Outcome processing and the sense of agency

People can distinguish outcomes they cause from those they do not; that is, they are quite able to sense self-agency in outcomes. A well-received idea is that the sense of agency is produced by a comparison between a predicted outcome and the actual outcome that occurs. While research has generally focused on understanding predictive representations and the comparison process, less work has been done on the actual outcomes and, in particular, how these are perceived or apprehended. Here, we studied this issue. In two experiments, we found outcomes are continuously, as opposed to partially, sampled throughout their span. Specifically, we found that prediction-inconsistent signals embedded within otherwise prediction-consistent outcomes were able to influence agency ratings, and this was true whether the contrary signals were embedded early or late in the outcome.     

Discrepancy between explicit judgement of agency and implicit feeling of agency: Implications for sense of agency and its disorders

The sense of agency refers to the feeling of authorship that “I am the one who is controlling external events through my own action”. A distinction between explicit judgement of agency and implicit feeling of agency has been proposed theoretically. However, there has not been sufficient experimental evidence to support this distinction. We have assessed separate explicit and implicit agency measures in the same population and investigated their relationships. Intentional binding task was employed as an implicit measure and self-other attribution task as an explicit measure, which are known to reflect clinical symptoms of disorders in the sense of agency. The results of the implicit measure and explicit measure were not correlated, suggesting dissociation of the explicit judgement of agency and the implicit feeling of agency.     

The time windows of the sense of agency

The sense of agency depends on some internal cues that derive from action control, as well as external cues like contextual information and prior information (degree of contingency between an action and is effect). We assessed whether external agency cues are combined with internal agency cues to affect the sense of agency. In two experiments participants performed a movement (button press) that elicited, after a varying delay, an effect (ball appearing on a screen), and reported their sense of agency over the effect (full, partial or no-agency) while internal cues (premotor information) and external cues (contextual and prior information) were manipulated. We assessed the effect of agency cues on the delays at which the sense of agency varied. The delays were increased with premotor signals but were decreased with contextual information. These findings favour a model of integration of internal and external agency cues over time.     

The sense of agency in human-human vs human-robot joint action

Kinesthesis pertains to the perception of moving body parts, while the sense of agency refers to the experience of controlling one’s action-effects. Based on previous work, we hypothesized that the sense of agency would decrease in joint action with a robot compared to a human partner. Pairs of participants were jointly manipulating two interconnected haptic devices enabling them to feel each other’s forces. Unbeknown to participants, their partner was sometimes replaced by a robot. The sense of agency was assessed using intentional binding, which refers to a contraction of perceived time between an action and its effect for intentional actions, and participants’ judgment of their contribution to joint action. Participants judged their contribution as higher when they were initiating action and when they were paired with the robot. By contrast, intentional binding occurred only with a human partner. This outcome supports the hypothesis that human-robot joint action hinders intentional binding.     

Experience of agency and sense of responsibility

The experience of agency refers to the feeling that we control our own actions, and through them the outside world. In many contexts, sense of agency has strong implications for moral responsibility. For example, a sense of agency may allow people to choose between right and wrong actions, either immediately, or on subsequent occasions through learning about the moral consequences of their actions. In this study we investigate the relation between the experience of operant action, and responsibility for action outcomes using the intentional binding effect (Haggard, Clark, & Kalogeras, 2002) as an implicit, quantitative measure related to sense of agency. We studied the time at which people perceived simple manual actions and their effects, when these actions were embedded in scenarios where their actions had unpredictable consequences that could be either moral or merely economic. We found an enhanced binding of effects back towards the actions that caused them, implying an enhanced sense of agency, in moral compared to non-moral contexts. We also found stronger binding for effects with severely negative, compared to moderately negative, values. A tight temporal association between action and effect may be a low-level phenomenal marker of the sense of responsibility.     

