Most adults can recognize a familiar face whether it’s in profile, facing front on, or tilted quizzically to one side. New research shows that the ability to recognize and follow faces at different angles develops slowly in children, only reaching adult levels by the time they are 12 years old.
Both children and the elderly have more difficulty matching a front view face to a partial side view. Can you detect which side view corresponds to the front view at the top?
Photo courtesy of Senior Fellow Hugh Wilson
The ability of the visual system to adapt to head orientation is important not only for recognizing faces, but also socially for understanding body language, such as where people are looking and to what they are paying attention.
“We don’t keep our heads in the same orientation for much time at all, unless you’re a guard at Scotland Yard or Buckingham Palace,” says CIFAR Senior Fellow Hugh Wilson (York University), a co-author on the paper and a member of the Learning in Machines & Brains program (formerly known as Neural Computation & Adaptive Perception.)
“In order to recognize a face — a friend or an enemy or a famous person — you have to be able to recognize it independent of where it’s looking,” Wilson says.
The brains of adults with healthy vision are efficient at following the orientation of people’s heads, and at recognizing the same face when it is facing forward, sideways and at other angles, even though the apparent shapes of our features change with every movement. However, past research has shown that elderly people become worse at recognizing the same face at different head orientations, a finding that is consistent with the weakening of functions in the visual cortex with advanced age.
“That has all sorts of consequences. The simplest is that it’s going to be harder to recognize people,” Wilson says.
“We wondered whether the phenomenon might occur in reverse during development.”
And it did — children became better at recognizing face orientation as they grew older, reaching their peak at about 12 and remaining consistent throughout adulthood. Using a computer model, the researchers found the changes in performance during childhood matched an increase in the activity of inhibitory neurons in the brain. These same neurons slow down in old age, contributing to the trajectory of how perception develops and declines throughout life.
Wilson says the research touches on a key theme of the NCAP program: adaptation.
“NCAP is involved in studying how we adapt to the environment — largely by learning or improving our sensory apparatus — and that’s exactly what we’re looking at.”
The research is in press with the journal Vision Research.
The Natural Sciences and Engineering Research Council, a Vanier Canada Graduate Scholarship, the Canadian Institutes of Health Research and other organizations supported this research.