Sibling Interaction of Children with Autism: Development Over 12 Months

Transcription

1 J Autism Dev Disord (2007) 37: DOI /s z ORIGINAL PAPER Sibling Interaction of Children with Autism: Development Over 12 Months Fiona Knott Æ Charlie Lewis Æ Tim Williams Published online: 21 February 2007 Ó Springer Science+Business Media, LLC 2007 Abstract While deficits in social interaction are central to autism, the sibling relationship has been found to provide a key medium for the development of such skills. Naturalistic observations of sibling pairs including children with autism and controls with Down syndrome were made across two time periods, twelve months apart. Consistent with the evidence on typically developing children, the amount and rate of initiations of both prosocial and agonistic interaction increased, but further analysis suggested that these interactions were stage-managed by the typically developing children. Results show social interaction and imitation in children with autism and the special role that sibling interactions can play. Longitudinal research on the acquisition of social skills in children with developmental disabilities is needed. Keywords Autism Siblings Social interaction Longitudinal studies Introduction The social impairment of children with autism has been postulated as one of the defining characteristics of the disorder (Fein, Pennington, Markowitz, Braverman, & Waterhouse, 1986). Much is now known about these F. Knott (&) T. Williams School of Psychology and Clinical Language Science, University of Reading, Whiteknights, PO Box 217, Reading, Berkshire RG6 6AH, UK f.j.knott@reading.ac.uk C. Lewis Psychology Department, Lancaster University, Fylde College, Lancaster LA1 4YF, United Kingdom interaction and communication difficulties (Volkmar, Carter, Grossman, & Klin, 1997) and recent attempts to understand the underpinnings of social development in autism have placed cognitive accounts such as theory of mind and central coherence (for a review, see Frith, 2003) at the core. However, there is increasing awareness that children do not develop social understanding in a vacuum but within a diversity of social experiences (Carpendale & Lewis, 2004). Accordingly, there has been a welcome move to consider the natural contexts of children s interactions, but normative data are still required (Rogers, 2000). One such move is the study of sibling interactions in children with autism. Thus, in this paper, we examine the way social interaction in children with autism develops and is played out over 12 months with their siblings. In typically developing children, shared intentionality, or the ability to engage with others in collaborative activities with shared goals (e.g., Tomasello, Carpenter, Call, Behne & Moll, 2005), is a key precursor to later understanding of minds. Developing during infancy, shared intentionality requires both the ability to read others psychological states and the motivation to share them. Social interaction deficits in autism are not, therefore, explained by cognitive milestones identified in traditions like the theory of mind alone. These theories generally examine experimentally the evidence for impairment in children s skills, but fail to consider the processes by which children learn such skills and put them into practice in their daily lives. Furthermore, children across the range of the autism spectrum are far from devoid of ability in language and social interaction. Cognitive accounts rarely attempt to explain how these abilities develop, focusing instead on

2 1988 J Autism Dev Disord (2007) 37: deficit or difference. For example, in the theory of mind tradition it has long been shown that sibling interactions (e.g., Perner, Ruffman, & Leekam, 1994; Peterson, 2000), particularly those with older more able siblings (Ruffman, Perner, Naito, Parkin, & Clements, 1998), are related to the early acquisition of social-cognitive skills. While this pattern is not universally found and is colored by other social factors (see Carpendale & Lewis, 2006 for a review), it demonstrates the need to explore the social basis of social understanding in typically developing children and those with a range of types of mental retardation, particularly autism. Two further problems with existing research limit our understanding of the development of social skills in autism. First, much existing longitudinal research focuses on broad outcome measures, such as number of friends (e.g., Howlin, Mawhood, & Rutter, 2000), without analysis of the processes involved in change. Such impairments appear to be chronic (Beadle-Brown et al., 2002). Nevertheless, development for children with autism is not static (McGovern & Sigman, 2005) and significant change can occur, especially when adequate support is provided (Howlin et al., 2000). The few studies that have tracked the development of specific processes generally suggest that key social skills differentiate these children and those from matched groups consistently across time. Sigman and Ruskin (1999), for example, found that children with autism were characterized across an 8-year study by a particular deficit in joint attention, decreased functional and symbolic play and fewer empathic behaviors. Secondly, many investigations rely on structured tasks rather than utilizing naturalistic observational methods. Analog studies have limited external validity (Howlin, 1986) and repeated observations in natural settings may provide a different picture of changes over time. The tensions