Abstract

Recent studies revealed that persons with Autism Spectrum Disorder(ASD) showed reduced aftereffects in both facial identity and expression in adaptation paradigm. However, no previous study has examined whether these two aftereffects are independent or interactive. The purpose of this study was to investigate ‘expression-contingent’ identity aftereffect and ‘identity-contingent’ expression aftereffect in ASD using an adaptation paradigm. In study 1, two experiments were done with 37 neurotypical(NT) adults. First, in identity adaptation task, two male faces with expression(happy, sad) were used as adaptors, and 13 identity morphed images are used as probes. First, participants were shown the adaptor for 5000ms. Then, morphed images with either congruent or incongruent expression with the adaptor were presented for 500ms. Participants were asked to discriminate the identity of the probe. In expression adaptation task, the procedure was identical to that of identity adaptation task, except that ‘expression’ morphed images of either the congruent or incongruent identity with the adaptor were presented as probes, and participants were asked to discriminate the expression. Consistent with the previous study, only identity-contingent expression aftereffect was significant in NT adults. In study 2, same experiments was conducted to compare performance of 15 ASD children and matched NT children. Identical with adults, only identity-contingent expression aftereffect was significant in NT children. However, in ASD group, there was no significant contingent aftereffect in both identity and expression adaptation task. These findings suggest that independent, not integrated face coding mechanisms of identity and expression in persons with ASD.