Fitting Motivation to Fitts’ Law : Effect of a Penalty Contingency on Controlled Movement

摘要

An experiment examined the effect of a penalty on performance of target acquisition movements, focusingon overall movement time, the fit of the data to Fitts’ Law, and ballistic and homing submovements. Fitts’Law, MT = a + b[Index of Difficulty], where Index of Difficulty (ID) = log2[Movement distance/target size],focuses on the control of the movement by external stimuli, rather than the consequences of a movement. Inthis study, participants moved a cursor on a computer screen from a starting point to a target with movementdistance and target size varying systematically. In the Penalty condition, when the movement missed thetarget, the computer screen went blank and the next trial was delayed for 30 seconds. In the Nonpenaltycondition, participants did not receive a penalty for missing the target. The results showed that receiving apenalty led to higher movement times, a higher Fitts’ Law slope parameter, fewer errors, and fewer nonerrorovershoots of the target. Also, receiving penalties resulted in target acquisition movements with less timespent in the ballistic submovement. The results show that consequences of a movement control movementbehavior.