Seniors involved in the six-year project, which assessed 516 men and women aged 70 and older, revealed that they felt on average 13 years younger than their chronological age, with women perceiving they were closer to their actual age than men.
"People generally felt quite a bit younger than they actually were, and they also showed relatively high levels of satisfaction with aging over the time period studied," said Jacqui Smith, a psychologist at the University of Michigan who co-authored the study.
Participants initially said they felt an average of 10 years younger than they were, a number that fell to seven years by the end of the study, to be published in the forthcoming issue of the Journals of Gerontology.
In separate research not yet published, Smith and others found links between feeling youthful and improved health and longevity.
"Feeling positive about getting older may well be associated with remaining active and experiencing better health in old age," she said. "Perhaps feeling about 13 years younger is an optimal illusion in old age."
Some of the oldest participants said they felt even younger over time. But those in poor health said they felt closer to their actual age.
Smith explained the gender gap between women and men as being due to women being "more aware of their appearance than men, especially given the negative stereotypes of older bodies."
Although men were initially more satisfied than women with their aging, men's satisfaction decreased more rapidly than women's over the six-year period.