It is a commonly-held belief that everything, except time perhaps, slows down as we get older, and it seems that wisdom holds true when it comes to discriminating between faces.

A group of researchers from the University of Glasgow have found that older people are less accurate and slower at recognising faces than younger people.

Dr Guillaume Rousselet and his team in the Department of Psychology studied the electrical activity of the brains of young and old people - aged on average 22 and 70 - as a series of pictures of two different faces were shown to them which had varying levels of ‘noise’ in them.

The researchers confirmed previous findings of an age-related delay in face processing and were able to build on these findings by precisely quantifying the processing speed delay – 47 milliseconds (ms), around a 10ms delay for every extra decade from the age of 20.At 98-years-old, Ken, pictured wearing a 256 electrode EEG net to record electrical brain activity on the scalp surface, is the oldest participant in the study. Courtesy of JD Howell

Face processing produces a signal in the visual cortex of the brain, which peaks at 170ms after presentation of a face – resulting in this signal being called the N170.

In the young a strong N170 response was more closely associated with the appearance of faces, whilst in older subjects it also occurred in response to noise, perhaps implying a reduced ability to differentiate faces from noise in older brains.

Dr Rousselet said: “Very few studies have attempted to measure the effect of ageing on the time-course of visual processing in response to complex stimuli like faces. We found that, as well as an overall reduction in speed in the elderly, one particular component of the response to a face – the N170 – is less sensitive to faces in the elderly.”

“Our data supports the common belief that as we get older we get slower. Beyond this general conclusion, our research provides new tools to quantify by how much the brain slows down in the particular context of face perception.”

“Now, we need to identify the reasons for the speed reduction and for the heterogeneity of the effects – indeed, why the brains of some older subjects seem to tick as fast as the brains of some young subjects is at this point a complete mystery”.

The paper is published in the open access journal BMC Neuroscience.

For more information contact Stuart Forsyth in the University of Glasgow Media Relations Office on 0141 330 4831 or email s.forsyth@admin.gla.ac.uk

Pictured: At 98-years-old, Ken, pictured wearing a 256 electrode EEG net to record electrical brain activity on the scalp surface, is the oldest participant in the study. Courtesy: JD Howell

First published: 3 September 2009

<< September