The benefit of making voluntary choices generalizes across multiple effectors

It has been shown that cognitive performance could be improved by expressing volition (e.g., making voluntary choices), which necessarily involves the execution of action through a certain effector. However, it is unclear if the benefit of expressing volition can generalize across different effectors. In the present study, participants made a choice between two pictures either voluntarily or forcibly, and subsequently completed a visual search task with the chosen picture as a task-irrelevant background. The effector for choosing a picture could be the hand (pressing a key), foot (pedaling), mouth (commanding), or eye (gazing), whereas the effector for responding to the search target was always the hand. Results showed that participants responded faster and had a more liberal response criterion in the search task after a voluntary choice (vs. a forced choice). Importantly, the improved performance was observed regardless of which effector was used in making the choice, and regardless of whether the effector for making choices was the same as or different from the effector for responding to the search target. Eye-movement data for oculomotor choice showed that the main contributor to the facilitatory effect of voluntary choice was the post-search time in the visual search task (i.e., the time spent on processes after the target was found, such as response selection and execution). These results suggest that the expression of volition may involve the motor control system in which the effector-general, high-level processing of the goal of the voluntary action plays a key role.