The quick brown clerk jumped over the lazy one: Productive workers tend to spur their colleagues to be more productive, too, or at least so says an interesting survey reported in Slate. This suggests to me that hyperproductive workers are really labor-breaking scabs, moles planted by Corporate HR to get more out of the same employees. (OK, so I kid.) It’s fascinating research. Consider finding the fastest checker in the entire supermarket, and then go shopping at that time of day, when you can:

Since shoppers can and do move to fast-moving lines, a quick worker will tend to lighten the burden on their colleagues. That might encourage them to slack off, or it might encourage them to work harder. The positive effect dominates, according to Mas and Moretti: They find that a shop assistant sitting near someone who is 10 percent quicker than average will raise her own game by 1.7 percent.

This might be an illusory effect. Perhaps at busy times, all workers increase their speed and managers also throw on the fastest workers. What looks like a peer effect would be the coordination of two different responses to a rush of shoppers. But Mas and Moretti can tell which times are busy and which times are not; they also know that checkout staff, not managers, choose their hours (one of the few benefits of the job); and they are measuring productivity changes every 10 minutes, not over the course of an entire shift. They are convinced that the positive peer effect is real.

But why? There are, broadly, two explanations. One is that workers are spurred to greater efforts when contemplating the superior speed of their colleague. This is psychologically plausible but economically irrational. A more cynical explanation is that workers do not like it when faster colleagues are looking at them, because they fear being accused of slacking off.