Fig. 3.

Behavioral results for the reciprocal aiming task. Mean MTs plotted against ID, calculated using Fitts’ law for all task and tool conditions. A decrease in target box size corresponds to an increase in ID, which represents task difficulty. Linear fits plotted with dark solid lines denote closed-loop movements, faded solid lines denote open-loop movements, and dashed lines denote imagined movements. The linear relationship between duration and ID (i.e., Fitts’ law) held for all conditions. MTs for low < medium < high IDs. MTs for imagine were overestimated compared to both closed-loop and open-loop. Effect of ID was more prominent for closed-loop execution. Slopes for closed-loop > both imagine and open-loop conditions. Collapsed across conditions, MTs did not differ between stick and laser, but slopes for the laser were steeper, due to the imagery conditions. All p-values < .05.