Impaired metarepresentation in early childhood autism

Explaining the characteristic signs

Autism is now known to be a biologically caused disorder, although a complete picture of its biological basis has not yet emerged (see Bailey et a l, 1996, for a review). It occurs more commonly in males than in females, and this sex ratio is higher in intellectually unimpaired cases (Lord & Schopler, 1987, cited in Happé & Frith, 1996). In an influential epidemiological study. Wing & Gould (1979) showed that three behavioural features (the ‘autistic triad’) cluster together to form the autistic syndrome. These are:

1) Impaired socialization (e.g. behaving in a withdrawn, aloof, passive or ‘active-but-odd’ way);

2) Impaired communication, both receptive (e.g. failure to understand others’ body language or the figurative aspects of others’ speech) and productive (e.g. m uteness and the absence of facial expression and gesture, or various forms of inappropriate language such as verbosity or neologism);

3) A lack of imagination shown, for example, in stereotyped and repetitive activity with a marked absence of pretend play.

Happé & Frith (1996) reviewed a number of studies in which these particular characteristics were investigated empirically. In line with Wing and Gould’s triad of impairments, the DSM-IV criteria of the American Psychiatric Association (APA; 1994), define autistic disorder as “the presence of markedly abnormal or impaired development in social interaction and communication, and a markedly restricted repertoire of activity and interests” {ibid., p. 66). For DSM-IV diagnosis, such behaviour should be apparent before the age of 3 years. As discussed by Happé & Frith (1996), the condition known as ‘Asperger’s syndrome’ falls within the autistic spectrum, but people with this disorder tend to be less aloof than those with autism, showing more social interaction and language (although language is typically verbose or pedantic). The “restricted repertoire of activity and interests” often manifests here as an obsessional interest in unusual or arcane topics.

On a psychological level, a number of cognitive theories of social impairment have been advanced to explain the characteristic autistic behaviours (see Happé, 1994a and Happé & Frith, 1996, for reviews). For example, Hobson (e.g. Hobson, 1993) proposed that autism is characterised by an innate inability to engage emotionally with others, leading to a paucity of social experience during infancy and thus to enduring social deficits. His theory remains unproven as the crucial experiments investigating affective interaction in the earliest months of the autistic child’s life have not yet been carried out (Happé & Frith, 1996). Other workers have suggested that the absence of early joint attention behaviours (Mundy et a l, 1993), or a failure of early imitation of facial expression (Meltzoff & Gopnik, 1993) could underlie the social impairments characteristic of autism. However, as discussed by Happé & Frith (1996), although there is empirical evidence that these deficits are indeed present in autism, their causal status is as yet unresolved.

Probably the most influential cognitive theory of social impairment in autism is the theoiy of mind deficit account, which suggests that Wing & Gould’s (1979)

triad of impairments can be accounted for by a failure of metarepresentation - the inability of the autistic child to represent its own and others’ mental states (e.g. U. Frith et a l, 1991). Leslie’s (1987) metarepresentational account of pretense (see earlier discussions) means that impaired mental state representation in autism is easily able to account for the absence of pretend play, and the inability of autistic people to understand pretense in others. In the domains of socialization and commun­ ication, Frith & Frith (1991) drew parallels between the behavioural signs of schizo­ phrenia and the impairments shown by autistic people. Thus, in the social domain, autistic people may show social withdrawal and blunt affect, or socially inappropriate behaviours, and in the domain of communication, they may show poverty of speech or inappropriate language, and often fail to understand non-verbal gestures and figurative speech. As we saw for the case of schizophrenia, all of these behavioural signs can be explained in terms of an inability to represent one’s own and others’ mental states, so Frith & Frith (1991) suggested that this cognitive impairment may be a core deficit in autism as well as in schizophrenia.

