Inclusion criteria for all participants: Healthy controls, PwMS (Persons with Multiple Sclerosis) and stroke patients  Age > 18 years Able to understand and execute the test instructions Able to sit on a chair with low back support for 10 minutes  Inclusion criteria specific for PwMS:  Diagnosed with MS (Multiple Sclerosis) using McDonald criteria Able to move at least 1 out of 3 joints (wrist, elbow or shoulder): Medical Research Council score 3.  Inclusion criteria for stroke patients:  First- ever single, unilateral (ischemic or hemorrhagic) stroke No apraxia or hemi spatial neglect Able to move at least 1 out of 3 joints of the affected upper limb (wrist, elbow or shoulder): Medical Research Council score 3.  Exclusion Criteria:  Other medical conditions interfering with the upper limb function or trunk (orthopedic or rheumatoid impairment) Perceived pain in one of the upper limbs of more than 4/10 (Visual Analog Scale) Severe cognitive or visual deficits interfering with testing For the PwMS: a relapse or relapse-related treatment in the last month prior to the study