Abstract
Two important factors are related to haptic hand-motion perception: one factor is the sensations employed for perception and the other is the person's initiative in the hand movements. The following two sensations are considered representative for the sensation factor: the proprioceptive sensations that return the physical states of joint rotations and muscle activities with extension and flexion and the cutaneous sensations of fingerpads. Since these are primary and secondary in haptic motion perception, we examined the following two sensation modes: (1) cutaneous-combined proprioceptive mode, “Co” and (2) without-cutaneous proprioceptive mode, “Pr”. The former is expected to surpass the latter. For initiative factors, we considered the following two initiative modes important: (a) active mode, “Ac,” where persons move their hands with their intention and (b) passive mode, “Pa,” where their hands are pulled by a device against their intentions. The former is expected to surpass the latter. Considering these two factors, we examined haptic hand-motion perceptual performances among the following four perceptual modes by psychophysical experiments: (1-a) cutaneous-combined proprioceptive active, “CoAc mode,” (1-b) cutaneous-combined proprioceptive passive, “CoPa mode,” (2-a) proprioceptive active, “PrAc mode,” and (2-b) proprioceptive passive, “PrPa mode”. From the viewpoints of systematic and random errors, statistical test results suggest that two factors, sensation and initiative, almost independently contribute and additively enhance performance: CoAc mode showed the largest sensibility and the minimum random errors. We also found other haptic directional perceptual characteristics in systematic and random errors.
