Wikipedia
Self-agency, also known as the phenomenal will, is the sense that some actions are self-generated. Scientist Benjamin Libet was the first to study self-agency. He discovered that brain activity predicts the action before one even has conscious awareness of his or her intention to act upon that action. The most influential psychologist in the topic of self-agency was Daniel Wegner, who created the three criteria of self-agency: priority, exclusivity, and consistency.
According to Wegner, priority means that an action must be planned of being done before the action is initiated. The interval between the action and the effect is known as the intentional binding. Another criteria for self-agency is exclusivity, which means the effect is due to the person’s action and not because of other potential causes for the effect. The last criteria Wegner suggested was consistency. Consistency is the criteria that the one’s planned action must occur as planned.
Internal motor cues are also an indicator in deciding whether an action was used with self-agency and can be measured by the generation of movement. If the predicted sensory state matches the actual sensory state, then self-agency has likely occurred. No models that predict agency have ever been proved.