From action intentions to action effects: how does the sense of agency come about?

Abstract

Sense of agency refers to the feeling of controlling an external event through one's own action. On one influential view, agency depends on how predictable the consequences of one's action are, getting stronger as the match between predicted and actual effect of an action gets closer. Thus, sense of agency arises when external events that follow our action are consistent with predictions of action effects made by the motor system while we perform or simply intend to perform an action. According to this view, agency is inferred retrospectively, after an action has been performed and its consequences are known. In contrast, little is known about whether and how internal processes involved in the selection of actions may influence subjective sense of control, in advance of the action itself, and irrespective of effect predictability. In this article, we review several classes of behavioral and neuroimaging data suggesting that earlier processes, linked to fluency of action selection, prospectively contribute to sense of agency. These findings have important implications for better understanding human volition and abnormalities of action experience.

Keywords: action selection; agency; angular gyrus; fluency; human volition.

Figure 1

(A) Intention-Action-Effect chain. The action-selection processes operate between the formation of the initial intention and action execution. Dysfluency of action selection signals a break in the intention-action link, that occurs prior to the action and its sensory consequences. After the action has been selected, predicted and perceived consequences of this action are compared. On the comparator account (in bold), sense of agency is strong when there is a match between predicted and actually experienced consequences of an action, and is reduced in the case of a mismatch. (B) Example trial from the prime-target incompatible condition, adapted from Chambon et al. (2013). Participants were instructed to respond to the target stimulus, and were not informed of the presence of the arrow primes. Action effects consisted of colored circles that appeared on the screen after a varying delay. In this condition, sense of agency decreases relative to the compatible condition, even though predicted and perceived action effects are the same (yellow circles).

Figure 2

(A) Sense of agency is accounted for by exchange of signals across a prefrontal-parietal network: decreased DLPFC activity (in blue) due to incompatible primes results in a concomitant increase in AG activity (in yellow), and a subjective loss of control. The right chart shows a negative modulation of AG activity as a function of the level of experienced control (from low to high; adapted from Chambon et al., 2013). (B) TMS-induced disruption of left AG at the time of action selection abolishes the compatibility effect on sense of agency (right chart).