18 November 2011

Brain primed for nakedness

by Will Parker

The uniquely human part of the brain that allows us to recognize faces in microseconds is even more sensitive at recognizing another aspect of human bodies - whether they are clothed or naked.

Researchers in Finland say that the part of the brain known as the occipitotemporal N170 component is primed to recognize nude bodies at an elementary stage of visual processing, probably, they say, as an evolutionary mechanism to assist in mate selection.

In the study, male and female subjects were shown pictures of men and women in which the models wore either everyday clothes, swimsuits, or were nude. At the same time, visual cortex responses were recorded from the participants' electrical brain activity. This method allowed the researchers to investigate the primary stages of visual information processing.

The results showed that the less clothing the models in the pictures were wearing, the more enhanced was the information processing. Strikingly, the N170 response to nude bodies was even greater than that to faces, and the N170 amplitude to bodies was independent of whether the face was visible or not.

The brain responses were strongest when the participants looked at pictures of nude bodies, the second strongest to bodies in swimsuits, and the weakest to fully clothed bodies. Interestingly, while male participants' brain responses were stronger to nude female than to nude male bodies, female participants' brain responses were not affected by the gender of the bodies.

The results indicate that the brain "boosts" - at a very early stage - the processing of sexually arousing signals. The researchers, reporting their findings in PLoS ONE, suggest that this priority processing of nakedness may assist in efficient perception of potential mating partners - and mating competitors - in the environment.

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Source: Academy of Finland