Date of Award


Degree Type


Degree Name

Master of Science




Dr. Matthew Heath


My thesis sought to determine whether the presence of a proprioceptive map influences the degree to which goal-directed reaching movements are “tricked” by a pictorial illusion. To accomplish this objective, participants performed goal-directed reaches in both proprioceptive matching and no-matching conditions to targets embedded in a centered or proximally or distally displaced frame (the so-called induced Roelofs effect: IRE). During the proprioceptive matching condition, participants were instructed to match the location of a visual target with their unseen non-reaching hand. In the no­ matching condition, participants performed the same reaching response as above, but without the aid of proprioceptive matching from the non-reaching hand. Results showed that reaches in the proprioceptive matching condition were refractory to the IRE during the early and the late stages of the trajectory whereas no-matching reaches were tricked from40%to100%ofmovementtime. Moreover,detailedexaminationofreach kinematics indicated that responses in the matching condition were controlled more online than those in the no-matching condition. Thus, I propose that actions in a proprioceptive matching condition are supported via restrictive egocentric visual cues that are immune to the illusory properties of a visual stimulus. In contrast, when reaches are performed without a proprioceptive match, actions are specified offline and supported via integrative allo- and egocentric visual cues that render motor output susceptible to the illusion-inducing features of a visual stimulus



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