Misperceiving the speed-accuracy tradeoff: imagined movements and perceptual decisions.

Research has suggested that prospective motor decisions are consistent with actual motor action. In a study that we recently published (Young et al. in Exp Brain Res 185:681-688, 2008), however, participants demonstrated a preference for closer targets that was inconsistent with the predictions of Fitts's law. With a pair of experiments, the present paper investigates the underlying basis of this non-optimal behaviour. Participants showed a similar deviation from Fitts's law when imagining movements--believing that movement duration increased with distance within the same index of difficulty. Participants did not behave similarly, however, in a perceptual version of the decision task. These results suggest that imagined movements and motor decisions are linked, as well as demonstrating one situation in which both show a similar deviation from the patterns of actual movement duration.