ABSTRACT
In the previous chapter a psychological theory of autism was discussed which aimed to explain the triad of impairments in autism in terms of a single underlying cognitive deficit-a failure or delay in mentalizing. A desire for parsimony has been evident in many other theories of autism-with authors postulating the minimum number of underlying psychological impairments necessary to account for the behavioural manifestations of autism. However, more recently, other authors have suggested that autism is likely to be the result of multiple primary deficits, either at the biological (Goodman 1989) or at the psychological level (e.g. Ozonoff et al. 1991a). Clearly, it is possible that deficits which are unconnected at the psychological level may occur together more often than by chance alone, due to the spatial proximity of their biological substrates in the brain (cf. pattern (a) in Figure 1.1). In this case, just as for purely physical markers of disorders (e.g. physiognomy of Down’s syndrome), it may be futile to look for a common cause at the psychological level. Such theories of autism, then, are not primarily psychological in nature, and will not be considered here. However, noting this issue should act as a useful reminder of the importance of keeping clear at all times the level (biological, psychological, behavioural) at which one is attempting an explanation (Morton & Frith 1994). A number of recent theories of autism are based primarily at the biological level (e.g. Damasio & Maurer 1978, Panksepp & Shaley 1987, Dawson & Lewy 1989, Dawson 1991) and are reviewed elsewhere (Pennington & Welsh 1994).
