Children's Embodiment of Non-Human Virtual Hand Forms.

Adults are known to identify their own body through a combination of multisensory cues and top-down expectations regarding its form, while children may possess a more flexible body representation. Here we use virtual reality to test how children and adults use form cues to feel ownership over a virtual hand with novel, varying degrees of corporeality and how a sense of ownership of the hand and movement fluency with it may be trained. In Experiment 1, children (N = 40, 6-8 years) and adults (N = 45) experienced four virtual hand forms (Hand, hand with a missing Thumb, crab-like Claw, Cross). Participants had to catch slowly moving virtual feathers while the virtual hand form moved in and out of synchrony with their own hand movements. In Experiment 2, we gave each child (N = 10, 6-9 years) and adult (N = 11) repeated experience with the Claw. Across studies we found that sensations of ownership over the virtual hand were facilitated by human-like forms, movement synchrony, and short-term training. For children only, we also found that human-like forms maintained a strong facilitatory influence even when movement was asynchronous. Further, for children only, training improved movement fluency and increased the sense that the virtual form was a 'tool' rather than a hand. We suggest that children's top-down expectations regarding their body do not always interact with their multisensory inputs; their experiences are sharpened with training more than adults; and repeated short virtual experiences do not blur children's perceived distinction between the real and virtual self. SUMMARY: Both children and adults are sensitive to the corporeality of virtual hand forms, showing enhanced ownership for human-like forms. While adults rely on concurrent movement synchrony and form, children treat them independently-maintaining some ownership for human-like forms even when the movement was asynchronous. Short-term training with a non-human virtual form (crab-like claw) increased ownership and improved movement fluency particularly for children. Compared to adults, children's embodiment of moving virtual hands reflects distinct processes-showing greater flexibility, independent cue use, and functional relevance.