I move, therefore I am: a new theoretical framework to investigate agency and ownership

The neurocognitive structure of the acting self has recently been widely studied, yet is still perplexing and remains an often confounded issue in cognitive neuroscience, psychopathology and philosophy. We provide a new systematic account of two of its main features, the sense of agency and the sense of ownership, demonstrating that although both features appear as phenomenally uniform, they each in fact are complex crossmodal phenomena of largely heterogeneous functional and (self-)representational levels. These levels can be arranged within a gradually evolving, onto- and phylogenetically plausible framework which proceeds from basic non-conceptual sensorimotor processes to more complex conceptual and meta-representational processes of agency and ownership, respectively. In particular, three fundamental levels of agency and ownership processing have to be distinguished: The level of feeling, thinking and social interaction. This naturalistic account will not only allow to “ground the self in action”, but also provide an empirically testable taxonomy for cognitive neuroscience and a new tool for disentangling agency and ownership disturbances in psychopathology (e.g. alien hand, anarchic hand, anosognosia for one’s own hemiparesis).     

Active control as evidence in favor of sense of ownership in the moving Virtual Hand Illusion

The sense of ownership, the feeling that our body belongs to ourselves, relies on multiple sources of sensory information. Among these sources, the contribution of visuomotor information is still debated. We tested the effect of active control in the sense of ownership in the moving Virtual Hand Illusion. Participants reported sense of ownership and sense of agency over a virtual arm in which we manipulated the morphological congruence of the hand and the visuomotor information. We found that congruent active control enhanced and maintained the reported sense of ownership over a hand that appeared detached from the body, but not in a morphological congruent limb. Also, incongruent active control, achieved by adding noise to the trajectory of the movement, decreased both reported sense of agency and ownership. Overall, our results are consistent with a framework in which active control acts as evidence for eliciting a sense of ownership.     

Both motor prediction and conceptual congruency between preview and action-effect contribute to explicit judgment of agency

The sense of agency is the sense that one is causing an action. The inferential account of the sense of agency proposes that we experience the sense of agency when we infer that one’s own thoughts are the cause of an action. According to this account, the inference occurs when a thought appears in consciousness prior to an action, is consistent with the action, and is not accompanied by conspicuous other causes of the action. Alternatively, a predictive account of the sense of agency proposes that sensory prediction based on efferent (motor) information plays a critical role in generating the sense of agency. The present study investigated whether the sense of agency depended primarily on the conceptual congruence between preview information (i.e., to elicit a thought) and actual sensory feedback as suggested by the inferential account, or whether it depended primarily on the sensory-motor congruence between prediction and actual sensory feedback as suggested by the predictive account. The results indicated that both of these factors did contribute to the sense of agency, although sensory-motor congruence appears to have a more robust impact.     

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 "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.     

The case for the comparator model as an explanation of the sense of agency and its breakdowns

I compare Frith and colleagues’ influential comparator account of how the sense of agency is elicited to the multifactorial weighting model advocated by Synofzik and colleagues. I defend the comparator model from the common objection that the actual sensory consequences of action are not needed to elicit the sense of agency. I examine the comparator model’s ability to explain the performance of healthy subjects and those suffering from delusions of alien control on various self-attribution tasks. It transpires that the comparator model needs case-by-case adjustment to deal with problematic data. In response to this, the multifactorial weighting model of Synofzik and colleagues is introduced. Although this model is incomplete, it is more naturally constrained by the cases that are problematic for the comparator model. However, this model may be untestable. I conclude that currently the comparator model approach has stronger support than the multifactorial weighting model approach.     

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.     

Me or not me – An optimal integration of agency cues?

Recent work has demonstrated that the sense of agency is not only determined by efference-copy-based internal predictions and internal comparator mechanisms, but by a large variety of different internal and external cues. The study by Moore and colleagues [Moore, J. W., Wegner, D. M., & Haggard, P. (2009). Modulating the sense of agency with external cues. Conscious and Cognition] aimed to provide further evidence for this view by demonstrating that external agency cues might outweigh or even substitute efferent signals to install a basic registration of self-agency. Although the study contains some critical points that, so we argue, are central to a proper interpretation of the data, it hints at a new perspective on agency: optimal cue integration seems to be the key to a robust sense of agency. We here argue that this framework could allow integrating the findings of Moore and colleagues and other recent agency studies into a comprehensive picture of the sense of agency and its pathological disruptions.     

