Face perception is the process by which the human brain interprets information relayed by the eyes regarding other people's faces. This information is very complex and is often processed on an almost subconscious level. Facial recognition, interpretation of emotion, and information regarding social interaction are all part of face perception. Due to the great complexity of face perception, the specifics of how our brains process and utilize this information is not entirely understood. Many parts of the brain are involved in the process, and it is believed that they work together to perform this function.
The most basic aspect of face perception is recognition, which begins at a very early age. Even infants as young as two months old show some ability to recognize faces, particularly those of their parents and others with whom they interact regularly. Face recognition is a critical aspect of nearly all our human interactions, as it allows us to instantly and instinctively recognize most anyone we know. This faculty is tied to memory as well, as one may fail to recognize a face seen only once or twice. It also allows us to recall information about that person once the process of recognition identifies them.
Emotion is another key type of information relayed by face perception. Recognition of emotion is learned at a fairly early age but is not present in very young infants. This ability begins to develop at about one year of age. The human face is extremely complex, and is capable of conveying a large number of emotions, all of which we learn to recognize through interaction with others. This ability grows as we get older but may be more or less acute from individual to individual.
Some very subtle facial expressions and their meanings may not be perceived by the conscious mind. Some of these expressions are often made subconsciously and rather than affecting the entire face may only affect very small areas or muscle groups. Many of these types of micro-expressions are not consciously perceived by most people, but recognizing them and their meanings is a skill that can be learned.
Information about a person's age and gender are also relayed and processed by face perception. This is also a learned skill that is better developed as an individual becomes older and more experienced in processing this type of information. Very young children cannot distinguish between the ages of adults. They can discern that they are older but may have difficulty estimating actual age with any accuracy, a skill which improves with age and experience.
Social interactions and information regarding social group and ethnicity are another important part of face perception. People tend to have better face perception, particularly face recognition, with members of their own ethnic group. It has been shown that people tend to perceive most faces from other ethnic groups as all looking alike. This is a conditioned response due to environment. For example, while many Caucasians tend to think all Asian people look alike, a Caucasian child raised in Asia would not exhibit this tendency.