SSS 2011-01-20（在线收听）

This is Scientific American’s 60-Second Science. I’m Christopher Intagliata. Got a minute?

Ever been running the treadmill, exhausted, ready to quit—but you're at the 2.9 mile mark, so you run that last 10th to make it an even three? Why do you do it? Well it may be because round numbers are intrinsically motivating to us, even if there's no obvious reward for reaching them. That's according to a study in the journal Psychological Science. 

Researchers studied three decades of Major League Baseball batting averages and play-by-play data. They found that players were four times as likely to end the season with a batting average of 300, rather than 299. And players purposely manipulated their averages, by choosing when to swing away or work out a walk, or when to be pinch-hit for.

Examining over four million SAT scores revealed a similar trend. Students with scores of, say, 1,290 rather than 1,300 were more likely to retake the test—even though admissions data showed that administrators didn't seem to favor rounded scores.

It’s not clear why these seemingly arbitrary goals are important to us. But they illustrate internal motivation that could confound some ideas in economics, because some increments are apparently more equal than others.

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