Journal of Abnormal ChildPsyehology, Vol. 7, No. 4, 1979, pp. 357-380

Cognitive Abilities and Disabilities in Infantile Autism: A Review Margot R. Prior La Trobe University, Bundoora, Victoria, Australia

The literature on various aspects o f learning and performance in autistic children is reviewed and interpreted as indicating very little that is specific to autism. Inadequate and inconsistent methodology precludes generalizations concerning the nature o f the disorder. It is suggested that future research should be particularly concerned with controlling for developmental influences on performance, and with investigation of the higher functioning autistic children who are less governed by retardation factors. The current evidence is considered to support a hypothesis concerning abnormal hemisphere functioning in this group o f children. Reviews of most aspects of the syndrome of infantile autism have proliferated over the last 20 years (Hermelin & O'Conner, 1970; Margolies, 1977; Ornitz, 1974; Rutter, 1974; Simmons & Tymchuk, 1973) and in general have led to the conclusion that autism may be viewed as a severe disorder present from birth or shortly after, involving multiple perceptual and cognitive impairments that lead to the development of extreme behavioral maladjustment, and which, except for a small minority of cases, has a poor prognosis (Kanner, 1973; Lotter, 1974; Prior & Sanson, 1978; Rutter, 1970). The diagnostic difficulties that plagued earlier research are less in evidence or at least have ceased to be such a contentious issue, and recent research has been marked by more precise specification of the samples under investigation. Three issues considered of major importance in the further investigation of infantile autism form the basis for this review. First, it is now clear that autistic children may be considered as falling into at least two groups, which may be differentiated from each other on a number of important factors (Bartak & Rutter, 1976; Prior, 1977b). That is, it is possible to distinguish between mentally retarded autistic children who are a majority of cases, and children of borderline Manuscript received in final form July 19, 1979. 357 0 0 9 1 - 0 6 2 7 / 7 9 / 1 2 0 0 - 0 3 5 7 5 0 3 , 0 0 / 0 9 1979 P l e n u m Publishing C o r p o r a t i o n

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or normal tested intelligence who are in the minority and for whom the prognosis is much better. The two subgroups have in common many core autistic behavioral symptoms but these are less influential in the outcome of the disorder than the level of intelligence and the ability to understand and to use language. Experimental work with both retarded and normally intelligent autistic children produces findings that are influenced by MA and IQ much more than they are influenced by clinical condition (Bartak & Rutter, 1976; Frith, 1972; Fyffe & Prior, 1978; Hermelin & O'Connor, 1970; Prior, 1977a). Clearly, further research will have to be predicated on this evidence and further insight into the "autistic" disorder is most likely to come from study of the more intelligent subgroup whose behavior is less governed by severe developmental delay and intellectual retardation. Second, conclusions derived from experimental studies have provided little insight into the specific nature of autism because of serious methodological flaws in experimental design and argument. These problems are primarily those of failure to control for developmental and/or retardation factors and secondarily failure to ensure that acquisition of task-relevant information is controlled before assessing the ability to retain or otherwise manipulate that information. This latter problem has been common also in research with retardates (Bortner & Birch, 1970; Clarke & Clarke, 1974), with major implications for that area as well as for autism. Third, the currently available behavioral, psychometric, and experimental data relating to autism provide support for an hypothesis of dysfunction or lack of development of left or language hemisphere functions in autistic children with consequent implications for the etiology of the disorder. These contentions will be considered in the context of a review of the research literature from the mid-1960s on learning in autistic children, including perception, memory, cognition, language, and specific abilities. For this paper, experimental work with groups of children whose diagnosis is not clearly that of autism in the Kanner/Rutter (1974) sense is excluded.

PERCEPTION

It has been argued that distorted or immature perceptual experience in autistic children may provide the explanation for the disorder (Ornitz, 1974; Ornitiz & Ritvo, 1968; Ritvo, 1976; Schopler, 1966, 1971). Under- or oversensitivity to visual and auditory stimuli is commonly reported (Hingtgen & Coulter, 1967; Metz, 1967; Prior & Gajzago, 1974; Prior, Gajzago, & Knox, 1976), suggesting problems of sensory reception. Integration of and utilization of sensory

