Culture can alter the brain's perceptive mechanisms

Researchers in Illinois and Singapore have found that the aging brain reflects cultural differences in the way that it processes visual information.

This study appears this month in the journal Cognitive, Affective & Behavioral Neuroscience. This paper and another published by the same group in 2006 are the first to demonstrate that culture can alter the brain's perceptive mechanisms.

The new finding is the result of a collaboration between University of Illiniois psychology professor Denise Park and Michael W. Chee, of the Cognitive Neuroscience Laboratory, SingHealth, in Singapore. Park, Chee and their colleagues conducted an array of cognitive tests on study subjects at their facilities in the U.S. and Singapore, and used identical functional Magnetic Resonance Imaging (fMRI) scanners at both sites. Their analysis, of 37 young and old East Asians, and 38 young and old Westerners, found significant cultural differences in how the older adults, brains responded to visual stimuli.

"These are the first studies to show that culture is sculpting the brain," said Park, principal investigator on the study. "The effect is seen not so much in structural changes, but at the level of perception."

Park also will present these findings at the May 2007 meeting of the Association for Psychological Science in Washington, D.C.

Scientists have known for decades that East Asians and Westerners process visual information differently. An analysis published in 1972 noted that East Asians are more likely to pay attention to the context and relationships in a picture than are Westerners, who more often notice physical features or groupings of similar subjects.

More recent research, which analyzed the eye movements of East Asians and Westerners viewing identical images, found that Westerners were more attentive to central, or dominant, objects, while East Asians paid more attention to the background, or scene.

The use of fMRI technology allowed the researchers to determine which brain regions were activated when study subjects contemplated various images.

A 2006 analysis published by Park, Illinois postdoctoral fellow Angela Gutchess and colleagues at the University of Michigan reported differing neural activation patterns in the brains of East Asians and Americans shown identical pictures. The Americans showed more activity in brain regions associated with object processing than the East Asians, whose brains showed more activity in areas involved in processing background information.

The most recent study takes this work further, comparing neural responses to visual stimuli in young and old adults in both cultures. In this analysis, the researchers found equivalence between all four groups (young and old East Asians; young and old Americans) in terms of how they processed background information in the parahippocampal gyrus, a brain region vital to memory encoding and retrieval. As expected, older adults in both cultures exhibited diminished binding processes (the ability to connect a particular object to its background) in the hippocampus, as compared with younger study subjects. The older subjects also exhibited diminished object processing in the lateral occipital complex.

The most striking finding was that the object areas of the older East Asian subjects responded much more weakly to novel stimuli (that is, the appearance of new objects in the pictures) than did those same brain regions in the older Americans. For the older East Asians, a lifetime of enhanced attention to the backgrounds, or context, of pictures eventually showed up as a diminished response in the part of the brain that keeps track of foreground objects.

"These findings demonstrate the malleability of perceptual processes as a result of differences in cultural exposure over time," the researchers wrote.