Inclusion Criteria:  Chronic stroke (at least 8 months post stroke) Available medical records and radiographic information about lesion locations Hemiparesis Some degree of both shoulder and elbow movement A "moderate" impairment of arm function (Fugl-Meyer score between 15-50)  Exclusion Criteria:  Bilateral paresis Severe tactile deficits using the Two-Point Discrimination Test Severe Spasticity preventing movement Aphasia, cognitive impairment, or affective dysfunction that would influence ability to perform the experiment Inability to provide informed consent Severe current medical problems Diffuse/multiple lesion sites or multiple stroke events Hemispatial neglect or visual field cut that would prevent subjects from seeing the targets Individuals under the age of 21 will no be included since this study is focused on motor behavior and learning of fully developed nervous system Inability to attain and maintain testing positions Botox injection to the affected upper extremity within the previous 4 months Concurrent participation in upper extremity rehabilitation either as part of a research study intervention protocol or a prescribed therapy Participation in previous, similar robotics intervention study  None of the following special populations will be included in this research study:  Adults unable to consent Individuals who are not yet adults (infants, children, teenagers) Pregnant women Prisoners Vulnerable Populations