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information such as auditory imperception (Rutter, 1968) have been suggested as basic to autism. However, such abnormalities are characteristic of children with other disorders such as blindness and deafness, developmental aphasia, and mental deficiency (Wing, 1969), and as Rutter has noted (1974), visual or auditory imperception is neither necessary nor sufficient for the development of autism. Perceptual constancy which has been considered central to sensory integration was found to be commensurate with chronological age in a study of visual uprightness constancy (Gajzago, 1975) in autistic and normal children. The extended period of training necessary for autistic children to learn to discrimi. nate the stimuli and the marked variability in performance within the sample, which was related to the level of functioning and language development, underlined the strong developmental influence on the findings. Perceptual discrimination for these children appears to be aided by haptic cues (Frith & Hermelin, 1969; Hermelin & O'Connor, 1965, 1967b; Prior & Chen, 1975); however, such facilitation has also been reported for young normal children (Hermelin & O'Connor, 1967c) and so may relate to developmental rather than autistic characteristics. Thus none of the evidence from this area of research indicates any features specific to autism. Autistic children seem much less handicapped when given perceptual tasks suggesting their own solution (De Meyer, Alpern, Barton, De Meyer, Churchill, Hingtgen, Bryson, Pontius, & Kimberlin, 1972; Russell, 1975), such as the Seguin Formboard and the Decroly Matching Game. On tasks when instructions are minimal, imitation is not required, and there is little need to analyze stimulus properties, autistic children - though not performing at chronological age level - are clearly more successful. While Ornitz and Ritvo have claimed that their findings of perceptual, nystagmatic, and neurophysiological abnormalities may be interpreted to support a theory of perceptual inconstancy as basic to autism, despite a large number of studies (Ornitz, 1969, 1971, 1974; Ornitz & Ritvo, 1968; Ritvo, 1976), corroborative evidence for this theory has been lacking, while evidence supporting the fundamental nature of other kinds of information-processing difficulties has grown apace. O'Connor and Hermelin (1971) and Hermelin (1976) suggest that their extensive research has revealed no problems of "simple perception" in autistic children. However, the related work of Frith with pattern and sequence perception (1970, 1971) has suggested that selective perception (or attention) may be impaired and may lead to faulty or idiosyncratic output in tasks requireing selection and processing of specific features of material presented for perception and analysis. That is, perceptual activity may be relatively normal while perceptual analysis is impaired. Since this is also characteristic of young normal children, recourse to developmental explanations is again indicated.

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It seems that autistic children, like retarded children, are able to learn simple discriminations, given sufficient trials and if their attention can be directed to the stimulus dimension or dimensions to be discriminated (Hermelin & O'Connor, 1970; Prior, 1975). Performance varies as a function of IQ and MA, as it does in retarded groups (Zearnan & House, 1963). Even low-functioning autistic children are able to form a learning set (Prior &Chen, 1975) and their performance has been shown to be better than that of normal and retarded MA matched controls in that they required a lesser number of trials to reach criterion. A study of position and length discrimination by Hermelin and O'Connor (1967b) showing that autistic children as well as normals learned a position discrimination faster than they learned length discrimination suggested interpretation in developmental terms. Discrimination of dimensional differences also appears to be MA-related (Prior, 1975), as it is with retardates (Zeaman & House, 1963). Experiments involving discrimination of direction of an arrow (Hermelin & O'Connor, 1970; Prior, 1977a), a difficult task for young children (Bryant, 1969), produced performance again apparently MA-determined. Two other experiments reported by Prior (1977a) concerned more complex discrimination learning tasks. On a cue-matching task using arrow direction as the cue, her autistic subjects were significantly poorer fhan matched normals and subnormals. Autistic children were also unable to acquire a conditional matching learning set, although this was successfully achieved by matched normal controls. The contrast in performance on this task with that on a learning set task was attributed to the inability to use symbolic cues as a basis for problem solving, an interpretation similar to that proposed by Hermelin and O'Connor (1970) on the basis of their series of experiments. A follow-up of the conditional matching learning set experiment carried out by McGillivray and Prior (1979), using three-dimensional stimuli in a conditional discrimination learning set paradigm, found that 8 of 12 autistic children could learn to solve such problems and that performance was apparently a function of MA. Thus findings in this area may be stimulus-specific, suggesting the need for clarification of the proposed "~ processing" deficit. It seems that while autistic children undoubtedly have difficulties with many discrimination learning tasks, these difficulties are related to MA and IQ factors and the performance indicates developmental delay rather than specific autism-based deficiencies. In the only reviewed experiment where performance was better than that of controls (Prior &Chen, 1975), stimuli were three-dimensional, tactile feedback was provided, tangible rewards were used, and no verbal mediation was necessary for learning. This is a rare finding, which emphasizes the importance of task-specific factors.

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It has been claimed that autistic children have very good short-term (rote) memories (Hermelin, 1976; Lockyer & Rutter, 1970), although there are modality-specific differences. For example, auditory memory is apparently better than visual memory (Hermelin & O'Connor, 1970;Prior, 1977b). However, close scrutiny of the current evidence reveals equivocality and contradictions not only in the "quantity" aspect of memory but also in the "quality" or type of memory. Best performance is almost certainly in repetitive rote memory tasks such as digit span or repetition or rhymes, jingles, or phrases, without regard for communicative value. In normals this kind of memory is a brief, sensory-specific trace that is lost almost immediately in the absence of further coding (Hermelin, 1976). However, even on digit span tests, there are extreme differences in ability (Fyffe & Prior, 1978; Prior, 1977b) related to intellectual functioning level. Both Hagen, Winsberg, and Wolff (1969) and Bryson (1972) reported that autistic children had difficulty with visual and auditory memory tasks, but in neither of these studies were adequate attempts made to control for acquisition so that purely memory could be assessed. This factor was overcome in the Prior and Chen (1976) experiments on short-term and serial memory; in addition, memory over longer time intervals than had previously been used was measured (0-120 seconds). In this case, memory deteriorated over time intervals but the performance of autistic children was not different from that of MA-matched normals and MA-, CA-, and IQ-matched retarded controls. Hermelin's claims for the centrality of coding disabilities in autistic memory performance are based on a series of experiments in which autistic children were required to repeat lists of either random words or words making a meaningful sentence. Autistic children were not aided in recall of words by the semantic and syntactic cues that facilitate recording and storage of sentence material. Their recall of random material was as good as that for sentences, whereas normal children improved with sentence material. A replication and extension of the experiment by Fyffe and Prior (1978), however, found that autistic children were able to use meaning to facilitate recall; the recoding ability was not absent but was less effective. In addition, it was found that a higher functioning group of autistic children did not differ in any way from controls, indicating that with a higher developmental level no comparative impairment existed. Recall for ambiguous sentences (syntactically correct but semantically meaningless) was also better than that for random strings of words, indicating again that autistic children have the ability to use syntax to aid recall. Fyffe and Prior (1978) claimed that their results were interpretable in developmental terms and did not support a particular coding for memory deficit in autism. Reported recency effects that were similar to those found by Hermelin and O'Connor (1967c) may be similarly explained.