between experimental and naturalistic research paradigms described above may be exemplified by considering the role of imitation, which in recent years has become central to the debate about the underpinnings of autism (e.g., Rogers, Hepburn, Stackhouse, & Wehner, 2003). In typically developing children, from as early as 6 weeks, imitation serves to facilitate communication (Meltzoff & Moore, 2002) and provides a platform for early peer interactions (Rogers et al., 2003). If imitation is a foundation for the development of skills in typically developing children (e.g., Meltzoff & Decety, 2003), then it should be examined in the context of the social relationships in which it functions. Williams, Whiten, and Sing s (2004) systematic review confirms a deficit in imitation in ASD that cannot be explained entirely by nonspecific developmental delay or motor skill impairment. Yet, imitation in laboratory based task batteries may not mimic real life events, where performance is much less highly scaffolded (Rogers et al., 2003). Beadle-Brown and Whiten (2004) show that elicited imitation does not differentiate individuals with ASD from mental age matched controls, while a small number of studies in naturalistic settings (e.g., Brown & Whiten, 2000) confirm that children with autism spontaneously imitate less often than typically developing children. Taking account of the way social deficits and skills are manifested in different contexts and with different social partners may well help to delineate the developmental processes underlying autism. Hence, in a previous paper (Knott, Lewis, & Williams, 1995), we reported on the interaction of children with autism and Down syndrome and their siblings in free play. Our focus on social initiations and responses provided a window into the dynamics of the interaction between children, capturing bouts of shared exchanges and the processes by which children engage in them. We found greater levels of interaction, and more complex bouts, between these mentally retarded children than would be predicted from the literatures on peer interactions. In this follow up study, we examine changes in the amount and quality of reciprocal social interaction over twelve months of the children s lives and the occurrence of spontaneous imitation within the sibling relationship. For typically developing children, the sibling relationship provides a unique degree of familiarity and frequency of interaction (Abramovitch, Corter, Pepler, & Stanhope, 1986). It is a platform for development of numerous skills for both parties (e.g., Dunn, 1988). Sibling interaction is based on the adoption of asymmetric yet reciprocal roles (such as teacher and learner ), allowing children both to practise familiar roles and experiment with novel skills (Stoneman, 2001). Older siblings are responsible for the majority of initiations while the younger children maintain interaction by responding positively to prosocial initiations and submitting to agonism (Abramovitch et al., 1986). Over time, the rate of interaction increases, but this asymmetric pattern is stable throughout early and middle childhood. Similarly, from about 14 months, younger children imitate their siblings more they themselves are imitated (Dunn & Kendrick, 1979). However, over time, the rate of imitation in sibling dyads (especially in mixed sex pairs) decreases markedly (Abramovitch et al., 1986). Although the sibling interactions of typically developing children have been well described, few studies

3 J Autism Dev Disord (2007) 37: have involved sibling interactions of children with disabilities, including autism. The existing studies find clear, asymmetric roles, with the developmentally disabled child taking on the role of the younger child in the pair, regardless of their birth order position. This pattern is found in children with difficulties as diverse as Down syndrome (Abramovitch, Stanhope, Pepler, & Corter, 1987), cerebral palsy (Dallas, Stevenson, & McGurk, 1993) and autism (Knott et al., 1995). Children with disabilities are therefore able to participate in reciprocal interaction through a process in which the typically developing sibling scaffolds and supports the interaction. Longitudinal observational studies involving siblings with disabilities are rare, but Abramovitch et al. s (1987) examination of dyads containing a child with Down syndrome includes a longitudinal element. In observations 12 months apart, they found no significant differences in the frequency of prosocial or agonistic initiations or imitation, contrasting with the pattern seen in typically developing children. Other studies (e.g., Stoneman, Brody, Davis, & Crapps, 1989) have shown that sibling interaction becomes more asymmetric over time in dyads including a disabled child, while in typically developing pairs it becomes more egalitarian, such that neither child assumes dominance over the other. Given that deficits in affective sharing and symbolic play have been shown to persist in children with autism (Sigman & Ruskin, 1999), this study explores whether sibling interaction in pairs including a child with autism will become more asymmetrical over time. This study involved the follow up of a small number of children who participated in a first study (Knott et al., 1995) twelve months before. While the sample is relatively small (n = 16), these data present 48 h of observation. None of the developmentally disabled children were involved in any kind of therapy other than that normally offered at school, so any change can be attributed to typical developmental trends rather than the effects of intervention. Interaction was analyzed by examining initiations and responses (Abramovitch et al., 1987), thereby allowing the following questions about pairs with a mentally retarded child: 1. Does the number of bouts of interaction in these pairs increase over 12 months? This would be predicted from the literature on sibling interactions in typically developing dyads (Abramovitch et al., 1986) but it is not a clear prediction from the literature on children with autism (Sigman & Ruskin, 1999). 