Abstract
The emotional tone of a crowd of faces (e.g., whether friendly or threatening) guides our interactions with groups of people. However, little is known about the behavioral and neural bases of these socially important influences. Here we examined in 5 experiments how intrinsic factors, such as observers' goal (to avoid or approach) and anxiety level, and extrinsic factors, such as whether the faces were male or female and where they were presented spatially, affect crowd emotion perception and their underlying neural responses. Participants viewed two crowds of emotional faces in the left and right visual fields for 1 second (Fig.S1) and reported which crowd they would avoid (Exp.1-2) or approach (Exp.3-4). In Exp.5, a new cohort (N=24) was scanned with fMRI while they performed the avoidance task. Although it is thought that right hemisphere (RH) dominates perception of negative stimuli, and left hemisphere (LH) is dominant for positive stimuli, we found significant RH dominance for both angrier and happier crowds depending on task goal, avoidance and approach, respectively (Fig.S2). This finding suggests that RH dominates processing of task-congruent crowd emotion, irrespective of its valence. High-anxiety participants showed faster RTs overall and lower accuracy for happier, but not angrier, crowds. While the observers' sex had no effect, we found that crowds of happy females and angry males were perceived more accurately. Finally, fMRI results revealed greater RH activation while perceiving task-congruent, angry crowd during the avoidance task, with higher activation in the ROI's including amygdala, hippocampus, and face-sensitive cortex, compared with the corresponding regions in LH. When a happier crowd, incongruent for the avoidance task, was presented to RH, we found higher activation in the corpus callosum suggesting increased inter-hemispheric communication. In conclusion, perception of crowd emotion is substantially RH-lateralized and strongly modulated by task, stimulus characteristics, and observer anxiety.
Meeting abstract presented at VSS 2016