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In summary it may be said that autistic children vary considerably in memory ability even among diagnostically homogeneous groups. Acoustic memory is apparently relatively good. As with other aspects of learning, performance is apparently usually task-specific and very much dependent on developmental and intellectual level since high- and low-functioning children often behave in quite different ways. There seems no good evidence at the moment to suggest memory impairment as a central problem in autism; rather the evidence suggests that it is the higher (and later) stages of information processing that may be abnormal. Further systematic investigations of acquisition effects on memory and of information recoding processes that mediate recall and recognition are needed. It has too often been the case in studies of perception, various types of learning performance, and memory that a basic methodological problem has confounded results. Claims have been made concerning deficient response behavior (e.g., in remembering) as characteristic of a particular group but no control has been instituted to ensure that perceived input or acquisition of appropriate information necessary for the tested performance is constant for all compared groups. It has been shown that when groups such as retarded and autistic children are preliminary task-matched as well as MA- and IQ-matched, their performance is similar (Prior, 1975; Prior & Chen, 1976). This methodological problem is nowhere better illustrated than in studies of cross-modal processing in autistic children.

CROSS-MODAL LEARNING Deficits in cross-modal processing have been reported by a number of researchers with different groups of children (Birch & Hertzig, 1967; Bryson, 1972; Hermelin & O'Connor, 1965, 1970; Tubbs, 1966; Walker & Birch, 1970), although in all studies, within-group subject variability was noted, with some children performing at age-appropriate levels. Findings are somewhat equivocal, due perhaps to sampling and methodological differences. For example, although Birch and Hertzig (1967) reported deficiencies in visual, haptic, and kinesthetic cross-modal matching in their subjects, Hermelin and O'Connor (1970) found no differences between autistic children and controls on cross-modal tasks in the visual and haptic modalities. In a study designed to overcome the major defects of experimental design and data analysis of earlier studies (see Bryant, 1968, 1975; Friedes, 1974, for review), in controlling for within-modality learning before testing for transfer Herbert (1978) found no deficiencies in cross-modal transfer in a group of low-functioning autistic children, in visual or haptic modalities. Learning in the auditory modality was very poor to absent in her group, with consequent effects on auditory-visual and auditory-haptic cross-modal learning.

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Apart from sample differences, which have precluded generalizations about cross-modal deficiencies, research has also been characterized by lack of adequate MA matching (Birch & Hertzig, t967; Walker & Birch, 1970), uncontrolled task factors (such as whether subjects understood the concept of same vs. different), cues from other modalities being available and thus contaminating the cross-modal response (Bryson, t 972), tack of CA controls (Frith & Hermetin, 1969), floor effects (Hermelin & O'Connor, 1965), and most of all the failure to control for within-modal learning before testing for cross.modal transfer. Herbert's results suggest that with careful experimental control, many of the earlier reported sensory and perceptual learning disabilities either disappear or else are clearly- related to developmental effects. At this stage the conclusion from studies of perceptual, cross-modal, discrimination learning and memory in autistic children must be stated in developmental terms. Performance deficits in most reported studies are apparently related to mental age and to IQ, i.e., tow MA children behave like young normal children and retardation effects override any effects that may be characteristic of autism. Further study of higher functioning groups that can be matched with normal controls on all of CA, MA, and IQ would be necessary to assert that autistic children show perceptual abnormalities specific to their diagnostic classification. In addition, no further progress can be made unless control of the acquisition phase of any learning task is equivalent across different groups of children. The finding that even very low-functioning autistic children can make adequate cross-modal associations if within-modal learning is acheived, or can remember information if it has been acquired, stresses the importance of careful methodological controls.

