Electronic Thesis and Dissertation Repository


Master of Science




Dr. Matthew Heath


Goal-directed reaches performed with spatial overlap between stimulus and response (i.e., propointing) are supported by dedicated visuomotor networks that provide absolute visual information for movement planning and control. Furthermore, propointing adheres to speed-accuracy relations as defined by Fitts' equation such that movement time (MT) is predicted by the log/linear relationship between movement amplitude and target width. It is, however, unknown whether reaches with dissociable spatial relations between stimulus and response adhere to Fitts' law. To that end, I examined whether antipointing (i.e., reaching mirror-symmetrical to a target) adheres to Fitts' equation in the same vein as propointing. Results showed that propointing MTs adhered to Fitts’ equation, whereas antipointing adherence was amplitude-dependent. Further, that the deceleration phase of antipointing responses did not scale to IDFittssuggests a mode of control (i.e., offline) distinct from their propointing counterparts.