Cognitive load dissociates explicit and implicit measures of body ownership and agency

It is often claimed that the human self consists of perceived body ownership and agency, which are commonly assessed through explicit ownership and agency judgments and implicit measures, like proprioceptive drift, skin conductance responses, and intentional binding effects. Bottom-up multisensory integration and top-down modulation were predicted to be important for ownership and agency. In previous studies, cognitive load was revealed to affect the sense of agency in a top-down fashion, but its effect on ownership has not been fully investigated, not even its possibly different effect on explicit and implicit measures. Here we used cognitive load (small vs. large sets in a working-memory task) to disentangle explicit and implicit measures of ownership and agency in a task inducing the virtual hand illusion (VHI; stronger perceived ownership and agency over a virtual hand if it moves in synchrony with one's real hand). Results showed similar patterns for ownership and agency - both ownership and agency were affected by cognitive load, and importantly in the explicit measures, higher load increased the effect of synchrony (i.e., the VHI), but in implicit measures, higher load reduced indications of both ownership and agency. Hence, the load manipulation was selective with regard to the explicit versus implicit nature of the measure but not with respect to the measure's content. This provides strong evidence that explicit and implicit measures of both ownership and agency rely on at least partly separable informational sources, while the difference between ownership and agency as such does not seem to play a major role.