When performing actions with robots, attribution of intentionality affects the sense of joint agency

Sense of joint agency (SoJA) is the sense of control experienced by humans when acting with others to bring about changes in the shared environment. SoJA is proposed to arise from the sensorimotor predictive processes underlying action control and monitoring. Because SoJA is a ubiquitous phenomenon occurring when we perform actions with other humans, it is of great interest and importance to understand whether-and under what conditions-SoJA occurs in collaborative tasks with humanoid robots. In this study, using behavioral measures and neural responses measured by electroencephalography (EEG), we aimed to evaluate whether SoJA occurs in joint action with the humanoid robot iCub and whether its emergence is influenced by the perceived intentionality of the robot. Behavioral results show that participants experienced SoJA with the robot partner when it was presented as an intentional agent but not when it was presented as a mechanical artifact. EEG results show that the mechanism that influences the emergence of SoJA in the condition when the robot is presented as an intentional agent is the ability to form similarly accurate predictions about the sensory consequences of our own and others' actions, leading to similar modulatory activity over sensory processing. Together, our results shed light on the joint sensorimotor processing mechanisms underlying the emergence of SoJA in human-robot interaction and underscore the importance of attribution of intentionality to the robot in human-robot collaboration.

Neural correlates of an illusionary sense of agency caused by virtual reality

Sense of agency (SoA) is the sensation that self-actions lead to ensuing perceptual consequences. The prospective mechanism emphasizes that SoA arises from motor prediction and its comparison with actual action outcomes, while the reconstructive mechanism stresses that SoA emerges from retrospective causal processing about the action outcomes. Consistent with the prospective mechanism, motor planning regions were identified by neuroimaging studies using the temporal binding (TB) effect, a behavioral measure often linked to implicit SoA. Yet, TB also occurs during passive observation of another's action, lending support to the reconstructive mechanism, but its neural correlates remain unexplored. Here, we employed virtual reality (VR) to modulate such observation-based SoA and examined it with functional magnetic resonance imaging (fMRI). After manipulating an avatar hand in VR, participants passively observed an avatar's "action" and showed a significant increase in TB. The binding effect was associated with the right angular gyrus and inferior parietal lobule, which are critical nodes for inferential and agency processing. These results suggest that the experience of controlling an avatar may potentiate inferential processing within the right inferior parietal cortex and give rise to the illusionary SoA without voluntary action.

Exploring neurophysiological correlates of visually induced motion sickness using electroencephalography (EEG)

Visually induced motion sickness (VIMS) is a common phenomenon when using visual devices such as smartphones and virtual reality applications, with symptoms including nausea, fatigue, and headache. To date, the neuro-cognitive processes underlying VIMS are not fully understood. Previous studies using electroencephalography (EEG) delivered mixed findings, with some reporting an increase in delta and theta power, and others reporting increases in alpha and beta frequencies. The goal of the study was to gain further insight into EEG correlates for VIMS. Participants viewed a VIMS-inducing visual stimulus, composed of moving black-and-white vertical bars presented on an array of three adjacent monitors. The EEG was recorded during visual stimulation and VIMS ratings were recorded after each trial using the Fast Motion Sickness Scale. Time-frequency analyses were conducted comparing neural activity of participants reporting minimal VIMS (n = 21) and mild-moderate VIMS (n = 12). Results suggested a potential increase in delta power in the centro-parietal regions (CP2) and a decrease in alpha power in the central regions (Cz) for participants experiencing mild-moderate VIMS compared to those with minimal VIMS. Event-related spectral perturbations (ERSPs) suggested that group differences in EEG activity developed with increasing duration of a trial. These results support the hypothesis that the EEG might be sensitive to differences in information processing in VIMS and minimal VIMS contexts, and indicate that it may be possible to identify neurophysiological correlate of VIMS. Differences in EEG activity related to VIMS may reflect differential processing of conflicting visual and vestibular sensory information.