As mentioned in Section 3.1, a major difference between autism and schizo­ phrenia lies in age of onset, with autism being diagnosed in early childhood, and schizophrenia typically manifesting in the second or third decade of life, with an acute psychotic breakdown. Frith & Frith (1991) pointed out that these differing ages of onset can explain why a metarepresentational impairment gives rise to both positive symptoms and behavioural signs in people with schizophrenia, but only behavioural signs in people with autism. They suggested that in patients with schizo­ phrenia, the metarepresentational system usually develops normally throughout childhood, so that the person is able to correctly represent his own and others’ mental states. However, dysfunction of this system at the time of psychotic breakdown means either that the patient continues to represent his own and others’ mental states, but does so incorrectly (leading to positive symptoms), or fails to represent these mental states at all (leading mainly to behavioural signs). In contrast, early childhood

autism is thought to be characterised by a marked impairment in the development of the metarepresentational system, so that the child fails to fully acquire the ability to mentalise. In its simplest form, this theory suggests that autistic people fail to represent both their own and others’ mental states, so show behavioural signs; as they fail to acquire the ability to infer goals, intentions and beliefs, they will not make false inferences about others’ mental states, so do not report positive symptoms (Frith & Frith, 1991).

W ithin this model, it is possible that some children show a delay in meta­ representational development, but do eventually acquire a limited ability to represent mental states. One manifestation of this may be an autistic child who shows an ability to employ theory of mind in some real-life situations, and indeed, U. Frith et al.

(1994) found that a subgroup of their sample of autistic children did show some social behaviours (e.g. deception) thought to require mentalising ability. However, the children in this subgroup (who had better verbal and communicative abilities than the other autistic children), still showed relatively poor social adaptation for their age and developmental level. A second possibility is that some of the children who show delayed development of the ability to represent mental states may subsequently experience dysfunction of their emerging metarepresentational system, and thus report positive psychotic symptomatology. Clinically, this may appear as an autistic child progressing to a diagnosis of schizophrenia in later life. We might expect this to be a relatively rare phenomenon, as it will occur in only a subgroup of those autistic children who show evidence of emerging mentalising ability. In line with this, there are isolated reports in the literature of autistic children becoming schizophrenic in later hfe (e.g. Rodriguez et al, 1994). Petty et a l (1984) presented case reports of 3 children, all of whom were diagnosed as having autism prior to 30 months of age, but who by early adolescence had received a diagnosis of schizophrenia. Volkmar & Cohen (1991) examined the case records of 163 adolescents and adults with well- documented histories of autism, to check whether any characteristic schizophrenic

symptoms had been shown at any time. Although only one subject met diagnostic criteria for schizophrenia, 40 other patients (24%) showed some evidence of schizophrenic symptomatology. Moreover, almost 48% of the patients in this study were completely mute, so we cannot rule out the possibility that a number of these experienced one or more positive symptoms, but failed to report them. Finally, Watkins et a l (1988) examined the case records of 18 children with childhood-onset schizophrenia, and found that in the 0 - 3 0 month age range, 39% of the sample had shown signs of infantile autism. In addition, onset of schizophrenia occurred at an earlier age for those children with a history of autistic signs than for other children in the sample.

All of these studies may be consistent with suggestions by Murray et a l

(1992) that there is a ‘neurodevelopmental’ subtype of schizophrenia characterised by early onset, poor pre-morbid social adjustment and restricted affect. For example, a subgroup of patients with these features (and a male:female ratio of 7:3) emerged from a latent class analysis of 447 schizophrenic patients by Castle et a l (1994). This subgroup contrasted markedly with a second ‘paranoid’ type characterised by later onset, persecutory delusions and an almost equal sex ratio. It is possible that the relatively small number of schizophrenic patients in the ‘ neurodevelopmental’ category had shown some signs of autism early in their development, as their clinical history was characterised by poor pre-morbid social skills and a predominance of negative signs, and they were more likely to be male than female. Within Frith’s model, these patients may have had a delayed or dysfunctional metarepresentational system since early childhood, whereas the majority of Castle et a /.’s schizophrenics (i.e. those labelled within the ‘paranoid’ subtype) probably showed a normal ability to represent mental states during adolescence, with impairment only appearing at the time of their first breakdown.

