Face blindness

Face blindness, or prosopagnosia, can be the result of a brain injury or can be present from birth (developmental prosopagnosia, or DP). In extreme cases, patients cannot recognize loved ones or people they see every day. People with this condition cannot store a 3D map of a person’s face. Thus, every slight change in position makes a face appear to be of a completely different person.

Yunjo Lee and Hugh Wilson of York University plus Bradley Duchaine from University College London and Ken Nakayama from Harvard University studied a family with DP. They found that although the subjects could read facial expressions, and one member was even an artist with the ability to render detailed sculptured faces, they had great difficulty in recognizing the same face under different lighting conditions.

Sufferers of prosopagnosia often develop coping mechanisms, such as pretending to recognize people. They also latch onto distinctive features, such as long red hair, and hope the person doesn’t change those attributes.

One of the most famous sufferers of prosopagnosia is the neurologist Oliver Sacks, who wrote Awakenings, and The Man who mistook his wife for a hat. You can hear him and artist Chuck Close, who also has the condition, discuss living with prosopagnosia on this episode of Radiolab.