Older brains make good use of ‘irrelevant’ information

Scientists at Baycrest have found promising evidence suggesting that although aging adults have a more difficult time filtering out irrelevant information, this may actually give them a memory advantage over their younger counterparts.

A study by Karen Campbell, a PhD student in psychology at the University of Toronto, with supervision from Rotman senior scientist Dr. Lynn Hasher, demonstrated that when older adults are overwhelmed with unrelated information they are able to connect it to other information appearing at the same time, often without even knowing they’re doing it.

“This could be a silver lining to aging and distraction,” said Dr. Hasher. “As this type of knowledge is thought to play a critical role in real world decision- making, older adults may be the wiser decision-makers compared to younger adults because they have picked up so much more information.”

The study involved two computer-based memory tasks that were separated by a 10-minute break. In the first task, the participants were shown a series of pictures that were overlapped by irrelevant words (e.g. picture of a bird and the word “jump”). They were told to ignore the words and concentrate on the pictures only. Every time they saw the same picture twice in a row, they were to press the space bar.

After completing this task and following a 10-minute break, they were asked to recall how the pictures and words from the first task were paired together. They were shown three kinds of paired pictures – preserved pairs (pictures with overlap words that they saw in the first task), disrupted pairs (pictures they saw in the first task but with different overlap words) and new pairs (new pictures and new words they hadn’t seen before).

The older adults showed a 30% advantage over younger adults in their memory for the preserved pairs (the irrelevant words that went with the pictures in the first task).

“We found that older brains can link the relevant and irrelevant pieces of information together and unknowingly transfer this knowledge to subsequent memory tasks,” says Campbell.

The study was funded by the Canadian Institutes of Health Research and the U.S. National Institute on Aging. In addition to Campbell and Dr. Hasher, the research team included graduate student Ruthann Thomas, now at Washington University.

The study appeared in the online version of the journal Psychological Science and will be published in print shortly.

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