When feedback backfires: Knowledge of results can impair cognitive strategy choice.

Frequently, problems can be solved in more than one way. In modern computerised environments, more ways than ever exist. Naturally, human problem solvers do not always decide for the best-performing strategy available. One underlying reason might be the inability to continuously and correctly monitor each strategy's performance. Here, we supported some of our participants' monitoring ability by providing written feedback regarding their speed and accuracy. Specifically, participants engaged in an object comparison task, which they were asked to solve with one of two strategies: an internal strategy (mental rotation) or an extended strategy (manual rotation). After receiving no feedback (30 participants), trialwise feedback (30 participants), or blockwise feedback (30 participants) in these no choice trials, all participants were asked to estimate their performance with both strategies and were then allowed to freely choose between strategies in choice trials. Results indicated that written feedback improves explicit performance estimates. However, results also indicated that such increased awareness does not guarantee improved strategy choice and that attending to written feedback might tamper with more adaptive ways inform the choice. Thus, we advise against prematurely implementing written feedback. While it might support adaptive strategy choice in certain environments, it did not in the present setup. We encourage further research that improves the understanding of how we monitor the performance of different cognitive strategies. Such understanding will help create interventions that support human problem solvers in making better choices in the future.