Frequency-tagging EEG reveals spontaneous categorical discrimination of visual self-identity.

From early development, visual and sensorimotor representations of our hands are continually linked, allowing to develop a bodily self-representation. Here, we investigated the neural mechanisms of bodily self-identity discrimination, combining electroencephalography with fast periodic visual stimulation. In two experiments, participants' self-hand images appeared as oddball stimuli among others' hands. To control for statistical regularity and familiarity, oddball hand images could belong to a stranger (Exp1) or the partner (Exp2). In a third behavioral experiment, we verified participants could explicitly detect the presence of the self-hand in the sequence. Results revealed a neural marker for automatic hand identity discrimination, with greater responses in egocentric than allocentric perspective only for self-hand images. This interaction effect emerged over occipital, consistently with the visual nature of the task, and also over fronto-central regions, compatibly with the involvement of a sensorimotor network. These findings support that self-hand processing relies on associating visual and sensorimotor representations.