IMITATION LEARNING

Autistic children are particularly deficient in the ability to imitate and rarely do so spontaneously (De Meyer, 1976; Prior & Gajzago, 1974; Prior et al., 1976; Wing, 1976). Motor imitation, which develops quite early in normal infants with a minimum of encouragement, is difficult for autistic children to learn, especially by just watching. Wing (1976) has pointed out that autistic children may learn required motor movements, such as those involved in riding a tricycle or using cutlery, if their limbs are put through the activity by the trainer, thus circumventing the problem of imitation. However, since there are numerous anecdotal reports of children imitating, for example, the steps involved in setting in motion an interesting mechanical or electrical apparatus, the problems of attention, interest, and motivation cannot be ignored in considering this particular characteristic of autism. Extremely poor ability on the manual expression subtest of the ITPA, which requires the child to demonstrate the use of familiar objects such as a toothbrush and telephone, has been reported (Prior,

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1977b; Tubbs, 1966). Notably, performance was poor for both high- and lowfunctioning autistic subjects (Prior, 1977b) in spite of a high level of interest and cooperation in the autistic group. Operant conditioning methods have been used successfully to train imitative responses (Hewett, 1965; Lovaas, 1966), including speech sounds and words, but spontaneous imitation, for example, of words, phrases, or sentences appears to occur in a mechanical fashion without meaningful intent and is typified in the repetition of television commercials and tunes. Autistic children can learn to imitate with intensive training but rarely do so in a spontaneous and meaningful fashion. The only quasi-imitative ability that is common is echolalia and this of course has little adaptive value, although it may be helpful in language learning. The deficiency in imitation is one area in which autistic children appear to be distinct from other handicapped children, regardless of developmental level. It seems likely that this basic, probably innate learning mechanism is lacking from the beginning of life and is a major contributing factor to the deficit in social learning as well as in cognitive development. CODING PROCESSES

There have been several studies carried out by Frith and Hermetin and O'Connor (see Hermelin, 1976, for review) that have uncovered abnormalities in the coding and ordering of information input and output in autistic children. Frith's (1970, 1971, 1972) experiments were designed to examine the ways in which autistic children sequence information in both visual and auditory modalities. Autistic children showed both rule exaggeration and rigidity with auditory material, although with visual material their behavior was characterized by the imposition of their own idiosyncratic rules in the attempt to reproduce ordered sequences. However, a further experiment in which choice of pattern imposition was available in a card-guessing game showed no performance difference between autistic and matched controls and clear MA effects. Comparisons of information-processing strategies in normal, deaf, and autistic children have suggested handicaps in the ability to process temporal sequences but relative strength with visuospatial material (Hermelin, 1976) for autistic children. Most of these more recent experiments have been with relatively highfunctioning autistic children and it is readily apparent that understanding of the syndrome and its underlying dysfunctions can more profitably be gained though experimental work of this kind. The gross retardation of many autistic children makes it impossible to discover features of autism, as distinct from features of retardation in many studies. The findings of this type of research then are particularly valuable and worthy of extension. At this stage it can be concluded that higher functioning autistic children are able to process many different kinds of input but that the manner of their processing is often different from that of normal children and particularly subject to idiosyncratic, limited, and often stereotyped strategies.

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CONDITIONS OF LEARNING

The results of a series of experiments reported over the last few years have been interpreted as support for an hypothesis of "overselectivity" in the response and learning behavior of autistic children (Koegel & Rincover, 1976; Koegel & Schreibman, 1977; Koegel & Wilhelm, 1973; Lovaas & Schreibman, 1971; Lovaas, Schreibman, Koegel, & Rehm, 1971; Reynolds, Newsom, & Lovaas, 1974). Overselective attention in multiple-cue situations has been shown to be a developmental phenomenon (Eimas, 1969; Hale & Morgan, 1973; Levine, 1970) and its persistence in older children might be regarded as evidence for retarded development. It has been suggested that autistic children, like young normal or developmentally retarded children, respond to a restricted number of cues in a learning situation, i.e., are overselective (Lovaas et al., 1971). These authors reported that the responses of autistic children in a multiple-cue learning situation were controlled by only one of the available cues. No one modality predominated since autistic children could be trained to respond to single cues that had previously been nonfunctional. They have also been shown to be overselective within a single modality (Koegel & Wilhelm, 1973; Reynolds et al., 1974; Wing, 1976). Although the overselectivity hypothesis has some heuristic value, a close examination of its implications in a number of varying situations indicates that like other postulated theories it lacks generality and oversimplifies the problems of autistic children in cognitive and social areas. A serious drawback in this work is the frequent failure to control for MA and IQ in studies comparing autistic, retarde d, and normal subjects (Kovattana & Kraemer, 1974; Lovaas et al., 1971). Where attempts have been made to control for MA and IQ factors (e.g., Schover & Newsom, 1976) the evidence is clear: MA predicts overselectivity and learning ability just as it does for normal children (Hale & Morgan, 1973) and for retardates (Fisher & Zeaman, 1973). Furthermore, there is a strong relationship between intelligence level and the ability to use multiple cues (Wilhelm & Lovaas, 1976). These relationships suggest that ability to utilize multiple cues will increase as cognitive function improves for any group of children and that therefore overselectivity may be part of a developmental lag rather than a deficit specific to autism. Consistent findings of lack of deficit with high-functioning autistic groups, especially those with language competence, reinforce this view. Edwards, Shigley, and Edwards (1976) have also suggested on the basis of their work that overselectivity may be a function of the particular procedure used to test for it. A recent paper (Koegel & Lovaas, 1978) concedes that overselectivity is not a unique feature in autism. Recent reviews of behavioral methods of treatment (e.g., Frankel, Tymchuk, & Simmons, 1976; Margolies, 1977) indicate that operant methods have been used with success to increase learning of new behaviors (e.g., Hewett, 1967; Hingtgen, Coulter, & Churchill, 1967; Koegel & Rincover, 1976; Stark, 1972) and to reduce the exhibition of unwanted behaviors such as stereotypies, self-