2. Do responses to initiations change over 12 months? Interventions focusing on social interaction generally find superior rates of change in participants rather than controls over short time periods (e.g., Roeyers, 1996). However, it is unclear what typically occurs over a longer time period when children are not subject to specific interventions. 3. Is there a change in the rate of imitation over time? Given the stress placed in the recent literature on the role of imitation in early communication development (e.g., Meltzoff & Decety, 2003) we specifically examine this skill in the context of the sibling relationship and predict that increases in imitation will take place over time. Method Recruitment Thirty sibling pairs in the first phase of the study were recruited from the National Autistic Society, the Down s Syndrome Association and local schools. For diagnostic information, see Knott et al. (1995). 11 of the 15 families containing a child with autism who had participated in the first study were invited to participate in the second study, the remaining four not being invited because either they no longer met age criteria, or the family were experiencing high levels of stress. Six families agreed to participate again. Four of the five who did not agree were either unavailable during the data collection period, or felt that the child with autism was very disturbed at the time. Thirteen of the 15 families containing a child with Down syndrome were contacted again. The two children in the families who were not contacted were experiencing cardiac problems. Eleven agreed to take part. Participants Six sibling dyads comprising an autistic child and a developmentally typically developing child and 10 comprising a child with Down syndrome and a developmentally typically developing child took part in both the first (Knott et al., 1995) and the second phases of the study. Details of the ages of target children and their siblings at Time 2 are shown in Table 1. Estimates of the developmentally disabled children s developmental quotients were provided by assessments using the Weschler Intelligence Scale for Children, the

4 1990 J Autism Dev Disord (2007) 37: Table 1 Mean chronological and developmental ages of the sample Disability N Target Target Target Sibling CA MA DQ CA Autism 6 69 (5.5) 52 (14.5) 75 (25.1) 57 (28.8) Down syndrome (7.8) 47 (16.0) 61 (13.7) 75 (37.7) Note. One child with Down syndrome refused to co-operate during testing and no other data were available. Therefore, mean target MA and DQ for this group are based on a sample of 9 Merill Palmer Scale of Mental Tests or the Bayley Scale of Infant Development, chosen to obtain the most relevant information about the child. The children with autism were all male, 4 of their siblings were girls and 2 were boys. All were in 2 child families and the child with autism was the older in 5 families. The sample of children with Down syndrome was half male and half female and their siblings consisted of 4 girls and 6 boys. 4 pairs came from 2 child families and 6 from three child families. Five children with Down syndrome were the youngest, 2 were the middle of three and 2 were the oldest in the family. Measures The coding system used was based on Abramovitch et al. (1987). Twelve prosocial behaviors (give/share an object, cooperate/help, request, praise/approval, comfort/reassurance, physical affection, laugh/smile, approach, rough and tumble, clowning, establishing rules, establishing roles) and 10 agonistic behaviors (physical aggression, object struggle, command, threat, command with reason, territorial claim, repeats parent s commands, competitive statement, bribe/bargain and physical tease) were used to code initiations of interaction. Six responses to initiations were also coded (to prosocial: positive, negative, null [no observable change in behavior]; to agonism; submit, counter attack, null). The final category, Imitation, was also included but not classified as an initiation or response (Abramovitch et al., 1987). Procedure The procedures used at both Time 1 (Knott et al., 1995) and Time 2, a year later, were identical. The mean number of months between visits was 12 (range 11 14). Observations were carried out at both times by the same female observer (FK). Sibling pairs were observed at home at a time the mother thought the children would be likely to be playing together. The television was switched off during the observation. The mother (who was the primary care giver in all cases) was asked to go about her normal routine as far as possible. She was asked not to initiate interaction with the children but to respond to them as she normally would if approached. The children were told the observer had come to visit the mother and that they were free to do exactly as they liked, as long as they remained in the house or garden. If they enquired of the mother or observer if they were meant to be playing