Abstract
Introduction. Opposing aftereffects have been seen across groups that differ by sex and race. For example, viewing Caucasian expanded faces and Chinese contracted faces lead to opposite face aftereffects when participants subsequently viewed each set. Here we tested whether viewing Caucasian male faces and a diverse set of faces (male, female; Caucasian, Asian, Latino, African American) during adaptation would result in opposing aftereffects. Methods. 62 participants underwent an opposing aftereffects paradigm viewing a set of Caucasian male faces and a diverse face set. 31 participants viewed a contracted set of diverse faces and an expanded set of Caucasian male faces, and 31 viewed the opposite. In pre-adaptation trials, participants viewed 64 face pairs, one contracted and one expanded by 10%, selecting which they found more attractive. During adaptation, participants viewed faces altered by 60%. Post-adaptation trials were identical to pre-adaptation trials. Results. Using a mean change score (contracted faces selected before vs after adaptation) as the dependent variable, there was a significant interaction between the two conditions (F(1,25)=7.360, p=<.05). Aftereffects were then assessed for each condition separately. For the contracted Caucasian male and expanded diverse condition, significant opposing aftereffects were observed, with a greater change in preference for the contracted diverse faces than the expanded Caucasian male faces (t(12)=-4.770, p= <0.001), consistent with adaptation. Though the scores for contracted Caucasian male and expanded diverse faces did not differ significantly (t(13)=.901, p= .384), the change was in the expected direction. These results are the first to suggest that it is possible to induce opposing aftereffects across a diverse and a homogeneous set of faces. Past research has found opposing aftereffects using face sets that are homogeneous within and distinct across face sets. These results suggest the potential of face templates that are sensitive to variance.