Journal o f Autism and Developmental Disorders, VoL 20, No. 1, 1990
A Longitudinal Study of Joint Attention and Language Development in Autistic Children I Peter Mundy, 2 Marian Sigman, and Connie Kasari UCLA Center f o r the Health Sciences
This study was designed to examine the degree to which individual differences in gestural joint attention skills predicted language development among autistic children. A group o f 15 autistic children (mean CA = 45 months) were matched with one group of mentally retarded (MR) children on mental age and another group o f MR children on language age. These groups were administered the Early Social-Communication Scales. The latter provided measures o f gestural requesting, joint attention, and social behaviors. The results indicated that, even when controlling for language level mental age, or 1Q, autistic children displayed deficits in gestural joint attention skills on two testing sessions that were 13 months apart. Furthermore, the measure o f gestural nonverbal joint attention was a significant predictor o f language development in the autistic sample. Other variables, including initial language level and IQ were not significant predictors o f language development in this sample.
A paucity of nonverbal gestural joint attention or indicating skills have been noted in observations of samples of autistic individuals (Curcio, 1978; Wetherby & Prutting, 1984). Gestural joint attention skills refer to children's use and comprehension of conventional gestures such as pointing to objects and showing objects to other people. These social skills also involve the use of eye contact in conjuntion with gestures or alone as when children alternate their gaze between an interesting object and a care-giver. In general these behaviors serve to coordinate attention between interactive social partners
~This study was supported by NIMH grant 30530 and NINCDS grant 30527. 2Address all correspondence to Peter Mundy, UCLA Center for the Health Sciences, Department of Psychiatry, 760 Westwood Plaza, Los Angeles, California 90024. 115 0162-3257/90/0300-0115506.00/0 9 1990PlenumPublishingCorporation
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in order to share an awareness of objects or events. These behaviors typically emerge between 8 and 13 months of age in normally developing children (Bakeman & Adamson, 1984; Bates, 1979; Leung & Rheingold, 1981). Studies using mentally retarded and language-disabled control groups have shown that gestural attention deficits are specific to autism (Landry & Loveland, 1988 Loveland & Landry, 1986; Mundy, Sigman, Ungerer, & Sherman, 1986; Sigman, Mundy, Sherman, & Ungerer, 1986). Moreover, individual differences in gestural joint attention skills are concurrently associated with language abilities among autistic children (Loveland & Landry, 1986; Mundy, Sigman, Ungerer, & Sherman, 1987). The latter finding is consistent with theory that suggests that the development of gestural joint attention skills reflects the emergence of socialcognitive processes that provide a foundation for the acquisition of language (Bates, 1979; Sugarman, 1984; Werner & Kaplan, 1963). This theory suggests that the adequate development of gestural joint attention may predict individual differences in language acquisition among autistic children. However, an investigation of the predictive relation between gestural joint attention skill and language development among autistic children has not been conducted. For this reason the current longitudinal study was designed to determine the degree to which individual differences in gestural joint attention skills predicted language development among autistic children. This was considered an important goal for two reasons. First, autistic children exhibit a variety of severe problems in language development (Rutter, 1978) and individual differences in language development are related to variability in outcome among autistic individuals (Lotter, 1978). Not surprisingly, a common focus of early intervention efforts with these children is the facilitation of communication skills (Rutter, 1985; Prizant & Schuler, 1987). Thus, data on the predictors of language development among autistic children may be informative with respect to the design of these efforts. Second, joint attention skills typically emerge within the first year of life in normally developing children (Bakeman & Adamson, 1984; Hannan, 1987). Therefore, deficits in these skills may mark a fundamental aspect of the developmental disturbance that characterizes autism (Mundy & Sigman, 1989a). If this is so, then individual differences in this aspect of social behavior development should be associated with later emerging domains of development disturbance among autistic children. Thus, data on the predictive validity of gestural joint attention measures is pertinent to understanding the importance of this skill domain in the developmental process of autistic behavior pathology. To address these issues the gestural joint attention and language skills of a sample of young autistic children were assessed across a 13-month interval. Measures of nonverbal requesting and social skills were also included
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in this study to ascertain if language prediction is specific to gestural joint attention or more generally related to nonverbal social-communication skills. Comparative data from two control samples were also obtained in this study. Since most autistic children function in the retarded range of intelligence (e.g., Freeman, Ritvo, Needleman, & Yokota, 1985), a control sample of mentally retarded children matched on mental age was assessed. However, because the psychometric test performance of young autistic children is characterized by weakness on verbal test items (McDonald, Mundy, Kasari, & Sigman, 1989) matching on mental age may lead to mismatching on language level. Since language development was a focus of this study, comparisons between the autistic group and a mentally retarded control group, matched on a measure of expressive and receptive language, were also considered critical to this study. Comparisons of the samples were used to provide descriptive data on the relative rates of development displayed by young autistic and mentally retarded children on nonverbal communication and language skills over the course of 13 months. Moreover, the data from the comparison samples were used to determine if autistic children displayed a unique pattern of organization (i.e., profile of correlations) among the nonverbal communication and language measures. The inclusion of the language-matched mentally retarded sample also presented a design advance over studies that have controlled for language level or mental retardation, but not both, in previous attempts to define the nonverbal communication deficits that are specific to autistic children (Loveland & Landry, 1986; Mundy et al., 1986). METHOD
Subjects The autistic sample comprised 15 children. The diagnosis of each child was made independently of the experiments by psychiatrists who were experienced in the evaluation of developmental disorders and who used American Psychiatric Association (1980) criteria. These included (a) onset before 30 months of age; (b) pervasive lack of responsiveness to others; (c) gross deficits in language development; (d) if speech is present, peculiar speech patterns such as echolalia, pronomial reversal, etc.; (e) bizarre responses to various aspects of the environment; and (f) absence of delusions, hallucinations, loosening of associations, and incoherence as in schizophrenia. Since the focus of this study was on language acqusition, autistic children were selected for this study who exhibited little (fewer than five words) or no expressive language on the Reynell Developmental Language Scales (Reynell, 1977). Initial data from eight autistic children who had previously participated on our program of studies (e.g., Mundy et al., 1986) were in-
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Mundy, Sigman, and Kasari Table I. Initial Developmental and Language Levels of the Groups Autistic children
Language age-match MR children
(n = 15) CA (months) MA (months) IQ Language Initial Follow-up
(n = 15) M
SD
Mental age-match MR children
(n = 15)
M
SD
M
44.9 19.6 43.9
8.7 3.9 6.6
25.3 14.7 60.7
7.2 3.6 16.2
28.5 18.9 68.0
SD
10.1 4.1 14.4
12.5 16.7
1.0 6.1
13.6 18.7
1.9 5.3
16.9 23.2
4.3 5.8
cluded in this study. These children were selected for this follow-up study because they had little or no expressive language skills at the time of the initial assessment. Seven additional autistic children with little or no expressive language skills, who had not previously participated in our research program, were recruited to complete the sample. The mental age matched, mentally retarded (MR) sample included 6 children with down syndrome and 9 children with unspecified etiologies. As expected, MA matching was associated with lack of group correspondence on language level (see Table I). The language age matched sample was matched on the basis of Reynell language scores. This sample held 9 children in common with the mental age matched sample. This sample included 7 children with down syndrome and 8 children with unspecified etiologies. Data on the mean development, intellectual, and language levels obtained during the initial assessment are presented for the three samples in Table I.
Procedures The initial assessments for each child occured during two individual sessions scheduled in the UCLA medical center. These assessment sessions occurred within a 3-week period and included the administration of the nonverbal communication measure, the Cattell Scales of Infant Intelligence (Cattell, 1940) or the Stanford Binet, and the Reynell Language Scales (Reynell, 1977). All tasks were administrated by independent testers. Follow-up testing, including administration of the nonverbal communication measure, and the Reynell, was scheduled for each child approximately 1 year after the initial assessment. The mean intervals between initial and follow-up testing for the autistic, MA-matched, and language-matched mentally retarded groups were 13.4 months (SD = 1.5), 13.5 months (SD = 1.6), and 13.9 months (SD = 1.6), respectively.