with the other child, they were told It s up to you, just do what you would normally be doing at this time. Data Collection The data were collected in situ using a Cambridge Z88 computer. Observations began after a min settling-in period and continued for exactly 60 min. As only social interaction was observed, coding only took place when the children were in the same room or same part of the garden. If one child left the room, the observer stayed with the remaining child until either the first child returned or the second also left the room. Reliability As data were collected in two phases, two sets of reliability coefficients were established. During data collection for Time 1, median intra-rater reliability, calculated on 6 occasions using Cohen s Kappa, was.77 for both target and sibling initiations and responses. The majority of bids had a score above.6 (defined as acceptable by Hartman, 1977). One initiation, comment, which was not coded reliably, was removed from the analysis. Further details are reported in (Knott et al., 1995). Using videotapes of children with autism or Down syndrome playing with their siblings, a second rater, blind to the purpose of the study, was employed to calculate inter-rater reliability. Intra-rater reliability checks were made on five occasions during the course of the analysis. Cohen s Kappa was calculated for each code and for each child in the dyad across all 6 tapes, unless a social bid did not occur on the tapes. The median coefficients for the social codes used by developmentally disabled children were: inter-rater.78; intra-rater.83; and for the siblings were: inter-rater.7; intra-rater.67. Results The data from Time 1 were pooled as 2 visits were made. All data were prorated to 60 min to account for

5 J Autism Dev Disord (2007) 37: differences in the length of time the children were in the same room and are therefore reported as rate per hour. Initiations and Imitation were transformed using logarithmic transformations and responses, which were expressed as proportions, using an arcsine transformation. Separate multivariate analyses of variance were conducted. The rate of initiations (prosocial and agonistic) was analyzed using a 2 (disability; autism and Down syndrome) by 2 (time; one and two) by 2 (child; disabled child and sibling) multivariate analysis of variance, with the latter two as repeated measures. Follow up univariate analyses are reported as appropriate. The mentally retarded child will be referred to by the type of disability, while the typically developing child will be referred to as the sibling. Four separate analyses of responses to initiations were carried out; developmentally disabled child s responses to sibling initiations that were either prosocial or agonistic initiations, and sibling responses to developmentally disabled child s prosocial or agonistic initiations. In each analysis, the sum of the proportions always equals 1, as these represented all possible responses. Thus, analysis was conducted on the two variables of largest proportion which were included in a 2(time) by 2(child) multivariate analysis of variance, with follow up ANOVA where appropriate. Analysis of the third variable was conducted only if the multivariate F was significant. Question 1: Does the Number of Bouts of Interaction in These Pairs Increase Over 12 Months? Table 2 shows that the rate of initiating interaction increased between the two observations, 12 months apart. At both times, prosocial initiations were more common than agonistic, and siblings made more frequent initiations than the developmentally disabled children. Analysis revealed significant multivariate effects of child, F (2, 29) = 28.5, p <.0001 partial g 2 =.66; time, F (2, 29) = 13.1, p <.0001 partial g 2 =.47; and disability, F (2, 29) = 6.2, p <.01 partial g 2 =.30; Table 2 Mean number (standard deviation) of prosocial and agonistic initiations per hour Prosocial Agonistic Time 1 Time 2 Time 1 Time 2 Autistic child 8.0 (7.0) 11.1 (5.4) 3.5 (5.6) 4.5 (4.6) Autistic sibling 18.9 (15.4) 60.3 (49.8) 4.0 (4.3) 12.8 (9.9) Down child 18.5 (6.5) 30.5 (32.8) 5.5 (4.0) 8.6 (12.8) Down sibling 32.1 (23.9) 62 (41.5) 10.5 (6.9) 16.5 (8.5) and significant interactions between child and time, F (2, 29) = 6.6, p <.005 partial g 2 =.31; and child and disability, F (2, 29) = 3.9, p <.05 partial g 2 =.21. The univariate effects are described below. Prosocial initiations Table 2 shows that 42.3 initiations were made at Time 2, twice as many as the 20.8 initiations made at Time 1, F (1, 30) = 26.2, p <.0001 partial g 2 =.47. Siblings made on average 42 initiations an hour, twice as many as the developmentally disabled children, who initiated prosocial interaction 22 times per hour, F (1, 30) = 45.6, p <.0001 partial g 2 =.60. Dyads including an autistic child initiated fewer prosocial initiations than those with a Down syndrome child, F (1, 30) = 11.5, p <.005 partial g 2 =.23; 20.9 and 32.2 initiations per hour). Analysis of the child by disability interaction, F (1, 30) = 6.5, p <.05 partial g 2 =.18, revealed that while siblings of children with Down syndrome and autism made the same number of initiations per hour, F(1, 30) = 2.0, ns, children with autism made fewer initiations than children with Down syndrome, F(1, 30) = 22.6, p <.001 partial g 2 =.43. The child by time interaction, F (1, 30) = 9.8, p <.005 partial g 2 =.25, was not further explained by analysis of simple main effects (the simple main effects were all significant). However, the pattern