Agency and social affordance shape visual perception

Research on the sense of agency has shown that being the author of an action changes the way we estimate the timing and the intensity of the action-effect. Yet, there is a dearth of attempts to assess the influence of agency on perception per se. The present study used the Representational Momentum paradigm to measure participants' visual anticipation of movement while manipulating their agency. In line with previous literature emphasizing the impact of social factors on visual anticipation and on the sense of agency, we additionally investigated the modulating power of social affordances on the relationship between agency and visual anticipation. We conducted two experiments where participants viewed a virtual agent directing a handshake gesture toward a second virtual agent. In a first experiment, we addressed the role of agency on visual anticipation by comparing a condition in which participants triggered the virtual agent's gesture with a condition where the computer triggered the gesture. Results showed greater forward movement anticipation when participants triggered the gesture. The second experiment investigated how altering social interaction parameters (interindividual distance and body posture) modulated the relationship between agency and visual anticipation. The outcome contrasted with the first experiment, with participants anticipating a backward movement of the hand when the computer triggered the gesture and displaying a null anticipation when participants triggered the gesture. Those two experiments highlighted how active involvement and environmental affordance interact to shape perception and allowed us to propose an updated model of agency processing.

My view on your actions: Dynamic changes in viewpoint-dependent auditory ERP attenuation during action observation

It has been suggested that during action observation, a sensory representation of the observed action is mapped onto one's own motor system. However, it is largely unexplored what this may imply for the early processing of the action's sensory consequences, whether the observational viewpoint exerts influence on this and how such a modulatory effect might change over time. We tested whether the event-related potential of auditory effects of actions observed from a first- versus third-person perspective show amplitude reductions compared with externally generated sounds, as revealed for self-generated sounds. Multilevel modeling on trial-level data showed distinct dynamic patterns for the two viewpoints on reductions of the N1, P2, and N2 components. For both viewpoints, an N1 reduction for sounds generated by observed actions versus externally generated sounds was observed. However, only during first-person observation, we found a temporal dynamic within experimental runs (i.e., the N1 reduction only emerged with increasing trial number), indicating time-variant, viewpoint-dependent processes involved in sensorimotor prediction during action observation. For the P2, only a viewpoint-independent reduction was found for sounds elicited by observed actions, which disappeared in the second half of the experiment. The opposite pattern was found in an exploratory analysis concerning the N2, revealing a reduction that increased in the second half of the experiment, and, moreover, a temporal dynamic within experimental runs for the first-person perspective, possibly reflecting an agency-related process. Overall, these results suggested that the processing of auditory outcomes of observed actions is dynamically modulated by the viewpoint over time.

Instrumental responses and Pavlovian stimuli as temporal referents in a peak procedure

Three experiments investigated whether the nature of the temporal referent affects timing behaviour in rats. We used a peak procedure and assessed timing of food well activity as a function of whether the referent was an instrumental response (a lever press that resulted in the withdrawal of the lever) or a conditioned stimulus (CS) that was 2 s in Experiment 1, 500 ms in Experiment 2, and 800 ms in Experiment 3. In all experiments, the interval between the offset of the temporal referent and food was 5 s. The curve fits for each experiment revealed no differences in peak time, but magazine responding immediately following the CS was higher than following a lever press. This pattern of results was interpreted as reflecting a combination of (a) ambiguity in which component of the 500 ms-2-s auditory stimulus was serving as the referent and (b) response competition between lever pressing and magazine activity. Critically, these results suggest that peak timing in rats is unaffected by whether a lever press or CS serves as the referent. This conclusion is consistent with theoretical models of timing behaviour, but not with evidence from humans showing that the subjective perception of time is affected by whether the cause of an outcome was self-generated or not.

