From friends to famous people or shoppers at your local supermarket, how many faces do you think you recognise?
The answer is likely to be far higher than you imagine after scientists put a number on how many faces the average person recognises.
According to researchers from the University of York in the UK, it is 5000.
Humans once lived in small groups of about 100 individuals, but the study suggests our abilities are enough to cope with the thousands of faces we encounter in the modern world.
“Our study focused on the number of faces people actually know. We haven’t yet found a limit on how many faces the brain can handle,” Dr Rob Jenkins, from the Department of Psychology at the University of York, 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.”
Volunteers were asked to write down all the people whose faces they knew – including famous faces, people they went to school with, colleagues and family.
Researchers monitored how quickly the volunteers “slowed down”.
They were also shown thousands of photographs of famous people and asked which ones they recognised.
The participants knew between 1000 and 10,000 faces.
“The range could be explained by some people having a natural aptitude for remembering faces,” Dr Jenkins said.
“There are differences in how much attention people pay to faces and how efficiently they process the information.
“Alternatively, it could reflect different social environments. Some participants may have grown up in more densely populated places with more social input.”