in Table 2 suggests the increased rate of prosocial initiations was largely due to the behavior of the siblings. Siblings made 27.2 prosocial initiations at Time 1, and over twice as many, 61.4, at Time 2, F (1, 31) = 40.9, p <.0001 partial g 2 =.57. At the same time, there was a smaller, but still significant, increase in the initiation rate of developmentally disabled children who made 14.4 initiations at Time 1 and 23.2 at Time 2, F (1, 31) = 5.4, p <.05 partial g 2 =.15. Agonistic initiations Table 2 shows that the rate of agonistic initiations almost doubled at Time 2 (11.1 bids per hour) compared to Time 1 (6.4 bids per hour), F (1, 30) = 12.4, p <.001 partial g 2 =.29. Dyads with a child with autism were somewhat less agonistic than Down syndrome dyads, making, respectively, 5.3 and 9.5 initiations per hour F (1, 30) = 9.5, p <.005 partial g 2 =.24. Siblings initiated agonism 10.4 times per hour, twice as often as developmentally disabled children, who made 5.5 initiations per hour, F (1, 30) = 37.1, p <.0001 partial g 2 =.55. The significant interaction between child and time, F (1, 30) = 8.3, p <.01 partial g 2 =.21, showed the increased rate of agonistic

6 1992 J Autism Dev Disord (2007) 37: initiations to be due to the behavior of the siblings. Siblings made twice as many agonistic initiations at Time 2 (8.0 and 15.1 per hour), F (1, 30) = 23.6, p <.0001 partial g 2 =.43, but there was no increase by developmentally disabled children (4.7 and 7.0 initiations per hour). Question 2: How Do Responses to Initiations Change Over 12 Months? Developmentally Disabled Children s Responses to Sibling Prosocial Initiations. As can be seen in Table 3, children with autism only responded to about half of their siblings prosocial initiations but, when they did, these responses were more often positive than negative. Children with Down syndrome on the other hand, responded to more than three quarters of their siblings initiations, responding positively over two thirds of the time and negatively only about 10% of the time. This means that by Time 2, given the number of initiations made by the siblings, children with autism responded positively about 30 times an hour, and children with Down syndrome about 40 times an hour. Multivariate analyses were carried out on positive and null responses and are presented in Table 3. There was a significant effect of disability, F (2, 29) = 17.3, p <.0001 partial g 2 =.54; and an effect of time, F (2, 29) = 5.3, p <.01 partial g 2 =.27, but no interaction. Follow up univariate analyses showed that children with autism responded positively less often (.43 of responses) than children with Down syndrome (.66), F (1, 30) = 31.5, p <.0001 partial g 2 =.51. Instead, children with autism made more null responses than children with Down syndrome (.46 and.26), F (1, 30) = 25.3, p <.0001 partial g 2 =.48. There was a trend to a higher proportion of positive responses at time 2, F (1, 29) = 3.1, ns (.55 and.62 for times 1 and 2, respectively) but no Table 3 Mean proportion (standard deviation) of responses to prosocial initiations Positive Negative Null Autistic child Time 1.36 (.21).14 (.25).49 (.25) Time 2.56 (.15).02 (.02).42 (.18) Autistic sibling Time 1.67 (.15).1 (.1).23 (.13) Time 2.66 (.14).02 (.02).32 (.15) Down child Time 1.46 (.27).05 (.14).48 (.32) Time 2.47 (.29).15 (.2).37 (.32) Down sibling Time 1.55 (.24).13 (.1).32 (.24) Time 2.54 (.14).02 (.03).43 (.13) Table 4 Mean rate (standard deviation) of responses to agonistic initiations Submit Counter Null Autistic child Time 1.20 (.32).13 (.32).49 (.43) Time 2.07 (.1).20 (.09).72 (.18) Autistic sibling Time 1.26 (.38).25 (.4).16 (.32) Time 2.16 (.24).30 (.4).37 (.37) Down child Time 1.31 (.27).35 (.32).34 (.32) Time 2.17 (.14).07 (.09).74 (.14) Down sibling Time 1 40 (.38).39 (.36).15 (.23) Time 2.16 (.16).25 (.27).59 (.29) change in rate of null responses. Analyses of negative responses were not carried out due to the low occurrence of this type of response; these responses occurred around 10% of the time at Time 1, but dropped to about 2% at Time 2. Developmentally Disabled Children s Responses to Sibling Agonism Table 4 shows that, overall, developmentally disabled children responded to less than half of their siblings agonistic initiations and, when they did respond, submitted and counter attacked in approximately equal proportions. Multivariate analyses were carried out using submit and null responses as the dependent variables. This revealed a main effect of time, F (2, 29) = 6.5, p <.005 partial g 2 = 31. The proportion of submits decreased from.27 to.14 between Time 1 and Time 2, F (1, 30) = 5.7, p <.02 partial g 2 =.16; and counter attack decreased from.27 to.12, F (1, 30) = 4.7, p <.05 partial g 2 =.36. At the same time, the proportion of null responses increased from.40 to.74, F (1, 30) = 12.4, p <.001 partial g 2 =.29. Sibling Responses to Developmentally Disabled Children s Prosocial Initiations Table 3 shows that siblings responded positively to the developmentally disabled children s prosocial initiations 52% of the time. Given the relative differences in initiations, this means that siblings of children with autism responded positively on average about 5 times an hour, and siblings of children with Down syndrome about 12 times. Negative responses were relatively rare (less than 10%), with null responses occurring about 40% of the time. MANOVA was carried out using positive and null responses, revealing no significant main effect or interactions.