Human-likeness and attribution of intentionality predict vicarious sense of agency over humanoid robot actions

Sense of Agency (SoA) is the feeling of being in control of one's actions and their outcomes. In a social context, people can experience a "vicarious" SoA over another human's actions; however, it is still controversial whether the same occurs in Human-Robot Interaction (HRI). The present study aimed at understanding whether humanoid robots may elicit vicarious SoA in humans, and whether the emergence of this phenomenon depends on the attribution of intentionality towards robots. We asked adult participants to perform an Intentional Binding (IB) task alone and with the humanoid iCub robot, reporting the time of occurrence of both self- and iCub-generated actions. Before the experiment, participants' degree of attribution of intentionality towards robots was assessed. Results showed that participants experienced vicarious SoA over iCub-generated actions. Moreover, intentionality attribution positively predicted the magnitude of vicarious SoA. In conclusion, our results highlight the importance of factors such as human-likeness and attribution of intentionality for the emergence of vicarious SoA towards robots.

Dissociable effects of attention and expectation on perceptual sensitivity to action-outcomes

Self-generated sensations evoke attenuated neural response - physiological attenuation - and is perceived with less intensity - perceptual attenuation. This phenomenon is referred as sensory attenuation and is proposed to reflect the silencing of predicted sensations. The present study aimed to investigate the independent contribution of expectation and attention on sensory attenuation. The expectation associated with the stimulus feature and the focus of attention was manipulated independently by orthogonal cues. We found pronounced sensory attenuation at the unattended location when the stimulus was self-generated (Experiment 1). When the stimulus was externally-generated (Experiment 2), sensory attenuation was observed at the attended location. Sensory attenuation of expected action-outcome was not observed when the attention cue was uninformative (Experiment 3A). The findings corroborate the claim from Bayesian models that attention mediates sensory attenuation. The results also highlight the paradoxes in Bayesian proposals of perception-action interaction.

The auditory brain in action: Intention determines predictive processing in the auditory system-A review of current paradigms and findings

According to the ideomotor theory, action may serve to produce desired sensory outcomes. Perception has been widely described in terms of sensory predictions arising due to top-down input from higher order cortical areas. Here, we demonstrate that the action intention results in reliable top-down predictions that modulate the auditory brain responses. We bring together several lines of research, including sensory attenuation, active oddball, and action-related omission studies: Together, the results suggest that the intention-based predictions modulate several steps in the sound processing hierarchy, from preattentive to evaluation-related processes, also when controlling for additional prediction sources (i.e., sound regularity). We propose an integrative theoretical framework—the extended auditory event representation system (AERS), a model compatible with the ideomotor theory, theory of event coding, and predictive coding. Initially introduced to describe regularity-based auditory predictions, we argue that the extended AERS explains the effects of action intention on auditory processing while additionally allowing studying the differences and commonalities between intention- and regularity-based predictions—we thus believe that this framework could guide future research on action and perception.

Temporal Binding, Causation, and Agency: Developing a New Theoretical Framework

In temporal binding, the temporal interval between one event and another, occurring some time later, is subjectively compressed. We discuss two ways in which temporal binding has been conceptualized. In studies showing temporal binding between a voluntary action and its causal consequences, such binding is typically interpreted as providing a measure of an implicit or pre-reflective "sense of agency." However, temporal binding has also been observed in contexts not involving voluntary action, but only the passive observation of a cause-effect sequence. In those contexts, it has been interpreted as a top-down effect on perception reflecting a belief in causality. These two views need not be in conflict with one another, if one thinks of them as concerning two separate mechanisms through which temporal binding can occur. In this paper, we explore an alternative possibility: that there is a unitary way of explaining temporal binding both within and outside the context of voluntary action as a top-down effect on perception reflecting a belief in causality. Any such explanation needs to account for ways in which agency, and factors connected with agency, has been shown to affect the strength of temporal binding. We show that principles of causal inference and causal selection already familiar from the literature on causal learning have the potential to explain why the strength of people's causal beliefs can be affected by the extent to which they are themselves actively involved in bringing about events, thus in turn affecting binding.