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multilation, and antisocial behavior (Fox & Azrin, 1973; Jones, Simmons, & Frankel, 1974; Lovaas & Bucher, 1974; Tate & Baroff, 1966). Most school-based programs now utilize behavioral methods to facilitate the treatment and education of autistic children and some individual children have made good progress on a strict and comprehensive behavior modification program. A valuable body of literature describing procedures for successful classroom management of autistic children based largely on operant principles in both special and normal settings is building up, which should enable greater facilitation of learning in such settings in the future (e.g., Koegel & Rincover, 1976; Koegel, Russo, & Rincover, 1977; Rincover & Koegel, 1977). However, despite enormous progress with this technique, many children, especially severely retarded ones, remain resistant to modification except at a most basic level and are unable to learn even elementary academic skills. In addition, problems of generalization and spontaneous and creative use of learned behavior limit the effectiveness of behavior modification, especially if it is carried out only in clinic or school. Current techniques are increasingly involving families as well as professionals in helping autistic children to learn (Howlin, Marchant, Rutter, Berger, Hersov, & Yule, 1973) and generalization procedures are built into the more sophisticated programs, thus increasing the chances of progress among these children. The fact remains, however, that improvement and "recovery" is still clearly much more a function of factors within the child (Gajzago & Prior, 1974; Prior & Sanson, 1978) than of the intervention methods employed. The effect of treatment structure in enhancing the learning and progress of autistic children is best illustrated in the comparative study of three schools for autistic children reported by Bartak & Rutter (1973). Children showing the greatest gains were those attending the school that emphasized a well-controlled classroom situation with considerable specific teaching. However, individual progress was most closely related to nonverbal IQ, and no child with an IQ less than 43 showed any gains in reading, again reinforcing the conclusion that factors within the child are of paramount importance. Further studies of the effects of treatment structure (Rincover & Koegel, 1977; Schopler, Brehm, Kinsbourne & Reichler, 1971) confirm Bartak's findings. The powerful effects of success and failure on the learning and performance of autistic children have received little experimental investigation. Churchill (1971) reported a close relationship among several measures of "pathological" behavior and failure in a learning, testing situation. Those familiar with the behavior of autistic children in psychometric assessment situations have also reported increases in maladaptive behavior as items in tests become more difficult and failure increases. Davids (1974) also showed that learning improved considerably under reward conditions. These pieces of evidence of course indicate the similarity between autistic and any other type of children in learning situations: that success leads to success. Thus this principle can be seen to enhance learning ability in children who are frequently noncooperative or disinterested.

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LANGUAGE LEARNING The centrality of the language disorder in the syndrome of autism has recently been strongly argued (Churchill, 1972; Rutter, 1974) and it is clear that among the symptoms and behavior the language problem stands out as the most consistently noted one with important implications for prognosis (Rutter, 1970). However, the problem is not just simply severe dysphasia but must also involve those processes underlying and basic to language development per se. Unfortunately, we do not yet understand clearly the precise nature of the languagelearning difficulty in autism and its relationship to other perceptual and cognitive functions that are also impaired. For the minority of autistic children who do acquire language more or less spontaneously, the process of learning is apparently not only slower than normal but also deviant (Prior, 1979; Ricks & Wing, 1976) when compared with other groups. Ricks and Wing (1976) have suggested that words seem to be learned passively in an operant fashion and are not processed, stored, and related to a gathering of experience through which language is modifed. Thus there is none of the flexibility and creativity of the normal language-learning child. The lack of "inner language" stressed by Rutter (1974), Hermelin and O'Connor (1970), Prior (1977b), and Ricks and Wing (1976) is of course directly implicated in this failure to learn the complexity, abstractness, and subtlety of social language. A number of researchers have successfully trained autistic children to use words and both simple and compound sentences (Brawley, Harris, Allen, Fleming, & Peterson, 1969; Hewett, 1965; Lovaas, 1966; Risley & Wolf, 1967; Stevens-Long & Rasmussen, 1974) using operant methods. However, learning has often been situation-specific (Hartung, 1970; Koegel & Rincover, 1974; Weiss & Born, 1967), has not led to spontaneous and creative language production (as opposed to trained speech), while the acquired speech has remained at a mechanical and concrete level. In a critical review of the field, Harris (1975) has pointed out that many studies have suggested that generalization from expressive to receptive language and vice versa has been extremely difficult. An important point that may be extracted from her review is that the problems of generalization and spontaneity are not specific to autism but are common to other retarded and/or language-deficient groups as well. Language teaching of autistic children is easier with echolalic or minimally speaking subjects than it is with initially mute subjects (Evans, 1971; Lovaas et al., 1971) and best results are usually reported for children with some language repertoire before training (e.g., Stevens-Long, Schwarz, & Bliss, 1976). Degree of retardation is also an important prognostic sign for the ability to profit from language training. The overwhelming proportion of reported studies in this aspect of autism are single-case study designs, thus limiting conclusions relating to autism in general. Those studies that have reported on small groups of children have

