Quantifying the Cognitive Demand of Controlling a Prosthesis with a Secondary Detection Response Task

Up to 44% of upper-limb amputees abandon their prosthesis due to difficulty with control. More intuitive control is needed, but innovation is difficult without a valid and reliable way to measure intuitiveness. Here, we validate a secondary detection-response task (DRT) as a method to objectively measure the cognitive load of using a prosthesis. The DRT is a simple, yet sensitive measure of cognitive resource allocation based on response rate and reaction time to vibratory stimuli. Participants completed a primary task involving moving objects with varying fragility over a barrier without breaking them with their intact hand and with a prosthetic hand controlled by electromyography. While completing the primary task, participants also completed the secondary DRT in which they responded to randomly delivered vibratory stimuli as quickly as possible by pushing a button with their contralateral limb. Participants also completed the NASA Task Load Index, a survey commonly used to assess subjective workload. Results showed that response time and rate were reliable indicators of cognitive load, suggesting that the DRT can objectively measure cognitive load in prosthesis use, thereby guiding future innovation for more intuitive prosthetic control.Clinical Relevance— This research establishes the use of a secondary detection response task as a valid and reliable assessment of cognitive load during prosthesis use.