No role for lightness in adaptation for Black and White: Race-contingent face aftereffects depend on facial morphology, not skin tone
43.449, Monday, May 13, 8:30 am - 12:30 pm, Orchid Ballroom
O. Scott Gwinn1, Kevin R. Brooks1; 1Department of Psychology, Macquarie University
Adaptation and aftereffects are useful tools in revealing the structure of visual processing mechanisms. That opposing aftereffects can be simultaneously induced using faces of different race indicates the existence of dissociable pools of neurons sensitive to race. Research into race-contingent face aftereffects suggests that such effects cannot be accounted for solely by adaptation to physical properties of the stimulus. Instead, higher level judgments of race are involved. Investigations into the factors that determine perceptions of race indicate that such judgements are primarily based on facial morphology with little influence of skin tone. Together, these findings suggest that race-contingent face aftereffects should be more substantially influenced by differences in morphology than by skin tone. To test this, opposing aftereffects involving distortions of expansion and contraction were measured for African and Caucasian face pairs differing in both morphology and skin luminance (condition 1), differing only in morphology (condition 2) and differing only in skin luminance (condition 3). Significant opposing aftereffects were found in conditions 1 and 2, but not 3. Furthermore, the strength of the aftereffect found in condition 2 was not significantly different to that found in condition 1, suggesting that race-contingent face aftereffects can be accounted for by differences in morphology alone. These results support a growing body of work indicating that the neural mechanisms involved in perceiving race are primarily sensitive to morphology and not skin tone.