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Nonverbal Communication Measures The nonverbal communication skills o f the children were assessed with an abridged form of the Early Social-Communication Scales (ESCS; Seibert, Hogan, & Mundy, 1982). In this procedure the child and experimenter sat facing each other at a small table. A set of toys including a hat, a comb, a book, a ball, a car, 5 small (approximately 2 x 2 inches) wind-up mechanical toys, and five hand-operated mechanical toys including balloons were in view but out of reach to the child. Colorful posters were hung on the walls o f the room. The experimenter presented a n d / o r activated the toys on the table one at a time. When presented, these toys were not within the grasp of the child but were within reach of the child. Intermittently the experimenter pointed to and looked at the wall posters. The experimenter also presented the child with physical social games (tickling) and turn-talking opportunities (child and experimenter alternate rolling the car or ball, or take turns using the comb, glasses, or hat in a functionally appropriate fashion). Verbal interactions were kept to a minimum during the ESCS. The child-experimenter interaction was videotaped to record the front upper body view o f the child and the upper body prof'fle of the experimenter. The period of interaction with each child was approximately 25 min. Children occasionally left the table during testing. When this occurred they were directed back to their seats after 10-15 sec. The task demands o f the interaction were minimal and no children were excluded from this study because of an inability to sit through this procedure. Behavior ratings were collected from the ESCS videotapes by trained observers. Observations of the child's nonverbal communication behaviors were grouped into three mutually exclusive categories: social behavior, joint attention, and requesting. In rating social behavior the emphasis was on the capacity o f the child to elicit attention or physical contact form the experimenter and to engage in turn-taking with the experimenter. The joint attention category included behaviors used to direct attention to an object or event, thus establishing a c o m m o n focus o f attention between the child and the experimenter. In the requesting category the emphasis was on behaviors used to request aid in obtaining objects or events. The behaviors observed within these categories are listed and defined in Table II. Each child received a freguency score for the behaviors listed in Table II, except on the "looks" variable where children received a percentage correct score. Although all children received at least six trials on this variable, some trials for some children were difficult to rate (e.g., experimenter obscures camera angle) or additional trials were provided to assure clarity. Therefore, a percentage score was used. This reflected the proportion o f correct head-turn responses on trials when the experimenter pointed to the wall posters. No fewer than four or more than eight trials were rated for each
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Table II. Description of the Nonverbal Communication Behaviors
Social behavior Appeal Child reaches to tester and makes eye contact after being tickled. Turn-take Child initiates game by rolling ball or car to the tester. Invite Child uses comb, glasses, or hat on the tester when the tester leans his or her head toward the child. Tease Child engages in a prohibited activity (e.g., throwing toys from table) while smiling at the tester. Alternate Point Show Look
Reach Appeal Give Point
Joint attention Child alternates looking at active mechanical toy or a toy in their hand and the tester's face. Child extends index finger toward toy within reach or to part of the room (e.g., posters). Child extends toy toward the tester's face. Percentage of trials that the child turns head (45 ~) and eyes in the direction of the tester's points to the left, right, and behind the child. Requests Child reaches to toys which are out of reach. Child reaches to toys which are out of reach and makes eye contact with the tester. Child extends toy toward the tester's hand. Child points to toys that are out of reach.
child a n d the n u m b e r o f trials p r o v i d e d was s i m i l a r for all t h e g r o u p s . G e n e r alizability coefficients o f reliability were obtained f r o m independent, paired ratings o f videotape d a t a f r o m a sample o f 19 autistic, mentally retarded, a n d n o r m a l c h i l d r e n . T h e m e a n g e n e r a l i z a b i l i t y c o e f f i c i e n t s f o r the 12 E S C S b e h a v i o r s was .90 ( r a n g e .73-.98). G e n e r a l i z a b i l i t y c o e f f i c i e n t s a r e r e c o m m e n d e d f o r the e s t i m a t i o n o f the o b s e r v e r reliability o f c o n t i n u o u s d a t a sets with c o e f f i c i e n t s a b o v e .50 i n d i c a t i v e o f a d e q u a t e r e l i a b i l i t y (Mitchell, 1979).
Psychometric Measures T o assess g e n e r a l d e v e l o p m e n t level, each child was a d m i n i s t e r e d the C a t t e l l I n f a n t Intelligence Scale ( C a t t e l l , 1940) o r t h e S t a n f o r d - B i n e t Intelligence Scale ( T h o r n d i k e , 1972 n o r m s ) . B o t h m e a s u r e s yield I Q a n d M A estim a t e s . T o assess l a n g u a g e d e v e l o p m e n t , c h i l d r e n were a d m i n i s t e r e d t h e R e y n e l l D e v e l o p m e n t L a n g u a g e Scales (Reynell, 1977). T h e l a t t e r was u s e d to p r o v i d e a n o v e r a l l l a n g u a g e age e s t i m a t e b y c o m b i n i n g a n d a v e r a g i n g age e s t i m a t e s d e r i v e d f r o m t h e R e y n e l l m e a s u r e s o f expressive a n d r e c e p t i v e language.
RESULTS T h e n u m b e r o f b e h a v i o r v a r i a b l e s i n c l u d e d in t h e n o n v e r b a l c o m m u n i c a t i o n m e a s u r e was extensive a n d item b y item g r o u p c o m p a r i s o n s f o r simi-
121
Language Development in Autistic Children Table m . Summary Scores for the Initial and Follow-Up Nonverbal Communica-
tion Assessments Autistic Language age-match Mental age-match children MR children MR children M
SD
M
Joint Attention Initial 9.0 5.9 18.1" Follow-up 12.2 9.9 24.7* Social Initial 8.7 4.5 10.9 Follow-up 7.3 4.6 8.9 Request Initial 14.7 5.9 17.0 Follow-up 17.2 6.8 21.6 *Significantly different from the autistic group.
SD
M
SD
6.6 5.9
23.5* 25.9*
9.1 6.9
5.3 3.7
12.1 8.3
5.4 2.8
7.8 6.6
18.4 23.9*
5.6 6.5
lar samples have been presented (Mundy et al., 1986). Therefore, for the sake o f clarity, s u m m a r y variables were created and used in most o f the group comparisons. The summary variables for the nonverbal communication measures were obtained by summing the total frequency o f behaviors exhibited within each category o f nonverbal communication behavior. This was straightfoward for the social intercation and requesting categories. However, the L o o k variable in the joint attention category was a percentage score (see Table II). Since the range o f frequency scores for all other joint attention variables was zero to 11, the L o o k percentage scores were transformed into this range by multiplying the decimal equivalent o f the percentage scores by 10 (e.g., 24010 = 0.24 • 10 = 2.4) prior to inclusion in the sum of indicating behaviors computed for each child. The group means and standard deviations for these measures are presented in Table III. N o n v e r b a l C o m m u n i c a t i o n Group Comparisons
Since differences between the MR control groups were not of interest in this study, the autistic children were c o m p a r e d with the M A - m a t c h e d and language-matched mentally retarded children in independent analyses. Mixed A N O V A s , with the initial and follow-up nonverbal c o m m u n i c a t i o n assessment scores as repeated measures, were used in these comparisons. The autistic group displayed fewer joint attention behaviors than did the MR language controls, F(1, 28) = 18.83, p < .001, and the M R - M A controis, F(1, 28) = 26.45, p < .001. Main effects for the repeated joint attention measure (initial vs. follow-up scores) were obtained in both comparisons; with the language controls, F(1, 28) = 23.88, p < .001; and with the M A controls, F(1, 28) = 5.28, p < .025. These results indicated that all o f the groups displayed an increase in joint attention behavior .~cores across the
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Mundy, Sigman, and Kasari
follow-up period. However, a significant Groups x Repeated Measures interaction was not obtained suggesting that the rate of development of joint attention behavior was similar across the groups. Thus, these results indicated that, even when compared to a language-matched MR sample, autistic children displayed a deficit in gestural joint attention skills. Moreover, the initial deficit displayed by the autistic children was comparable to the extent of the deficit displayed on follow-up testing (see Table III). Since the groups in this study were not matched for IQ (see Table I), it was important to examine the effects of IQ on group differences in joint attention behavior. Therefore, analysis of covariance was used to estimate the effect of IQ on the comparison between the language-matched samples. The results of this ANCOVA indicated that even with IQ as the covariate the autistic children displayed a deficit on the residual gestural joint-attention scores compared to the language-matched MR group: F(I, 27) = 6.44, p < .025. The effect for the repeated joint attention measure was also significant, F(1, 28) = 27.47, p < .01, however, the Group x Repeated Measure interaction was not significant. Thus, a significant deficit in the gestural joint attention skills of the autistic sample was observed after statistically controlling for the effect of IQ. The autistic children also displayed fewer requesting gestures than did the MR-MA control group, F ( I , 28) = 9.39, p < .005. However, they were not significantly different on the requesting measure compared to the language control group, F(1, 28) = 2.76, p > .10. Since this critical comparison was not significant an analysis covarying the effects of IQ was not considered necessary. Comparisons again indicated main effects for the repeated measure reflecting an increase in the number of requests displayed by all groups: with the language controls, F(1, 28) = 5.87, p < .025; with the MA controls, F(1, 28) = 9.39, p < .005. None of the Group x Repeated Measures interactions approached significance. Analyses also indicated that the autistic group did not differ from either control sample on the social interaction measure. Moreover, none of the interactions examined in these group comparisons were significant. The only significant effect was obtained for the repeated measure in the autistic and MR-MA analyses. This reflected a significant decrease in the number of social interaction behaviors displayed in the data from both of these groups, F(1, 28) = 8.05, p < .01. Finally, discriminant analyses were computed to determine if the group differences on the ESCS summary scores reflected the behavior of most of the autistic children or a subgroup. Thus, these analyses were used to estimate the clinical as well as statistical significance of the findings. The most conservative analysis here involved a comparison of the autistic and languagematched controls. In an analysis including the initial joint attention, social
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interaction, and requesting summary scores, only the joint attention summary score significantly contributed to the discriminant function, F t o enter = 24.16, p < .001. the jacknifed classification was successful for 12 autistic children (80%) and 10 MR children (67%). On follow-up testing the joint attention measure again was the only measure to contribute to the discriminant function, F to enter = 18.11, p < .001. The rate of successful jacknifed classification was 11 autistic children (73%) and 13 MR children (87~ In summary, the results indicated that, across a 13-month period, these autistic children consistently displayed a significant impairment in gestural joint attention skills compared to both language-matched and MA-matched mentally retarded controls. In the critical comparison involving the languagematched group, anlysis of convariance indicated that the autistic deficit in nonverbal indicating skill could not be explained in terms of group difference on IQ. Consistent impairments were not evident on the other measures of nonverbal communication skills.
