Robust neurophysiological correlates of the rubber hand illusion emerge at early latencies but are unrelated to changes in skin conductance accompanying the illusion

The neurophysiological processes reflecting body illusions such as the rubber hand remain debated. In particular, previous studies investigating neural responses evoked by the illusion-inducing stimuli provide diverging reports as to when these responses reflect the illusory state. To resolve these controversies in previous work we applied multivariate (cross-) classification to EEG responses obtained during the rubber hand illusion and multiple control conditions in human participants. These controls were designed to test for markers of the illusory state that generalize across the spatial arrangements of limbs or the specific nature of the control condition (rubber hand or participants real hand) - hence which are independent of the precise experimental conditions used as contrast for the illusion. This revealed a parcellation of evoked responses into a temporal sequence of events that each differentiate the illusion and control conditions along distinct dimensions. Importantly, around 130-150 ms following stimulus onset the neurophysiological signals reliably differentiated the illusory-state from all non-illusion epochs. This neurophysiological signature was not correlated with changes in skin conductance accompanying the illusion, suggesting that neurophysiological and bodily signals reflect distinct illusion-related processes.