Attribution of intentional causation influences the perception of observed movements: behavioral evidence and neural correlates

Sense of agency and its disturbances: A systematic review targeting the intentional binding effect in neuropsychiatric disorders

Sense of agency (SoA) indicates a person's ability to perceive her/his own motor acts as actually being her/his and, through them, to exert control over the course of external events. Disruptions in SoA may profoundly affect the individual's functioning, as observed in several neuropsychiatric disorders. This is the first article to systematically review studies that investigated intentional binding (IB), a quantitative proxy for SoA measurement, in neurological and psychiatric patients. Eligible were studies of IB involving patients with neurological and/or psychiatric disorders. We included 15 studies involving 692 individuals. Risk of bias was low throughout studies. Abnormally increased action-outcome binding was found in schizophrenia and in patients with Parkinson's disease taking dopaminergic medications or reporting impulsive-compulsive behaviors. A decreased IB effect was observed in Tourette's disorder and functional movement disorders, whereas increased action-outcome binding was found in patients with the cortico-basal syndrome. The extent of IB deviation from healthy control values correlated with the severity of symptoms in several disorders. Inconsistent effects were found for autism spectrum disorders, anorexia nervosa, and borderline personality disorder. Findings pave the way for treatments specifically targeting SoA in neuropsychiatric disorders where IB is altered.

When did it happen? Verbal information about causal relations affects time estimation

Usually, the closer two events occur, the more likely people infer a causal relationship between them. Recent studies have shown that this relationship between time and causality is bidirectional. Participants also tend to judge events closer in time if they assume that they are causally related. We present six experiments showing causal binding, but unlike other experiments, participants do not emit any motor action, and no physical feedback is given. Rather, all stimuli and causal information are provided verbally. After reading a list of events, participants were asked to estimate the time elapsed between two of them. Those participants who were informed that there was a causal relationship between the two events estimated them as occurring closer to each other. These results support causality- and heuristic-based explanations of temporal binding, as opposed to other explanations such as sensory integration or intentionality of action.

The sense of agency for brain disorders: A comprehensive review and proposed framework

Sense of Agency (SoA) refers to the feeling of control over voluntary actions and the outcomes of those actions. Several brain disorders are characterized by an abnormal SoA. To date, there is no robust treatment for aberrant agency across disorders; this is, in large part, due to gaps in our understanding of the cognitive mechanisms and neural correlates of the SoA. This apparent gap stems from a lack of synthesis in established findings. As such, the current review reconciles previously established findings into a novel neurocognitive framework for future investigations of the SoA in brain disorders, which we term the Agency in Brain Disorders Framework (ABDF). In doing so, we highlight key top-down and bottom-up cues that contribute to agency prospectively (i.e., prior to action execution) and retrospectively (i.e., after action execution). We then examine brain disorders, including schizophrenia, autism spectrum disorders (ASD), obsessive-compulsive disorders (OCD), and cortico-basal syndrome (CBS), within the ABDF, to demonstrate its potential utility in investigating neurocognitive mechanisms underlying phenotypically variable presentations of the SoA in brain disorders.

Non-motor cues do not generate the perception of self-agency: A critique of cue-integration

How does one know that (s)he is the causal agent of their motor actions? Earlier theories of sense of agency have attributed the capacity for perception of self-agency to the comparator process of the motor-control/action system. However, with the advent of the findings implying a role of non-motor cues (like affective states, beliefs, primed concepts, and social instructions or previews of actions) in the sense of agency literature, the perception of self-agency is hypothesized to be generated even by non-motor cues (based on their relative reliability or weighting estimate); and, this theory is come to be known as the cue-integration of sense of agency. However, the cue-integration theory motivates skepticism about whether it is falsifiable and whether it is plausible that non-motor cues that are sensorily unrelated to typical sensory processes of self-agency have the capacity to produce a perception of self-agency. To substantiate this skepticism, I critically analyze the experimental operationalizations of cue-integration-with the (classic) vicarious agency experiment as a case study-to show that (1) the participants in these experiments are ambiguous about their causal agency over motor actions, (2) thus, these participants resort to reports of self-agency as heuristic judgments (under ambiguity) rather than due to cue-integration per se, and (3) there might not have occurred cue-integration based self-agency reports if these experimental operationalizations had eliminated ambiguity about the causal agency. Thus, I conclude that the reports of self-agency (observed in typical non-motor cues based cue-integration experiments) are not instances of perceptual effect-that are hypothesized to be produced by non-motor cues-but are of heuristic judgment effect.

