Tactile discrimination
We assessed whether participants could discriminate between the
different stimulus intensities. In each trial, vibrotactile stimuli of
two different stimulus intensities were presented to the right fingertip
for 80 ms each, separated by a 1 s pause. Participants then had to
indicate whether they perceived the first or second vibration to be
stronger by pressing either ‘1’ or ‘2’ on a keyboard, and how confident
they were in this choice by providing a certainty score on a scale
ranging from 0 (not at all sure) to 100 (completely sure), by providing
a mouse click. There were five trials per unique stimulus pair and
order, resulting in a total of 30 randomly presented trials.