Expressions of emotions in minimal face perception stimuli.

Face perception is considered to be a canonical example of configurational visual processing. However, not all facial information is equally important when reading facial expressions. The eyes and mouth seem to be crucial, but they seem to have different roles and significance. By varying the shape of the mouth, eyes, and other factors, we conducted two experiments: first, we examined eye movements depending on different facial configurations and different types of instructions (neutral and emotionally valenced); second, we used the same types of stimuli in a rating task. Our results indicate that the eyes provide a primary impact (when eye fixations are measured), which can be explained by the evolutionary need to establish gaze contact, but once facial expressions are observed, the mouth seems to be more significant.