Sensory Attenuation of the Auditory P2 Differentiates Self- from Partner-Produced Sounds during Joint Action

Successful human interaction relies on people's ability to differentiate between the sensory consequences of their own and others' actions. Research in solo action contexts has identified sensory attenuation, that is, the selective perceptual or neural dampening of the sensory consequences of self-produced actions, as a potential marker of the distinction between self- and externally produced sensory consequences. However, very little research has examined whether sensory attenuation distinguishes self- from partner-produced sensory consequences in joint action contexts. The current study examined whether sensory attenuation of the auditory N1 or P2 ERPs distinguishes self- from partner-produced tones when pairs of people coordinate their actions to produce tone sequences that match a metronome pace. We did not find evidence of auditory N1 attenuation for either self- or partner-produced tones. Instead, the auditory P2 was attenuated for self-produced tones compared to partner-produced tones within the joint action. These findings indicate that self-specific attenuation of the auditory P2 differentiates the sensory consequences of one's own from others' actions during joint action. These findings also corroborate recent evidence that N1 attenuation may be driven by general rather than action-specific processes and support a recently proposed functional dissociation between auditory N1 and P2 attenuation.

Neural correlates of implicit agency during the transition from adolescence to adulthood: An ERP study

Sense of agency (SoA), the experience of being in control of our voluntary actions and their outcomes, is a key feature of normal human experience. Frontoparietal brain circuits associated with SoA undergo a major maturational process during adolescence. To examine whether this translates to neurodevelopmental changes in agency experience, we investigated two key neural processes associated with SoA, the activity that is leading to voluntary action (Readiness Potential) and the activity that is associated with the action outcome processing (attenuation of auditory N1 and P2 event related potentials, ERPs) in mid-adolescents (13-14), late-adolescents (18-20) and adults (25-28) while they perform an intentional binding task. In this task, participants pressed a button (action) that delivered a tone (outcome) after a small delay and reported the time of the tone using the Libet clock. This action-outcome condition alternated with a no-action condition where an identical tone was triggered by a computer. Mid-adolescents showed greater outcome binding, such that they perceived self-triggered tones as being temporally closer to their actions compared to adults. Suggesting greater agency experience over the outcomes of their voluntary actions during mid-adolescence. Consistent with this, greater levels of attenuated neural response to self-triggered auditory tones (specifically P2 attenuation) were found during mid-adolescence compared to older age groups. This enhanced attenuation decreased with age as observed in outcome binding. However, there were no age-related differences in the readiness potential leading to the voluntary action (button press) as well as in the N1 attenuation to the self-triggered tones. Notably, in mid-adolescents greater outcome binding scores were positively associated with greater P2 attenuation, and smaller negativity in the late readiness potential. These findings suggest that the greater experience of implicit agency observed during mid-adolescence may be mediated by a neural over-suppression of action outcomes (auditory P2 attenuation), and over-reliance on motor preparation (late readiness potential), which we found to become adult-like during late-adolescence. Implications for adolescent development and SoA related neurodevelopmental disorders are discussed.

Temporal Binding in Multisensory and Motor-Sensory Contexts: Toward a Unified Model

Our senses receive a manifold of sensory signals at any given moment in our daily lives. For a coherent and unified representation of information and precise motor control, our brain needs to temporally bind the signals emanating from a common causal event and segregate others. Traditionally, different mechanisms were proposed for the temporal binding phenomenon in multisensory and motor-sensory contexts. This paper reviews the literature on the temporal binding phenomenon in both multisensory and motor-sensory contexts and suggests future research directions for advancing the field. Moreover, by critically evaluating the recent literature, this paper suggests that common computational principles are responsible for the temporal binding in multisensory and motor-sensory contexts. These computational principles are grounded in the Bayesian framework of uncertainty reduction rooted in the Helmholtzian idea of unconscious causal inference.

