Freedom, choice, and the sense of agency

Abstract

The sense of agency is an intriguing aspect of human consciousness and is commonly defined as the sense that one is the author of their own actions and their consequences. In the current study, we varied the number of action alternatives (one, three, seven) that participants could select from and determined the effects on intentional binding which is believed to index the low-level sense of agency. Participants made self-paced button presses while viewing a conventional Libet clock and reported the perceived onset time of either the button presses or consequent auditory tones. We found that the binding effect was strongest when participants had the maximum number of alternatives, intermediate when they had medium level of action choice and lowest when they had no choice. We interpret our results in relation to the potential link between agency and the freedom to choose one's actions.

Keywords: action awareness; action choice; authorship; freedom; intentional binding; sense of agency.

Figure 1

Trial procedure in the operant condition. Each trial began with a fixation cross displayed for 500 ms, participants then made a key press at their own pace after the clock started rotating. They were told to press a specific button in the no-choice condition or select one of three (medium level of choice) or seven (high level of choice) buttons on the response pad. The key press was followed by the auditory tone after a delay of 200 ms. In the baseline condition, participants either made a key press without hearing the tone and judged the timing of their key press, or heard the tone which occurred alone and judged the timing of the tone.

Figure 2

Mean perceptual shift (difference between the judgment errors in the operant and baseline conditions) for key press (lower) and tone (upper) judgments. Error bars represent SEM (*indicates that the perceptual shift for key presses in the high level of choice condition was significantly greater than the medium level of choice and no choice conditions, p < .05. The difference between medium level of choice and no choice conditions was not significant, p > .05. **Indicates that the perceptual shift for the tone judgments in the high level of choice and the medium level of conditions were significantly greater than no choice condition, p < .05. The difference between high and medium levels of choice was not significant, p > .05).

Figure 3

Mean overall binding as a function of action choice. Error bars represent SEM (*indicates that binding is significantly greater in the high level of choice condition than in the no choice condition, p < .05).