Psychologists' face off reveals humans can recognise 5,000 people

University of York says first evidence-based study nails down facial-recognition ability

The next time an old friend meets your greeting with a quizzical who-are-you stare, you're right to take offence: new research suggests the average person can recognise 5,000 different faces.

Psychologists at the University of York embarked on the study after realising that for all the work scientists have done on faces, they had never nailed down, even roughly, the number of faces the average human knows. They say it is the first evidence-based estimate of this figure.