The influence of performance on action-effect integration in sense of agency

Sense of agency refers to the subjective feeling of being able to control an outcome through one’s own actions or will. Prior studies have shown that both sensory processing (e.g., comparisons between sensory feedbacks and predictions basing on one’s motor intentions) and high-level cognitive/constructive processes (e.g., inferences based on one’s performance or the consequences of one’s actions) contribute to judgments of sense of agency. However, it remains unclear how these two types of processes interact, which is important for clarifying the mechanisms underlying sense of agency. Thus, we examined whether performance-based inferences influence action-effect integration in sense of agency using a delay detection paradigm in two experiments. In both experiments, participants pressed left and right arrow keys to control the direction in which a moving dot was travelling. The dot’s response delay was manipulated randomly on 7 levels (0–480 ms) between the trials; for each trial, participants were asked to judge whether the dot response was delayed and to rate their level of agency over the dot. In Experiment 1, participants tried to direct the dot to reach a destination on the screen as quickly as possible. Furthermore, the computer assisted participants by ignoring erroneous commands for half of the trials (assisted condition), while in the other half, all of the participants’ commands were executed (self-control condition). In Experiment 2, participants directed the dot as they pleased (without a specific goal), but, in half of the trials, the computer randomly ignored 32% of their commands (disturbed condition) rather than assisted them. The results from the two experiments showed that performance enhanced action-effect integration. Specifically, when task performance was improved through the computer’s assistance in Experiment 1, delay detection was reduced in the 480-ms delay condition, despite the fact that 32% of participants’ commands were ignored. Conversely, when no feedback on task performance was given (as in Experiment 2), the participants reported greater delay when some of their commands were randomly ignored. Furthermore, the results of a logistic regression analysis showed that the threshold of delay detection was greater in the assisted condition than in the self-control condition in Experiment 1, which suggests a wider time window for action-effect integration. A multivariate analysis also revealed that assistance was related to reduced delay detection via task performance, while reduced delay detection was directly correlated with a better sense of agency. These results indicate an association between the implicit and explicit aspects of sense of agency.     

Testosterone facilitates the sense of agency

Sense of agency (SoA) refers to feelings of being in control of one’s actions. Evidence suggests that SoA might contribute towards higher-order feelings of personal control – a key attribute of powerful individuals. Whether testosterone, a steroid hormone linked to power in dominance hierarchies, also influences the SoA is not yet established. In a repeated-measures design, 26 females participated in a double-blind, placebo-controlled trial to test the effects of 0.5 mg testosterone on SoA, using an implicit measure based upon perceived shifts in time between a voluntary action and its outcome. Illusions of control, as operationalized by optimism in affective forecasting, were also assessed. Testosterone increased action binding but there was no significant effect on tone binding. Affective forecasting was found to be significantly more positive on testosterone. SoA and optimistic expectations are basic manifestations of power which may contribute to feelings of infallibility often associated with dominance and testosterone.     

Synchronous stimulation in the rubber hand illusion task boosts the subsequent sense of ownership on the vicarious agency task

The relationship between sense of agency and sense of ownership remains unclear. Here we investigated this relationship by manipulating ownership using the rubber hand illusion and assessing the resulting impact on self-experiences during the vicarious agency illusion. We tested whether modulating ownership towards another limb using the rubber hand illusion would subsequently influence the illusory experience of ownership and agency towards a similar-looking limb in the vicarious agency task. Crucially, the vicarious agency task measures both sense of agency and sense of ownership at the same time, while removing the confounding influence of motor signals. Our results replicated the well-established effects of both paradigms. We also found that manipulating the sense of ownership with the rubber hand illusion influenced the subsequent vicarious experience of ownership but not the vicarious experience of agency. This supports the idea that sense of agency and sense of ownership are, at least partially, independent experiences.     

The evolving sense of agency: Context recency and quality modulate the interaction between prospective and retrospective processes

Humans acquire a sense of agency through their interactions with the world and their sensory consequences. Previous studies have highlighted stable agency-related phenomena like intentional binding, which depend on both prospective, context-dependent and retrospective, outcome-dependent processes. In the current study, we investigated the interaction between prospective and retrospective processes underlying the adaptation of an ongoing sense of agency. The results showed that prospective intentional binding developed during a temporal window of up to 20 prior events was independent of the nature of the ongoing event. By contrast, the characteristics of the ongoing event retrospectively influenced prospective intentional binding developed during a temporal window narrower than 6 prior events. These findings characterize the interaction between prospective and retrospective mechanisms as a fundamental process to continuously update the sense of agency through sensorimotor learning. High psychosis-like experience traits weakened this interaction, suggesting that reduced adaption to the context contributes to altered self-experience.     

