TOWARDS QUANTIFYING THE SENSE OF AGENCY AND ITS CONTRIBUTION TO EMBODIMENT OF MYOELECTRIC PROSTHESES

Abstract

Myoelectric technology has the potential to improve prosthetic device functionality. However, rejection rates remain high, related to lack of sensory feedback and difficult control strategies associated with these devices. Sense of agency, or feeling of control over one’s actions, may be able to address these high rejection rates, but existing studies tend to rely on subjective questionnaires to study this experience. Evidence suggests that intentional binding, the compression of the time interval between a voluntary action and its sensory effect when an individual feels in control, may be a quantifiable correlate of the sense of agency. However, existing intentional binding protocols are susceptible to expectation bias and are attentionally demanding for participants. Psychometric assessment tools, such as two-alternative forced choice, may be able to quantify this subjective experience while avoiding bias and attentional demand. In this work, we developed an experimental protocol that uses a psychometric assessment method, namely two-alternative forced choice paradigm, to study intentional binding and sense of agency. Here we present preliminary results from 2 able-bodied participants using a myoelectric simulated prosthesis fitted with mechanotactile feedback during voluntary and involuntary control conditions for a grasp-and-release task. These results show that responses to sense of agency questionnaire items are affected by voluntary and involuntary control of a prosthesis.