Forgetting can be hard work for your brain

NEW YORK — Sometimes forgetting can be harder than remembering. When people forced themselves to forget a recently seen image, select brain activity was higher than when they tried to remember that image.

Forgetting is often a passive process, one in which the memory slips out of the brain, Tracy Wang of the University of Texas at Austin said April 2 at the annual meeting of the Cognitive Neuroscience Society. But in some cases, forgetting can be deliberate.

Twenty adults saw images of faces, scenes and objects while an fMRI scanner recorded their brains’ reactions to the images. If instructed to forget the preceding image, people were less likely to remember that image later. Researchers used the scan data to build a computer model that could infer how strongly the brain responds to each particular kind of image. In the ventral temporal cortex, a part of the brain above the ear, brain patterns elicited by a particular image were stronger when a participant was told to forget the sight than when instructed to remember it.

Of course, everyone knows that it’s easy to forget something without even trying. But these results show that intentional forgetting isn’t a passive process — the brain has to actively work to wipe out a memory on purpose.