A new study in the journal Psychological Science musters the evidence for a curious psychological phenomenon called the N-effect.

In a nutshell, the N-effect is the idea that the more competitors you have, the less motivated you are to do your best. In their article, researchers Stephen M. Garcia and Avishalom Tor show, for instance, that average test scores on the SAT and other tests go down as the number of test-takers increases. In fact, the researchers find, the test-takers don't even have to see their competition. Just knowing they're out there seems to be enough to depress the motivation to compete.

This is especially true, the authors find, if you are the kind of person who takes some satisfaction in measuring your own performance against those of your friends and neighbors.

There are some obvious implications in the findings for education. Academic effort is likely to decrease, the authors say, as the number of students in the classroom rises. Also, they wonder whether recent decreases in average SAT scores could have something to do with growing crowds at the venues where students sit for the exam? Perhaps the authors will do a follow-up study and let us know.