7 J Autism Dev Disord (2007) 37: Sibling Responses to Developmentally Disabled Agonistic Initiations The multivariate analysis revealed only a significant main effect of time, F (2, 29) = 7.4, p <.005, partial g 2 =.34. The proportion of submits, shown in Table 4, decreased over time, F (1, 30) = 5.2, p <.05 partial g 2 =.15 (.35 at Time 1 to.16 at Time 2), while no response became more common, F (1, 30) = 12.1, p <.001, partial g 2 =.29, increasing from.15 to.51. The proportion of counter attacks did not alter significantly over time. Question 3: Is There a Change in the Rate of Imitation Over Time? The frequency of Imitation was analyzed using a 2 (disability) by 2 (child) by 2 (time) analysis of variance and is presented in Table 5. The overall rate of Imitation increased between Time 1 and Time 2 (4.0 and 6.4 per hour), F (1, 30) = 21.6, p <.0001) partial g 2 =.42. A significant time by disability interaction, F (1, 30) = 4.1, p <.05 partial g 2 =.12, showed that Imitation increased in autistic dyads between Time 1 and two, F (1, 11) = 15.9, p <.005 partial g 2 =.67, (2.5 and 7.4 times per hour), but there was no such increase in Down syndrome dyads (4.9 and 5.8 per hour). Secondly, a significant time by child interaction, F (1, 30) = 6.3, p <.05 partial g 2 =.17, showed that target children engaged in Imitation the same amount at Times 1 and 2, 4.8 and 5.6 times per hour, but that siblings imitated more at Time 2, F (1, 31) = 20.3, p <.0001, partial g 2 =.40 (3.2 times and 7.2 per hour). There was also a significant interaction between disability and child, F (1, 30) = 18.0, p <.0001 partial g 2 =.38. Simple main effects analyses showed that while children with autism imitated less often than their siblings, F(1, 10) = 5.96, p <.05 partial g 2 =.37, (2.0 and 6.2), children with Down syndrome imitated more than their siblings F(1,19) = 6.2, p <.05 partial g 2 =.25 (6.9 and 3.6). Table 5 Mean rate (standard deviation) of Imitation per hour Imitation Time 2 Time 1 Autistic child 1.2 (1.7) 3.8 (4.7) Autistic sibling 3.8 (3.5) 10.9 (8.5) Down child 6.9 (6.5) 6.7 (4.5) Down sibling 2.9 (3.6) 4.9 (1.9) Discussion These data provide a rare analysis of the development of social interaction in children with autism and Down syndrome across a 12-month period and help to tease apart some of the processes by which children with autism develop social skills. While the sample sizes were small, the large number of significant results and effect sizes testify to the magnitude of the differences between groups and over time. To address our first two research questions: in keeping with the literature on typically developing children, the amount and rate of both prosocial and agonistic initiations and the pattern of responses changed over time. Developmentally disabled children responded positively more often at Time 2 while their siblings responses to prosocial initiations did not change. All children ignored agonism more often at Time 2, while the rate of submits decreased. This study contrasts with Abramovitch et al. (1987), who found that there was no increased rate of initiations by siblings of Down syndrome children over 12 months. The children s ages, the age gap between children, and the sex composition of the dyads very closely resembled those of participants in our study. Given the paucity of studies of children s sibling relationships, contradictory findings are not uncommon (Stoneman, 2001). Most of these rely on cross sectional methodology, and there is an urgent need for prospective longitudinal studies to tease out the development of social processes involving siblings over time. Nonetheless, it is noteworthy that both dyads followed typical patterns by increasing their rates of initiations over time. However, close analysis of the patterns of initiations suggested that these were stage- managed by the typically developing children who dramatically increased their rate of initiations at the second observation period. Indeed the slight increase in number made by developmentally disabled children over time was not statistically significant. In this natural setting, the enduring nature of the social impairment in autism is emphasized. Nevertheless, their interactions did not remain static: the number of bouts of positive interactions they engaged in showed a clear change. In response to the doubling of prosocial initiations by typically developing children, the proportions of positive responses by the developmentally disabled children remained stable. In real terms, this is a fourfold increase in the numbers of positive responses by the children with autism, who did so 7 times per hour at Time 1 and over 30 at Time 2. For children with Down syndrome, positive responses occurred 21 times at Time 1 and 41 times at Time 2. As the real number of positive social

