Many people consider someone smart if they get good academic grades, or get ahead in business. But scientists say someone's intelligence and cognitive function isn't limited to being good at memorizing information from books ? it comes from good frequent interactions with people as well. As Rose Hoban reports, scientists are starting to think that more social interaction is integral to being ? and staying ? smart.

Social psychologist Oscar Ybarra from the University of Michigan says the more social interaction people have, the better they perform cognitively. It's a consistent relationship. He's wondered if people are smart because they socialize, or whether they socialize more ? and are more successful at it ? because they're smart.

So he did several experiments. He took his volunteer subjects and split them in three smaller groups. People in one group were given 10 minutes to debate a particular topic.

He also set up a control group of people who watched a video clip for 10 minutes, but didn't interact with each other

In the third group, Ybarra had people do 10 minutes of brainteasers, crossword puzzles and other mental exercises usually recommended for staying mentally sharp.

Then he tested the subjects' cognition by giving them memory tests, and tests that challenged them to remember items quickly.

"What we found in that experiment, which I think is very cool," Ybarra says "is that social interaction people performed as well on measures of memory, and measures of how quickly they can process patterns of information? they performed as well as people in the brain teaser condition. "

And both of those groups performed better than the control group, the people who simply watched television.

Ybarra says it seems that interacting does have some cognitive benefits. But he says that people have to do it ? with feeling.

"I think being around others will be stimulating,' Ybarra says."But to really reap benefits, cognitive benefits, I think people need to be more engaged and actually trying to understand the other's perspective, where they are coming from and so forth."

Ybarra did these tests with people of all ages ? from college students to seniors as old as their 90s ? and he says social interaction helped people stay sharper throughout their entire lives.

His research is published in Personality and Social Psychology Bulletin.