Voluntary action facilitates self-other discrimination but leaves metacognition unchanged

Author

Takada, Kazuma and Wen, Wen and Kasahara, Shunichi and Froese, Tom

Abstract

Voluntary action contributes to self-other discrimination, that is, the perception of whether changes in the environment are caused by oneself or others, and plays a central role in the emergence of the sense of agency. However, whether voluntary action facilitates the metacognitive monitoring of self-other discrimination remains unclear. This question is important because the processes underlying self-other discrimination are likely to differ between voluntary and involuntary actions, and answering it can clarify whether these processes are accessible to conscious monitoring, thereby revealing how different mechanisms underlying the sense of agency differ and relate to one another. To address this, we developed a device that passively moved participants' hands, allowing a direct comparison between voluntary and involuntary conditions within the same control-detection task. On each trial, participants viewed two visual stimuli whose motion was coupled to their hand movement, selected the one more consistent with their own movement, and rated their confidence. Across two experiments, perceptual sensitivity was reliably higher under voluntary than involuntary movement, whereas metacognitive sensitivity showed no comparable group-level difference and exhibited substantial individual variability. These results reveal a dissociation between perceptual processes and metacognitive monitoring in self-other discrimination and suggest that while voluntary action sharpens the perceptual basis of agency judgments, metacognitive monitoring appears to rely on at least partially independent mechanisms that do not depend on prediction.