The contribution of configuration, facial features and low-level properties to the adaptation of facial expression

Abstract

Adaptation aftereffects to expression in faces have been reported by Webster, Kaping, Mizokami, & Duhamel (2004) and Fox & Barton (2006). Here we investigated which aspects of facial stimuli contribute to these aftereffects. In Experiment 1 we examined the role of low-level image properties such as curvature, shape and orientation, independent of expression, by using hybrid faces constructed from either the same or opposing expressions. While hybrid faces made with consistent expressions generated adaptation effects as large as those generated by normal whole faces, there were no aftereffects from hybrid faces made from conflicting expressions. This suggests that adaptation to low-level properties does not make a significant contribution to expression aftereffects in our paradigm. In Experiment 2 we examined the role of facial features independent of the normal facial configuration, by contrasting adaptation with whole faces to that with scrambled faces. We found that scrambled faces also generated significant aftereffects, indicating that features in the absence of a facial configuration could generate expression adaptation. In Experiment 3 we examined the role of facial configuration, by using stimuli made from line elements (e.g. curved segments and straight lines) that in isolation do not carry expression-related information, but that convey a coherent expression when arranged in the configuration of a face. We obtained a significant aftereffect for facial configurations but not scrambled configurations of these line elements. We conclude that face expression aftereffects are due to adaptation of neural representations of expression involving facial configuration or facial features alone, but are not due to adaptation of low-level image properties.

Footnotes

 This work was supported by NIH grant 1R01 MH069898 and CIHR grant MOP 77615. CJF was supported by a Michael Smith Foundation for Health Research Junior Graduate Studentship and a CIHR Canada Graduate Scholarship Doctoral Award.