Goal sharing with others modulates the sense of agency and motor accuracy in social contexts

Sense of agency (SoA), the feeling of control over one’s own actions and their effects, is fundamental to goal-directed actions at the individual level and may constitute a cornerstone of everyday life, including cooperative behavior (i.e., goal sharing). Previous studies have demonstrated that goal sharing can activate the motor prediction of both agent’s action and partner’s action in joint-action tasks. Moreover, given that from an SoA perspective, predictive processes are an essential basis, there is a possibility that goal sharing may modulate SoA. However, the possibility for goal sharing to modulate SoA remains unclear. This study aimed to investigate whether goal sharing modulates the intentional binding (IB) effect (a method that can quantitatively measure SoA) of self-generated and observed partner’s actions and improves motor accuracy. Participants were required to stop a circular horizontal moving object by pressing a key when the object reaches the center of a target in a social situation. This task measured IB by having participants estimate the time interval between action and effect in several 100 milliseconds, with shorter time interval estimations indicating enhancement of SoA. Participants were randomly divided into 13 Cooperative groups (goal sharing) and 13 Independent groups (non-goal sharing). Cooperative groups were instructed to perform the task together, while Independent groups did so individually. Participants estimated the time interval between them by pressing the key and hearing the corresponding sound (Self-generated action) and the other person pressing the key and hearing the sound (Observed action). Our results indicated that goal sharing improved motor accuracy and enhanced both the IB of Self-generated and Observed actions compared to non-goal sharing. We suggest that SoA can be modulated by goal sharing in specific social contexts.

Similarities and Differences between Performers and Observers in Processing Auditory Action Consequences: Evidence from Simultaneous EEG Acquisition

In our social environment, we easily distinguish stimuli caused by our own actions (e.g., water splashing when I fill my glass) from stimuli that have an external source (e.g., water splashing in a fountain). Accumulating evidence suggests that processing the auditory consequences of self-performed actions elicits N1 and P2 ERPs of reduced amplitude compared to physically identical but externally generated sounds, with such reductions being ascribed to neural predictive mechanisms. It is unexplored, however, whether the sensory processing of action outcomes is similarly modulated by action observation (e.g., water splashing when I observe you filling my glass). We tested 40 healthy participants by applying a methodological approach for the simultaneous EEG recording of two persons: An observer observed button presses executed by a performer in real time. For the performers, we replicated previous findings of a reduced N1 amplitude for self- versus externally generated sounds. This pattern differed significantly from the one in observers, whose N1 for sounds generated by observed button presses was not attenuated. In turn, the P2 amplitude was reduced for processing action- versus externally generated sounds for both performers and observers. These findings show that both action performance and observation affect the processing of action-generated sounds. There are, however, important differences between the two in the timing of the effects, probably related to differences in the predictability of the actions and thus also the associated stimuli. We discuss how these differences might contribute to recognizing the stimulus as caused by self versus others.

Intentional Binding Effects in the Experience of Noticing the Regularity of a Perceptual-Motor Task

Noticing the regularity of the task is necessary to enhance motor performance. The experience of noticing further motivates improvement in motor performance. Motor control is explained by a comparator model that modifies the motor command to reduce discrepancies between sensory predictions and actual outcomes. A similar model could apply to sense of agency (SoA). SoA refers to the sensation of controlling one’s own actions and, through them, the outcomes in the external world. SoA may also be enhanced by the experience of noticing errors. We recently reported gradual enhancement of SoA in participants with high perceptual-motor performance. However, what component of the motor task changed the SoA is unclear. In this study, we aimed to investigate the influence over time of the experience of noticing during a motor task on SoA. Participants performed an implicit regularity perceptual-motor task and an intentional binding task (a method that can quantitatively measure SoA) simultaneously. We separated participants into groups after the experiment based on noticing or not noticing the regularity. SoA was gradually enhanced in the noticing group, compared with that of the non-noticing group. The results suggest that the experience of noticing may enhance SoA during perceptual-motor tasks.

