Fast periodic visual stimulation EEG reveals reduced social bias in autism

Abstract

Developmental accounts of autism spectrum disorder (ASD) state that infants and children with ASD are less attracted by and less proficient in processing social stimuli, such as faces. While reduced viewing preferences for social stimuli have indeed been demonstrated in ASD, it is unclear how this reduced social bias is manifested at the neural level. Social cues may be neglected in ASD because they are represented less saliently, or they may actively be avoided because they are experienced too intensively. To address this issue, we used EEG recording during fast periodic visual stimulation (FPVS) in combination with eye tracking. We tested 21 boys with ASD (8–12 years old) and 21 typically developing (TD) control boys, matched for age and IQ. In a first experiment, streams of images of faces were presented at 6 Hz alongside images of houses presented at 7.5 Hz or vice versa. Eye-tracking data showed that TD children looked significantly longer to faces than to houses, while this social viewing preference was not present in the ASD group. Likewise, EEG data revealed that the relative neural response to faces versus houses was significantly larger in the TD group as in the ASD group, especially along lateral occipito-temporal areas. The strong correlation (r=0.74) between the social bias (i.e. response to faces minus response to houses) measured by eye-tracking and by EEG suggests a close link between viewing preferences and neural responses. The neural observations were closely replicated in a second experiment where we superimposed the two streams of stimulation, thereby controlling for possible effects of spatial attention and disengagement. Accordingly, in both experiments, the data shows that preference for social visual information, i.e. faces, is lower in children with ASD.

Acknowledgement: Research Foundation Flanders (FWO), Marguerite-Marie Delacroix foundation