The implicit sense of agency is not a perceptual effect but is a judgment effect

The sense of agency (SoA) is characterized as the sense of being the causal agent of one's own actions, and it is measured in two forms: explicit and implicit. In the explicit SoA experiments, the participants explicitly report whether they have a sense of control over their actions or whether they or somebody else is the causal agent of seen actions; the implicit SoA experiments study how do participants' agentive or voluntary actions modify perceptual processes (like time, vision, tactility, and audition) without directly asking the participants to explicitly think about their causal agency or sense of control. However, recent implicit SoA literature reported contradictory findings of the relationship between implicit SoA reports and agency states. Thus, I argue that the purported implicit SoA reports are not agency-driven perceptual effects per se but are judgment effects, by showing that (a) the typical operationalizations in implicit SoA domain lead to perceptual uncertainty on the part of the participants, (b) under uncertainty, participants' implicit SoA reports are due to heuristic judgments which are independent of agency states, and (c) under perceptual certainty, the typical implicit SoA reports might not have occurred at all. Thus, I conclude that the instances of implicit SoA are judgments (or response biases)-under uncertainty-rather than perceptual effects.

Temporal binding and agency under startle

Forward models are a component of the motor system that predicts the sensory consequences of our actions. These models play several key roles in motor control and are hypothesized to underlie (among other things) the two phenomena under investigation in this experiment: The feeling of agency that we have over self-initiated actions (as opposed to reflexes), and "temporal binding", in which self-caused sensations are judged to have occurred earlier in time than they actually did. This experiment probes the connection between forward models and both of these phenomena using the "Startle" paradigm. In the Startle paradigm, a startlingly loud sound causes people to initiate a prepared action at a very short latency. It is hypothesized that the latency of a startle-initiated action is so short that normal cortical operations (including forward models) are circumvented. This experiment replicates the temporal-binding effect and simultaneously measures participants' sense of agency over their actions. The results show that both the temporal-binding effect and the sense of agency we have over our own actions is disrupted under the startle paradigm in line with the theory that these phenomena both rely on forward models. Furthermore, this experiment provides evidence in support of the claim that a startle-induced action is qualitatively different from other actions.

A Bayesian psychophysics model of sense of agency

Sense of agency (SoA) refers to the experience or belief that one’s own actions caused an external event. Here we present a model of SoA in the framework of optimal Bayesian cue integration with mutually involved principles, namely reliability of action and outcome sensory signals, their consistency with the causation of the outcome by the action, and the prior belief in causation. We used our Bayesian model to explain the intentional binding effect, which is regarded as a reliable indicator of SoA. Our model explains temporal binding in both self-intended and unintentional actions, suggesting that intentionality is not strictly necessary given high confidence in the action causing the outcome. Our Bayesian model also explains that if the sensory cues are reliable, SoA can emerge even for unintended actions. Our formal model therefore posits a precision-dependent causal agency.

Sense of agency (SoA) refers to the experience that one's own actions caused an external event. Here, the authors present a model of SoA in terms of optimal Bayesian cue integration taking into account reliability of action and outcome sensory signals and judging if the action caused the outcome.

