Consistent social context improves ensemble perception of facial expressions

Abstract

Abstract Observers could rapidly and automatically summarize statistical information from groups of similar objects with remarkable precisions through a specific ability, known as ensemble coding. Although previous studies demonstrated that matched physical backgrounds, such as oriented lines, between the encoding and retrieving phases of working memory improved the precisions of ongoing ensemble tasks, few studies have examined whether this facilitation effect still occurs when high-level social contexts utilized. In two experiments, participants performed an emotional judgment task about mean facial expressions that were paired with task-irrelevant movement trajectories of three dots. The information conveyed by the movement trajectories were either social (i.e., two white dots cooperatively chased a black dot) or non-social (i.e., reversed social movement trajectories). In Experiment 1, we manipulated the movement trajectories to be either consistent by presenting an identical social movement trajectory, or inconsistent by presenting one social and one non-social movement trajectories, in encoding and response phases. Participants showed a higher ensemble precision and better discrimination sensitivity when the movement trajectories were consistent than when they were inconsistent. In Experiment 2, similar manipulations were employed with one exception that two different movement trajectories but carrying a same type of social information were used in the consistent condition. The results of Experiment 2 revealed a similar and comparable effect as in Experiment 1. The present study extends the context matching facilitation effect on ensemble perception to social contexts, and suggests that the abstract social contexts in working memory exert a unique and obligatory influence on perceptual averaging.