Figure 4.

Experiment 2, Experimental design of social categorization task. In pre- and post-association phase, each trial started with a central fixation point, followed by a face that subjects had to categorize as flexible or determined as quickly as possible and before the face disappearance. The face remained on-screen until subjects’ response or for up to 1.5 s. In pre- and post-association phase, a confidence rating screen was presented. Subjects had to rate the confidence they had in their personality judgment between one (random guess) to six (absolutely sure). Inter-trial was initiated by subjects’ response or after up to 4 s. In the association phase, after the fixation point a face was presented with the percentage of persons that had categorized this face as flexible or determined. Unknown to the subject, narrow inter-eye distance faces were systematically paired with a high percentage for one personality trait, while large inter-eye distance faces were systematically paired with a high percentage for the other personality trait, to induce an arbitrary association between personality trait and physical feature. There was no stimulus repetition across the successive phases of the study; every face and every face feature (including the eyes) were new for each phase. This procedure was replicated identically for non-social categorization task (with the category labels A and B).