Volition motivates cognitive performance at the response-execution level by attenuating task-irrelevant motor activations

Humans express volition by making voluntary choices which, relative to forced choices, can motivate cognitive performance in a variety of tasks. However, a task that requires the generation of motor responses on the basis of external sensory stimulation involves complex underlying cognitive processes, e.g., pre-response processing, response selection, and response execution. The present study investigated how these underlying processes are facilitated by voluntary choice-making. In five experiments, participants were free or forced to choose a task-irrelevant picture from two alternatives, and then completed a conflict task, i.e., Flanker, Stroop, Simon, Stroop-Simon, or Flanker-Simon task, where the conflict effect could occur at different processing levels. Results consistently showed that responses in all tasks were generally faster after voluntary (vs. forced) choices. Importantly, the conflict effect at the response-execution level (i.e., the Simon effect), but not the conflict effect at the pre-response and response-selection levels (i.e., the Flanker and Stroop effects), was reduced by the voluntary choice-making. Model fitting revealed that the peak amplitude of automatic motor activations in the response-execution conflict was smaller after voluntary (vs. forced) choices. These findings suggest that volition motivates subsequent cognitive performance at the response-execution level by attenuating task-irrelevant motor activations.