With age, we lose our visual learning filter

(Press-News.org) Older people can actually take in and learn from visual information more readily than younger people do, according to new evidence reported in the Cell Press journal Current Biology on November 26. This surprising discovery is explained by an apparent decline with age in the ability to filter out irrelevant information.

"It is quite counterintuitive that there is a case in which older individuals learn more than younger individuals," says Takeo Watanabe of Brown University.

Older individuals take in more at the same time as the stability of their visual perceptual learning declines. That's because the brain's capacity to learn is limited, Watanabe explains. When we learn something new, there is always a risk that information already stored in the brain may be replaced with new and less-important information. A stable mind must be resistant to learning new and trivial details in order to protect what is already there.

In the new study, Watanabe and his colleagues trained a group of older people aged 67 to 79 and a group of younger people aged 19 to 30 on a visual learning task in which they were asked to watch a series of six letters interspersed with two numbers and report back the numbers only. In the background, participants in the study were presented with an array of dots, some moving in a clear direction from frame to frame and others moving randomly. The strength of that "coherent motion" signal was varied over the course of the visual learning task.

As it turned out, the older individuals generally took in more about the directional movement of those irrelevant dots than the younger individuals did.

The researchers explain that our brains normally have the ability to detect and suppress our attention to obvious and irrelevant features. As features become harder to pick up on, we simply tend to miss them altogether. As a result, we are usually able to ignore or filter out information that is not pertinent to the task at hand.

The fact that older people continued to pick up on irrelevant information over a range of signal strengths therefore suggests a failure of their brains' attentional systems to suppress task-irrelevant signals. Watanabe says that the findings in visual perceptual learning will likely apply in other areas of life, since the ability to filter out irrelevant information is generally important to all forms of learning.

The researchers are now using brain-imaging techniques to observe what's happening in the brains of older people as they learn. With greater understanding, it may be possible to devise strategies not only to help older people learn more effectively, but also to keep them from learning things they really shouldn't.

INFORMATION:

Current Biology, Chang et al.: "Age-related declines of stability in visual perceptual learning"