Language Development To examine the development of language the initial and follow-up Reynell language age scores for the autistic and language-matched MR group were compared. The language means for these groups appear in Table I. As expected the autistic and MA-matched MR groups differed in initial language level (p < .025) as well as on the follow-up measure (p < .025, see Table I). Therefore, the latter group was not included in these analyses. A mixed ANOVA, 2 (Autistic Group vs. Language-Matched MRs) • 2 (Initial and Follow-up Language Age Estimates), yielded a significant main effect for the repeated language measures, F(1, 28) = 26.2, p < .001. However, neither the group main effect (F = 1.61) nor the group by repeated measures interaction (F = 0.23) were significant. These results indicated that the groups did not display differences on the language measure, but the groups did display comparable and significant improvement on the language scores over the 13-month follow-up interval.
Correlations With Language To examine the predictive relations between nonverbal communication measures and langag~, the ESCS scores from the first testing session were correlated with the Reynell language age estimates from the follow-up testing. These correlations were computed for the autistic and language-matched MR samples. For comparative purposes the correlations between the scores
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Mundy, Sigman, and Kasari
on the psychometric cognitive assessment, the Reynell, and chronological age from the first testing session were also correlated with the follow-up Reynell language scores. The results of these analyses appear in Table IV. Correlations Within the Autistic Sample. The joint attention summary score was a significant predictor of language development in the autistic sample. None of the other nonverbal communication variables were predictive o f language development in this sample. Moreover, neither initial language score, mental age, chronological age, nor IQ were significant predictors o f language development within this sample. In addition to the data on predicting language, gestural joint attention was also a significant concurrent correlate of language at the time of the initial assessment (r = .63, p < .05) and at the time o f the follow-up assessment (r = .52, p < .05). Mental age with the initial language assessment scores was the only other significant concurrent correlate in this sample (r = .51, p < .05). Correlations Within the Language-Matched MR Group. Gestural joint attention was only a marginally significant predictor of language development in the language-matched MR sample (r = .49, p < .07). However, initial language level and mental age were significant predictors o f language development in this sample (see Table IV). Partial correlations revealed that when the variance associated with inital langauge level was controlled, the partial correlation between MA and follow-up language scores was lowered to a nonsignificant value, pr -- .03. Interestingly, the partial correlation between initial gestural joint attention and follow-up language approached significance even after initial language performance had been taken into account, pr = .46, t = 1.783, p < .10. The concurrent correlations provide other evidence of an association between joint attention and language development in this sample. Nonverbal joint attention at follow-up was significantly correlated with language scores obtained at follow-up (r -- .64, p < .01). The only other significant concurrent correlate obtained in this sample was MA and initial language scores (r = .59, p < .05). Table IV. Predictors of Language Developmentin the Au-
tistic and Language-Matched MR Samples Follow-up Language age scores Autistic Language-matched Initial testing children MR children Joint attention .61a .49 Social -.10 .16 Request .09 .19 Language .37 .81b Mental .22 .60* Chronological age .17 -.06 IQ .03 .47 *p < .05 (two-tailed). ~p < .01 (two-tailed).
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In summary, the principal difference between these data and those from the autistic group was that inital language scores but not nonverbal joint attention was a significant predictor of language development. However, there was a marginally significant trend for initial nonverbal joint attention scores to be correlated with language at follow-up after partialling variance associated with inital language scores. Moreover, gestural joint attention was a significant concurrent correlate of language at follow-up.
DISCUSSION
The autistic children displayed a deficit in the nonverbal joint attention skills measured in this study as opposed to other forms of nonverbal social and communication skills. This deficit remained stable over a 13-month period and was apparent in comparison with language-matched mentally retarded children as well as mental age matched retarded children. Moreover, evidence for this deficit was obtained when group IQ differences between the language-matched samples were statistically controlled. These results are consistent with earlier findings that autistic and IQ-matched mentally retarded children differ with respect to joint attention skills (Mundy et al., 1986). These results may be specific to the structured interaction task used in this study and may differ in unstructured measurements of nonverbal communication. However, at least one study (Sigman et al., 1986) has reported joint attention deficits among autistic children in observations of a less structured care-giver interaction paradigm. These results may also be specific to the particular set of nonverbal behaviors examined in this study. Other research may profitably examine the production of other aspects of nonverbal joint attention behaviors especially in autistic individuals of varying age. Discriminant analyses provided data on the clinical as well as statistical significant of the results. These analyses indicated that the measure of gestural joint attention could distinguish 70 to 80~ of the autistic and language-matched MR control children at the time of both the initial and follow-up assessments. Thus, a large majority of autistic children, rather than a subgroup, displayed deficits in this area and very few nonautistic mentally retarded children displayed comparable deficits. We note, however, that these estimates of the discriminant power of the joint attention measures are slightly lower than those reported earlier (Mundy et al., 1986). This difference likely reflects the variation in findings that are apt to occur across studies with small samples. Not only did the autistic children exhibit a marked deficit on gestural joint attention skills but individual variation in these skills was a significant
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predictor of language development in this sample of autistic children. Furthermore, gestural joint attention was a significant concurrent correlate of language at the time of both the initial and follow-up assessments in this sample. Other variables such as initial IQ and performance on the Reynell were not predictive of Reynell language level at follow-up. These negatives should be interepreted with caution, given the small sample in this study. These negative findings may have been due to the relative constriction on the variance (i.e., low standard deviations) in these measures among the autistic children at the initial assessment (see Table I). These data on joint attention skills support general developmental theory that suggests that the preverbal ability to coordinate attention between objects and people via the expression and understanding of gestures, such as pointing and showing, are important precursors of language development (Bates, 1979; Bruner & Sherwood, 1983; Sugarman, 1984). The pattern of these data suggest that examining the nature of gestural joint attention skills may be especially important with respect to understanding autistic developmental psychopathology and the impediments to language acquisition among these children. Although currently poorly understood, the ability to use these gestures is assumed to reflect developments in the ability to regulate attention deployment between self, other, and object (Bakeman & Adamson, 1984) and in social cognition. With respect to the latter, joint attention skills may mark the development of the child's awareness that other people can see objects or events that the child sees (Rheingold, Hay, & West, 1976). In addition, joint attention skills may differ from other types of nonverbal communication skills such as requesting skills in that they frequently involve the conveyance of affect (Mundy & Sigman, 1989b). This suggestion is supported by data indicating that development of joint attention skills may be associated with the tendency of children to share affect with others in regard to interesting objects and events (Kasari, Sigman, Mundy, & Yirmiya, 1990). Accordingly, autistic deficits in this area may reflect not only a disturbance in attention regulation and social-cognitive processes but also disturbances in affective processes (Kasari et al., 1990; Mundy & Sigman, 1989a, 1989b). 3 Thus, the acquisition of joint attention skills may be a major developmental milestone that reflects the integration of several important develop-
3Mundyet al. (1986)initiallyproposedthat a disturbancein meta-representationaithought(see Baron-Cohen, 1988)mayexplainautisticjointattentiondeficits.However,this hypothesisseems less likelyto be valid in light of developmentaldata indicatingthat gestural joint attention skills emergeprior to meta-representationalskillsin normaldevelopment(see Mundy& Sigman, 1989b).