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reported great interindividual variation, again precluding the establishment of firm principles. Much recent reported research on language training for autistic children has concentrated on the use of sign language and there has been enthusiastic adoption of methods established in animal work (Gardner & Gardner, 1971; Premack, 1971) and also of those methods used with deaf children. Since most autistic children are mute, these procedures offer some promise of success in learning to communicate to some extent with a larger range of children than has been hitherto possible with expensive and time-consuming operant speech training methods (Bonvillian & Nelson, 1976; Fulwiler & Fouts, 1976; Miller & Miller, 1973; Salvin, Routh, Foster, & Lovejoy, 1977; Webster, McPherson, Sloman, Evans, & Kuchar, 1973). It has been suggested that whereas the training of verbal language does not lead to increased spontaneous communication, the training of manual sign language sometimes does (Creedon, 1973). Almost invariably, workers achieving success in teaching autistic children to communicate, whether by signs or speech, report changes in the child's behavior, including increased responsiveness to the environment and to other people and decreased maladaptive behavior such as stereotypies. Although some workers have worked on the principle that shaping of imitative behaviors not necessarily related to speech is a necessary first step for the successful teaching of speech, this assumption has not apparently been specifically empirically tested for autistic children (Yule, Berger, & Howlin, 1975). Bricker and Bricker (1970) claim that evidence of improved general behavior as speech is learned would tend to suggest that such preparation is not a prerequisite for success. In fact, what the child probably needs is some perceived success, and once this occurs other behaviors may be modified without requiring any kind of developmental or other assumed prerequisite training. At this stage of research in this area, two points seem to emerge. First, some autistic children can learn to speak via operant procedures, especially if there is some existing language on which to build. However, problems of creativity, spontaneity, and generalization are rarely overcome even with carefully planned additional training extending into all facets of the child's life. The disabilities in language functions shown by children who learn to speak without special training (Prior, 1977b; Tubbs, 1966) are also seen in trained individuals (Prior, 1979). Speech may be relatively competent but language and communication of any but the most concrete type continue to be limited. Second, the recent development of sign language training may be of benefit to low-functioning children who cannot or do not acquire speech. Further research will doubtless follow and should be aimed at the delineation of the optimal procedures and conditions for training and of the factors within the child that predict successful training and allow the selection of this as the training of choice for that child.

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There have been several accounts of autistic individuals with special highlevel abilities in a background of retarded functioning. However, although Kanner (1943) paid considerable attention to this feature of the syndrome, especially in his early writings, expanding knowledge has suggested that idiot savanttype abilities (i.e., particular and idiosyncratic skills in a background of lowlevel functioning) are just as rare among the autistic population as they are among the retarded population. It is almost certainly true to say that the vast majority of autistic children show no special skills in the true sense of the word. What are sometimes called "islets of ability" are in reality patches of behavior where the general retardation is a little tess severe. For example, it is frequently said that autistic children perform particularly well in visuospatial tasks, or show accurate and extensive rote memories for both verbal and visual material (Wing, 1976). However, the fact that performance in such areas is usually still retarded and well below the age-appropriate level (see, e.g., auditory memory span in Prior, 1977b) is usually glossed over. Knox (1974) investigated one common claim experimentally, i.e., the widely held view that autistic children are good at jigsaw puzzles. She found that in fact performance on jigsaw puzzle tasks was the same as that of mental-age-matched controls. It seems that willingness to engage in 9some forms of activity (e.g., jigsaws or music) while refusing others is interpreted as a special skill. A further confounding factor is that estimated level of abilities is often accepted from parental reports. Prior and Bence (1975) have shown that parents tend to overestimate the abilities of their autistic children when compared with assessments of teachers. In an epidemiological study of more than 100 cases, Prior et al. (1976) found only 3 children who could actually be shown to have particular abilities and for all 3 the description "circumscribed interest patterns" (Robinson & Vitale, 1954) would be more appropriate than special abilities. It is probably significant that special abilities have almost never been mentioned in reviews of autism over the last 10 years or so. Turning more specifically to the idiot savant fiterature, one finds that indeed these cases with such abilities are extremely rare. Rothstein (1942)found 8 cases in a retarded population of 4,000. A recent survey by Hill (1977) suggested a prevalence rate of .06%, although the need for cautious interpretation of this estimate was stressed. It is not known how many of these cases from either the early or the later study would be classed as autistic. In a recent brief review, Lester (1978) draws attention to the relationship between psychosis and idiot savant individuals and it is likely that cases reported more than 30 years ago (e.g., Scheerer, Rothmann, & Goldstein, 1945) could now be called autistic. However, it is rarely the case that idiot savant histories permit a confident rediagnosis and the best that can be said is that there is almost certainly some overlap between diagnostic categories (Goodman, 1972). The male pre-

