Temporal dynamics of adaptation to same- and other-race faces: buildup, decay and sustained effects.

The perceived characteristics of faces are strongly biased by the faces seen previously. Previous studies have reported an increase in the magnitude of face identity aftereffects with a logarithmic increase in adaptation duration and exponential decay with an increase in test duration. Here, we explored whether face ethnicity aftereffects show similar build-up and decay and how temporal dynamics differ when participants adapt to their own- and other-race faces. In addition, we tested whether face ethnicity aftereffects are merely perceptual changes that can only be captured immediately after the adaptation phase or whether they involve adjustments that lead to long-lasting changes and can be captured after delayed periods between the adaptation and testing phases. Aftereffects induced by other-race faces built up and decayed faster compared to own-race faces. For both own- and other-race faces, the period of delay between the adaptation and test phases led to a faster decay of aftereffects. Our finding that changes induced by adaptation to other-race faces led to rapid changes in facial representation as opposed to own-race faces suggests that the temporal dynamics of changes in facial representation might depend on the amount of experience an individual has had with a particular facial category.