The developmental profile of temporal binding: From childhood to adulthood

Temporal binding refers to a phenomenon whereby the time interval between a cause and its effect is perceived as shorter than the same interval separating two unrelated events. We examined the developmental profile of this phenomenon by comparing the performance of groups of children (aged 6–7, 7–8, and 9–10 years) and adults on a novel interval estimation task. In Experiment 1, participants made judgements about the time interval between (a) their button press and a rocket launch, and (b) a non-causal predictive signal and rocket launch. In Experiment 2, an additional causal condition was included in which participants made judgements about the interval between an experimenter’s button press and the launch of a rocket. Temporal binding was demonstrated consistently and did not change in magnitude with age: estimates of delay were shorter in causal contexts for both adults and children. In addition, the magnitude of the binding effect was greater when participants themselves were the cause of an outcome compared with when they were mere spectators. This suggests that although causality underlies the binding effect, intentional action may modulate its magnitude. Again, this was true of both adults and children. Taken together, these results are the first to suggest that the binding effect is present and developmentally constant from childhood into adulthood.

The impact of eye contact on the sense of agency

Recent research suggests that eye contact can lead to enhanced self-awareness. A related phenomenon, the sense of agency deals with the notion of the self as the origin of our actions. Possible links between eye contact and agency have been so far neglected. Here, we investigated whether an implicit sense of agency could be modulated by eye gaze. We asked participants to respond (button press) to a face stimulus: looking or not at the participant (experiment 1); or displaying distinct eye gaze before or after a mask (experiment 2). After each trial, participants estimated the time between their key press and the ensuing effects. We found enhanced intentional binding for conditions that involved direct compared to averted gaze. This study supports the idea that eye contact is an important cue that affects complex cognitive processes and suggests that modulating self-processing can impact the sense of agency.

Changes in intentional binding effect during a novel perceptual-motor task

Perceptual-motor learning describes the process of improving the smoothness and accuracy of movements. Intentional binding (IB) is a phenomenon whereby the length of time between performing a voluntary action and the production of a sensory outcome during perceptual-motor control is perceived as being shorter than the reality. How IB may change over the course of perceptual-motor learning, however, has not been explicitly investigated. Here, we developed a set of IB tasks during perceptual-motor learning. Participants were instructed to stop a circular moving object by key press when it reached the center of a target circle on the display screen. The distance between the center of the target circle and the center of the moving object was measured, and the error was used to approximate the perceptual-motor performance index. This task also included an additional exercise that was unrelated to the perceptual-motor task: after pressing the key, a sound was presented after a randomly chosen delay of 200, 500, or 700 ms and the participant had to estimate the delay interval. The difference between the estimated and actual delay was used as the IB value. A cluster analysis was then performed using the error values from the first and last task to group the participants based on their perceptual-motor performance. Participants showing a very small change in error value, and thus demonstrating a small effect of perceptual-motor learning, were classified into cluster 1. Those who exhibited a large decrease in error value from the first to the last set, and thus demonstrated a strong improvement in perceptual-motor performance, were classified into cluster 2. Those who exhibited perceptual-motor learning also showed improvements in the IB value. Our data suggest that IB is elevated when perceptual-motor learning occurs.

