美国科学60秒 SSS 2013-03-26（在线收听）

 　　Teachers might want to think twice about posting 'no gum chewing' signs in the classroom. It turns out that the sticky substance might help students concentrate. Researchers had two groups of 20 people each listen to a 30-minute recording that included a sequence of numbers. After listening, the participants were asked to remember the sequence. But only one group chewed gum, and they had higher accuracy rates and faster reaction times than the non-gum chewers. Those chewing gum also maintained focus longer during the exercise. The study is in the British Journal of Psycology and contradicts a 2012 study that found gum-chewing decreased shot-term memory performance. The researchers say that gum increases the flow of oxygen to regions of the brain responsible for attention. More oxygen can keep people alert and improve their reflexes. Research also shows that you won't get the same effect by just pretending to chew gum. So the next time you mind is wondering in class, maybe try some gum. If it doesn't help you concentrate, you'll at least be asked to leave.