Visuo-tactile synesthesia in non-synethetic subjects: a distinction between self and other.

Visuo-tactile synesthesia in non-synesthetic subjects. A distinction between self and other. Andrea Serino 1,2, Francesca Pizzoferrato 2 & Elisabetta Làdavas1,2. 1 – Dipartimento di Psicologia, Università degli Studi di Bologna. 2 – Centro studi e ricerche in Neuroscienze Cognitive, Cesena Abstract Observation of actions, sensations or emotions activates the same brain areas directly involved in action execution, sensory and emotional feelings, respectively, i.e. the so called “mirror system” (Rizzolatti & Craighero, 2004). In this study, we show that such resonance of brain activity when observing and feeling has a behavioural landmark in the domain of touch. Observing an image of a face being touched by human hands enhanced tactile processing on the face. This effect was: a) specific for observation of touch: tactile enhancement was found when the hands touched the face compared to when they just approached the face; b) specific to viewing a body part: viewing the image of a house being touched did not improve touch; c) sensitive to the identity of the observed face: tactile enhancement was stronger when subjects viewed their own face rather than another person’s face. These findings suggest that observation of touch directly modulates tactile processing, probably by activating primary somatosensory areas in a mirror-like way. Such modulation is stronger when visual information is related to the self. This suggests a gradient in mirror-like activity due to observation of touch that discriminates between observing an another person and the self.