Something in the way she moves--movement trajectories reveal dynamics of self-control.

This study examined the dynamic impact of self-control conflict on action execution. We reasoned that the tug-of-war between antagonistic action tendencies is not ultimately solved before movement initiation but leaks into action execution. To this end, we measured mouse trajectories to quantify the dynamic competition between initial temptations and the struggle to overcome them. Participants moved the mouse cursor from a start location to one of two targets. Each target represented a gain or a loss of points. Although participants earned points on the majority of the trials, they also had to make movements to the loss target on some trials to prevent an even higher loss. Two experiments found that movement trajectories on these loss trials deviate toward the tempting stimulus: The way we move reveals self-control conflicts that have not been resolved prior to action execution.