Overconfidence in an objective anticipatory motor task.

Overconfidence can place humans in hazardous situations, and yet it has been observed in a variety of cognitive tasks in which participants have to rate their own performance. We demonstrate here that overconfidence can be revealed in a natural and objective visuo-motor task. Participants were asked to press a key in synchrony with a predictable visual event and were rewarded if they succeeded and sometimes penalized if they were too quick or too slow. If they had used their own motor uncertainty in anticipating the timing of the visual stimulus, they would have maximized their gain. However, they instead displayed an overconfidence in the sense that they underestimated the magnitude of their uncertainty and the cost of their error. Therefore, overconfidence is not limited to subjective ratings in cognitive tasks, but rather appears to be a general characteristic of human decision making.