Search

One recent, promising account of Autism Spectrum Disorders (ASD) situates the cause of the disorder in an atypicality in basic neural information processing, more specifically in how activity of one neuron is modulated by neighboring neurons. The canonical neural computation that implements such contextual influence is called divisive (or suppressive) normalization. The account proposes that this normalization is reduced in ASD. We tested one fundamental prediction of this model for low-level perception, namely that individuals with ASD would show reduced cross-orientation suppression (leading to an illusory tilt perception). 11 young adults with an ASD diagnosis and 12 age-, gender-, and IQ-matched control participants performed a psychophysical orientation perception task with compound grating stimuli. Illusory tilt perception did not differ significantly between groups, indicating typical divisive normalization in individuals with ASD. In fact, all individuals with ASD showed a considerable orientation bias. There was also no correlation between illusory tilt perception and autistic traits as measured by the Social Responsiveness Scale. These results provide clear evidence against the decreased divisive normalization model of ASD in low-level perception, where divisive normalization is best characterized. We evaluate the broader existing evidence for this model and propose ways to salvage and refine the model.

We explored the strength of implicit social inferences in adolescents with and without Autism Spectrum Disorder (ASD) using a chasing paradigm in which participants judged the absence/presence of a chase within a display of four seemingly randomly moving dots. While two of these dots always moved randomly, the two others could fulfill the role of being either the chasing (wolf) or chased (sheep) dot. In the chase-present (but not the chase-absent) trials the wolf displayed chasing behavior defined by the degree to which the dot reliably moved towards the sheep (chasing subtlety). Previous research indicated that chasing subtlety strongly influenced chase detection in typically developing (TD) adults. We intended to replicate and extend this finding to adolescents with and without ASD, while also adding either a social or a non-social cue to the displays. Our results confirmed the importance of chasing subtlety and indicated that adding social, but not non-social, information further improved chase detection performance. Interestingly, the performance of adolescents with ASD was less dependent on chasing subtlety than that of their TD counterparts. Nonetheless, adolescents with and without ASD did not differ in their use of the added social (or non-social) cue.