Action observation modulates auditory perception of the consequence of others' actions

We can easily discriminate self-produced from externally generated sensory signals. Recent studies suggest that the prediction of the sensory consequences of one’s own actions made by forward model can be used to attenuate the sensory effects of self-produced movements, thereby enabling a differentiation of the self-produced sensation from the externally generated one. The present study showed that attenuation of sensation occurred both when participants themselves performed a goal-directed action and when they observed experimenter performing the same action, although they clearly reported that the tones were produced by other during action observation and by themselves during their own action. These results suggest that sensory prediction of action modulates ongoing auditory processing irrespective of who produces the sounds and that the explicit judgment of agency does not necessarily rely on the same mechanisms on which implicit perceptual measures such as sensory attenuation rely.     

Subliminal action priming modulates the perceived intensity of sensory action consequences

The sense of control over the consequences of one’s actions depends on predictions about these consequences. According to an influential computational model, consistency between predicted and observed action consequences attenuates perceived stimulus intensity, which might provide a marker of agentic control. An important assumption of this model is that these predictions are generated within the motor system. However, previous studies of sensory attenuation have typically confounded motor-specific perceptual modulation with perceptual effects of stimulus predictability that are not specific to motor action. As a result, these studies cannot unambiguously attribute sensory attenuation to a motor locus. We present a psychophysical experiment on auditory attenuation that avoids this pitfall. Subliminal masked priming of motor actions with compatible prime–target pairs has previously been shown to modulate both reaction times and the explicit feeling of control over action consequences. Here, we demonstrate reduced perceived loudness of tones caused by compatibly primed actions. Importantly, this modulation results from a manipulation of motor processing and is not confounded by stimulus predictability. We discuss our results with respect to theoretical models of the mechanisms underlying sensory attenuation and subliminal motor priming.     

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.     

The relation between the sense of agency and the experience of flow

This article investigates the relation between people’s feelings of agency and their feelings of flow. In the dominant model describing how people are able to assess their own agency—the comparator model of agency—when the person’s intentions match perfectly to what happens, the discrepancy between intention and outcome is zero, and the person is thought to interpret this lack of discrepancy as being in control. The lack of perceived push back from the external world seems remarkably similar to the state that has been described as a state of flow. However, when we used a computer game paradigm to investigate the relation between people’s feelings of agency and their feelings of flow, we found a dissociation between these two states. Although these two states may, in some ways, seem to be similar, our data indicate that they are governed by different principles and phenomenology.     

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.     

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.     

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.     

Sense of agency for mental actions: Insights from a belief-based action-effect paradigm

A substantial body of research has converged on the idea that the sense of agency arises from the integration of multiple sources of information. In this study, we investigated whether a measurable sense of agency can be detected for mental actions, without the contribution of motor components. We used a fake action-effect paradigm, where participants were led to think that a motor action or a particular thought could trigger a sound. Results showed that the sense of agency, when measured through explicit reports, was of comparable strength for motor and mental actions. The intentional binding effect, a phenomenon typically associated with the experience of agency, was also observed for both motor and mental actions. Taken together, our results provide novel insights into the specific role of intentional cues in instantiating a sense of agency, even in the absence of motor signals.     

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.     

Multiple aspects in the sense of agency

Recent significant research in a number of disciplines centers on the concept of the sense of agency. Because many of these studies cut across disciplinary lines there is good reason to seek a clear consensus on what ‘sense of agency’ means. In this paper I indicate some complexities that this consensus might have to deal with. I also highlight an important phenomenological distinction that needs to be considered in any discussion of the sense of agency, regardless of how it gets defined. Finally, I suggest that the sense of agency has an ambiguous phenomenology and I offer some critical comments on current models that fail to notice this ambiguity.     

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.     

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.     

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.     

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.     

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.     

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.     

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.     

Action co-representation and the sense of agency during a joint Simon task: Comparing human and machine co-agents

Recent studies have suggested that individuals are not able to develop a sense of joint agency during joint actions with artificial systems. We sought to examine whether this lack of joint agency is linked to individuals’ inability to co-represent the machine-generated actions. Fifteen participants observed or performed a Simon response time task either individually, or jointly with another human or a computer. Participants reported the time interval between their response (or the co-actor response) and a subsequent auditory stimulus, which served as an implicit measure of participants’ sense of agency. Participants’ reaction times showed a classical Simon effect when they were partnered with another human, but not when they collaborated with a computer. Furthermore, participants showed a vicarious sense of agency when co-acting with another human agent but not with a computer. This absence of vicarious sense of agency during human-computer interactions and the relation with action co-representation are discussed.     

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.     

自我表征的可塑性:基于橡胶手错觉的研究

自我识别是人类自我觉知的行为标记。传统方法认为稳定的自我表征是自我识别的基础。随着对橡胶手错觉及一系列自我表征和自我识别错觉的揭示,这一能让人将外部客体感知为自身一部分的错觉研究使得我们能够以多感官整合的方式来研究自我表征和自我识别。拥有感和自主感被认为是我们进行自我识别的两类基本体验,本文对一系列橡胶手错觉范式研究的系统回顾表明,拥有感和自主感会发生改变,这说明人的自我表征是可变的和可塑的。