Embodiment of a functionally altered virtual arm in children and adults

This study aimed to investigate whether human embodiment is dependent on the sensorimotor functions of one’s body. We hypothesised that body function constrains both the sense of ownership and sensorimotor control of the body movements. We studied these relationships in the context of control of unilateral goal-directed forward arm reaching movements made with a virtual arm. In addition, we expected that children possess more adaptable body representations compared to adults, facilitating greater acceptance of virtual bodies with altered sensorimotor contingencies. We tested 5-7 and 8-10-year-old children, and young adults. Participants took part in an animal feeding game within a Virtual Reality environment. At each age, we manipulated the visual gain of hand movements to alter reaching functionality in three groups: compared to a normal (100%) gain, reaching arm length was slightly reduced (80%); slightly increased (120%); or greatly increased (400%). Parameters representing reach kinematics, subjective perception of arm length, and subjective limb embodiment were assessed during and after reaching with normal and altered control gain. In addition to changes in their reach kinematics, changes in subjective embodiment and reaching affordance were recorded compared to baseline reaching without altered visual gain.