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m e n t a l precesses. A d i s t u r b a n c e in t h e a c h i e v e m e n t o f this m i l e s t o n e m a y b e a f u n d a m e n t a l c o m p o nfe n t o f d e v e l o p m e n t a l p s y c h o p a t h o l o g y a m o n g y o u n g autistic c h i l d r e n . T h e d a t a is this s t u d y also suggest t h a t a failure to achieve this milestone m a y have a n i m p a c t o n the d e v e l o p m e n t o f subsequent aspects o f autistic p s y c h o p a t h o l o g y , such as i m p a i r m e n t s in l a n g u a g e a c q u i sition. T h e s e c o n c l u s i o n s , especially the latter, a r e s t a t e d with c a u t i o n since the s a m p l e here is small a n d the need f o r r e p l i c a t i o n is c o m m e n s u r a t e l y large. Nevertheless, the p r e s e n t d a t a suggest t h a t gestural j o i n t a t t e n t i o n skills m a y be i m p o r t a n t targets f o r e a r l y c o m m u n i c a t i o n f o c u s e d i n t e r v e n t i o n e f f o r t s with y o u n g autistic c h i l d r e n . R e c e n t studies h a v e d e s c r i b e d t e c h n i q u e s t h a t m a y be effective in m o d i f y i n g aspects o f j o i n t a t t e n t i o n skills such as the r e g u l a t i o n o f eye c o n t a c t ( D a w s o n & A d a m s , 1984; T i e g e r m a n & P r i m a v e r a , 1984). A n e m p i r i c a l e x a m i n a t i o n o f this p o s s i b i l i t y w o u l d be u s e f u l in furture r e s e a r c h .
REFERENCES
American Psychiatric Association. (1980). Diagnostic and statistical manual of mental disorders (3rd ed.). Washington, DC: Author. Bakeman, R., & Adamson, L. B. (1984). Coordinating attention to people and objects in motherinfant and peer-infant interaction. Child Development, 55, 1278-1289. Bates, E. (1979). The emergence of symbois: Cognition and communication in infancy. New York: Academic Press. Baron-Cohen, S. (1988). Social and pragmatic deficits in autism: Cognitive or affective? Journal of Autism and Developmental Disorders, 18, 379-401. Bruner, J., & Sherwood, V. (1983). Thought, language and interaction in infancy. In J. D. Call, E. Galenson, & R. L. Tyson (Eds.), Frontiers of infant psychiatry. New York: Basic Books. Cattell, P. (1940). The measurement of intelligence of infants and young children. New York: Basic Books. Curcio, F. (1978). Sensorimotor functioning and communication in mute autistic children. Journal of Autism and Childhood Schizophrenia, 8, 281-292. Dawson, G., & Adams, A. (1984). Imitation and social responsiveness in autistic children. Journal of Abnormal Child Psychology, 12, 209-226. Freeman, B., Ritvo, E., Needleman, R., & Yokota, A. 0985). The stability of cognitive and linguistic parameters in autism: A 5-year study. Journal of the American Academy of Child Psychiatry, 24, 290-311. Hannan, T. (1987). A cross-sequential assessment of the occurrences of pointing in 3- to 12-monthold human infants. Infant Behavior and Development. 10, 11-12. Kasari, C., Sigman, M., Mundy, P., & Yirmiya, N. (1990). Affective sharing in the context of attention interaction of normal, autistic, and mentally retarded children. Journal of Autism and Developmental Disorders, 20, 87-100. Landry, S., & Loveland, K. (1988). Communication behaviors in autism and developmental language delay. Journal of Child Psychology and Psychiatry, 29, 621-634. Leung, E., & Rheingold, H. (1981). Development of pointing as a social gesture. Developmental Psychology, 11, 215-220. Lotter, V. (1978). Follow up studies. In M. Rutter & E. Schopler (Eds.), Autism: A reappraisal of concepts and treatment (pp. 475-495). New York: Plenum Press. Loveland, K., & Landry, S. (1986). Joint attention in language in autism and developmental language delay. Journal of Autism and Developmental Disorders, 16, 335-349.
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McDonald, M., Mundy, P., Sigman, M., & Kasari, C. (1989). Psychometric scatter antistic preschoolers as measured by the CatteU. Journal of Child Psychology and Psychiatry, 30, 594-604. Mitchell, F. (1979). Interobserver agreement, reliability, and generalizability of data collected in observational studies. Psychological Bulletin, 86, 376-390. Mundy, P., & Sigman, M. (1989a). Specifying the nature of the social impairment in autism. In G. Sawson (Ed.), Autism: New Perspectives on diagnosis, nature, and treatment (pp. 3-12). New York: Guilford. Mundy, P., & Sigman, M. (1989b). The theoretical implications of joint attention deficits in autism. Development and Psychology, 1, 173-183. Mundy, P., Sigman, M., Ungerer, J., & Sherman, T. (1986). Defining the social deficits of autism: The contribution of nonverbal communication measures. Journal of Child Psychology and Psychiatry, 27, 657-669. Mundy, P., Sigman, M., Ungerer, J., & Sherman, T. (1987). Play and nonverbal communication correlates of language development in autistic children. Journl of Autism and Developmental Disabilites, 17, 349-363. Prizant, B., & Schuler, A. (1987). Facilitating communication: Theoretical foundations. In D. Cohen, A. Donnellan, & R. Paul (Eds.), Handbook of autism and pervasive developmental disorders (pp. 289-300). New York: Wiley. Reynen, J. (1977). Reynell developmental language scales. Windsor, England: NFER Publishing. Rheingold, H., Hay, D., & West, M. (i 976). Sharing in the second year of life. Child Development, 83, 898-913. Rutter, M. (1978). Diagnosis and definition. In M. Rutter & E. Schopler, (Eds.), Autism: A reappraisal of concepts and treatment. New York: Plenum Press. Rutter, M. (1985). The treatment of autistic children. Journal of Child Psychology and Psychiatry, 26, 193-214. Seibert, J., Hogan, A., & Mundy, P. (1982). Assessing interactional competencies: The Early Social-Communication Scales. Infant Mental Health Journal, 3, 244-259. Sigman, M., Mundy, P., Sherman, T., Ungerer, J. (1986). Social interactions of autistic, mentally retarded, and normal children and their caregivers. Journal of Child Psychology and Psychiarty, 27, 647-656. Sugarman, S. (1984). The development of preverhal communication. In R. L. Schiefelbusch & J. Pickar (Eds.), The acquisition of communicative competence. Baltimore: University Park Press. Thorndike, R. (1972). Stanford-Binet Intelligence Scale."Norms tables. Boston: Houghton Mifflin. Tiegerman, E., & Primavera, L. (1984). Imitating the autistic child: Facilitating communicative gaze. Journal of Autism and Developmental Disorders, 14, 27-38. Werner, H., & Kaplan, B. (1963). Symbol formation. New York: Wiley. Wetherby, A., & Prutting, C. (1984). Profiles of communicative and cognitive-social abilities in autistic children. Journal of Speech and Hearing Research, 27, 364-377.
