Fig. 4.

(A) Standard choice-from-array expression recognition task requiring participants to label facial expressions evolved by a separate group of participants. (B) Probability of correct expression identification as a function of stimulus emotion category, averaged across participants. (C) Probability of correct expression identification as a function of test stimulus/preferred expression CD. Within each participant, stimuli were binned based on their CD relative to the participant’s preferred expression for the corresponding emotion category. Higher bin numbers correspond to greater CD (i.e., greater difference) between the participant preferred expression and tested stimulus. To control for central tendency effects, we performed a permutation test comparing participants’ data (red line) against permutated data (blue histograms), in which preferred expressions were iteratively swapped across participants. Performance was significantly (P = 0.03) affected only when participants were presented with a stimulus very different from their preferred expression. The expression highlighted in orange (Left) shows the sad representation of a sample participant. The 4 stimuli on its right represent sad stimuli samples randomly drawn from bins 1 to 4, arranged from most similar (bin 1) to least similar (bin 4) to the participant’s preferred expression.