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This feels like my hand! The contributions of posture and size to embodiment across development

Fri, March 22, 3:00 to 4:30pm, Baltimore Convention Center, Floor: Level 3, Room 349

Integrative Statement

The feeling of inhabiting a body (embodiment) is fundamental for the development of the self and the distinction between the self and others. For human adults, embodiment is constrained by bottom-up multisensory information such as visuotactile correlations, and by top-down information such as knowledge of possible body postures and sizes. Here, we asked whether children are subject to the same constraints on embodiment as adults, or if children – whose bodies are rapidly changing – might be more flexible in their own-body representations.
In two studies, we presented 6- to 7-year-olds, and adults with the Rubber Hand Illusion, in which adults embody a fake hand stroked in synchrony with a hidden real hand. In the second study, we included an additional sample of 12- to 13-year-olds – whose hands are adult-sized, but whose bodies are still changing. We measured embodiment through proprioceptive drift and self-report.
In Study 1 on Hand Posture (N = 180), the fake hand was either congruent, or incongruent (by 20° or 90°) from the participants’ own hand. At both ages (Figure 1), congruent visuotactile information contributed to embodiment, which is indicated by significant effects of Synchrony and Posture on proprioceptive drift. The fake hand was accepted as one’s own when multisensory information was synchronous and the hand was in a congruent posture, but not when it was in an incongruent posture. Subjective ratings of embodiment were also higher when visual-tactile information was congruent, however, were not affected by posture. Top-down knowledge of body posture partly constrains embodiment in middle childhood as in adulthood.
In Study 2 on Hand Size, we used five differently sized fake hands (relative to the participants’ own hand). Preliminary data (n = 136 of N = 225) suggest that hand size may have an impact on embodiment, as indicated by a significant effect of Synchrony and a marginal significant effect of Hand Size. The fake hand was accepted as one’s own when multisensory information was synchronous. Data analysis is ongoing; full results will be reported in this symposium.
These findings have implications for existing models of own-body perception in childhood, and for our understanding of the developing bodily self. Specifically, own-body representations seem to be constrained by top-down as well as multisensory information even by mid-childhood.