A Longitudinal Study of Joint Attention and Language Development in Autistic Children I Peter Mundy, 2 Marian Sigman, and Connie Kasari UCLA Center f o r the Health Sciences
This study was designed to examine the degree to which individual differences in gestural joint attention skills predicted language development among autistic children. A group o f 15 autistic children (mean CA = 45 months) were matched with one group of mentally retarded (MR) children on mental age and another group o f MR children on language age. These groups were administered the Early Social-Communication Scales. The latter provided measures o f gestural requesting, joint attention, and social behaviors. The results indicated that, even when controlling for language level mental age, or 1Q, autistic children displayed deficits in gestural joint attention skills on two testing sessions that were 13 months apart. Furthermore, the measure o f gestural nonverbal joint attention was a significant predictor o f language development in the autistic sample. Other variables, including initial language level and IQ were not significant predictors o f language development in this sample.
A paucity of nonverbal gestural joint attention or indicating skills have been noted in observations of samples of autistic individuals (Curcio, 1978; Wetherby & Prutting, 1984). Gestural joint attention skills refer to children's use and comprehension of conventional gestures such as pointing to objects and showing objects to other people. These social skills also involve the use of eye contact in conjuntion with gestures or alone as when children alternate their gaze between an interesting object and a care-giver. In general these behaviors serve to coordinate attention between interactive social partners
~This study was supported by NIMH grant 30530 and NINCDS grant 30527. 2Address all correspondence to Peter Mundy, UCLA Center for the Health Sciences, Department of Psychiatry, 760 Westwood Plaza, Los Angeles, California 90024. 115 0162-3257/90/0300-0115506.00/0 9 1990PlenumPublishingCorporation
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in order to share an awareness of objects or events. These behaviors typically emerge between 8 and 13 months of age in normally developing children (Bakeman & Adamson, 1984; Bates, 1979; Leung & Rheingold, 1981). Studies using mentally retarded and language-disabled control groups have shown that gestural attention deficits are specific to autism (Landry & Loveland, 1988 Loveland & Landry, 1986; Mundy, Sigman, Ungerer, & Sherman, 1986; Sigman, Mundy, Sherman, & Ungerer, 1986). Moreover, individual differences in gestural joint attention skills are concurrently associated with language abilities among autistic children (Loveland & Landry, 1986; Mundy, Sigman, Ungerer, & Sherman, 1987). The latter finding is consistent with theory that suggests that the development of gestural joint attention skills reflects the emergence of socialcognitive processes that provide a foundation for the acquisition of language (Bates, 1979; Sugarman, 1984; Werner & Kaplan, 1963). This theory suggests that the adequate development of gestural joint attention may predict individual differences in language acquisition among autistic children. However, an investigation of the predictive relation between gestural joint attention skill and language development among autistic children has not been conducted. For this reason the current longitudinal study was designed to determine the degree to which individual differences in gestural joint attention skills predicted language development among autistic children. This was considered an important goal for two reasons. First, autistic children exhibit a variety of severe problems in language development (Rutter, 1978) and individual differences in language development are related to variability in outcome among autistic individuals (Lotter, 1978). Not surprisingly, a common focus of early intervention efforts with these children is the facilitation of communication skills (Rutter, 1985; Prizant & Schuler, 1987). Thus, data on the predictors of language development among autistic children may be informative with respect to the design of these efforts. Second, joint attention skills typically emerge within the first year of life in normally developing children (Bakeman & Adamson, 1984; Hannan, 1987). Therefore, deficits in these skills may mark a fundamental aspect of the developmental disturbance that characterizes autism (Mundy & Sigman, 1989a). If this is so, then individual differences in this aspect of social behavior development should be associated with later emerging domains of development disturbance among autistic children. Thus, data on the predictive validity of gestural joint attention measures is pertinent to understanding the importance of this skill domain in the developmental process of autistic behavior pathology. To address these issues the gestural joint attention and language skills of a sample of young autistic children were assessed across a 13-month interval. Measures of nonverbal requesting and social skills were also included
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in this study to ascertain if language prediction is specific to gestural joint attention or more generally related to nonverbal social-communication skills. Comparative data from two control samples were also obtained in this study. Since most autistic children function in the retarded range of intelligence (e.g., Freeman, Ritvo, Needleman, & Yokota, 1985), a control sample of mentally retarded children matched on mental age was assessed. However, because the psychometric test performance of young autistic children is characterized by weakness on verbal test items (McDonald, Mundy, Kasari, & Sigman, 1989) matching on mental age may lead to mismatching on language level. Since language development was a focus of this study, comparisons between the autistic group and a mentally retarded control group, matched on a measure of expressive and receptive language, were also considered critical to this study. Comparisons of the samples were used to provide descriptive data on the relative rates of development displayed by young autistic and mentally retarded children on nonverbal communication and language skills over the course of 13 months. Moreover, the data from the comparison samples were used to determine if autistic children displayed a unique pattern of organization (i.e., profile of correlations) among the nonverbal communication and language measures. The inclusion of the language-matched mentally retarded sample also presented a design advance over studies that have controlled for language level or mental retardation, but not both, in previous attempts to define the nonverbal communication deficits that are specific to autistic children (Loveland & Landry, 1986; Mundy et al., 1986). METHOD
Subjects The autistic sample comprised 15 children. The diagnosis of each child was made independently of the experiments by psychiatrists who were experienced in the evaluation of developmental disorders and who used American Psychiatric Association (1980) criteria. These included (a) onset before 30 months of age; (b) pervasive lack of responsiveness to others; (c) gross deficits in language development; (d) if speech is present, peculiar speech patterns such as echolalia, pronomial reversal, etc.; (e) bizarre responses to various aspects of the environment; and (f) absence of delusions, hallucinations, loosening of associations, and incoherence as in schizophrenia. Since the focus of this study was on language acqusition, autistic children were selected for this study who exhibited little (fewer than five words) or no expressive language on the Reynell Developmental Language Scales (Reynell, 1977). Initial data from eight autistic children who had previously participated on our program of studies (e.g., Mundy et al., 1986) were in-
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Mundy, Sigman, and Kasari Table I. Initial Developmental and Language Levels of the Groups Autistic children
Language age-match MR children
(n = 15) CA (months) MA (months) IQ Language Initial Follow-up
(n = 15) M
SD
Mental age-match MR children
(n = 15)
M
SD
M
44.9 19.6 43.9
8.7 3.9 6.6
25.3 14.7 60.7
7.2 3.6 16.2
28.5 18.9 68.0
SD
10.1 4.1 14.4
12.5 16.7
1.0 6.1
13.6 18.7
1.9 5.3
16.9 23.2
4.3 5.8
cluded in this study. These children were selected for this follow-up study because they had little or no expressive language skills at the time of the initial assessment. Seven additional autistic children with little or no expressive language skills, who had not previously participated in our research program, were recruited to complete the sample. The mental age matched, mentally retarded (MR) sample included 6 children with down syndrome and 9 children with unspecified etiologies. As expected, MA matching was associated with lack of group correspondence on language level (see Table I). The language age matched sample was matched on the basis of Reynell language scores. This sample held 9 children in common with the mental age matched sample. This sample included 7 children with down syndrome and 8 children with unspecified etiologies. Data on the mean development, intellectual, and language levels obtained during the initial assessment are presented for the three samples in Table I.
Procedures The initial assessments for each child occured during two individual sessions scheduled in the UCLA medical center. These assessment sessions occurred within a 3-week period and included the administration of the nonverbal communication measure, the Cattell Scales of Infant Intelligence (Cattell, 1940) or the Stanford Binet, and the Reynell Language Scales (Reynell, 1977). All tasks were administrated by independent testers. Follow-up testing, including administration of the nonverbal communication measure, and the Reynell, was scheduled for each child approximately 1 year after the initial assessment. The mean intervals between initial and follow-up testing for the autistic, MA-matched, and language-matched mentally retarded groups were 13.4 months (SD = 1.5), 13.5 months (SD = 1.6), and 13.9 months (SD = 1.6), respectively.
