The study was stopped during the COVID-19 Pandemic in March 2020 to prevent transmission. It did not reopen due to aging of the virtual reality technology.

People with one arm that does not function well due to a stroke, head injury, or cerebral palsy, and a fully functional other arm, will be randomly assigned to receive one of the two interventions first, followed by the other intervention. The two interventions include a task-based intervention and a virtual reality intervention that provides a reflected image of the involved arm. The task-based intervention will consist of setting up activities of interest to be done using the involved arm and structuring practice and meaningful feedback to assist learning. The virtual reality intervention will consist of the person wearing the virtual reality device and practicing virtual tasks using the intact arm while seeing the involved arm. Intervention sessions will last approximately 30 minutes and will be held 3 times/week for 3 weeks each for a total of 9 sessions for each intervention. Testing of the involved arm's function will be done before the interventions, after receiving 9 sessions of each intervention, and one month after completing the second intervention received.

Potential participants will be screened for age, history of stroke, brain injury, or cerebral palsy, and having one functional arm and one poorly functioning arm by phone. Those who meet the basic criteria will be scheduled for an Intake Evaluation consisting of obtaining voluntary informed consent, complete a demographic survey, visual field testing, cognitive screening, perceptual testing, and an arm/hand function test. Participants who meet the inclusion criteria will be scheduled for a Preliminary Evaluation.

The Preliminary Evaluation will measure the current motor control ability, perception of level of disability, and amount of active and passive motion in the involved arm.

Participants will participate in the first form of intervention (randomly assigned) for three 30 minute sessions per week for 3 weeks (total of 9 sessions) and be re-evaluated using the same tests conducted during the Preliminary Evaluation with the addition of the arm/hand function test conducted during the initial screening.

Participants will participate in the second form of intervention for three 30 minute sessions per week for 3 weeks (total of 9 sessions) and be re-evaluated using the same tests conducted following the first intervention.

One month after completing the second form of intervention, participants will be re-evaluated using the same tests used following the second intervention and will also receive a semi-structured interview regarding their thoughts and experiences during the study and their perceptions of the outcomes.

Inclusion Criteria:

• 18 - 89 years old
• One arm not fully functional due to a stroke, brain injury, or cerebral palsy
• More than 1 year since neurologic even that impaired arm function

Exclusion Criteria:

• Cognitive impairment
• visual field loss (homonymous hemianopsia)
• perceptual deficits (MVPT4 lower than 2 standard deviations from the norm)
• Seizure disorder
• Currently receiving rehabilitation services (PT or OT) for the involved arm.

The occupational therapist providing all of the functional assessments will be blinded to sequence of interventions provided.