Two Rapid Alternatives Compared to the Staircase Method for the Estimation of the Vibrotactile Perception Threshold

Wearable vibrotactile devices seem now mature for entering the daily lives and practices of more and more users. However, vibrotactile perception can greatly differ between individuals, in terms of psychophysics and physiology, not to mention higher levels (cognitive or affective for example). Broadly-distributed and affordable vibrotactile devices hence must be adapted to each user's own perception, first of all by delivering intensity levels that are in the perceptible range of the user. This implies determining the user's own thresholds of perception, and then adapting the devices' output levels. Classical methods for the estimation of thresholds elicit too long procedures, and little is known about the reliability of other methods in the vibrotactile domain. This article focuses on two alternative methods for the estimation of amplitude thresholds in the vibrotactile modality ("increasing-intensity" and "decreasing-intensity" methods), and compares their estimations to the estimations from a staircase method. Both rapid methods result in much shorter test durations, and are found less stressful and tiring than the classic method, while showing threshold estimations that are never found to differ by more than 1.5 JND from the estimations by the classic method.