Electronic Thesis and Dissertation Repository


Master of Science




Dr. Matthew Heath


An issue of current debate in the visuomotor control literature surrounds whether 2D and 3D objects rely on similar or dissociable visual information in supporting goal-directed grasping. Accordingly, in Experiment One I had participants grasp 2D and 3D objects wherein just-noticeable-difference (JND) scores for aperture shaping were computed to determine the extent to which such actions adhere to the psychophysical principles of Weber’s law. Results demonstrated that JNDs scaled in accordance with Weber’s law in a time-independent and time-dependent manner for 2D and 3D grasping, respectively. In Experiment Two, I sought to further explore the cognitive demands of grasping by having participants pantomime the grasping of 2D and 3D objects. Results showed that grasping 2D objects and pantomime grasping elicited a common time-independent adherence to Weber’s law that is distinct from grasping a 3D object. Thus, results demonstrate that 2D and 3D grasping are mediated by distinct visual information.