The "sense of agency" and its underlying cognitive and neural mechanisms

The sense of agency is a central aspect of human self-consciousness and refers to the experience of oneself as the agent of one’s own actions. Several different cognitive theories on the sense of agency have been proposed implying divergent empirical approaches and results, especially with respect to neural correlates. A multifactorial and multilevel model of the sense of agency may provide the most constructive framework for integrating divergent theories and findings, meeting the complex nature of this intriguing phenomenon.     

Musical expertise affects the sense of agency: Intentional binding in expert pianists

Intentional Binding (IB), a subjective compression of the time interval between a voluntary action and its consequence, is an implicit measure of the sense of agency (the feeling of controlling one's own actions and their outcomes). The sense of agency is influenced by experience, e.g. learning, development, or learned contingency. The present study aimed at analyzing expertise – an expert competence acquired through experience alone – as a possible means to affect the sense of agency. We compared performance of expert pianists and non-musicians within the IB paradigm with two types of sensory outcome – a piano note and an electronic sound. Pianists showed significantly greater outcome binding and composite binding for both types of stimuli. Therefore, musical expertise might influence the sense of agency, possibly due to continuous exposure to action-outcome associations during the musical training. Additionally, such effect might extend beyond the specific expertise to the other types of auditory outcomes.     

The relationship between human agency and embodiment

Humans regularly feel a sense of agency (SoA) over events where the causal link between action and outcome is extremely indirect. We have investigated how intermediate (here, a robotic hand) events that intervene between action and outcome may alter SoA, using intentional binding measures. The robotic hand either performed the same movement as the participant (active congruent), or performed a similar movement with another finger (active incongruent). Binding was significantly reduced in the active incongruent relative to the active congruent condition, suggesting that altered embodiment influences SoA. However, binding effects were comparable between a condition where the robot hand made a congruent movement, and conditions where no robot hand was involved, suggesting that intermediate and embodied events do not reduce SoA. We suggest that human sense of agency involves both statistical associations between intentions and arbitrary outcomes, and an effector-specific matching of sensorimotor means used to achieve the outcome.     

Uncovering effects of self-control and stimulus-driven action selection on the sense of agency

The sense of agency refers to feelings of causing one’s own action and resulting effect. Previous research indicates that voluntary action selection is an important factor in shaping the sense of agency. Whereas the volitional nature of the sense of agency is well documented, the present study examined whether agency is modulated when action selection shifts from self-control to a more automatic stimulus-driven process. Seventy-two participants performed an auditory Simon task including congruent and incongruent trials to generate automatic stimulus-driven vs. more self-control driven action, respectively. Responses in the Simon task produced a tone and agency was assessed with the intentional binding task – an implicit measure of agency. Results showed a Simon effect and temporal binding effect. However, temporal binding was independent of congruency. These findings suggest that temporal binding, a window to the sense of agency, emerges for both automatic stimulus-driven actions and self-controlled actions.     

Intentional binding coincides with explicit sense of agency

Sense of agency, a feeling of generating actions and events by oneself, stems from action–outcome congruence. An implicit marker of sense of agency is intentional binding, which is compression of subjective temporal interval between action and outcome. We investigated relationships between intentional binding and explicit sense of agency. Participants pressed a key triggering auditory (Experiment 1) or visual outcome (Experiment 2) that occurred after variable delays. In each trial, participants rated their agency over the outcome and estimated the keypress–outcome temporal interval. Results showed that delays decreased agency ratings and intentional binding. There was inter-individual correlation between sensitivities to outcome delay (i.e., regression slope) of agency rating and intentional binding in the auditory but not visual domain. Importantly, we found intra-individual correlations between agency rating and intentional binding on a trial-by-trial basis in both outcome modalities. These results suggest that intentional binding coincides with explicit sense of agency.     

Simulated thought insertion: Influencing the sense of agency using deception and magic

In order to study the feeling of control over decisions, we told 60 participants that a neuroimaging machine could read and influence their thoughts. While inside a mock brain scanner, participants chose arbitrary numbers in two similar tasks. In the Mind-Reading Task, the scanner appeared to guess the participants’ numbers; in the Mind-Influencing Task, it appeared to influence their choice of numbers. We predicted that participants would feel less voluntary control over their decisions when they believed that the scanner was influencing their choices. As predicted, participants felt less control and made slower decisions in the Mind-Influencing Task compared to the Mind-Reading Task. A second study replicated these findings. Participants’ experience of the ostensible influence varied, with some reporting an unknown source directing them towards specific numbers. This simulated thought insertion paradigm can therefore influence feelings of voluntary control and may help model symptoms of mental disorders.     