8 1994 J Autism Dev Disord (2007) 37: encounters in which the developmentally disabled children engaged increased, this presents us with a changing pattern of interaction in which role asymmetry increases as the relative gap in mental age between the siblings widens (Stoneman et al., 1989). This prompts typically developing children to scaffold the bids by the developmentally disabled children. To answer the third question, children with ASD imitated their siblings spontaneously less often overall than those with Down syndrome or the typically developing siblings. In pairs including a child with Down syndrome, the disabled child maintains the interaction by imitating the sibling. However, in the pairs including a child with autism, the pattern was reversed. The rate of Imitation increased in both types of dyad over time, but this seems largely to have been due to a large increase in rate of Imitation by the siblings of children with autism. Although rates of Imitation remained at odds with patterns reported in typically developing siblings, children with autism imitated twice as often at Time 2. Indeed children in these pairs appeared to demonstrate increased interest and social engagement in each other over time. The children with autism had developmental levels of about four years, around the age when imitation in typical children appears to be highest (Brown & Whiten, 2000). Further work is required to explore this pattern, as it would be expected that with increasing developmental ability, the rate of imitation by the children with autism would decline. At the same time, siblings of children with autism may use imitation in free play to encourage interaction, further supporting the notion that they stage-manage the relationship by tuning into the behavior of the child with autism. The data presented in this study illustrate the robustness of sibling interaction, even with children with autism, whose social skills must make them particularly challenging as play partners. Although the roles adopted become increasingly asymmetrical, of equal note is the finding that children with autism demonstrate skills in interaction with their siblings which is rarely reported with their peers (e.g., McGee, Feldman, & Morrier, 1997). With their siblings at least, children with autism appear to develop in line with other children, albeit more slowly. Their ability to engage in collaborative interaction appears to be uniquely enhanced by the role reciprocity inherent in the sibling relationship. A rich vein of information can be gained from examining the way such relationships are played out in their natural contexts. The potential for harnessing these naturally occurring patterns of interaction to intervene in the development of social skills in children with autism is underlined by the continued ease in which siblings engage in interaction over time. Interventions grounded firmly in existing interaction (Rogers, 2000) will therefore enhance naturally occurring patterns of interaction, arguably with more success than interventions which are not. References Abramovitch, R., Corter, C., Pepler, D. J., & Stanhope, L. (1986). Sibling and peer interaction; a final follow up and comparison. Child Development, 57, Abramovitch, R., Stanhope, L., Pepler, D. J., & Corter, C. (1987). Influence of Down s Syndrome on sibling interaction. Journal of Child Psychology and Psychiatry, 28, Beadle-Brown, J., Murphy G., Wing, L., Gould, J., Shah, A., & Holmes, N. (2002). Changes in social impairment for people with intellectual disabilities: A follow-up of the Camberwell cohort. Journal of Autism and Developmental Disorders, 32, Beadle-Brown, J., & Whiten, A. (2004). Elicited imitation in children and adults with autism: is there a deficit? Journal of Intellectual and Developmental Disability, 29, Brown, J., & Whiten, A. (2000). Imitation, theory of mind and related activities in autism. An observational study of spontaneous behavior in everyday contexts. Autism, 4, Carpendale, J. I. M, & Lewis, C. (2004). Constructing an understanding of mind: The development of children s social