Predictive Mechanisms Are Not Involved the Same Way during Human-Human vs. Human-Machine Interactions: A Review

Nowadays, interactions with others do not only involve human peers but also automated systems. Many studies suggest that the motor predictive systems that are engaged during action execution are also involved during joint actions with peers and during other human generated action observation. Indeed, the comparator model hypothesis suggests that the comparison between a predicted state and an estimated real state enables motor control, and by a similar functioning, understanding and anticipating observed actions. Such a mechanism allows making predictions about an ongoing action, and is essential to action regulation, especially during joint actions with peers. Interestingly, the same comparison process has been shown to be involved in the construction of an individual's sense of agency, both for self-generated and observed other human generated actions. However, the implication of such predictive mechanisms during interactions with machines is not consensual, probably due to the high heterogeneousness of the automata used in the experimentations, from very simplistic devices to full humanoid robots. The discrepancies that are observed during human/machine interactions could arise from the absence of action/observation matching abilities when interacting with traditional low-level automata. Consistently, the difficulties to build a joint agency with this kind of machines could stem from the same problem. In this context, we aim to review the studies investigating predictive mechanisms during social interactions with humans and with automated artificial systems. We will start by presenting human data that show the involvement of predictions in action control and in the sense of agency during social interactions. Thereafter, we will confront this literature with data from the robotic field. Finally, we will address the upcoming issues in the field of robotics related to automated systems aimed at acting as collaborative agents.

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.

Interplay of agency and ownership: the intentional binding and rubber hand illusion paradigm combined

The sense of agency (SoA) refers to the phenomenal experience of initiating and controlling an action, whereas the sense of ownership (SoO) describes the feeling of myness an agent experiences towards his or her own body parts. SoA has been investigated with intentional binding paradigms, and the sense of ownership (SoO) with the rubber-hand illusion (RHI). We investigated the relationship between SoA and SoO by incorporating intentional binding into the RHI. Explicit and implicit measures of agency (SoA-questionnaire, intentional binding) and ownership (SoO-questionnaire, proprioceptive drift) were used. Artificial hand position (congruent/incongruent) and mode of agent (self-agent/other-agent) were systematically varied. Reported SoO varied mainly with position (higher in congruent conditions), but also with agent (higher in self-agent conditions). Reported SoA was modulated by agent (higher in self-agent conditions), and moderately by position (higher in congruent conditions). Implicit and explicit agency measures were not significantly correlated. Finally, intentional binding tended to be stronger in self-generated than observed voluntary actions. Results provide further evidence for a partial double dissociation between SoA and SoO, empirically distinct agency levels, and moderate intentional binding differences between self-generated and observed voluntary actions.

Do implicit and explicit measures of the sense of agency measure the same thing?

The sense of agency (SoA) refers to perceived causality of the self, i.e. the feeling of causing something to happen. The SoA has been probed using a variety of explicit and implicit measures. Explicit measures include rating scales and questionnaires. Implicit measures, which include sensory attenuation and temporal binding, use perceptual differences between self- and externally generated stimuli as measures of the SoA. In the present study, we investigated whether the different measures tap into the same self-attribution processes by determining whether individual differences on implicit and explicit measures of SoA are correlated. Participants performed tasks in which they triggered tones via key presses (operant condition) or passively listened to tones triggered by a computer (observational condition). We replicated previously reported effects of sensory attenuation and temporal binding. Surprisingly the two implicit measures of SoA were not significantly correlated with each other, nor did they correlate with the explicit measures of SoA. Our results suggest that some explicit and implicit measures of the SoA may tap into different processes.

Loss of agency in apraxia

The feeling of acting voluntarily is a fundamental component of human behavior and social life and is usually accompanied by a sense of agency. However, this ability can be impaired in a number of diseases and disorders. An important example is apraxia, a disturbance traditionally defined as a disorder of voluntary skillful movements that often results from frontal-parietal brain damage. The first part of this article focuses on direct evidence of some core symptoms of apraxia, emphasizing those with connections to agency and free will. The loss of agency in apraxia is reflected in the monitoring of internally driven action, in the perception of specifically self-intended movements and in the neural intention to act. The second part presents an outline of the evidences supporting the functional and anatomical link between apraxia and agency. The available structural and functional results converge to reveal that the frontal-parietal network contributes to the sense of agency and its impairment in disorders such as apraxia. The current knowledge on the generation of motor intentions and action monitoring could potentially be applied to develop therapeutic strategies for the clinical rehabilitation of voluntary action.

