Observing being touched enhances the neural processing and perception of digital gentle stroking

Observing touch activates similar brain regions as experiencing an actual touch, suggesting that visual information can cross-modally influence tactile perception. This electroencephalography (EEG) study investigated how observing being touched affects the processing and perception of digitally delivered tactile stimuli resembling affective stroking or non-affective tapping. Thirty-three participants received touch patterns on their left forearm via a wearable sleeve while viewing spatiotemporally aligned videos of touch or a photo of an arm. Continuity and pleasantness ratings were higher for stroking than tapping. Correlations between continuity and pleasantness ratings for stroking or tapping conditions were stronger when presented with touch videos than with photos. Analysis of evoked brain activity revealed cross-modal effects after 0.6 seconds at centro-parietal and frontal electrodes for stroking, which differed from the effects observed for tapping. Visual modulation of pleasantness ratings correlated positively with processing differences between stroking and tapping in two right frontal clusters in later time windows around 1.36 and 1.8 s. These results suggest that visual inputs influence tactile pleasantness through somatosensory and multisensory processing, as well as frontal valuation of pleasantness. Our study extends previous research on affective touch by demonstrating informative visual cross-modal influences on digitally actuated touch at behavioural and neural levels.