Temporal characteristics of skin conductance and subjective intensity in response to unpleasant audio-visual and vibrotactile stimuli

In this study, we measured and modeled the changes in physiological and subjective signals when the participants were subjected to unpleasant stimuli, such as, a horror movie and vibrotactile stimuli to the upper body. We measured skin conductance as a physiological value and grip force, which was adjusted to express the level of subjective unpleasantness. We then modeled the skin conductance and grip force as second-order lag systems and computed their characteristic parameters. The damping ratios for skin conductance and grip force were slightly greater than 1.0, and the natural frequency of the grip force was greater than that of the skin conductance. The response delay of the skin conductance was longer than that of grip force by approximately 1 s. In terms of the behavior of the skin conductance, the differences among individuals and the types of stimuli were almost null from the stimulus onset to the peak, but after the peak, the differences were substantial. The temporal changes in the subjective intensity were significantly different among participants. These characteristics are useful for designing emotionally responsive systems that use emotional signals to adapt their behavior.