When subjects view stimulation of a rubber hand while feeling congruent stimulation of their own hand, they may come to feel that the rubber hand is part of their own body. This illusion of body ownership is termed ‘Rubber Hand Illusion’ . We investigated sensitivity of RHI to spatial mismatches between visual and somatic experience. We compared the effects of spatial mismatch between the stimulation of the two hands, and equivalent mismatches between the postures of the two hands. We created (...) the mismatch either by adjusting stimulation or posture of the subject’s hand, or, in a separate group of subjects, by adjusting stimulation or posture of the rubber hand. The matching processes underlying body ownership were asymmetrical. The illusion survived small changes in the subject’s hand posture, but disappeared when the same posture transformations were applied to the rubber hand. Mismatch between the stimulation delivered to the subject’s hand and the rubber hand abolished the illusion. The combination of these two situations is of particular interest. When the subject’s hand posture was slightly different from the rubber hand posture, the RHI remained as long as stimulation of the two hands was congruent in a hand-centred spatial reference frame, even though the altered posture of the subject’s hand meant that stimulation was incongruent in external space. Conversely, the RHI was reduced when the stimulation was incongruent in hand-centred space but congruent in external space. We conclude that the visual–tactile correlation that causes the RHI is computed within a hand-centred frame of reference, which is updated with changes in body posture. Current sensory evidence about what is ‘me’ is interpreted with respect to a prior mental body representation. (shrink)

The mental representation of one’s own body does not necessarily correspond to the physical body. For instance, a dissociation between perceived and actual reach-ability has been shown, that is, individuals perceive that they can reach objects that are out of grasp. We presented participants with 3D pictures of objects located at four different distances, namely near-reaching space, actual-reaching space, perceived-reaching space and non-reaching space. Immediately after they were presented with function, manipulation, observation or pointing verbs and were required to judge (...) if the verb was compatible with the object.Participants were faster with function and manipulation verbs than with observation and pointing verbs. Strikingly, with both function and manipulation verbs participants were faster when objects were presented in actual than the perceived reaching space. These findings suggest that our knowledge of the world is implicitly built online through behaviour, and is not necessarily reflected in explicit estimates or conscious representations. (shrink)

Embodiment matters to perception and action. Beyond the triviality that, under normal circumstances, we need a body in order to perceive the world and act in it, our particular embodiment, right here, right now, both enables and constrains our perception of possibilities for action. In this chapter, we provide empirical support for the idea that the structural and morphological features of the body can narrow the set of our possible interactions with the environment by shaping the way we perceive the (...) possibilities for action provided. We argue that this narrowing holds true in the perception of what we call strongly embodied affordances, that is, relevant micro-affordances that have a genuinely demanding characteristic, as well as in the perception of actions performed by others. In particular, we show that perceptual contents are shaped by fine-grained morphological features of the body, such as specific hand-shapes, and that they change according to our possibility to act upon them with this body, in this situation, at this moment. We argue that these considerations provide insight into distinguishing a variety of experienced affordance relations that can aid us in better understanding the relevance of embodiment for perception and experience. (shrink)

How deeply does action influence perception? Does action performance affect the perception of object features directly related to action only? Or does it concern also object features such as colors, which are not held to directly afford action? The present study aimed at answering these questions. We asked participants to repeatedly grasp a handled mug hidden from their view before judging whether a visually presented mug was blue rather than cyan. The motor training impacted on their perceptual judgments, by speeding (...) participants’ responses, when the handle of the presented mug was spatially aligned with the trained hand. The priming effect did not occur when participants were trained to merely touch the mug with their hand closed in a fist. This indicates that action performance may shape the perceptual judgment on object features, even when these features are colors and do not afford any action. How we act on surrounding objects is therefore not without consequence for how we experience them. (shrink)