from that of the CWS (U = 28.0, p = 0.034) nor from that of the children with ND (U = 37.0, p = 0.133). The distribution of TWD in the CWS was significantly different from that of the children with ND (U = 13.0, p = 0.001). Cohen s d calculated on pairwise comparisons (Thalheimer and Cook 2002) indicated a large effect size (d = 1.57) between CWS and children with ND, a medium effect size (d = 0.71) between children with AS and children with ND, and a large effect size (d = 0.89) between children with AS and CWS for TWD. Types of disfluency Non-stuttering-like disfluencies The Kruskal Wallis test indicates that the three participant groups could not be differentiated based upon the dependent measure of percentage of words containing non-stuttering-like disfluencies, χ 2 (2) = 4.05, p = 0.13 Adjusted partial eta squared was 0.036, suggesting a small effect (Cohen 1988). Stuttering-like disfluencies Kruskal Wallis results revealed that there were significant differences between the groups in terms of percentage of words containing stuttering-like disfluencies, χ 2 (2) = 22.23, p < Adjusted partial eta squared was 0.378, suggesting a large effect (Cohen 1988). Significant differences were found for percentage of words containing stuttering-like disfluencies between the group of children with AS and the CWS (U = 20.0, p = 0.007), between the group of children with AS and the children with ND (U = 9.00, p < 0.001) and between the CWS and the children with ND (U = 0.000, p < 0.001). Cohen s d calculated on pairwise comparisons indicated a large effect size (d = 1.83) between CWS and children with ND, a large effect size (d = 1.37) between children with AS and children with ND, and a large effect size (d = 1.09) between children with AS and CWS for percentage of words containing stuttering-like disfluencies. Word-final disfluencies The Kruskal Wallis test indicates that the three participant groups could not be differentiated based upon the dependent measure of percentage of words containing word-final disfluencies, χ 2 (2) = 5.22, p = Adjusted partial eta squared was 0.047, suggesting a small effect (Cohen 1988). Medians and interquartile rankings for all disfluency types are presented in table 1. Other observations regarding fluency disorders Of the sample of 11 children with AS in the current study, eight (72%) qualified as exhibiting at least very mild severity on the SSI-3. However, only three of these children qualified as diagnosable stuttering, as indicated by a qualifying score on the SSI-3 and concerns either by self-report or report of parents and/or professionals. Table 1. Per cent of disfluency by type and participant group AS (n = 11) CWS (n = 11) ND (n = 11) Median (IQR) Median (IQR) Median (IQR) Percentage words disfluent ( ) ( ) 8.46 ( ) Percentage words w/nslds ( ) ( ) 8.05 ( ) Percentage words w/slds 2.37 ( ) 8.74 ( ) 0.65 ( ) Percentage words w/wfds 0.24 ( ) 0.00 ( ) 0.00 ( ) Notes: a AS, Asperger s syndrome; CWS, child who stutters; ND, no diagnosis; NSLDs, non-stuttering-like disfluencies; SLDs, stuttering-like disfluencies; WFDs, word-final disfluencies; and IQR, interquartile range.