Disappearing and appearing: Temporal binding effects are consistent across situations

Sense of agency refers to the feeling of control over actions and action outcomes. Previous studies were mostly confined to the situation of performing actions to make objects appear, while it remains unexplored whether we experience sense of agency when making objects disappear. Here, we examined the temporal binding effect, an implicit index of sense of agency, in performing actions to make objects disappear and compared the magnitude of this effect in the appearing and disappearing situations. Results showed that the temporal binding effect emerged when object’s disappearances served as action outcomes. Moreover, the temporal binding effects in the appearing and disappearing situations did not differ significantly. Our findings extend the temporal binding effect to the situation of voluntarily making objects disappear, suggesting a comparable level of implicit sense of agency when voluntarily making objects disappear and appear.     

Modulating the sense of agency with external cues

We investigate the processes underlying the feeling of control over one’s actions (“sense of agency”). Sense of agency may depend on internal motoric signals, and general inferences about external events. We used priming to modulate the sense of agency for voluntary and involuntary movements, by modifying the content of conscious thought prior to moving. Trials began with the presentation of one of two supraliminal primes, which corresponded to the effect of a voluntary action participants subsequently made. The perceived interval between movement and effect was used as an implicit measure of sense of agency. Primes modulated perceived intervals for both voluntary and involuntary movements, but the modulation was greatest for involuntary movements. A second experiment showed that this modulation depended on prime–movement (temporal) contiguity. We propose that sense of agency is based on a combination of internal motoric signals and external sensory evidence about the source of actions and effects.     

When our thoughts are not our own: Investigating agency misattributions using the Mind-to-Mind paradigm

At the core of the sense of agency for self-produced action is the sense that I, and not some other agent, am producing and directing those actions. While there is an ever-expanding body of empirical research investigating the sense of agency for bodily action, there has, to date, been little empirical investigation of the sense of agency for thought. The present study uses the novel Mind-to-Mind paradigm, in which the agentive source of a target thought is ambiguous, to measure misattributions of agency. Seventy-two percent of participants made at least one misattribution of agency during a 5-min trial. Misattributions were significantly more frequent when the target thought was an arousing negative thought as compared to a neutral control. The findings establish a novel protocol for measuring the sense of agency for thought, and suggest that both contextual factors and emotional experience play a role in its generation.     

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.     

Out of nowhere: Thought insertion,ownership and context-integration

We argue that thought insertion primarily involves a disruption of the sense of ownership for thoughts and that the lack of a sense of agency is but a consequence of this disruption. We defend the hypothesis that this disruption of the sense of ownership stems from a failure in the online integration of the contextual information related to a thought, in particular contextual information concerning the different causal factors that may be implicated in their production. Loss of unity of consciousness, manifested by incoherent subjective experiences is a general phenomenal characteristic of schizophrenia. This loss of coherence has been hypothesized to reflect a generalized deficit of contextual information integration not conveyed by, but related to, a target event. This deficit is manifested across many cognitive domains. We argue that it is also manifested in the process of thinking itself, resulting in causally decontextualized thoughts that are experienced as inserted thoughts.     

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.     

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.     

On agency and body-ownership: phenomenological and neurocognitive reflections

The recent distinction between sense of agency and sense of body-ownership has attracted considerable empirical and theoretical interest. The respective contributions of central motor signals and peripheral afferent signals to these two varieties of body experience remain unknown. In the present review, we consider the methodological problems encountered in the empirical study of agency and body-ownership, and we then present a series of experiments that study the interplay between motor and sensory information. In particular, we focus on how multisensory signals interact with body representations to generate the sense of body-ownership, and how the sense of agency modulates the sense of body-ownership. Finally, we consider the respective roles of efferent and afferent signals for the experience of one's own body and actions, in relation to self-recognition and the recognition of other people's actions. We suggest that the coherent experience of the body depends on the integration of efferent information with afferent information in action contexts. Overall, whereas afferent signals provide the distinctive content of one's own body experience, efferent signals seem to structure the experience of one's own body in an integrative and coherent way.     

