Högskolan i Skövde

The phenomenon of somatosensory attenuation describes the perception that self-generated touch feels weaker than externally generated touch of identical intensity. Previous studies have shown that besides intensity, self-generated touches feel less pleasant and less ticklish than identical externally generated touches. However, previous studies did not systematically assess attenuation across a range of stimuli that can elicit intensity, pleasantness, and ticklishness more efficiently. This thesis aims to replicate these previous observations across a range of tactile stimuli of different intensities and velocities and investigate whether people who attenuate their self-generated touches to a greater extent do so for all aforementioned qualities. Previous studies have shown that participants with lower levels of somatosensory attenuation have more schizotypal personality traits. Twelve volunteers participated in three perceptual tasks where they received touches on their sole generated either by a robot(External) or the participants(Self). Following the strokes, participants had to rate the sensation from 0(not at all) to 100(extremely). For the intensity task, we manipulated the intensity of the applied forces (1,2,3,4N). For the pleasantness and ticklishness tasks, we manipulated the velocity of the applied strokes (0.3,1,10,30cm/s). After the tasks, participants completed a Schizotypal Personality Questionnaire (SPQ). Significant somatosensory attenuation was observed in all tasks, but for specific, not all, stimuli: forces of 4N in terms of intensity, strokes of 1cm/s in terms of pleasantness, and strokes of 10cm/s and 30cm/s in terms of ticklishness. These results suggest that the ability to suppress the tactile consequences of self-generated touch occurs in all three tactile qualities.