Abstract
Face and body perception are both disrupted by picture-plane inversion 180-degree rotation leads to poorer recognition and discrimination. For face stimuli, the inversion effect appears to be carried by horizontally-oriented structures (Goffaux & Dakin, 2010), which appear to also carry more information for identity than vertical orientations. Here, we asked whether the inversion effect for faces and bodies expressing different emotional expressions (happy and sad) was carried by different orientation sub-bands. Specifically, we measured observers performance at classifying emotional faces and bodies that were filtered to include either horizontal structure, vertical structure, or both orientation bands. Two groups of participants completed the face (N=22) and body (N=25) tasks, in each case asking participants to distinguish happy and sad stimuli. In both tasks, participants viewed stimuli in a fully randomized order for 2000ms each and classified images by emotion as quickly and as accurately as possible. Picture-plane orientation varied across experimental blocks while filter orientation was randomized within blocks. The results of Experiment 1 revealed that inversion negatively impacted accuracy for both horizontally-filtered (p<.001) and vertically-filtered (p<.001) faces, but only marginally affected faces containing both orientation information (p=.051). By contrast, in Experiment 2 we found that inversion significantly lowered accuracy for horizontally-filtered bodies (p=0.001), but that inversion significantly improved accuracy for vertically-filtered stimuli (p<0.001). Bodies with both orientations present exhibited no inversion effect. We conclude that the inversion effects dependence on orientation sub-bands differs for faces and bodies, which may reflect distinct "tuning" of face and body representations for low-level image features. Observers may also adopt different strategies for processing faces and bodies, leading to differential impact of orientation filtering as a function of stimulus category. Body inversion could have led to differential use of the upper vs. lower body, for example.
Meeting abstract presented at VSS 2014