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Nonverbal Communication Measures The nonverbal communication skills o f the children were assessed with an abridged form of the Early Social-Communication Scales (ESCS; Seibert, Hogan, & Mundy, 1982). In this procedure the child and experimenter sat facing each other at a small table. A set of toys including a hat, a comb, a book, a ball, a car, 5 small (approximately 2 x 2 inches) wind-up mechanical toys, and five hand-operated mechanical toys including balloons were in view but out of reach to the child. Colorful posters were hung on the walls o f the room. The experimenter presented a n d / o r activated the toys on the table one at a time. When presented, these toys were not within the grasp of the child but were within reach of the child. Intermittently the experimenter pointed to and looked at the wall posters. The experimenter also presented the child with physical social games (tickling) and turn-talking opportunities (child and experimenter alternate rolling the car or ball, or take turns using the comb, glasses, or hat in a functionally appropriate fashion). Verbal interactions were kept to a minimum during the ESCS. The child-experimenter interaction was videotaped to record the front upper body view o f the child and the upper body prof'fle of the experimenter. The period of interaction with each child was approximately 25 min. Children occasionally left the table during testing. When this occurred they were directed back to their seats after 10-15 sec. The task demands o f the interaction were minimal and no children were excluded from this study because of an inability to sit through this procedure. Behavior ratings were collected from the ESCS videotapes by trained observers. Observations of the child's nonverbal communication behaviors were grouped into three mutually exclusive categories: social behavior, joint attention, and requesting. In rating social behavior the emphasis was on the capacity o f the child to elicit attention or physical contact form the experimenter and to engage in turn-taking with the experimenter. The joint attention category included behaviors used to direct attention to an object or event, thus establishing a c o m m o n focus o f attention between the child and the experimenter. In the requesting category the emphasis was on behaviors used to request aid in obtaining objects or events. The behaviors observed within these categories are listed and defined in Table II. Each child received a freguency score for the behaviors listed in Table II, except on the "looks" variable where children received a percentage correct score. Although all children received at least six trials on this variable, some trials for some children were difficult to rate (e.g., experimenter obscures camera angle) or additional trials were provided to assure clarity. Therefore, a percentage score was used. This reflected the proportion o f correct head-turn responses on trials when the experimenter pointed to the wall posters. No fewer than four or more than eight trials were rated for each
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Table II. Description of the Nonverbal Communication Behaviors
Social behavior Appeal Child reaches to tester and makes eye contact after being tickled. Turn-take Child initiates game by rolling ball or car to the tester. Invite Child uses comb, glasses, or hat on the tester when the tester leans his or her head toward the child. Tease Child engages in a prohibited activity (e.g., throwing toys from table) while smiling at the tester. Alternate Point Show Look
Reach Appeal Give Point
Joint attention Child alternates looking at active mechanical toy or a toy in their hand and the tester's face. Child extends index finger toward toy within reach or to part of the room (e.g., posters). Child extends toy toward the tester's face. Percentage of trials that the child turns head (45 ~) and eyes in the direction of the tester's points to the left, right, and behind the child. Requests Child reaches to toys which are out of reach. Child reaches to toys which are out of reach and makes eye contact with the tester. Child extends toy toward the tester's hand. Child points to toys that are out of reach.
child a n d the n u m b e r o f trials p r o v i d e d was s i m i l a r for all t h e g r o u p s . G e n e r alizability coefficients o f reliability were obtained f r o m independent, paired ratings o f videotape d a t a f r o m a sample o f 19 autistic, mentally retarded, a n d n o r m a l c h i l d r e n . T h e m e a n g e n e r a l i z a b i l i t y c o e f f i c i e n t s f o r the 12 E S C S b e h a v i o r s was .90 ( r a n g e .73-.98). G e n e r a l i z a b i l i t y c o e f f i c i e n t s a r e r e c o m m e n d e d f o r the e s t i m a t i o n o f the o b s e r v e r reliability o f c o n t i n u o u s d a t a sets with c o e f f i c i e n t s a b o v e .50 i n d i c a t i v e o f a d e q u a t e r e l i a b i l i t y (Mitchell, 1979).
Psychometric Measures T o assess g e n e r a l d e v e l o p m e n t level, each child was a d m i n i s t e r e d the C a t t e l l I n f a n t Intelligence Scale ( C a t t e l l , 1940) o r t h e S t a n f o r d - B i n e t Intelligence Scale ( T h o r n d i k e , 1972 n o r m s ) . B o t h m e a s u r e s yield I Q a n d M A estim a t e s . T o assess l a n g u a g e d e v e l o p m e n t , c h i l d r e n were a d m i n i s t e r e d t h e R e y n e l l D e v e l o p m e n t L a n g u a g e Scales (Reynell, 1977). T h e l a t t e r was u s e d to p r o v i d e a n o v e r a l l l a n g u a g e age e s t i m a t e b y c o m b i n i n g a n d a v e r a g i n g age e s t i m a t e s d e r i v e d f r o m t h e R e y n e l l m e a s u r e s o f expressive a n d r e c e p t i v e language.
RESULTS T h e n u m b e r o f b e h a v i o r v a r i a b l e s i n c l u d e d in t h e n o n v e r b a l c o m m u n i c a t i o n m e a s u r e was extensive a n d item b y item g r o u p c o m p a r i s o n s f o r simi-
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Language Development in Autistic Children Table m . Summary Scores for the Initial and Follow-Up Nonverbal Communica-
tion Assessments Autistic Language age-match Mental age-match children MR children MR children M
SD
M
Joint Attention Initial 9.0 5.9 18.1" Follow-up 12.2 9.9 24.7* Social Initial 8.7 4.5 10.9 Follow-up 7.3 4.6 8.9 Request Initial 14.7 5.9 17.0 Follow-up 17.2 6.8 21.6 *Significantly different from the autistic group.
SD
M
SD
6.6 5.9
23.5* 25.9*
9.1 6.9
5.3 3.7
12.1 8.3
5.4 2.8
7.8 6.6
18.4 23.9*
5.6 6.5
lar samples have been presented (Mundy et al., 1986). Therefore, for the sake o f clarity, s u m m a r y variables were created and used in most o f the group comparisons. The summary variables for the nonverbal communication measures were obtained by summing the total frequency o f behaviors exhibited within each category o f nonverbal communication behavior. This was straightfoward for the social intercation and requesting categories. However, the L o o k variable in the joint attention category was a percentage score (see Table II). Since the range o f frequency scores for all other joint attention variables was zero to 11, the L o o k percentage scores were transformed into this range by multiplying the decimal equivalent o f the percentage scores by 10 (e.g., 24010 = 0.24 • 10 = 2.4) prior to inclusion in the sum of indicating behaviors computed for each child. The group means and standard deviations for these measures are presented in Table III. N o n v e r b a l C o m m u n i c a t i o n Group Comparisons
Since differences between the MR control groups were not of interest in this study, the autistic children were c o m p a r e d with the M A - m a t c h e d and language-matched mentally retarded children in independent analyses. Mixed A N O V A s , with the initial and follow-up nonverbal c o m m u n i c a t i o n assessment scores as repeated measures, were used in these comparisons. The autistic group displayed fewer joint attention behaviors than did the MR language controls, F(1, 28) = 18.83, p < .001, and the M R - M A controis, F(1, 28) = 26.45, p < .001. Main effects for the repeated joint attention measure (initial vs. follow-up scores) were obtained in both comparisons; with the language controls, F(1, 28) = 23.88, p < .001; and with the M A controls, F(1, 28) = 5.28, p < .025. These results indicated that all o f the groups displayed an increase in joint attention behavior .~cores across the
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Mundy, Sigman, and Kasari
follow-up period. However, a significant Groups x Repeated Measures interaction was not obtained suggesting that the rate of development of joint attention behavior was similar across the groups. Thus, these results indicated that, even when compared to a language-matched MR sample, autistic children displayed a deficit in gestural joint attention skills. Moreover, the initial deficit displayed by the autistic children was comparable to the extent of the deficit displayed on follow-up testing (see Table III). Since the groups in this study were not matched for IQ (see Table I), it was important to examine the effects of IQ on group differences in joint attention behavior. Therefore, analysis of covariance was used to estimate the effect of IQ on the comparison between the language-matched samples. The results of this ANCOVA indicated that even with IQ as the covariate the autistic children displayed a deficit on the residual gestural joint-attention scores compared to the language-matched MR group: F(I, 27) = 6.44, p < .025. The effect for the repeated joint attention measure was also significant, F(1, 28) = 27.47, p < .01, however, the Group x Repeated Measure interaction was not significant. Thus, a significant deficit in the gestural joint attention skills of the autistic sample was observed after statistically controlling for the effect of IQ. The autistic children also displayed fewer requesting gestures than did the MR-MA control group, F ( I , 28) = 9.39, p < .005. However, they were not significantly different on the requesting measure compared to the language control group, F(1, 28) = 2.76, p > .10. Since this critical comparison was not significant an analysis covarying the effects of IQ was not considered necessary. Comparisons again indicated main effects for the repeated measure reflecting an increase in the number of requests displayed by all groups: with the language controls, F(1, 28) = 5.87, p < .025; with the MA controls, F(1, 28) = 9.39, p < .005. None of the Group x Repeated Measures interactions approached significance. Analyses also indicated that the autistic group did not differ from either control sample on the social interaction measure. Moreover, none of the interactions examined in these group comparisons were significant. The only significant effect was obtained for the repeated measure in the autistic and MR-MA analyses. This reflected a significant decrease in the number of social interaction behaviors displayed in the data from both of these groups, F(1, 28) = 8.05, p < .01. Finally, discriminant analyses were computed to determine if the group differences on the ESCS summary scores reflected the behavior of most of the autistic children or a subgroup. Thus, these analyses were used to estimate the clinical as well as statistical significance of the findings. The most conservative analysis here involved a comparison of the autistic and languagematched controls. In an analysis including the initial joint attention, social
Language Development in Autistic Children
123
interaction, and requesting summary scores, only the joint attention summary score significantly contributed to the discriminant function, F t o enter = 24.16, p < .001. the jacknifed classification was successful for 12 autistic children (80%) and 10 MR children (67%). On follow-up testing the joint attention measure again was the only measure to contribute to the discriminant function, F to enter = 18.11, p < .001. The rate of successful jacknifed classification was 11 autistic children (73%) and 13 MR children (87~ In summary, the results indicated that, across a 13-month period, these autistic children consistently displayed a significant impairment in gestural joint attention skills compared to both language-matched and MA-matched mentally retarded controls. In the critical comparison involving the languagematched group, anlysis of convariance indicated that the autistic deficit in nonverbal indicating skill could not be explained in terms of group difference on IQ. Consistent impairments were not evident on the other measures of nonverbal communication skills.