8 82 Kathleen Scaler Scott et al. Figure 1. Stuttering severity by group. One of these three presented with secondary behaviours and avoidance of stuttering. He discussed stuttering s negative impact upon his communication, whereas the other two did not discuss this impact. Figure 1 displays box plots comparing the distribution of SSI-3 severity ratingswithineachofthethreegroups.theseboxplots demonstrate that the median stuttering severity was no stuttering for the ND group, very mild severity for the group of children with AS, and mild to moderate severity for the group of CWS. The variability within the group of children with AS ranges from no stuttering to moderate, while the variability within the group of CWS ranges from very mild to very severe. Three of the group of children with AS met the diagnostic criteria for cluttering, according to the St. Louis and Schulte (2011) definition. Specifically, these children first met the primary criteria mandatory for diagnosis of cluttering, i.e. perceived rapid and/or irregular rate of speech. Additionally, each participant diagnosed with cluttering met at least one of the following criteria outlined by the St. Louis and Schulte definition: (1) excessive non-stuttering-like disfluencies; (2) excessive collapsing or deletion of syllables; and (3) atypical pauses. Diagnosis was made upon review of all speech samples collected (conversation, monologue, reading) by an SLP with 15 years of experience and extensive experience in diagnosing and treating cluttering according to this definition. Diagnosis was also confirmed by a second SLP and board-recognized specialist in fluency disorders with more than 20 years of experience diagnosing fluency disorders. Two of the three participants who presented with cluttering were the same two who also presented with a prior diagnosis of stuttering. Neither parent nor child was aware of this dual diagnosis, though one parent reported concern over effectiveness of communication. In summary, two of the

9 Disfluency in autism 83 Table 2. Distribution of word-final disfluencies exhibited by each participant by type Number Group Grade Percentage WFDs = PWR Percentage WFDs = Pr Percentage TWD = WFDs 1 AS AS AS AS AS AS AS AS CWS CWS CWS CWS ND ND ND Note: AS, Asperger s syndrome; CWS, child who stutters; ND, child with no diagnosis; WFDs, word-final disfluencies; PWR, part-word repetition; Pr, prolongation; and TWD, total words disfluent. participants with AS presented with stuttering and cluttering, one with only stuttering and one with only cluttering. Among the children with AS, word-final disfluencies were present in the speech samples of eight out of 11 children, or 72% of the group. By comparison, wordfinal disfluencies were present in 36% (four out of 11 children) of the group of CWS and 27% (three out of 11 children) of the group of children with ND. The percentage of each child s TWD that were word-final disfluencies ranged from 1% to 39% in the group of children with AS, from 0.3% to 7% in the group of CWS, and from 1% to 2% in the group of children with ND. Although in each of their group s distribution of overall disfluencies, both the CWS and the children with AS presented with the highest percentage of non-stutteringlike disfluencies (74% for children with AS and 58% for CWS), the CWS presented with a higher percentage of stuttering-like disfluencies (41% for CWS; 21% for children with AS), while the children with AS a higher percentage of word-final disfluencies (5% for children with AS and 1% for CWS). Details regarding the frequency and types of word-final disfluencies exhibited by each participant are presented in table 2. Similar to the findings of Plexico et al. (2010) and Sisskin (2006), several instances of sound insertions (e.g. gravity-sh-ty) were noted among the samples of children with AS. These insertions were not observed among the CWS or the children with ND. In summary, results reveal statistically significant differences between CWS and children with ND in terms of percentage of words containing disfluencies, and percentage of words containing stuttering-like disfluencies. Results also reveal statistically significant differences between children with AS and CWS and between children with AS and children with ND for percentage of words containing stuttering-like disfluencies. No statistically significant differences were found between the three participant groups for percentage of words containing non-stuttering-like disfluencies or word-final disfluencies. Descriptive findings indicated that one of the participants with AS presented with pure stuttering, one with pure cluttering, and two with stuttering-cluttering. Discussion Frequency and type of speech disfluencies It was expected that the percentage of words containing stuttering-like disfluencies would be significantly greater in the CWS than in the children with ND. Given that stuttering-like disfluencies have not been identified as a diagnostic hallmark of AS, it is also not surprising that the CWS presented with a higher percentage of words containing stuttering-like disfluencies than did the children with AS. Since there are no baseline data comparing the disfluencies in children with AS with CWS, there was potential for children with AS to exhibit a significantly greater percentage of words containing non-stuttering-like disfluencies and/or TWD than CWS. It is possible that a factor contributing to the lack of significant difference between the group of children with AS and the group of CWS in terms of TWD was that the AS group was comprised of three children with a concomitant stuttering diagnosis. This factor alone cannot account for the similar patterns observed in the data, given notable effect sizes between groups for TWD. Results of analyses did provide support for a conclusion that the AS children differ from the ND children in terms of percentage of words containing stutteringlike disfluencies. The fact that eight of the 11 children

