The Frontal Cortex

Judith Rich Harris Was Right

Peers matter. According to two recent economics papers, the behavior of our peers determines our own. Alexandre Mas and Enrico Moretti looked at worker productivity:

A 10% increase in average co-worker permanent productivity is associated with 1.7% increase in a worker’s effort. Most of this peer effect arises from low productivity workers benefiting from the presence of high productivity workers.

A separate working paper looked at the peer effects on 6th graders. Was their behavior affected by whether or not they went to a middle school (with older peers) or an elementary school (with younger peers)? According to Philip J. Cook, Robert MacCoun, Clara Muschkin, and Jacob Vigdor, the effect is clear:

sixth grade students attending middle schools are much more likely to be cited for discipline problems than those attending elementary school….Furthermore, the higher infraction rates recorded by sixth graders who are placed in middle school persist at least through ninth grade. A plausible explanation is that sixth graders are at an especially impressionable age; in middle school, the exposure to older peers and the relative freedom from supervision have deleterious consequences.

I’m especially intrigued by the second paper. I’ve thought for awhile that the rise of middle schools is a bad trend. I know school distrcts face increasing crowding at the elementary school level – the alarming rate of high school dropouts means high schools are relatively uncrowded – but 6th graders are clearly not ready to cavort with older adolescents.

Hat tip: Mankiw