Facial expressions and eye gaze: fundamental cues for social interactions.

We, as humans beings, draw inferences about others' emotions, intentions, and state of mind to deduce their mental states and intentions. Analogously, by observing where other individuals gaze at, we grasp their focus of interest as we know that people tend to look at what they like and look away from what they dislike. Recognition of facial expression is related to functioning of specific mechanisms and brain structures, among which the amygdala plays a pivotal role. It is currently debated whether the very mechanisms and neural structures are responsible for emotion recognition and production, but data on brain-damaged patients would indicate that a defect in recognizing facial expressions can be independent from deficits in producing the same expressions. This neuropsychological dissociation calls for future studies to clarify mechanisms related to production and recognition of emotions. As regards eye gaze, development of gaze perception in infants allows understanding of other people's intentions and mental states. Several developmental disorders are related to impairments in processing other's gaze as in the case of autism, but recent behavioral data show that processing of eye gaze and facial expressions is highly variable even in normal individuals, and can be modulated by factors such as high levels of trait anxiety, autistic-like traits or introversion.