Most people think older and wiser go together, but that may not be true. Older people may actually be less likely than those who are younger to realize when they've made a mistake.

That's what happened when older and younger generations were pitted against each other in a test of their ability to spot their visual errors on a computer screen.

“The older adults often have no idea at all that they were wrong.”

The University of Iowa trial compared young people, average age 22, to older adults, average age 68. The set up was simple: all they had to do was look away from a computer screen whenever a circle appeared inside of a box. Of course, this wasn't always possible; sometimes they inadvertently ended up glancing at the circle.

Both older and younger adults performed equally well at the task. It was when they made an error that differences showed up.

Youngsters realized when they had made an error about 75 percent of the time. Oldsters failed to notice over a third of their errors, recognizing them about 63 percent of the time. Even worse, when older folks unknowingly made an error and were asked how confident they were that they hadn't made one, they were far more certain that they hadn't made a mistake than younger people were.

“It shows when the younger adults thought they were correct, but in fact had made an error, they still had some inkling that they might have erred,” said study co-author Jan Wessel. “The older adults often have no idea at all that they were wrong.”

Interestingly, this was all reflected in the movements of the pupil of the eye. Pupils dilate in response to many different situations — surprise, fright, pleasure and also when people think they've blundered.

Everyone's pupils dilated — enlarged — when they thought they had made an error, though less so in the older group. And while the younger group's pupils dilated more and more on their unreported errors as their uncertainty rose, older adults showed no pupil dilation at all during unreported errors, in line with their greater certainty that they hadn't made one.

While this was only a test of visual errors made while looking at a computer screen, it does reflect a growing tendency of people not to notice their mistakes as they get older. The finding has a host of implications, ranging from people's ability to judge how safely they drive to their ability to remember to take their medications.

The study appears in Neurobiology of Aging.