Faces are essential to expressing emotion, consciously or unconsciously. A frown denotes disapproval; a smile usually means someone is pleased. Being able to read emotion in anothers face is "the fundamental basis for empathy and the ability to interpret a person’s reactions and predict the probability of ensuing behaviors". One study used the Multimodal Emotion Recognition Test to attempt to determine how to measure emotion. This research aimed at using a measuring device to accomplish what people do so easily everyday: read emotion in a face.
The muscles of the face play a prominent role in the expression of emotion, and vary among different individuals, giving rise to additional diversity in expression and facial features.
Variations of the risorius, triangularis and zygomaticus muscles.
People are also relatively good at determining if a smile is real or fake. A recent study looked at individuals judging forced and genuine smiles. While young and elderly participants equally could tell the difference for smiling young people, the "older adult participants outperformed young adult participants in distinguishing between posed and spontaneous smiles". This suggests that with experience and age, we become more accurate at perceiving true emotions across various age groups.
Caricatures often exaggerate facial features to make a face more easily recognized in association with a pronounced portion of the face of the individual in question—for example, a caricature of Osama bin Laden might focus on his facial hair and nose; a caricature of George W. Bush might enlarge his ears to the size of an elephants; a caricature of Jay Leno may pronounce his head and chin; and a caricature of Mick Jagger might enlarge his lips. Exaggeration of memorable features helps people to recognize others when presented in a caricature form.
he face changes over time, and features common in children or babies, such as prominent buccal fat-pads disappear over time, their role in the infant being to stabilize the cheeks during suckling. While the buccal fat-pads often diminish in size, the prominence of bones increase with age as they grow and develop.
Facial shape is an important determinant of beauty, particularly facial symmetry.