From Harvard Magazine:
In 1981, early in her career at Harvard, Ellen Langer and her colleagues piled two groups of men in their seventies and eighties into vans, drove them two hours north to a sprawling old monastery in New Hampshire, and dropped them off 22 years earlier, in 1959. The group who went first stayed for one week and were asked to pretend they were young men, once again living in the 1950s. The second group, who arrived the week afterward, were told to stay in the present and simply reminisce about that era. Both groups were surrounded by mid-century mementos—1950s issues of Life magazine and the Saturday Evening Post, a black-and-white television, a vintage radio—and they discussed the events of the time: the launch of the first U.S. satellite, Castro’s victory ride into Havana, Nikita Khrushchev and the need for bomb shelters. There was entertainment (a screening of the 1959 film Anatomy of a Murder with Jimmy Stewart) and spirited discussions of such 1950s sports greats as Mickey Mantle and Floyd Patterson. One night, the men sat glued to the radio, listening as Royal Orbit won the 1959 Preakness. For the second group it brought back a flood of memories; for the other group, it was a race being run for the first time. As a young professor of psychology, Langer hoped to document through these men what she had long suspected: that our fixed ideas, internalized in childhood, can affect the way we age.
…
What she found, however, surprised even her own team of researchers. Before and after the experiment, both groups of men took a battery of cognitive and physical tests, and after just one week, there were dramatic positive changes across the board. Both groups were stronger and more flexible. Height, weight, gait, posture, hearing, vision—even their performance on intelligence tests had improved. Their joints were more flexible, their shoulders wider, their fingers not only more agile, but longer and less gnarled by arthritis. But the men who had acted as if they were actually back in 1959 showed significantly more improvement. Those who had impersonated younger men seemed to have bodies that actually were younger.
More here.