Empirical evidence for impaired theory of mind in autism

As already mentioned at various points in this chapter, much empirical evidence now supports the notion of impaired theory of mind in childhood autism. Extensive reviews of the area are provided by Baron-Cohen et al. (1993b) and Happé (1994a), but a selection of studies will be presented here to give some idea of the variety o f paradigms used. It should be noted that many of these paradigms have subsequently been used to investigate theory of mind in schizophrenic populations; those studies were discussed earlier in this chapter (see Section 3.1).

The first study to test autistic children on a version of Wimmer & Pem er’s (1983) first-order false belief task, was carried out by Baron-Cohen et al. (1985). These workers contrasted the performance of autistic children with that of control groups of normal children and mentally retarded children with Down’s syndrome. The autistics were selected to be of higher mental age (MA) (e.g. mean verbal MA = 5;5) than the control children, to rule out explanations of task failure in terms of IQ, and control questions were also used to check the childrens’ memory for the story. The results were clear: 80% of the autistic sample failed the false belief question, whereas it was passed by 86% and 85% respectively of Down’s syndrome and normal 4-year old children. Pemer et al. (1989) introduced a different first-order false b elief task, the so-called ‘Smarties task’ (Perner et a l, 1987) into the autism literature. In this task, the child is shown a cardboard tube, (readily recognisable as the packaging for the well-known brand of sweets known as ‘Smarties’), and is asked what the tube contains. After he has replied “Smarties”, the tube is opened to reveal a pencil. The child is then asked the false belief question, namely “What will your friend say is in the tube when he comes into the room?” . Perner et al. (1989) found that only 15% of their autistic children answered this question correctly (by saying “Sm arties”), whereas is was passed by 92% of an MA-matched control group of children with specific language impairment. Baron-Cohen (1991) used a very similar

paradigm to test autistic childrens’ ability to represent their own mental states. Thus, instead of asking about the mental state of a friend, he posed the question, “W hen I first asked you, before we opened the carton, what did you think was inside?”. Results showed that only 27% of the autistic children passed this task; this was a significantly poorer performance than that shown by mentally handicapped controls of lower verbal MA.*’ Taken together, then, these data are consistent with an impairment in autism in the representation of both own and others’ beliefs.

These findings have been replicated and extended in many further studies. A notable methodological feature running through a number of experiments has been use of the ‘fine cuts’ technique (e.g. U. Frith & Happé, 1994), which employs two very similar tasks, only one of which requires the ability to represent mental states. By analogy with the arguments of Chapman & Chapman (1973) in the schizophrenia literature (see Chapter 1 of this thesis), this technique has the potential to reveal a specific autistic deficit in mental state understanding, as the use of a non-mental state task controls for deficits in other cognitive functions such as attention, memory and general problem-solving ability. Thus, with MA co-varied, Sodian & Frith (1992) found that autistic subjects were significantly worse than normal and retarded controls at deception (i.e. lying to a ‘nasty’ puppet, in order to stop it opening an unlocked box, by saying that the box was actually locked), but performed as well as controls in a sabotage condition, (in which they prevented the ‘nasty’ puppet gaining access to the box by actually locking it). Similarly, Baron-Cohen et al. (1986) found that high-MA autistics performed significantly worse than lower-MA normal and

It should be noted that a number of workers (e.g. Leslie & Thaiss, 1992; Naito et a l,

1994; Pemer et a l, 1989) found that autistic children performed well on this type of task, but in all of these studies, the question was posed in the form “W hen I first asked you, . . . what did you say was inside?” . As pointed out by Leslie & Thaiss (1992), this question could have been answered correctly by the autistic children simply repeating their earlier response without any awareness that that response reflected a false behef. Thus, Baron-Cohen’s (1991) use of the think question seems

D ow n’s syndrome children at sequencing pictures requiring mental state under­ standing, but performed as well (or better) than controls when the story sequences could be understood in terms of physical-causal relations, or by reference to a character’s overt behaviour.

