Abstract
Adaptation studies showed that the longer the adaptation duration, the larger the face identity or expression aftereffect. However, the adaptation duration in these timecourse studies starts from 1s and onwards. How does short adaptation duration affect facial expression aftereffect? In the current study, we adapted the subjects to short adaptation durations (17, 34, 50, 100, and 1000ms) of happy or angry faces, and baseline (without adaptor), and examined their judgment on subsequently presented facial expression in a 2-alternative-forced-choice task. We also asked the subjects to report the emotion of the adapting faces at these adaption durations. We found that the facial expression aftereffect starts at 100 ms adaptation duration (Angry: p = .04, d = 0.66; Happy: p = .04, d = 0.62), and increases with adaptation duration at 1000ms (Angry: p = .01, d = 0.89; Happy: p = .02, d = 0.73). It therefore supports the previous findings that the longer the adaptation duration, the larger the adaptation aftereffect. Moreover, recognition of the adapting face is significantly correlated with the aftereffect, r = .19, p =.03. This suggests that awareness of the adapting stimulus modules adaptation aftereffect. However, what happened to the adaptation duration that is shorter than 100ms? Priming has been studied with short exposure of the prime. We investigated the reaction time patterns, a key indicator for priming. When the adaptation duration was short (17 - 50ms) and the adapting face was angry, there was a significant correlation between the awareness of the adapting faces and the reaction time towards angry test faces, r = .33, p = .04, such that the more invisible the adapting angry face was, the faster the participants could respond to an angry face. This supports previous studies showing stronger subliminal than supraliminal priming effect. Together, these findings suggest that there is a smooth transition between priming and adaptation in exposure time.
Meeting abstract presented at VSS 2018