10 84 Kathleen Scaler Scott et al. in the AS sample (72%) qualified as exhibiting at least very mild severity on the SSI-3 is consistent with the disfluencies found among 67% of the AS sample in the Shriberg et al. (2001) study. Although the criteria in the current study and the Shriberg et al. study were different, in that Shriberg et al. included single-word revisions in their analysis while the SSI-3 does not, the trend of disfluent speech within more than half of a sample of individuals with AS is the same. The apparent trend of increased stuttering-like disfluencies among children with AS in this study is also consistent with findings in the literature regarding increased stuttering-like disfluencies among other communication-disordered populations (Blood et al. 2003, van Borsel and Tetnowski 2007), including children with language disorders (Hall 1977, 1996, Hall et al. 1993) and the school-aged children in a study conducted by Boscolo et al. (2002). Participants in the Boscolo et al. study had a history of specific expressive language impairment in preschool but by school age, similar to children with AS, scored within normal limits on standardized language testing. Boscolo et al. suggest a potential relationship between subclinical language disorders and development of fluency in such children (Boscolo et al. 2002). The nature of this relationship in the AS population requires further study. The large percentage of children with AS in the current study who qualified as stuttering on the SSI-3 clearly distinguish this group from the study s children with ND. The most recent prevalence estimate of stuttering among school age children is 1% (for a review, see Bloodstein and Bernstein Ratner 2008). At first glance, the high rate of at least very mild stuttering among the group of children with AS in this study suggests that this diagnosed group may be more prone to concomitant stuttering than children with ND. However, the observation of a high rate of stuttering among the AS group must be tempered with the fact that among the eight children with AS who qualified as stuttering on the SSI-3, only three (37%) presented with a diagnosable stuttering disorder. Although the majority of the group of children with AS may have demonstrated a propensity toward increased stuttering-like disfluencies, the presence of increased stuttering-like disfluencies did not always result in a diagnosis of stuttering. It is possible that at least a subgroup of children with AS are more prone to stuttering symptoms than children with ND, but that the typical severity of symptoms for this subgroup is less than that among CWS with no other diagnosis. Location and atypical fluency patterns in AS No statistically significant differences were found between the three participant groups in the frequency of word-final disfluencies. Given the limited production of word-final disfluencies in all groups, there may not have been enough evidence to judge this aspect of the problem effectively. The data seem to suggest a possible trend toward increased frequency of occurrence in this sample of children with AS as compared with the other two groups. In each of their group s distribution of overall disfluencies, the CWS presented with a higher percentage of stuttering-like disfluencies, while the children with AS a higher percentage of word-final disfluencies. This suggests that in this study s sample of children with AS, word-final disfluencies were more commonly part of their disfluency types than they were in CWS. Although it is clear that the trend in these samples is for increased word-final disfluencies among children with AS, there is a much wider range of variability within the group of children with AS than within the other two groups. Thus, any trend of significant differences between the AS group and the other two groups may be masked in this small sample by such differences in within versus between group variability. Among the children with AS who presented with word-final disfluencies, 75% of this group (i.e. six out of eight participants) scored within at least a very mild severity rating on the SSI-3. The other 25% of the group therefore had word-final disfluencies in their speech samples but did not demonstrate any other signs of stuttering. At times, the word-final disfluencies presented like stuttering-like disfluencies in a different location of the word than is typically observed in CWS. That is, the word-final disfluencies presented as a partword repetition (e.g. light-t-t ) or a prolongation (e.g. wishessssss ) at the end rather than the beginning of the word. At other times, however, the word-final disfluencies among the group of children with AS appeared differently than moments of stuttering. For example, the repetition might appear after a delay, and without evidence of tension in speech (e.g. It s usually working with another agent(pause)-t and erosion... ). These patterns were not observed among the other two participant groups, and suggest that word-final disfluencies may represent a pattern of disfluency different from stuttering which is observed more frequently in the AS population than in CWS and children with ND. The current study s finding of increased word-final disfluencies in the children with AS is consistent with the aforementioned research that has identified word-final disfluencies in populations within a diagnostic category other than stuttering, including in preschoolers with autism (Plexico et al. 2010), school-aged children (Hietala and Spillers 2005, Sisskin 2006, Tetnowski et al. 2012) and adolescents with AS (Sisskin 2006) and other neurologically based disorders (Ardila and Lopez 1986, Bijleveld et al. 1994, Cosyns et al. 2010, Lebrun and Leleux 1985, Lebrun and van Borsel 1990, Rosenfield

