SSS 2010-09-16（在线收听）

You know how grandma's always criticizing your new haircut or choice of clothing? Well, it might not hurt to listen. Because old folks who can't hold their tongues may give the best advice. That’s according to a study in the Journal of Experimental Social Psychology.

Researchers recruited 19 undergrads and 32 adults in their 60s and 70s. They split the older adults into two groups, based on the adults' abilities to control their behaviors and impulses—called executive function, which naturally declines with age. Then the researchers showed all three groups a photo of a visibly obese teen, along with a list of her complaints, like trouble sleeping and lack of energy—symptoms associated with childhood obesity.

What advice could they offer this girl? Well, only half of the higher functioning adults and a third of the college kids brought up the girl's weight as the possible source for her problems. But 80 percent of the adults with cognitive declines mentioned weight. They also gave twice as many helpful tips, like more exercise, a better diet, and delivered them with more empathy. So next time you need advice, try grandma or grandpa. But be prepared for brutal honesty.

Thanks for the minute. For Scientific American's 60-Second Science. I’m Christopher Intagliata.