顔順応は顔検索タスクのパフォーマンスを向上させる

Adaptation to faces produces large aftereffects in the appearance of subsequently viewed faces, yet the functional consequences of these aftereffects remain unclear. We investigated the effects of face adaptation on performance in face search and discrimination tasks. Participants searched for faces manipulated by varying the level of morphing between averaged White and Asian faces, and had to respond to a unique target face (morph level) among 5 distractor faces shown simultaneously. Before adaptation, reaction times averaged 4 or more seconds, implying that the stimuli were difficult to distinguish and that a serial search was required to scan each face in turn. Adaptation markedly reduced the search times (by roughly 2 s), with similar improvements after brief (12 s) or prolonged (20 min) adaptation periods, and with little effect on search accuracy. Separate measurements showed that the adaptation also produced large changes in facial appearance (as assessed by the perceived ethnicity category boundary), but did not affect thresholds for discriminating the face differences. These findings provide further evidence for the notion that adaptation heightens the salience of novel stimuli by renormalizing perception for the adapting stimuli.