Motor imagery describes the process by which a prosthesis user mentally simulates the execution of a desired limb movement and activates the musculature of the residual limb that would generate the desired movement.

The CRT has been adapted from an arm training tool to create an instrument to measure hand function. The CRT is a timed task that measures the time taken to move three standard clothespins from three locations on a horizontal bar to a vertical bar. It tests at least two motor functions simultaneously: hand open/close and wrist pronation/supination.

At the onset of the task, a virtual hand is displayed, and a target appears in a location or orientation indicating the final target posture. The targets were specifically designed through iterative focus group testing to ensure they minimally occluded the hand and wrist position during the task. For hand grasp tasks, a translucent grey sphere represents the target location and a red sphere represents a marker tracking the virtual hand's finger position. For wrist pronation/supination tasks, a translucent grey bar appears in a target orientation and a red bar acts a visual marker indicating the virtual hand's current orientation. The goal of the task is to match the hand or wrist orientation with the target location or orientation, respectively. Four metrics are all measured during each task: Movement Completion Rate, Movement Completion Time, Number of Overshoots, and Path Efficiency. The task is failed if the participant does not complete the task within 10 seconds.

PROMIS is a set of self-reported person-centered measures that evaluate and monitor physical, mental, and social health in adults and children developed by the National Institutes of Health (NIH) to improve outcome reporting across medical sciences. The PROMIS measures were designed to reduce administration time of patient reported outcomes through the use of algorithmically selected surveys. There are 5 instruments of PROMIS that we plan to use for this study: Social Isolation, Ability to Participate, Upper Limb Functionality, Physical Function, and Satisfaction Roles Activities. PROMIS measures are scored according a common metric called the T-score. Typically, the mean of 50 (standard deviation of 10) corresponds to the mean in normative U.S. population.

The controller does not send any outputs to the prosthesis when "rest" is decoded by the pattern recognition classifier. For all other pattern recognition outputs, movement commands are sent to the prosthesis. Thus, the controller is in a good position to be able to record the amount of prosthesis usage as measured by the frequency of control signals. Such activity is measured in terms of series of continuous movement commands called "movement bouts." The number movement bouts will be recorded and stored in the controller memory.