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ponderance, apparent lack of CNS pathology, inability to abstract, sensory hyperacuity, social withdrawal, and types of skills shown (e.g., music, calendar memory, calculation, and rote memory) characterize both autistic and idiot savant case reports. In reports of individual cases including artistic talent (Morishima & Brown, 1977), special drawing ability (Morishima & Brown, 1977), musical talent (Anastasi & Levee, 1960; O'Connell, 1974), verbal memory, music and visual memory, mechanical, mathematical, reading, and motor abilities (Cain, 1969), and memory for encyclopedic type information (Goodman, 1972) it is usual to find emphasis on the extreme restriction of interests shown and the obsessive quality of the particular activity. Furthermore, in all cases, abnormal memory capability is basic to the behavior described. In only the Japanese cases, where special training programs were devised, was the presence of the ability of assistance in further intellectual development. It is clear that the quality and quantity of special abilities in autistic idiot savants varies considerably and that factors underlying such abnormal development may also be numerous and variable. Moreover, what constitutes a "special ability" is never clearly defined and must vary with the subjective bias of the person applying the term. While autisticlike behavior seems to be characteristic of the idiot savant condition, savant behavior is not usually found in the great majority of autistic children. Unfortunately, it is also the case that at this point in research the study of idiot savant behavior does not add in any definable way to our knowledge of autism. Those rare cases among the autistic population show the same difficulties with adaptive learning as do children without such abilities.

INTERPRETATION OF THE PATTERN OF ABILITIES AND DISABILITIES

So far, one may conclude from this review of research on learning abilities and disabilities in childhood autism that a large proportion of experimental findings are interpretable by reference to developmental parameters. Further researchers can not afford to ignore MA and IQ effects in comparative studies of behavior in autistic groups. Since the effects of retardation on learning and performance are more influential than autism-specific effects (or at least do not permit the latter to be ascertained), investigation of low-functioning children would seem to be of little value in behavioral research aimed at the elucidation of specific characteristics of autism. It is also worth noting that the same criticism logically applies to recent biochemical and physiological research such as that of Coleman and her associates (Coleman, 1976). Studies of higher functioning groups are needed to delineate features of autism per se. It might be profitable to look again at Despert and Sherwin's (1958) discussion of differential diagnosis and consider that children with below-normal functioning in all areas

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could be classified as a separate group (see also Bartak & Rutter, 1976). The question of whether higher functioning autistic children are less severely affected with the same disorder or whether they constitute a different defineable group remains an important and difficult issue requiring further attention. However, this is not the only important aspect of research in autism and a further profitable avenue of exploration is that of individual behavior analysis, which can be independent of functioning level (or clinical group, for that matter). In terms of teaching, training, and the improvement of adaptive functioning of autistic children, this is probably most productive at this stage of knowledge. In spite of the accoumulated research, we still lack prescriptions for treatment that are related to diagnosis. Until this becomes available, applied research into teaching methodology and evaluation with these children should not be neglected. The remaining issue concerns the pattern of learning and performance disabilities that is evident from research data, suggesting some hypotheses regarding the nature of causal factors in the development of autism. Hermelin (1976), Ricks (1975), Blackstock (1978), Tanguay (1977), and Prior and Bradshaw (1979) have all recently drawn attention to abnormalities in information processing in autistic children that implicate dysfunction of the left cerebral hemisphere. Among autistic chidlren those cognitive functions traditionally considered mediated by the left hemisphere (i.e., verbal, sequential processing, and analytic skills) are almost uniformly extremely poor or absent, while those functions thought mediated by the right hemisphere (i.e., visuospatial skills, recognition without analysis) are much less handicapped and are in almost all cases well ahead of left-hemisphere-mediated functions. For those autistic children who are testable on standard intelligence tests, a particular and idiosyncratic pattern of performance is notable with verbal measures being almost invariably below performance measures. Subtests in which functioning is least retarded are those believed to reflect right-hemispheremediated abilities: i.e., visuospatial tasks such as object assembly, block design, and matching and fitting form board-type tasks. Items that suggest their own solution and do not require analytic skills or sequential processing are those solved most successfully by autistic children. Visual route finding, a right hemisphere function, is often very good. A recent unpublished study by Prior, Hoffmann, Redman, and Nichols (1978) showed that autistic children were not different from matched normals on a battery of tests including the aforementioned, which purport to reflect right hemisphere mediation, although significantly poorer on a verbal test. Further evidence for the proposition comes from the more recent experimental work reported by Hermelin and O'Connor (see Hermelin, 1976), which has been designed to explore strategies of coding information in autistic and other handicapped groups. Some experiments have shown the relative normality of higher functioning children in the ability to use a visualspatial framework (i.e., a right hemisphere approach) in a location task involving conflict; but when memory for ordering of digits was required, autistic children (like deaf children) employed a spatial rather than the normal temporal coding

