Abstract
Whether adaptation aftereffects occur for high-level stimuli features without conscious perception remains controversial. For example, adaptation aftereffects for unconscious stimuli features have been found for facial emotional expressions but not for face gender, race, or identity. Here, we tested two hypotheses that can account for the discrepancy in the results. The first hypothesis proposes that the null results of adaptation aftereffects on identity-related features is due to some unaccounted motion aftereffects or forward masking by the image used to suppress images from consciousness. To test this hypothesis, we rendered faces with strong gender characteristics unconscious with continuous flash suppression (CFS) on one half of the hemifield. Then, we briefly presented a face with neutral gender identity on the other unsuppressed hemifield and asked subjects to classify the gender of the face. We observed a gender adaptation aftereffect in trials without CFS. That is, the neutral face was more likely to be classified as male when observers were presented with a face with strong female features beforehand and vice versa. This effect, however, is absent in trials with CFS. The results suggest that the absence of an adaptation aftereffect is not due to unaccounted effects of the mask used for CFS. The second hypothesis proposes that emotionally salient stimuli are a special case of stimuli that can be processed to an advanced stage without conscious perception. We replicated the experimental procedure for the first experiment, but we made the faces with strong gender features emotionally salient by using faces with fearful facial expressions. Note that the observers were still classifying the gender of the neutral gender face presented afterwards. We find that a face gender aftereffect for trials without and with CFS. This suggests that emotional information is processed unconsciously in a manner that can support identity processing of a face.
Meeting abstract presented at VSS 2012