Rule discovery performance unchanged by incentives

Human behavior is modulated by financial incentives, but it is not well understood what types of behavior are immune to incentive and why. The cognitive processes underlying behavior appear to create restrictions on the effect an individual's motivation will have on their performance. We investigate a classic category learning task for which the effect of financial incentives is still unknown (Shepard, Hovland, & Jenkins, 1961). Across four renditions of a category learning experiment, we find no effect of incentive on performance. On a fifth experiment requiring category recognition but not learning, we find a large effect on response time and small effect on task performance. Humans appear to selectively apply more effort in valuable contexts, but the effort is disproportionate with the performance improvement. Taken together, the results suggest that performance in tasks which require novel inductive insights are relatively immune to financial incentive, while tasks that require rote perseverance of a fixed strategy are more malleable.