"You're wrong!": The impact of accuracy feedback on the bat-and-ball problem.

The popular bat-and-ball problem is a relatively simple math riddle on which people are easily biased by intuitive or heuristic thinking. In two studies we tested the impact of a simple but somewhat neglected manipulation - the impact of minimal accuracy feedback - on bat-and-ball performance. Participants solved a total of 15 standard and 15 control versions of the bat-and-ball problem in three consecutive blocks. Half of the participants received accuracy feedback in the intermediate block. Results of both studies indicated that the feedback had, on average, no significant effect on bat-and-ball accuracy over and above mere repeated presentation. We did observe a consistent improvement for a small number of individual participants. Explorative analyses indicated that this improved group showed a more pronounced conflict detection effect (i.e., latency increase) at the pretest and took more deliberation time after receiving the negative feedback compared to the unimproved group.