Detection of visual feedback delay in active and passive self-body movements.

Temporal congruency between the efference copy of a motor command and the reafferent sensory feedback is crucial for identifying self-generated body movements. We investigated how temporal discrepancy between the efference copy and visual feedback affects the self-body movement recognition process. Subjects experienced active and passive hand movements under conditions of delayed visual feedback (118-352 ms) and judged whether observed hand movements were delayed with respect to the felt movement. The results showed that the discrimination threshold of visual feedback delay (50% detection rate) was not significantly different between active and passive movements. In contrast, the judgment probability curve was significantly steeper for active than passive movements. This indicates that the efference copy enhances the contrast between synchronous and asynchronous movements but does not narrow the time window in this process. We discuss processing of active and passive movements in relation to the senses of self-agency and self-ownership.