Last updated on March 15, 2014 at 9:21 EDT

Memories May Skew Visual Perception

July 20, 2011


“This study shows that holding the memory of a visual event in our mind for a short period of time can “Ëœcontaminate’ visual perception during the time that we’re remembering,” Randolph Blake, study co-author and Centennial Professor of Psychology, said.

“Our study represents the first conclusive evidence for such contamination, and the results strongly suggest that remembering and perceiving engage at least some of the same brain areas.”



Illusion offers clues

In this study, the researchers used a visual illusion called motion repulsion to learn whether information held in working memory affects perception. This illusion is produced when two sets of moving dots are superimposed, with dots in one set moving in a different direction from those in the other set. Under these conditions, people tend to misperceive the actual directions of motion, and perceive a larger difference between the two sets of motions than actually exists.

Ordinarily this illusion is produced by having people view both sets of motion at the same time. Kang and colleagues set out to determine if the illusion would occur when one set of motions, rather than being physically present, was held in working memory.

In the experiment, participants were shown a random pattern of dots and were asked to remember the direction in which the dots were moving. They were then were shown a second pattern of moving dots. They were asked to report on the direction of second dots’ movement.

The research subjects’ reports of the second dots’ movement was exaggerated and influenced by what they had previously seen. If they were first shown dots moving in one direction and later shown dots moving in a slightly counterclockwise direction relative to the first presented dots, they reported the counterclockwise movement to be more dramatic than it had actually been.



“Our findings provide compelling evidence that visual working memory representations directly interact with the same neural mechanisms involved in processing basic sensory events,” Kang and his colleagues wrote.

Kang and Blake’s co-authors were research associate Sang Wook Hong and Assistant Professor of Psychology Geoffrey Woodman. Funding from the National Institutes of Health, the National Science Foundation and the World Class University Initiative of the National Research Foundation of Korea and the Ministry of Education, Science and Technology supported the research.


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