Washington: New research shows that even in people who have been blind since birth, the brain still separates living and non-living objects.
"If both sighted people and people with blindness process the same ideas in the same parts of the brain, then it follows that visual experience is not necessary in order for those aspects of brain organisation to develop," said Bradford Mahon, study co-author, University of Rochester.
"We think this means significant parts of the brain are innately structured around a few domains of knowledge that were critical in humans' evolutionary history."
Previous studies have shown that the sight of certain objects, such as a table or mountain, activate regions of the brain other than the sight of living objects, such as an animal or face -- but why the brain would choose to process these two categories differently has remained a mystery, said Mahon.
Since the regions were known to activate when the objects were seen, scientists wondered if something about the visual appearance of the objects determined how the brain would process them.
For instance, said Mahon, most living things have curved forms, and so many scientists thought the brain prefers to process images of living things in an area that is optimised for curved forms.
To see if the appearance of objects is indeed key to how the brain conducts its processing, Mahon and his team, led by Alfonso Caramazza, director of the Cognitive Neuropsychology Laboratory at Harvard University, asked people who have been blind since birth to think about certain living and non-living objects.
These people had no visual experience at all, so their brains necessarily determined where to do the processing using some criteria other than an object's appearance.
"When we looked at the MRI scans, it was pretty clear that blind people and sighted people were dividing up living and non-living processing in the same way," said Mahon.
These findings were published in Neuron.