Interplay of tactile and motor information in constructing spatial self-perception

Touching with the eyes: Oculomotor self-touch induces illusory body ownership

“…However, direct comparison of active-versus-passive movements has already been extensively investigated in previous studies. 8 , 11 , 14 , 28 , 40 , 41 Moreover, the present study did not aim to investigate voluntary movements per se . Instead, it was aimed to test whether proprioceptive signals during self-touch were strictly necessary to modulate body ownership.…”

“…4 , 12 Our results align with recent studies suggesting that active self-touch movements enhance body ownership compared to passive movements and play a key role in the spatial coherence of bodily self-awareness. 14 , 28 Yet, most of the previous studies on self-touch employed an active-versus-passive movements paradigm. Because proprioceptive signals were equally present in active and passive movements, those studies could not conclusively rule out that proprioception contributed to modulate body ownership through self-touching movements.…”

“…The voluntary nature of self-touching movements might, in fact, be sufficient to explain the binding properties of self-touch. 11 , 14 , 15 , 16 , 17 For example, Hara et al. found that voluntary self-touch boosts the sense of body ownership compared to passive self-touch and classical multisensory stimulation.…”

Interhemispheric communication during haptic self-perception

“…Our finding of unsigned, as opposed to signed, integration does not simply reflect a general inability to combine spatial information in self-touch. Indeed, in a recent self-touch experiment [10], we showed that spatial extent perception involved signed interhemispheric integration, so that tactile strokes that were longer or shorter than a self-touch movement produced positive and negative biases, respectively, in judgements of movement extent. By contrast, in the present experiment, tactile pressure information exhibited unsigned interhemispheric integration.…”

“…When the surface that we are haptically exploring is our own skin (as when feeling a pimple, or examining our body for a lump under the skin), besides the tactile and kinaesthetic information from the moving effector, the brain additionally receives tactile sensory information from the touched skin. To the best of our knowledge, a few studies investigated how the brain combines all these different sources [9,10]. Most studies assume that the brain acquires and uses internal models of body-object interactions to combine the weighted tactile and movement information, to estimate properties such as object size [1,11] or compliance [12].…”