Intact Face-Specific Adaptation in Autistic Adults

Background:  Reports of diminished facial aftereffects in autistic populations have been interpreted as evidence of deficient adaptive recalibration of face-specific representations. However, previous studies of facial adaptation in ASC populations have presented adapting and test stimuli at the same display location and at either the same or similar scales, thereby confounding face-specific and retinotopic adaptation. This raises the possibility that diminished aftereffects seen in autism reflect an absence of retinotopic adaptation, potentially due to atypical patterns of facial fixation, rather than deficient face-specific representations.

Objectives:  The present study sought to determine whether ASC populations demonstrate reduced facial aftereffects when steps are taken to minimize the influence of low-level retinotopic adaptation, and guide participants’ fixations when viewing the adapting stimuli.

Methods:  Thirty-two participants completed expression and identity adaptation procedures; 16 with (15 males; mean age = 39.2 years) and 16 without (12 males; mean age = 32.6 years) a clinical diagnosis of ASC. To minimize the effects of retinotopic adaptation, adapting and test stimuli were presented at different locations and were subject to a substantial scale disparity.

Results:  Both the ASC and neurotypical groups demonstrated robust identity aftereffects, M = 10.3% (SD = 7.7%) and M = 11.9% (SD = 4.2%), respectively. The magnitude of the identity aftereffects did not differ between the groups, or correlate with autism severity, as indexed by either ASQ or ADOS score. Similarly, both the ASC and neurotypical groups demonstrated substantial expression aftereffects, M = 6.8% (SD = 7.5%) and M = 6.0% (SD = 6.6%), respectively, but no group difference emerged. Again, the magnitude of the expression aftereffects failed to correlate with either the ASQ or ADOS indices of autism severity.

Conclusions:  Having adopted methods that reduce the contribution of retinotopic adaptation, we observed intact facial identity and expression aftereffects in adult participants with ASC. Crucially, these results argue against disturbed face-specific representation in ASC. Instead these data suggest that diminished aftereffects reported in ASC populations likely reflect reduced low-level retinotopic adaptation. In the absence of a fixation guide during the presentation of adapting stimuli, atypical patterns of gaze fixations may render ASC individuals less susceptible to the effects of retinotopic adaptation. Alternatively, ASC participants may fixate typically during adaption, but show a genuine deficit of adaptation-induced calibration in retinotopic visual areas.