The direct perception hypothesis: perceiving the intention of another's action hinders its precise imitation

We argue that imitation is a learning response to unintelligible actions, especially to social conventions. Various strands of evidence are converging on this conclusion, but further progress has been hampered by an outdated theory of perceptual experience. Comparative psychology continues to be premised on the doctrine that humans and non-human primates only perceive others' physical "surface behavior," while mental states are perceptually inaccessible. However, a growing consensus in social cognition research accepts the direct perception hypothesis: primarily we see what others aim to do; we do not infer it from their motions. Indeed, physical details are overlooked - unless the action is unintelligible. On this basis we hypothesize that apes' propensity to copy the goal of an action, rather than its precise means, is largely dependent on its perceived intelligibility. Conversely, children copy means more often than adults and apes because, uniquely, much adult human behavior is completely unintelligible to unenculturated observers due to the pervasiveness of arbitrary social conventions, as exemplified by customs, rituals, and languages. We expect the propensity to imitate to be inversely correlated with the familiarity of cultural practices, as indexed by age and/or socio-cultural competence. The direct perception hypothesis thereby helps to parsimoniously explain the most important findings of imitation research, including children's over-imitation and other species-typical and age-related variations.

Vocal recruitment for joint travel in wild chimpanzees

Joint travel is a common social activity of many group-living animals, which requires some degree of coordination, sometimes through communication signals. Here, we studied the use of an acoustically distinct vocalisation in chimpanzees, the ‘travel hoo’, a signal given specifically in the travel context. We were interested in how this call type was produced to coordinate travel, whether it was aimed at specific individuals and how recipients responded. We found that ‘travel hoos’ were regularly given prior to impending departures and that silent travel initiations were less successful in recruiting than vocal initiations. Other behaviours associated with departure were unrelated to recruitment, suggesting that ‘travel hoos’ facilitated joint travel. Crucially, ‘travel hoos’ were more often produced in the presence of allies than other individuals, with high rates of recruitment success. We discuss these findings as evidence for how motivation to perform a specific social activity can lead to the production of a vocal signal that qualifies as ‘intentional’ according to most definitions, suggesting that a key psychological component of human language may have already been present in the common ancestor of chimpanzees and humans.

What is social about social perception research?

A growing consensus in social cognitive neuroscience holds that large portions of the primate visual brain are dedicated to the processing of social information, i.e., to those aspects of stimuli that are usually encountered in social interactions such as others' facial expressions, actions, and symbols. Yet, studies of social perception have mostly employed simple pictorial representations of conspecifics. These stimuli are social only in the restricted sense that they physically resemble objects with which the observer would typically interact. In an equally important sense, however, these stimuli might be regarded as “non-social”: the observer knows that they are viewing pictures and might therefore not attribute current mental states to the stimuli or might do so in a qualitatively different way than in a real social interaction. Recent studies have demonstrated the importance of such higher-order conceptualization of the stimulus for social perceptual processing. Here, we assess the similarity between the various types of stimuli used in the laboratory and object classes encountered in real social interactions. We distinguish two different levels at which experimental stimuli can match social stimuli as encountered in everyday social settings: (1) the extent to which a stimulus' physical properties resemble those typically encountered in social interactions and (2) the higher-level conceptualization of the stimulus as indicating another person's mental states. We illustrate the significance of this distinction for social perception research and report new empirical evidence further highlighting the importance of mental state attribution for perceptual processing. Finally, we discuss the potential of this approach to inform studies of clinical conditions such as autism.