Robust intentional binding for causally-linked sequences of naturalistic events but not for abstract event sequences

Past studies have shown that when a voluntary action produces a sensory effect, the action and the effect will be perceived as being closer in time. This subjective temporal 'attraction' is known as intentional binding (IB). Induction of IB is dependent on the intentionality of one's actions, the predictability of the effect, and the causality between the action and the effect. Previous investigations of IB have utilized abstract stimuli (e.g., flashes and beeps) with adaptation so as to associate the abstract action-effect link. Yet, events from our everyday experiences already have an inherent action-effect link. We, thus, investigated, for the first time, IB under naturalistic, multisensory stimulation by manipulating the intentionality, predictability, and causal event link. A total of five experiments without adaptation were conducted examining IB with: abstract stimuli (Experiment 1), naturalistic effects (Exp. 2), naturalistic action cue and effect matching (Exp. 3), naturalistic action cue and effect mismatching (Exp. 4), and naturalistic action cue and effect matching but mismatched response mapping (Exp. 5). Analyses of the data showed the absence of IB for abstract stimuli without action-effect adaptation (Exp. 1) and for effects that were not inherently causal or predictable of one's action (Exp. 2, 4, and 5). IB, however, was induced when the naturalistic sequence of action cue-effect was casually linked and predictable in terms of timing (Exp. 3). Overall, our results showed that induction of IB is dependent on the inherent causal and predictable association of an event from the cue to act to the consequence of that action, an association that is already present in everyday multisensory events.

Intentionality of a co-actor influences sensorimotor synchronisation with a virtual partner

Interpersonal sensorimotor synchronisation requires individuals to anticipate and adapt to their partner's movement timing. Research has demonstrated that the intentionality of a co-actor affects joint action planning, however, less is known about whether co-actor intentionality affects sensorimotor synchronisation. Explicit and implicit knowledge of a synchronisation partner's intentionality may influence coordination by modulating temporal anticipation and adaptation processes. We used a computer-controlled virtual partner (VP) consisting of tempo-changing auditory pacing sequences to simulate either an intentional or unintentional synchronisation partner. The VP was programmed to respond to the participant with low or moderate degrees of error correction, simulating a slightly or moderately adaptive human, respectively. In addition, task instructions were manipulated so that participants were told they were synchronising with either another person or a computer. Results indicated that synchronisation performance improved with the more adaptive VP. In addition, there was an influence of the explicit partner instruction, but this was dependent upon the degree of VP adaptivity and was modulated by subjective preferences for either the human or the computer partner. Beliefs about the intentionality of a synchronisation partner may thus influence interpersonal sensorimotor synchronisation in a manner that is modulated by preferences for interacting with intentional agents.

Enhanced perceptual processing of self-generated motion: Evidence from steady-state visual evoked potentials

The sense of agency emerges when our voluntary actions produce anticipated or predictable outcomes in the external world. It remains unclear how the sense of control also influences our perception of the external world. The present study examined perceptual processing of self-generated motion versus non-self-generated motion using steady-state visual evoked potentials (SSVEPs). Participants continuously moved their finger on a touchpad to trigger the movements of two shapes (Experiment 1) or two groups of dots (Experiment 2) on a monitor. Degree of control was manipulated by varying the spatial relation between finger movement and stimulus trajectory across conditions. However, the velocity, onset time, and offset time of visual stimuli always corresponded to participants' finger movement. Stimuli flickered at a frequency of either 7.5 Hz or 10 Hz, thus SSVEPs of these frequencies and their harmonics provided a frequency-tagged measurement of perceptual processing. Participants triggered the motion of all stimuli simultaneously, but had greater levels of control over some stimuli than over others. Their task was to detect a brief colour change on the border(s) of one shape (Experiment 1) or of one group of dots (Experiment 2). Although control over shapes/dots was irrelevant to the visual detection task, we found stronger SSVEPs for stimuli that were under a high level of control, compared with the stimuli that were under a low level of control. Our results suggest that the spatial regularity between self-generated movements and visual input boosted the neural responses underlying perceptual processing. Our results support the preactivation account of sensory attenuation, suggesting that perceptual processing of self-generated events is enhanced rather than inhibited.

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.