11 Disfluency in autism 85 et al. 1991, Scott et al. 2006, Stansfield 1995, van Borsel et al. 1996, 2005). Within these studies, some participants also presented with other patterns of stuttering, while others did not. In their study of word-final disfluencies of an adult with neurofibromatosis type I, Cosyns et al. (2010) hypothesize that the word-final disfluencies are possibly related to stuttering, if not true stuttering, and may relate to difficulties terminating speech. Further study of these patterns is needed. Other fluency concerns in AS Although there is limited research regarding prevalence of cluttering within the general population, experts estimate that between one-third and two-thirds of individuals who stutter also clutter (Ward 2006). It is important to note, however, that because lack of awareness is common in cluttering (St. Louis et al. 2007, Scaler Scott et al. 2010, Weiss 1964), many cases may have gone unidentified. Therefore, there is potential that such estimates are less than reliable. Nonetheless, in the current study, two out of three, or 67%, of the children with AS identified as stuttering were also identified as cluttering. Thus, the thought that stuttering and cluttering often co-occur appears to be consistent with the findings among the children with AS in this study s sample. It is also important to note that the patterns of disfluency noted among the group of school-aged children with AS in this study seem to follow the frequency and type of trends of both adults with AS (Shriberg et al. 2001) and preschoolers on the autism spectrum (Plexico et al. 2010). This repeated pattern of disfluent speech in three distinct samples of 15 individuals or less on the autism spectrum suggests a strong trend in at least a subset of individuals with AS. Clinical Implications Clinically, this study has implications in terms of assessment of both children with AS and CWS. Specifically, when evaluating children with AS, SLPs need to be aware of the potential for increased speech disfluency, particularly stuttering-like disfluencies and word-final disfluencies, within this population. The fact that the disfluency patterns within this population may not mirror those within the population of CWS does not imply that the fluency concerns among the children with AS are insignificant. Rather, they suggest that SLPs need to examine the potential impact of the disfluency patterns (including stuttering and non-stuttering like, and word-final disfluencies) upon each individual s overall effectiveness and efficiency of communication. Additionally, the small sample of students with AS presented with a higher percentage of diagnosable stuttering than within the larger school-age population (Bloodstein and Bernstein Ratner 2008), and within other diagnosed populations such as ADHD (Blood et al. 2003). Consequently, SLPs should evaluate students with AS for the possibility of concomitant stuttering. Given, however, the high number of false positives for stuttering within the AS group using the SSI-3 alone, and similar concerns expressed in the literature (Lewis 1995), the SLP is cautioned against relying solely upon use of the SSI- 3 for a diagnosis of stuttering. Rather, the SLP needs to obtain a comprehensive assessment of a child s disfluency in meaningful contexts, as well as assessment of both overt and covert symptoms (Yaruss 1998a). Finally, given that cluttering can have a significant impact upon the effectiveness of an individual s communication success (Dewey 2005, Myers and Kissagizlis 2007, Scaler Scott and St. Louis 2011), ruling out cluttering when evaluating students with AS is critical. The fact that only one of the four participants with AS diagnosed with a fluency disorder expressed concern and avoidance behaviours, and that one of the four parents noted difficulties with communication effectiveness must be considered in planning treatment. Whether treatment of disfluencies should be initiated will depend largely upon the impact of the disfluency upon effective communication skills. Additionally, given that disfluency presented in a variety of patterns in the children with AS, it is important to consider that students with AS may require different treatments dependent upon the nature of the fluency disorder presented. The current study was the first to compare speech disfluencies among school-aged children in the context of expository discourse. Trautman et al. (1999) studied disfluency among school-aged children in the speaking contexts of story retelling and story generation. These speaking contexts and the ages of the children were most similar to the current study, in that they both involved a more taxing linguistic context than conversation. Comparing group means for stuttering-like disfluencies between the current study and the Trautman et al. study, it was noted that increased stuttering-like disfluencies were noted in the current study s sample of CWS (mean = 9.92, SD = 7.54) as compared with those in the Trautman et al. study in contexts of story retelling (mean = 7.0, SD = 5.87) and story generation (mean = 3.75, SD = 4.80). Therefore, the assessment of stuttering within the context of expository discourse may provide a taxing context that will bring about stuttering-like disfluencies not observed in other contexts. Given that expository discourse is a common speaking format beginning in fourth grade (Nelson 1998, Rupp 2000), evaluation of this context is important to help assess the impact of real-life communication upon a student s stuttering. It is important to note that the stuttering severity of the sample of children in the Trautman et al. study fell mostly into the mild category (i.e. six mild