Abstract:
In this thesis, we simulated active touch by measuring absolute and masked thresholds in the Pacinian channel during cyclic self-movement. Based on previous work we hypothesized improvement in the absolute thresholds and increase of masking e ciency compared to passive touch condition. An aluminum contactor (r=0.685 cm) was used for the stimulation of the left middle ngertip of the subjects. The measurements of the psychophysical thresholds were repeated for three conditions: no movement, slow self-movement (0.1-0.2 m/s), and fast self-movement (0.5-0.6 m/s). The slow movement condition (-20.8 dB) and the fast movement condition (-21.8 dB) yielded on average lower thresholds than the passive condition (-17.9 dB). Paired t-tests showed that the di erences between the movement conditions and the passive condition were signi cant (p=0.023 for passive vs. slow; p=0.024 passive vs. fast). Interestingly the threshold shift due to masking increased with self-movement (2.9 dB for passive; 7.9 dB for slow; 9.2 dB for fast). The di erences between the threshold shift due to masking for passive and individual movement conditions were signi cant. According to these results, self-movement signi cantly enhanced sensation in the Pacinian channel. However the speed of the self-movement did not matter. Forward- masking e ciency also increased due to self-movement. Therefore this enhancement seems to operate at both threshold and suprathreshold levels. Since self-movement involves both proprioceptive and motor signals, the exact source of this enhancement currently cannot be identified.|Keywords : Psychophysics, somatosensation, vibratory stimulus, Pacinian, human, active touch.
