THE EFFECTS OF MOTION AND ORIENTATION ON PERCEPTION OF FACIAL EXPRESSIONS AND FACE RECOGNITIONZara Ambadar, PhDUniversity of Pittsburgh, 2002Research on perception of facial expressions has neglected an important characteristic of facial expression, its dynamic property. In this dissertation, two experiments were conducted to assess the effect of motion on perception of facial expressions and to test three (3) possible mechanisms by which motion facilitates perception of facial expressions. (1) motion provides more static information than is available in a single image. This hypothesis was tested by comparing performances in single image presentations (Single-Static) with those in multiple image presentations (Multi-Static). (2) motion provides temporal information about expressions which aids perception. This was tested by comparing performances in multiple image presentations with those in moving sequence presentations (Dynamic). (3) motion improves perception of facial expressions by facilitating configural processing. This was tested by comparing the effect of motion in upright and inverted presentations of the stimuli. In Experiment 1, participants were shown posed faces with subtle facial expressions in one of three modes (Single-Static, Multi-Static, or Dynamic). Experiment 1 revealed a robust effect of motion relative to both Multi-Static and Single- Static condition. This finding, in addition to the absence of an interaction effect between motion and inversion suggest that the effect of motion was not due to additional static information and was not mediated by configural processing. Experiment 2 replicated the basic procedure of Experiment 1 and in addition included a face recognition task and a memory measure of facial expression. The advantage for dynamic presentation was replicated. Converging evidence from Experiment 1 and 2 supported the second mechanism and suggests that the effect of motion on judgment of facial expressions is inherent in the dynamic property of the sequence. The nature of this dynamic property was discussed with regards to the possibility that motion might enhance the perception of change (change sensitivity hypothesis).
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