Language Development To examine the development of language the initial and follow-up Reynell language age scores for the autistic and language-matched MR group were compared. The language means for these groups appear in Table I. As expected the autistic and MA-matched MR groups differed in initial language level (p < .025) as well as on the follow-up measure (p < .025, see Table I). Therefore, the latter group was not included in these analyses. A mixed ANOVA, 2 (Autistic Group vs. Language-Matched MRs) • 2 (Initial and Follow-up Language Age Estimates), yielded a significant main effect for the repeated language measures, F(1, 28) = 26.2, p < .001. However, neither the group main effect (F = 1.61) nor the group by repeated measures interaction (F = 0.23) were significant. These results indicated that the groups did not display differences on the language measure, but the groups did display comparable and significant improvement on the language scores over the 13-month follow-up interval.
Correlations With Language To examine the predictive relations between nonverbal communication measures and langag~, the ESCS scores from the first testing session were correlated with the Reynell language age estimates from the follow-up testing. These correlations were computed for the autistic and language-matched MR samples. For comparative purposes the correlations between the scores
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on the psychometric cognitive assessment, the Reynell, and chronological age from the first testing session were also correlated with the follow-up Reynell language scores. The results of these analyses appear in Table IV. Correlations Within the Autistic Sample. The joint attention summary score was a significant predictor of language development in the autistic sample. None of the other nonverbal communication variables were predictive o f language development in this sample. Moreover, neither initial language score, mental age, chronological age, nor IQ were significant predictors o f language development within this sample. In addition to the data on predicting language, gestural joint attention was also a significant concurrent correlate of language at the time of the initial assessment (r = .63, p < .05) and at the time o f the follow-up assessment (r = .52, p < .05). Mental age with the initial language assessment scores was the only other significant concurrent correlate in this sample (r = .51, p < .05). Correlations Within the Language-Matched MR Group. Gestural joint attention was only a marginally significant predictor of language development in the language-matched MR sample (r = .49, p < .07). However, initial language level and mental age were significant predictors o f language development in this sample (see Table IV). Partial correlations revealed that when the variance associated with inital langauge level was controlled, the partial correlation between MA and follow-up language scores was lowered to a nonsignificant value, pr -- .03. Interestingly, the partial correlation between initial gestural joint attention and follow-up language approached significance even after initial language performance had been taken into account, pr = .46, t = 1.783, p < .10. The concurrent correlations provide other evidence of an association between joint attention and language development in this sample. Nonverbal joint attention at follow-up was significantly correlated with language scores obtained at follow-up (r -- .64, p < .01). The only other significant concurrent correlate obtained in this sample was MA and initial language scores (r = .59, p < .05). Table IV. Predictors of Language Developmentin the Au-
tistic and Language-Matched MR Samples Follow-up Language age scores Autistic Language-matched Initial testing children MR children Joint attention .61a .49 Social -.10 .16 Request .09 .19 Language .37 .81b Mental .22 .60* Chronological age .17 -.06 IQ .03 .47 *p < .05 (two-tailed). ~p < .01 (two-tailed).
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In summary, the principal difference between these data and those from the autistic group was that inital language scores but not nonverbal joint attention was a significant predictor of language development. However, there was a marginally significant trend for initial nonverbal joint attention scores to be correlated with language at follow-up after partialling variance associated with inital language scores. Moreover, gestural joint attention was a significant concurrent correlate of language at follow-up.
DISCUSSION
The autistic children displayed a deficit in the nonverbal joint attention skills measured in this study as opposed to other forms of nonverbal social and communication skills. This deficit remained stable over a 13-month period and was apparent in comparison with language-matched mentally retarded children as well as mental age matched retarded children. Moreover, evidence for this deficit was obtained when group IQ differences between the language-matched samples were statistically controlled. These results are consistent with earlier findings that autistic and IQ-matched mentally retarded children differ with respect to joint attention skills (Mundy et al., 1986). These results may be specific to the structured interaction task used in this study and may differ in unstructured measurements of nonverbal communication. However, at least one study (Sigman et al., 1986) has reported joint attention deficits among autistic children in observations of a less structured care-giver interaction paradigm. These results may also be specific to the particular set of nonverbal behaviors examined in this study. Other research may profitably examine the production of other aspects of nonverbal joint attention behaviors especially in autistic individuals of varying age. Discriminant analyses provided data on the clinical as well as statistical significant of the results. These analyses indicated that the measure of gestural joint attention could distinguish 70 to 80~ of the autistic and language-matched MR control children at the time of both the initial and follow-up assessments. Thus, a large majority of autistic children, rather than a subgroup, displayed deficits in this area and very few nonautistic mentally retarded children displayed comparable deficits. We note, however, that these estimates of the discriminant power of the joint attention measures are slightly lower than those reported earlier (Mundy et al., 1986). This difference likely reflects the variation in findings that are apt to occur across studies with small samples. Not only did the autistic children exhibit a marked deficit on gestural joint attention skills but individual variation in these skills was a significant
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predictor of language development in this sample of autistic children. Furthermore, gestural joint attention was a significant concurrent correlate of language at the time of both the initial and follow-up assessments in this sample. Other variables such as initial IQ and performance on the Reynell were not predictive of Reynell language level at follow-up. These negatives should be interepreted with caution, given the small sample in this study. These negative findings may have been due to the relative constriction on the variance (i.e., low standard deviations) in these measures among the autistic children at the initial assessment (see Table I). These data on joint attention skills support general developmental theory that suggests that the preverbal ability to coordinate attention between objects and people via the expression and understanding of gestures, such as pointing and showing, are important precursors of language development (Bates, 1979; Bruner & Sherwood, 1983; Sugarman, 1984). The pattern of these data suggest that examining the nature of gestural joint attention skills may be especially important with respect to understanding autistic developmental psychopathology and the impediments to language acquisition among these children. Although currently poorly understood, the ability to use these gestures is assumed to reflect developments in the ability to regulate attention deployment between self, other, and object (Bakeman & Adamson, 1984) and in social cognition. With respect to the latter, joint attention skills may mark the development of the child's awareness that other people can see objects or events that the child sees (Rheingold, Hay, & West, 1976). In addition, joint attention skills may differ from other types of nonverbal communication skills such as requesting skills in that they frequently involve the conveyance of affect (Mundy & Sigman, 1989b). This suggestion is supported by data indicating that development of joint attention skills may be associated with the tendency of children to share affect with others in regard to interesting objects and events (Kasari, Sigman, Mundy, & Yirmiya, 1990). Accordingly, autistic deficits in this area may reflect not only a disturbance in attention regulation and social-cognitive processes but also disturbances in affective processes (Kasari et al., 1990; Mundy & Sigman, 1989a, 1989b). 3 Thus, the acquisition of joint attention skills may be a major developmental milestone that reflects the integration of several important develop-
3Mundyet al. (1986)initiallyproposedthat a disturbancein meta-representationaithought(see Baron-Cohen, 1988)mayexplainautisticjointattentiondeficits.However,this hypothesisseems less likelyto be valid in light of developmentaldata indicatingthat gestural joint attention skills emergeprior to meta-representationalskillsin normaldevelopment(see Mundy& Sigman, 1989b).
