Average person can recall up to 5,000 faces
People can remember up to 10,000 faces, with the average person able to recall around 5,000, a new study has found.
The "facial vocabulary" comprises both people known personally to an individual and famous faces such as celebrities and politicians.
A team at York University developed a laboratory technique based on a theory called recognition and recall that showed everyone fell within a 1,000 to 10,000 range.
This is despite humans typically living and interacting in groups of smaller than 100 throughout evolution. For the study, 25 participants spent an hour writing down as many faces from their personal lives as possible, including those they went to school with, colleagues and family.
They then did the same for famous faces.
The participants found it easy to come up with lots of faces at first, but harder to think of new ones by the end of the hour. That change of pace allowed the researchers to estimate when they would run out of faces completely.
The participants were also shown thousands of photographs of famous people, such as Barack Obama, and asked which ones they recognised.
Dr Rob Jenkins, who led the research, said: "The ability to distinguish different individuals is clearly important - it allows you to keep track of people's behaviour over time, and to modify your own behaviour accordingly. The range could be explained by some people having a natural aptitude for remembering faces."