An Average Person Can Recognize 5,000 Faces.

Jenkins et al. recruited 25 undergraduate or postgraduate students at the University of Glasgow and the University of Aberdeen (15 female, 10 male; mean age 24, age range 18–61 years). They were given 1 hour to list as many faces from their personal lives as possible, and then another hour to do the same with famous faces, like those of actors, politicians, and musicians. To figure out how many additional faces people recognized but were unable to recall without prompting, they showed the participants photographs of 3441 celebrities, including Barack Obama and Tom Cruise. To qualify as “knowing” a face, the participants had to recognize two different photos of each person. Here is a video done by Science Magazine to describe the work: