Poster F27, Tuesday, March 28, 8:00 – 10:00 am, Pacific Concourse
Modulating vicarious tactile perception: Performance-specific outcomes of transcranial current stimulation of primary somatosensory cortex on empathy for touch
Natalie Bowling1, Michael Banissy1; 1Goldsmiths College, University of London
Passive observation of touch elicits vicarious neural representations similar to when we are touched on our own bodies, including activity in primary somatosensory cortex (SI). Vicarious tactile perception, conscious or unconscious, is associated with heightened empathy. Conscious experiences can be quantified using a visuotactile interference task, in which participants report the location of a tactile stimulus whilst viewing touch to another person. Observed touch is either spatially congruent or incongruent with the tactile stimulus. Increased reaction times on incongruent versus congruent trials are thought to reflect interference from competing tactile sensations. These congruency effects have previously been induced by increasing excitability of SI with transcranial direct current stimulation (tDCS). The present study aimed to identify whether individual variation in baseline task performance interacts with transcranial current stimulation (tCS) effects. In Experiment One, tDCS targeted at SI significantly increased congruency effects only for participants with lower effects at baseline. Experiment Two confirmed these performance-specific effects with transcranial random noise stimulation (tRNS) over SI. This experiment contained four versions of the task, in which participants observed touch to human hands in a first- or third-person perspective, dummy hands, or an object. Performance-specific tRNS effects were found on the first-person human and dummy hands tasks, but not the third-person human or object tasks, indicating that visual perspective may be more relevant than perception of animacy in modulating vicarious tactile perception. The results provide causal evidence for the role of SI in tactile empathy, and highlight the importance of individual differences in tCS research.
Topic Area: EMOTION & SOCIAL: Person perception