Investigating opposing aftereffects in 8-year-olds and adults

Abstract

Previous studies have shown that adults and 8-year-olds process faces using norm-based coding and that prolonged exposure to one kind of facial distortion (e.g., compressed features) temporarily shifts the prototype, a process called adaptation, making similarly distorted faces appear more attractive (Anzures et aI., 2009; Valentine, 1999; Webster & MacLin, 1999). Aftereffects provide evidence that our prototype is continually updated by experience. When adults are adapted to two face categories (e.g., Caucasian and Chinese; male and female) distorted in opposing directions (e.g., expanded vs. compressed), their attractiveness ratings shift in opposite directions (Bestelmeyer et aI., 2008; Jaquet et aI., 2007), indicating that adults have dissociable prototypes for some face categories. I created a novel meth04 to investigate whether children show opposing aftereffects. Children and adults were adapted to Caucasian and Chinese faces distorted in opposite directions in the context of a computerized storybook. When testing adults to validate my method, I discovered that opposing aftereffects are contingent on how participants categorize faces and that this categorization is dependent on the context in which adapting stimuli are presented. Opposing aftereffects for Caucasian and Chinese faces were evident when the salience of race was exaggerated by presenting faces in the context of racially segregated birthday parties; expanded faces selected as most normal more often for the race of face that was expanded during adaptation than for the race of face that was compressed. However, opposing aftereffects were not evident when members of the two groups were presented engaging in cooperative social interactions at a racially integrated birthday party. Using the storybook that emphasized face race I 11 provide the first evidence that 8-year-olds demonstrate opposing aftereffects for two face categories defined by race, both when judging face normality and when rating attractiveness.