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m e n t a l precesses. A d i s t u r b a n c e in t h e a c h i e v e m e n t o f this m i l e s t o n e m a y b e a f u n d a m e n t a l c o m p o nfe n t o f d e v e l o p m e n t a l p s y c h o p a t h o l o g y a m o n g y o u n g autistic c h i l d r e n . T h e d a t a is this s t u d y also suggest t h a t a failure to achieve this milestone m a y have a n i m p a c t o n the d e v e l o p m e n t o f subsequent aspects o f autistic p s y c h o p a t h o l o g y , such as i m p a i r m e n t s in l a n g u a g e a c q u i sition. T h e s e c o n c l u s i o n s , especially the latter, a r e s t a t e d with c a u t i o n since the s a m p l e here is small a n d the need f o r r e p l i c a t i o n is c o m m e n s u r a t e l y large. Nevertheless, the p r e s e n t d a t a suggest t h a t gestural j o i n t a t t e n t i o n skills m a y be i m p o r t a n t targets f o r e a r l y c o m m u n i c a t i o n f o c u s e d i n t e r v e n t i o n e f f o r t s with y o u n g autistic c h i l d r e n . R e c e n t studies h a v e d e s c r i b e d t e c h n i q u e s t h a t m a y be effective in m o d i f y i n g aspects o f j o i n t a t t e n t i o n skills such as the r e g u l a t i o n o f eye c o n t a c t ( D a w s o n & A d a m s , 1984; T i e g e r m a n & P r i m a v e r a , 1984). A n e m p i r i c a l e x a m i n a t i o n o f this p o s s i b i l i t y w o u l d be u s e f u l in furture r e s e a r c h .
REFERENCES
American Psychiatric Association. (1980). Diagnostic and statistical manual of mental disorders (3rd ed.). Washington, DC: Author. Bakeman, R., & Adamson, L. B. (1984). Coordinating attention to people and objects in motherinfant and peer-infant interaction. Child Development, 55, 1278-1289. Bates, E. (1979). The emergence of symbois: Cognition and communication in infancy. New York: Academic Press. Baron-Cohen, S. (1988). Social and pragmatic deficits in autism: Cognitive or affective? Journal of Autism and Developmental Disorders, 18, 379-401. Bruner, J., & Sherwood, V. (1983). Thought, language and interaction in infancy. In J. D. Call, E. Galenson, & R. L. Tyson (Eds.), Frontiers of infant psychiatry. New York: Basic Books. Cattell, P. (1940). The measurement of intelligence of infants and young children. New York: Basic Books. Curcio, F. (1978). Sensorimotor functioning and communication in mute autistic children. Journal of Autism and Childhood Schizophrenia, 8, 281-292. Dawson, G., & Adams, A. (1984). Imitation and social responsiveness in autistic children. Journal of Abnormal Child Psychology, 12, 209-226. Freeman, B., Ritvo, E., Needleman, R., & Yokota, A. 0985). The stability of cognitive and linguistic parameters in autism: A 5-year study. Journal of the American Academy of Child Psychiatry, 24, 290-311. Hannan, T. (1987). A cross-sequential assessment of the occurrences of pointing in 3- to 12-monthold human infants. Infant Behavior and Development. 10, 11-12. Kasari, C., Sigman, M., Mundy, P., & Yirmiya, N. (1990). Affective sharing in the context of attention interaction of normal, autistic, and mentally retarded children. Journal of Autism and Developmental Disorders, 20, 87-100. Landry, S., & Loveland, K. (1988). Communication behaviors in autism and developmental language delay. Journal of Child Psychology and Psychiatry, 29, 621-634. Leung, E., & Rheingold, H. (1981). Development of pointing as a social gesture. Developmental Psychology, 11, 215-220. Lotter, V. (1978). Follow up studies. In M. Rutter & E. Schopler (Eds.), Autism: A reappraisal of concepts and treatment (pp. 475-495). New York: Plenum Press. Loveland, K., & Landry, S. (1986). Joint attention in language in autism and developmental language delay. Journal of Autism and Developmental Disorders, 16, 335-349.
128
Mundy, Sigman, and Kasari
McDonald, M., Mundy, P., Sigman, M., & Kasari, C. (1989). Psychometric scatter antistic preschoolers as measured by the CatteU. Journal of Child Psychology and Psychiatry, 30, 594-604. Mitchell, F. (1979). Interobserver agreement, reliability, and generalizability of data collected in observational studies. Psychological Bulletin, 86, 376-390. Mundy, P., & Sigman, M. (1989a). Specifying the nature of the social impairment in autism. In G. Sawson (Ed.), Autism: New Perspectives on diagnosis, nature, and treatment (pp. 3-12). New York: Guilford. Mundy, P., & Sigman, M. (1989b). The theoretical implications of joint attention deficits in autism. Development and Psychology, 1, 173-183. Mundy, P., Sigman, M., Ungerer, J., & Sherman, T. (1986). Defining the social deficits of autism: The contribution of nonverbal communication measures. Journal of Child Psychology and Psychiatry, 27, 657-669. Mundy, P., Sigman, M., Ungerer, J., & Sherman, T. (1987). Play and nonverbal communication correlates of language development in autistic children. Journl of Autism and Developmental Disabilites, 17, 349-363. Prizant, B., & Schuler, A. (1987). Facilitating communication: Theoretical foundations. In D. Cohen, A. Donnellan, & R. Paul (Eds.), Handbook of autism and pervasive developmental disorders (pp. 289-300). New York: Wiley. Reynen, J. (1977). Reynell developmental language scales. Windsor, England: NFER Publishing. Rheingold, H., Hay, D., & West, M. (i 976). Sharing in the second year of life. Child Development, 83, 898-913. Rutter, M. (1978). Diagnosis and definition. In M. Rutter & E. Schopler, (Eds.), Autism: A reappraisal of concepts and treatment. New York: Plenum Press. Rutter, M. (1985). The treatment of autistic children. Journal of Child Psychology and Psychiatry, 26, 193-214. Seibert, J., Hogan, A., & Mundy, P. (1982). Assessing interactional competencies: The Early Social-Communication Scales. Infant Mental Health Journal, 3, 244-259. Sigman, M., Mundy, P., Sherman, T., Ungerer, J. (1986). Social interactions of autistic, mentally retarded, and normal children and their caregivers. Journal of Child Psychology and Psychiarty, 27, 647-656. Sugarman, S. (1984). The development of preverhal communication. In R. L. Schiefelbusch & J. Pickar (Eds.), The acquisition of communicative competence. Baltimore: University Park Press. Thorndike, R. (1972). Stanford-Binet Intelligence Scale."Norms tables. Boston: Houghton Mifflin. Tiegerman, E., & Primavera, L. (1984). Imitating the autistic child: Facilitating communicative gaze. Journal of Autism and Developmental Disorders, 14, 27-38. Werner, H., & Kaplan, B. (1963). Symbol formation. New York: Wiley. Wetherby, A., & Prutting, C. (1984). Profiles of communicative and cognitive-social abilities in autistic children. Journal of Speech and Hearing Research, 27, 364-377.