understanding within social interaction. Behavioral and Brain Sciences, 27, Carpendale, J. I. M., & Lewis, C. (2006). How children develop social understanding. Oxford: Blackwell. Dallas, E., Stevenson, J., & McGurk, H. (1993). Cerebral-palsied children s interactions with siblings II. Interactional structure. Journal of Child Psychology and Psychiatry, 34, Dunn, J. (1988). Sibling influences on childhood development. Journal of Child Psychology and Psychiatry, 29, Dunn, J., & Kendrick, C. (1979). Interaction between young siblings in the context of family relationships. In: M. Lewis, & L. Rosenblum (Eds.), The child and its family. New York:Plenum Press. Fein, D., Pennington, B., Markowitz, P., Braverman, M., & Waterhouse, L. (1986). Towards a neuropsychological model of infantile autism: are the social deficits primary? Journal of the American Academy of Child Psychiatry, 25, Frith, U. (2003). Autism. Oxford: Basil Blackwell. Hartmann, G. (1977). Considerations in the choice of interobserver reliability estimates. Journal of Applied Behavior Analysis 10, Howlin, P. (1986). An overview of social behaviour in autism In E. Schopler, & G. Mesibov (Eds.), Social behaviour in autism. New York: Plenum Press. Howlin, P., Mawhood, L., & Rutter, M. (2000). Autism and developmental receptive language disorder - a follow-up comparison in early adult life. II: Social, behavioural, and psychiatric outcomes. Journal of Child Psychology and Psychiatry, 41, Knott, F., Lewis, C., & Williams, T. (1995). Sibling interaction of children with learning disabilities: a comparison of autism and Down s syndrome. Journal of Child Psychology and Psychiatry, 36,

9 J Autism Dev Disord (2007) 37: McGee, G., Feldman, R., & Morrier, M. (1997) Benchmarks of social treatment for children with autism. Journal of Autism and Developmental Disorders, 27, McGovern, C., & Sigman, M. (2005). Continuity and change from early childhood to adolescence in autism. Journal of Child Psychology and Psychiatry, 46, Meltzoff, A., & Decety, J. (2003). What imitation tells us about social cognition: a rapprochement between developmental psychology and cognitive neuroscience. Philosophical transactions of the Royal Society of London Series B Biological Sciences, 358, 1431, Meltzoff, A., & Moore, M. (2002). Imitation, memory, and the representation of persons. Infant Behavior and Development, 25, Perner, J., Ruffman, T., & Leekam, S.R. (1994). Theory of mind is contagious: You catch it from your sibs. Child Development, 65, Peterson, C.C. (2000). Kindred spirits: Influences of siblings perspectives on theory of mind. Cognitive Development, 15, Roeyers, H. (1996). The influence of non-handicapped peers on the social interactions of children with a pervasive developmental disorder. Journal of Autism and Developmental Disorders, 26, Rogers, S. (2000). Interventions that facilitate socialization in children with autism. Journal of Autism and Developmental Disorders, 30, Rogers, S., Hepburn, S., Stackhouse, T., & Wehner, E. (2003). Imitation performance in toddlers with autism and those with other developmental disorders. Journal of Child Psychology and Psychiatry, 44, Ruffman, T., Perner, J., Naito, M., Parkin, L., & Clements, W.A. (1998). Older (but not younger) siblings facilitate false belief understanding. Developmental Psychology, 34, Sigman, M., & Ruskin, E. (1999). Continuity and change in the social competence of children with autism, Down syndrome and developmental delays. Monographs of the Society for Research in Child Development, 64. Stoneman, Z. (2001). Supporting positive sibling relationships during childhood. Mental Retardation and Developmental Disabilities Research Reviews, 7, Stoneman, Z., Brody, G., Davis, C., & Crapps, J. (1989). Role relations between children who are mentally retarded and their older siblings: observations in three home contexts. Research in Developmental Disabilities, 10, Tomasello, M., Carpenter, M., Call, J., Behne, T., & Moll, H. (2005). Understanding and sharing intentions: The origins of cultural cognition. Behavioral and Brain Sciences, 28, Volkmar, F., Carter, A., Grossman J., & Klin, A. (1997) Social development in autism. In D. Cohen, & F. Volkmar (Eds.), Handbook of autism and pervasive developmental disorders. New York: John Wiley and Sons. Williams, J., Whiten, A., & Sing, T (2004). A systematic review of action imitation in autistic spectrum disorder. Journal of Autism and Developmental Disorders, 34,