One example of the ‘fine cuts’ method involved contrasting the child’s understanding of false beliefs and ‘false’ photographs, a distinction first used by Zaitchik (1990) in the normal developmental hterature. In the Zaitchik task, an object is placed in location A, and a polaroid photograph is taken of it. The photo is then laid face down, the object is moved to location B, and the child is asked, “In the photograph, where is the object?”. This has the same structure as Wimmer & Perner’s (1983) false behef task but, rather than involving an out-of-date belief held by a story character, it involves out-of-date representation by a non-mental medium (the photo). Leshe & Thaiss (1992) predicted that if autistic children have a specific impairment in mental state representation, they should fail a false belief task but pass the ‘false’ photo task, as only the former requires representation of the attitude of an agent towards a situation (i.e. metarepresentation). This prediction was supported by Experiment 1 of their study (Leslie & Thaiss, 1992): high-MA autistic children performed almost at ceiling on the photo task, but were significantly worse at false belief. In contrast, normal 4-year old children showed similar scores on belief and photo tasks, with about 70% passing in each case. These results were replicated (Leekam & Pemer, 1991) and extended using a ‘false’ map (Leslie & Thaiss, 1992; Experiment 2) and out-of-date drawings (Charman & Baron-Cohen, 1992). These latter two paradigms are employed in the first study of this thesis (see Chapter 4) to provide a stringent test of Frith’s (1992) prediction that certain schizophrenic patients should be differentially impaired in mental state representation.

By analogy with the evidence discussed earlier for impaired theory of mind in schizophrenia, empirical studies in autism have also revealed deficits in the

processing of facial affect, in the understanding and production of gestures and non­ verbal signals, and in the comprehension of figurative language. For example, Baron- Cohen e ta l (1993a) employed the ‘fine cuts’ technique by testing autistic childrens’ recognition of the facial emotions ‘happy’, ‘sad’, and ‘surprise’. In accordance with the theory of mind deficit model, the autistics were impaired relative to verbal MA- matched normal and mentally handicapped controls at the recognition of surprise (an emotion usually caused by beliefs), but showed an intact ability to recognise happiness and sadness (emotions often caused by situations rather than mental states). In a study investigating the production of gestures, Attwood et ah (1988) found that autistic people specifically lacked the types of gesture associated with mental states (e.g. expressions of embarrassment), whereas gestures used to m anipulate behaviour (e.g. a signal to be quiet) were as common as in a group of mentally handicapped controls. As with research in schizophrenia, studies of eye- contact in autism suggest an abnormality, and Baron-Cohen et a l (1995) concluded that autistic people have a specific deficit, relative to normal and mentally hand­ icapped controls, in the use of eye-direction as a cue for inferring mental states such as intentions, goals and desires. These workers suggested that this deficit may underlie the lack of joint attention behaviours in autism, so it is notable that the absence of early joint attention (proposed by Mundy et a l, 1993, to be the primary impairment in autism) may itself be rationalised within a metarepresentational account of autism (see also Leslie & Happé, 1989). Finally, studies exploring the understanding of intentional speech again suggest a specific autistic deficit. Thus, in Une with her analysis of metaphor and irony comprehension as requiring first-order and second-order theory of mind respectively. Happé (1993) found that autistic children who failed false belief tasks at these two levels of complexity, showed an inability to understand the corresponding figurative utterances. Similarly, by analogy with the schizophrenia research described earlier, Sudan et a l (1996) showed that autistic children were impaired relative to controls at choosing utterances which conformed to Grice’s (1975) conversational maxims and to the conversational

convention of politeness. In contrast, the autistics performed as well as controls on a task requiring the selection of grammatical rather than non-grammatical utterances. Surian et a l suggested that their maxims task required an intact theory of mind, and indeed the scores of autistic children were related to their performance on a first- order false belief task. This study provides further evidence, therefore, for a specific mentalising deficit in autism.

A notable feature of research in this area is that, despite showing the marked social impairments characteristic of their disorder, a small number of autistic subjects (usually the older ones) pass theory of mind tasks. In an analysis of pooled data from a number of studies. Happé (1995) showed that these autistic ‘passers’ tend to be those subjects with a higher verbal mental age, and as discussed by Happé & Frith (1995), two possible models are consistent with these findings. Firstly, U. Frith et a l