The developing bodily self: Posture constrains embodiment in children and adults

For adults, the feeling of inhabiting a body (a sense of embodiment) is constrained by bottom-up multisensory information such as spatiotemporal correlations between visual and tactile sensations, and by top-down knowledge of the body such as its possible postures. However, to date it is unknown what kinds of body models children have. Here we asked whether common factors constrain embodiment in children and adults. In two experiments, we compared 6- to 7-year-olds’ and adults’ embodiment of a fake hand in the rubber hand illusion, measuring illusion-induced proprioceptive drift and questionnaire responses. In Experiment 1 (N = 120), the fake hand was either congruent with the participant’s own hand, or incongruent by 90° and, as a result, in an impossible posture with respect to the current position of their body. In Experiment 2 (N = 60), the fake hand was incongruent with the participant’s own hand by 20°, but still in a possible posture. Across both experiments, and in both children and adults, visual-proprioceptive congruency of posture, and visual-tactile spatiotemporal congruency in stroking independently yielded greater proprioceptive drift towards the rubber hand. Subjective ratings of embodiment were also higher when visual-tactile information was congruent, but were not affected by posture. Top-down knowledge of body posture therefore partially constrains embodiment in middle childhood, as in adulthood. This shows that, although childhood is a period of significant change in both bodily dimensions and sensory capabilities, 6- to 7-year-olds have sensitive, robust mechanisms for maintaining a sense of bodily self