Individual differences in perceived pinch force and bite force.

Six subjects made cross-modal matches of pinch force and bite force to an electrocutaneous stimulus. The electrocutaneous stimulus consisted of bursts of pulses, and the intensity of the stimulus was varied by changing the number of pulses per burst. All of the individual matching functions were fit well by power functions. The scaling constants and exponents of the power functions covaried systematically with the maximum pinch force for 5 of the 6 subjects. The relationship was consistent with the hypothesis that subjects perceive their physical maxima equally, in agreement with Borg's theory of relative perceived exertion. For both pinch force and bite force functions, the scale factors could be described by a single linear function of the exponents, suggesting that all of the matching functions converged at a single point with extreme values.