Methods for Measuring the Just Noticeable Difference for Variable Stimuli: Implications for Perception of Metabolic Rate with Exoskeleton Assistance

reduction of metabolic rate has become a pillar for quantifying the success of exoskeletons for performance augmentation, but how well can humans perceive these metabolic benefits? Measuring human perceptual ability in this context presents a unique challenge, since the stimulus of metabolic rate is not directly controllable. In this paper we introduce and compare two methods for addressing indirect stimuli: conventional method of constant stimuli (MOCS) with binning, and single presentation (SP). Both methods are based on a maximum likelihood estimation for a sigmoidal psychometric curve, under the assumption of a constant Weber fraction. Using Monte Carlo simulations, we conclude that while conventional MOCS with binning performs better for low actuation noise levels, single presentation strategies are better otherwise. We additionally present a pilot result for one subject using the single presentation strategy, which quantified the Just Noticeable Difference (JND) of changes to metabolic rate of 25.2 ±23.2%.