I was never addicted to skydiving, but I definitely enjoyed it. I made my first skydiving when I was 19. I was one of a selected few who got a chance to attend the US Air Force Academy’s Freefall school, a program that taught mostly Air Force Academy cadets how to jump out of planes. It wasn’t intended to make us operational paratroopers(伞兵), but to teach us about accomplishing tasks in high-stress situations. And this training program was the only one that allowed jumpers to perform freefall skydiving and pull their own ripcords(开伞索) without a trained instructor jumping alongside of them.

When I returned to Columbus for my college study, I proudly wore my parachutist badge(伞兵徽章). About a month later, I made my first private skydiving and the rest was history. I jumped more and more, only paying for the jumps and necessary training when I had the funds to do it.

Eventually, I had made 10 skydiving, and then it was 20, and I found that I was making jumps at different drop zones. I even bought my own parachute system.

I kept jumping during my senior year. The last jump I made, however, was in the fall of 2006 when I was in Cleveland. My new job needed me to work six days a week and I just didn’t have time to skydive regularly. When I moved to the DC area, I suffered from herniated disk(椎间盘突出) and I knew I would never jump out of a plane again.

My skydiving career ended with 55 jumps, with more than 40 minutes of freefall time. I met great people along the way and did some pretty crazy jumps. I’ll never forget meeting Adam Abelow, the head of the skydiving club, who gave me a ride to get my first jump, and Jen White, who coached me on many of my jumps. I’ll never forget getting my license and the time when my grandparents came to watch me jump.

A baby smiles and laughs. You also smile and laugh. The baby pounds (敲打) his tiny fist on the table. You mirror his action, lightly pounding your back. This imitation game comes naturally. It’s a simple way for parents to have fun with their babies. And new research shows that babies not only realize that adults are imitating them, but they also seem to enjoy it.

For the study, some researchers from Lund University in Sweden met 6-month-old babies in their homes and played with them. They either imitated everything the babies did in mirror-like fashion, or imitated the actions without any expressions on their face, or responded with a different action when the babies acted.

In the study, the babies looked and smiled longer and tried to approach the adult more often when their actions were being most closely mirrored. “Imitating young babies seems to be an effective way to attract their interest and build relationships with them,” lead author Sauciuc said in a statement.

While the babies were playing with the researchers, they also showed some testing behavior. For example, if the baby hit the table just once and the researcher imitated the action, then the baby would hit the table several times, carefully watching the researcher for a response. When the researcher showed no emotions (情绪) while imitating the baby, the babies still seemed to recognize that they were being imitated and they responded with testing behavior to the researcher.

“This was quite interesting. When someone actively tests the person who is imitating them, the imitated individual usually realizes that there is a link between their own behavior and the behavior of the other,” Sauciuc said. The results were published in PLOS One.

Scientists have guessed that imitation is key for babies about how to get on with others, and that sharing actions is linked with sharing feelings. But there isn’t a lot of research to back up those theories.

“By showing that 6-month-old babies recognize when they’re being imitated, and that imitation has a positive effect on communication, we begin to fill this gap (空缺),” Sauciuc added.