Here’s how people recognize faces

March 17th, 2011 - 1:24 pm ICT by ANI  

Washington, Mar 17 (ANI): Scientists have developed a new technique to find out how our brain processes facial identity.

They have used an innovative technique called steady-state visual evoked potential (SSVEP) to evaluate the sensitivity of brain to perceiving facial identity.

The method ’shakes’ the brain gently and repeatedly by making an image appear and disappear at a constant rate.

“If we measure global human brain activity when one face is viewed, it cannot be differentiated from brain activity when another face is viewed,” said author Bruno Rossion, a researcher at the Institute of Psychology and Institute of Neuroscience, Universite Catholique de Louvain, Belgium.

“This is why we relied on a method in which brain activity is compared between repetition of the same face and the presentation of different faces in succession,” he said.

During the experiment, 12 participants were presented with a series of faces appearing at a frequency of 3.5 faces per second.

The result showed the brain signal at that specific frequency only was much larger when a sequence of different faces was presented at that rate than when an identical face was repeated.

The researcher team was surprised by the resulting large size of the difference between the two conditions, obtained only after one minute and a half of testing, and was equally astonished that the difference in conditions did not exist when the faces were inverted.

The study also confirmed that the region for face perception lies primarily in the posterior part of the brain’s right hemisphere.

Rossion said that an advantage of using this highly sensitive SSVEP methods is that it can be used and compared objectively in different human populations - adults, infants, children, neurological patients, people with long-life face recognition impairments or autism - without requiring complex instructions and a long testing duration.

“Face recognition involves the most complex aspects of perception and memory and, for this reason, understanding how it works has large-scale implication,” said Rossion.

“Ultimately, through a better understanding of this function, we will make tremendous progress in our understanding of how the brain works in general, develop tools to detect its dysfunction and hopefully help remedy it,” he added.

The study was recently published in the Journal of Vision. (ANI)

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