The purpose of this research study with a randomized controlled design is to examine the effects of prism adaptation treatment on two visual-spatial recovery components. After a stroke, an "internal GPS", locating where objects or people lie in a particular area of space, may be impaired. Alternately, a stroke may impair precise visual-spatial hand and body aiming movements. The research team wishes to discover whether prism adaptation treatment (two weeks of daily 20-min sessions of goal-directed movement with prism goggles) affects visual-spatial where or aiming errors selectively after stroke.