Syllogistic reasoning reveals reduced bias in people with higher autistic-like traits from the general population.

Recent theories of autism have emphasised the cognitive strengths and weaknesses in those with autism, which are also seen to some degree in non-clinical samples with higher autistic-like traits. The dual process theory of autism proposes that people with autism and non-clinical people with a higher degree of autistic-like traits have a propensity to show reduced intuitive processing (automatic and typically faster) alongside enhanced propensity towards deliberative processing (dependent on general cognitive ability and typically slower). This study aimed to further test the dual process theory of autism by investigating syllogistic reasoning (whether a conclusion can be logically deduced from two propositions) in addition to the cognitive reflection test (correct responses to which reflect deliberative processing over-riding intuitive processing) with respect to the degree of autistic-like traits and general cognitive ability in a non-clinical sample of 189 adults. Results showed that higher levels of autistic-like traits were related to lower levels of intuitive processing and higher levels of deliberative processing, which was found across both the syllogistic reasoning and cognitive reflection test measures - over and above the effect of general cognitive ability. The findings are consistent with the dual process theory of autism, and implications for autism are discussed.