Illusion of sense of self-agency: discrepancy between the predicted and actual sensory consequences of actions modulates the sense of self-agency, but not the sense of self-ownership

It is proposed that knowledge of motor commands is used to distinguish self-generated sensation from externally generated sensation. In this paper, we show that the sense of self-agency, that is the sense that I am the one who is generating an action, largely depends on the degree of discrepancy resulting from comparison between the predicted and actual sensory feedback. In Experiment 1, the sense of self-agency was reduced when the presentation of the tone was unpredictable in terms of timing and its frequency, although in fact the tone was self-produced. In Experiment 2, the opposite case was found to occur. That is, participants experienced illusionary sense of self-agency when the externally generated sensations happened to match the prediction made by forward model. In Experiment 3, the sense of self-agency was reduced when there was a discrepancy between the predicted and actual sensory consequences, regardless of presence or absence of a discrepancy between the intended and actual consequences of actions. In all the experiments, a discrepancy between the predicted and actual feedback had no effects on sense of self-ownership, that is the sense that I am the one who is undergoing an experience. These results may suggest that both senses of self are mutually independent.     

Unravelling intention: Distal intentions increase the subjective sense of agency

Experimental studies investigating the contribution of conscious intention to the generation of a sense of agency for one’s own actions tend to rely upon a narrow definition of intention. Often it is operationalized as the conscious sensation of wanting to move right before movement. Existing results and discussion are therefore missing crucial aspects of intentions, namely intention as the conscious sensation of wanting to move in advance of the movement. In the present experiment we used an intentional binding paradigm, in which we distinguished between immediate (proximal) intention, as usually investigated, and longer standing (distal) intention. The results showed that the binding effect was significantly enhanced for distal intentions compared to proximal intentions, indicating that the former leads to stronger sense of agency. Our finding provides empirical support for a crucial distinction between at least two types of intention when addressing the efficacy of conscious intentions.     

Power to the will: How exerting physical effort boosts the sense of agency

The sense of agency refers to the experience of being in control of one’s actions and their consequences. The 19th century French philosopher Maine de Biran proposed that the sensation of effort might provide an internal cue for distinguishing self-caused from other changes in the environment. The present study is the first to empirically test the philosophical idea that effort promotes self-agency. We used intentional binding, which refers to the subjective temporal attraction between an action and its sensory consequences, as an implicit measure of the sense of agency. Effort was manipulated independent of the primary task by requiring participants to pull stretch bands of varying resistance levels. We found that intentional binding was enhanced under conditions of increased effort. This suggests not only that the experience of effort directly contributes to the sense of agency, but also that the integration of effort as an agency cue is non-specific to the effort requirement of the action itself.     

Cultural background influences implicit but not explicit sense of agency for the production of musical tones

The sense of agency is suggested to occur at both low and high levels by the involvement of sensorimotor processes and the contribution of retrospective inferences based on contextual cues. In the current study, we recruited western and non-western participants and examined the effect of pleasantness of action outcomes on both feeling of control ratings and intentional binding which refers to the perceived compression of the temporal delay between actions and outcomes. We found that both western and non-western groups showed greater feeling of control ratings for the consonant (pleasant) compared to dissonant (unpleasant) outcomes. The intentional binding effect, on the other hand, was stronger for the consonant compared to dissonant outcomes in the western group only. We discuss the results in relation to how cultural background might differentially influence the effect of outcome pleasantness on low and high levels of the sense of agency.     

Emotional valence,sense of agency and responsibility: A study using intentional binding

We investigated how the emotional valence of an action outcome influences the experience of control, in an intentional binding experiment. Voluntary actions were followed by emotionally positive or negative human vocalisations, or by neutral tones. We used mental chronometry to measure a retrospective component of sense of agency (SoA), triggered by the occurrence of the action outcome, and a prospective component, driven by the expectation that the outcome will occur. Positive outcomes enhanced the retrospective component of SoA, but only when both occurrence and the valence of the outcome were unexpected. When the valence of outcomes was blocked – and therefore predictable – we found a prospective component of SoA when neutral tones were expected but did not actually occur. This prospective binding was absent, and reversed, for positive and negative expected outcomes. Emotional expectation counteracts the prospective component of SoA, suggesting a distancing effect.