动作自主性与结果性质对不同预测性条件下施动感的影响

采用时间估计法考察动作自主性水平、动作结果性质(利己、利他、中性)以及结果是否可预测对施动感的影响。结果发现, 高自主性的自由选择条件比低自主性的服从条件增强了个体的施动感, 且不受动作结果性质与结果是否可预测的影响; 在低自主性的服从条件下, 当结果可预测时利己结果比利他结果的施动感更强, 而在结果不可预测时利己和利他结果的施动感没有区别, 但均弱于中性结果。这揭示出动作的主观意愿在施动感产生过程中的重要作用, 同时在自主性较低的服从条件下, 对利己或利他道德属性的动作结果能否被预测, 对个体的施动感产生了不同的影响。研究结果说明具有利己或利他道德属性的动作对施动感会产生自上而下的调节作用, 且这种调节作用在低自主条件下较为突显。     

Effects of stimulus order on discrimination processes in comparative and equality judgements: Data and models

In typical discrimination experiments, participants are presented with a constant standard and a variable comparison stimulus and their task is to judge which of these two stimuli is larger (comparative judgement). In these experiments, discrimination sensitivity depends on the temporal order of these stimuli (Type B effect) and is usually higher when the standard precedes rather than follows the comparison. Here, we outline how two models of stimulus discrimination can account for the Type B effect, namely the weighted difference model (or basic Sensation Weighting model) and the Internal Reference Model. For both models, the predicted psychometric functions for comparative judgements as well as for equality judgements, in which participants indicate whether they perceived the two stimuli to be equal or not equal, are derived and it is shown that the models also predict a Type B effect for equality judgements. In the empirical part, the models' predictions are evaluated. To this end, participants performed a duration discrimination task with comparative judgements and with equality judgements. In line with the models' predictions, a Type B effect was observed for both judgement types. In addition, a time-order error, as indicated by shifts of the psychometric functions, and differences in response times were observed only for the equality judgement. Since both models entail distinct additional predictions, it seems worthwhile for future research to unite the two models into one conceptual framework.     

Using suggestion to model different types of automatic writing

Our sense of self includes awareness of our thoughts and movements, and our control over them. This feeling can be altered or lost in neuropsychiatric disorders as well as in phenomena such as “automatic writing” whereby writing is attributed to an external source. Here, we employed suggestion in highly hypnotically suggestible participants to model various experiences of automatic writing during a sentence completion task. Results showed that the induction of hypnosis, without additional suggestion, was associated with a small but significant reduction of control, ownership, and awareness for writing. Targeted suggestions produced a double dissociation between thought and movement components of writing, for both feelings of control and ownership, and additionally, reduced awareness of writing. Overall, suggestion produced selective alterations in the control, ownership, and awareness of thought and motor components of writing, thus enabling key aspects of automatic writing, observed across different clinical and cultural settings, to be modelled.     

The sense of agency: a philosophical and empirical review of the "Who" system

How do I know that I am the person who is moving? According to Wittgenstein (1958), the sense of agency involves a primitive notion of the self used as subject, which does not rely on any prior perceptual identification and which is immune to error through misidentification. However, the neuroscience of action and the neuropsychology of schizophrenia show the existence of specific cognitive processes underlying the sense of agency--the "Who" system--which is disrupted in delusions of control. Yet, we have to be careful in the interpretation of such clinical symptoms, which cannot be so easily reduced to deficit of action monitoring or to lack of action awareness. Moreover, we should refine the definition of the sense of agency by distinguishing the sense of initiation and the sense of one's own movements. A conceptual analysis of the empirical data will lead us to establish the taxonomy of the different levels of action representations.