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strategy (left hemisphere approach) (Hermelin, 1976). This suggests that autistic children use a different method of decoding temporally ordered (languagelike) input and prefer a right-hemisphere-mediated approach, even when it is not the optimum strategy. De Meyer (1976) has drawn attention to the finding of poor performance in the comprehension subtest (abstract reasoning) of the WlSC even when social withdrawal has decreased and she notes very low or absent verbal abstraction abilities, again left hemisphere functions (see also Churchill, 1972). A recent study of recognition of faces, known to be a right hemisphere function (Langdell, 1978), found no disability peculiar to autism, and in fact older autistic children were more proficient than normal controls. The most persuasive kind of evidence indicating the pattern of left hemisphere dysfunction is that provided by specific consideration of language processes in autism. Detailed analysis of language characteristics, in the comparative study of autistic and developmentally aphasic children reported by Bartak, Rutter, and Cox (t975), underlined the serious difficulties in language comprehension and the very deviant quality of the language of the autistic group. Language usage, even among reasonably high-functioning speakers, is characterized by concreteness, repetitiveness, recognition without analysis, and a mechanical noncommunicative approach-all considered right-hemisphere-type language. Like hemispherectomized patients whose language functions are restricted to the right hemisphere, there is a lack of ability to deal with long sequential information although some ability to decode single word meanings remains (Zaidel, 1976). "Automatic" language, which is also thought to be located in the right hemisphere, is common in autistic children and in fact is sometimes their only form of spoken language. It is apposite to note here the recently published case of "Genie" (Curtiss, 1977), who was discovered in a state of extreme sensory and emotional deprivation at the age of 1389 years. Genie's therapists report that she has developed some language in the 6 years since her discovery and they argue that this language appears localized in the right hemisphere. There are many similarities between Genie's language and that of autistic children, as well as similarities in her other (mostly considered right hemisphere) abilities, to behavior reported commonly in autistic cases. "Genie is an 'appositional' thinker, visually and tactilely oriented, better at holistic than sequential analytic thinking" (Curtiss, 1977, p. 234). Thus consideration of the pattern of cognitive and language functioning in autistic children suggests that right-hemisphere-mediated functions are relatively strong (given the degree of overall retardation often operating) and that right hemisphere approach to information processing is the generally preferred approach on a variety of tasks. On the other hand, functions located in the left hemisphere are weak and in many cases do not develop at all. Tanguay (1977) has suggested that hemisphere specialization may not develop normally in autistic children but that the two hemispheres might remain immature and plastic

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and process information in a holistic manner. Such a hypothesis has value in the understanding of both high- and low-functioning children since it allows for degrees of development rather than suggesting absolute damage. Prior and Bradshaw (1979) have suggested that for some children there may be transfer of language functions to the right hemisphere, albeit incomplete. Using a dichotic listening technique they found that among a group of 19 autistic children (mean IQ 68) there was a significant excess of autistic children showing a left ear (right hemisphere) advantage for a word recognition task, when compared with a normal control group. Furthermore, there was a strong relationship between lateralization and IQ, and between lateralization and presence or absence of speech before the age of 5 years [currently considered to be the age at which hemisphere specialization may be relatively complete (Krashen, 1973; Witelson & Pallie, 1973)]. It might be suggested that some children are able to develop language in the right hemisphere, although since there are deficiencies in abstract linguistic abilities even in relatively well-adjusted autistic adults, transfer is probably incomplete where it does occur. If damage is severe and bilateral, then not only is it functioning at an extremely low level in all areas but the children do not acquire language. Thus it seems that if language fimctions can be taken over by the right hemisphere, prognosis is much better than if it is not. It has also been suggested that where this occurs then right hemisphere functions are disadvantaged, since concentration of all functions in one hemisphere leads to a lowering of all abilities. This might thus contribute to the general retardation seen in a majority of cases. While it might be argued that the theory of equipotentiality for functional development early in life would suggest that left hemisphere functions would be taken over by the right almost completely since autism has its onset in infancy, recent evidence (Annett, 1973; Dennis & Whitaker, 1977) indicates that although there is good evidence for the plasticity of the system, the hypothesis of equipotentiality of the hemispheres is currently being challenged. Dennis and Whitaker (1977) in a review of the evidence on this latter question claim that not only are the two hemispheres not equally at risk for language disorder early in life but they are in addition not equivalent as substrates for language development. Kinsbourne and Hiscock (1977) have claimed that laterality or specialization is present at birth (see also Entus, 1977; Molfese, 1972). Their evidence suggests that even when early left hemisphere damage allows the takeover of the function by the right hemisphere, the language pattern is different from that of an early right-hemisphere-damaged individual (see Zaidel, 1976). A further question of interest, of course, is that concerning the nature of differential processing by the two hemispheres. That is, one may consider the issue to be not one of language in the left and visuospatial abilities in the right but rather one of a sequential analytical mode of processing in the left and a holistic gestalt, nonanalytical mode in the right. If this hypothesis should gain support as a result of future research, it would still be the case that the disabilities of autistic children are left-hemisphere-type disabilities, not just language-type disabilities.

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One other problem with this line of argument concerns the nature of the postulated dysfunction or damage that may be biochemical rather than structural, since none of the rare autopsies has provided evidence of structural damage. However, since our knowledge of brain physiology and its relationship to behavior remains relatively diffuse and primitive, much further research in both neurophysiological and neuropsychological fields is essential. With clarification and solution of the methodological problems in autism research reviewed here, exploration of lateralization of function in higher functioning autistic children should provide further insights into this perplexing disorder.

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