Cognitive theories of autism Rajendran and Mitchell 2007

Considerations Uniqueness (specificity) Universality Domain Specificity Modularity

What’s wrong with the ToM hypothesis? Deviance or delay? If deviant, then maybe modular; if delay, then modularity is less plausible Problem: Happe (1995) meta-analysis suggests delay Uniqueness Individuals with sensory impairment also suffer delay Universality Not all people with ASD have difficulty with ToM tasks (Bowler, 1992) Hacking: getting the right answer by a different route (Frith et al, 1994)

What’s wrong with the ToM hypothesis? Continued… Problems with operational definition FB task might be ok, but not clear about the justification for ‘mind in eyes’ task. Should a categorical disorder be investigated with a task that yields categorical data? FB task does the job, but ‘mind in eyes’ task gives graded data.

What’s wrong with the ToM hypothesis? Continued… Besides, it turns out that individuals with ASD are not specifically impaired in interpreting mental states from the eyes (Back et al, 2007)

What’s wrong with the EF hypothesis? Uniqueness… no ADHD, OCD, Tourette, Schizophrenia…. Universality… maybe Ozonoff et al (1991): 96% Pellicano et al (2006): 50% Domain Specificity… maybe but probably not (pre-frontal cortex) Definition is just a list; EF is a function and neither a structure nor a mechanism (Zelazo et al, 1997)

What’s wrong with the EF hypothesis? Continued… Uniqueness in relation to components of EF? Planning (e.g. Tower of Hanoi). Impaired, but maybe linked with IQ. Mental Flexibility. Impairments in 9/14 studies but IQ again plays mediating role Inhibition. No difference between people with ASD on stroop task, though differences between populations are usually found on the windows task. Generativity. Mixed findings

Weak central coherence Uniqueness Universality Domain Specificity No, cognitive style Modularity No

What’s wrong with the theory of WCC? Problems with definition – at what level of processing is WCC supposed to be manifest? Low level, e.g. visual illusions: failure to demonstrate the effect (Ropar & Mitchell) Focus on detail at the expense of focus on global: But global precedence is apparent in the Navon task

What’s wrong with the theory of WCC? Continued… WCC isn’t a unitary construct Pellicano et al (2006) presented a variety of tests that supposedly measure WCC and found not one but two factors using a factor analysis technique. Both of these factors were related with measures of executive function

Autism as a multiple deficit According to this account, autism is not a singular deficit but a collection of features that happen to coincide. According to Bishop & Norbury (2002), these features appear in different ways and to different degrees, in determining developmental outcome: E.g. ASD, ADHD, Tourette, pragmatic language impairment, dyslexia

Conclusion It is unlikely that autism can be explained in terms of a singular factor It is very likely that autism has a polygenetic basis, where the developmental outcome depends on environmental factors to some extent The mix of genetic and environmental factors will probably determine whether the individual has ASD, ADHD, PLI, etc.