Sound-Making Actions Lead to Immediate Plastic Changes of Neuromagnetic Evoked Responses and Induced β-Band Oscillations during Perception

Auditory and sensorimotor brain areas interact during the action-perception cycle of sound making. Neurophysiological evidence of a feedforward model of the action and its outcome has been associated with attenuation of the N1 wave of auditory evoked responses elicited by self-generated sounds, such as talking and singing or playing a musical instrument. Moreover, neural oscillations at β-band frequencies have been related to predicting the sound outcome after action initiation. We hypothesized that a newly learned action-perception association would immediately modify interpretation of the sound during subsequent listening. Nineteen healthy young adults (7 female, 12 male) participated in three magnetoencephalographic recordings while first passively listening to recorded sounds of a bell ringing, then actively striking the bell with a mallet, and then again listening to recorded sounds. Auditory cortex activity showed characteristic P1-N1-P2 waves. The N1 was attenuated during sound making, while P2 responses were unchanged. In contrast, P2 became larger when listening after sound making compared with the initial naive listening. The P2 increase occurred immediately, while in previous learning-by-listening studies P2 increases occurred on a later day. Also, reactivity of β-band oscillations, as well as θ coherence between auditory and sensorimotor cortices, was stronger in the second listening block. These changes were significantly larger than those observed in control participants (eight female, five male), who triggered recorded sounds by a key press. We propose that P2 characterizes familiarity with sound objects, whereas β-band oscillation signifies involvement of the action-perception cycle, and both measures objectively indicate functional neuroplasticity in auditory perceptual learning.SIGNIFICANCE STATEMENT While suppression of auditory responses to self-generated sounds is well known, it is not clear whether the learned action-sound association modifies subsequent perception. Our study demonstrated the immediate effects of sound-making experience on perception using magnetoencephalographic recordings, as reflected in the increased auditory evoked P2 wave, increased responsiveness of β oscillations, and enhanced connectivity between auditory and sensorimotor cortices. The importance of motor learning was underscored as the changes were much smaller in a control group using a key press to generate the sounds instead of learning to play the musical instrument. The results support the rapid integration of a feedforward model during perception and provide a neurophysiological basis for the application of music making in motor rehabilitation training.

Physical and mental effort disrupts the implicit sense of agency

We investigated the effect of effort on implicit agency ascription for actions performed under varying levels of physical effort or cognitive load. People are able to estimate the interval between two events accurately, but they underestimate the interval between their own actions and their outcomes. This effect is known as 'intentional binding', and may provide feedback regarding the consequences of our actions. Concurrently with the interval reproduction task, our participants pulled sports resistance bands at high and low resistance levels (Experiments 1 and 2), or performed a working memory task with high and low set-sizes (Experiment 3). Intentional binding was greater under low than high effort. When the effort was task-related (Experiment 1), this effect depended on the individual's explicit appraisal of exertion, while the effect of effort was evident at the group level when the effort was task-unrelated (physical, Experiment 2; mental, Experiment 3). These findings imply that the process of intentional binding is compromised when cognitive resources are depleted, either through physical or mental strain. We discuss this notion in relation to the integration of direct sensorimotor feedback with signals of agency and other instances of cognitive resource depletion and action control during strain.

Cultural Differences in Perceiving Sounds Generated by Others: Self Matters

Sensory consequences resulting from own movements receive different neural processing compared to externally generated sensory consequences (e.g., by a computer), leading to sensory attenuation, i.e., a reduction in perceived intensity or brain evoked responses. However, discrepant findings exist from different cultural regions about whether sensory attenuation is also present for sensory consequences generated by others. In this study, we performed a cross culture (between Chinese and British) comparison on the processing of sensory consequences (perceived loudness) from self and others compared to an external source in the auditory domain. We found a cultural difference in processing sensory consequences generated by others, with only Chinese and not British showing the sensory attenuation effect. Sensory attenuation in this case was correlated with independent self-construal scores. The sensory attenuation effect for self-generated sensory consequences was not replicated. However, a correlation with delusional ideation was observed for British. These findings are discussed with respects to mechanisms of sensory attenuation.