Sensory attenuation for jointly produced action effects

Sense of agency in joint action: a critical review of we-agency

The sense of agency refers to the experience of control over voluntary actions and their effects. There is growing interest in the notion of we-agency, whereby individual sense of agency is supplanted by a collective agentic experience. The existence of this unique agentic state would have profound implications for human responsibility, and, as such, warrants further scrutiny. In this paper, we review the concept of we-agency and examine whether evidence supports it. We argue that this concept entails multiplying hypothetical agentic states associated with joint action, thus ending up with an entangled phenomenology that appears somewhat speculative when weighted against the available evidence. In light of this, we suggest that the concept of we-agency should be abandoned in favor of a more parsimonious framework for the sense of agency in joint action.

Movement predictability modulates sensorimotor processing

Introduction

An important factor for optimal sensorimotor control is how well we are able to predict sensory feedback from internal and external sources during movement. If predictability decreases due to external disturbances, the brain is able to adjust muscle activation and the filtering of incoming sensory inputs. However, little is known about sensorimotor adjustments when predictability is increased by availability of additional internal feedback. In the present study we investigated how modifications of internal and external sensory feedback influence the control of muscle activation and gating of sensory input.

Methods

Co-activation of forearm muscles, somatosensory evoked potentials (SEP) and short afferent inhibition (SAI) were assessed during three object manipulation tasks designed to differ in the predictability of sensory feedback. These included manipulation of a shared object with both hands (predictable coupling), manipulation of two independent objects without (uncoupled) and with external interference on one of the objects (unpredictable coupling).

Results

We found a task-specific reduction in co-activation during the predictable coupling compared to the other tasks. Less sensory gating, reflected in larger subcortical SEP amplitudes, was observed in the unpredictable coupling task. SAI behavior was closely linked to the subcortical SEP component indicating an important function of subcortical sites in predictability related SEP gating and their direct influence on M1 inhibition.

Discussion

Together, these findings suggest that the unpredictable coupling task cannot only rely on predictive forward control and is compensated by enhancing co-activation and increasing the saliency for external stimuli by reducing sensory gating at subcortical level. This behavior might serve as a preparatory step to compensate for external disturbances and to enhance processing and integration of all incoming external stimuli to update the current sensorimotor state. In contrast, predictive forward control is accurate in the predictable coupling task due to the integrated sensory feedback from both hands where sensorimotor resources are economized by reducing muscular co-activation and increasing sensory gating.

The auditory P2 differentiates self- from partner-produced sounds during joint action: Contributions of self-specific attenuation and temporal orienting of attention

Sensory attenuation of the auditory P2 event-related potential (ERP) has been shown to differentiate the sensory consequences of one's own from others' action in joint action contexts. However, recent evidence suggests that when people coordinate joint actions over time, temporal orienting of attention might simultaneously contribute to enhancing the auditory P2. The current study employed a joint tapping task in which partners produced tone sequences together to examine whether temporal orienting influences auditory ERP amplitudes during the time window of self-other differentiation. Our findings demonstrate that the combined requirements of coordinating with a partner toward a joint goal and immediately adjusting to the partner's tone timing enhance P2 amplitudes elicited by the partner's tone onsets. Furthermore, our findings replicate prior evidence for self-specific sensory attenuation of the auditory P2 in joint action, and additionally demonstrate that it occurs regardless of the coordination requirements between partners. Together, these findings provide evidence that temporal orienting and sensory attenuation both modulate the auditory P2 during joint action and suggest that both processes play a role in facilitating precise interpersonal coordination between partners.

The sense of agency in joint action: An integrative review

When people perform joint actions together, their individual actions (e.g., moving one end of a heavy couch) must be coordinated to achieve a collective goal (e.g., moving the couch across the room). Joint actions pose unique challenges for understanding people's sense of agency, because each person engaged in the joint action can have a sense of agency not only at the individual level (a sense that "I moved my end of the couch" or "My partner moved their end of the couch"), but also at the collective level (a sense that "We moved the couch together"). This review surveys research that has examined people's sense of agency in joint action, including explicit judgments of agency, implicit measures of agency, and first-hand accounts of agency in real-world settings. The review provides a comprehensive summary of the factors that influence individual- and collective-level agency in joint action; reveals the progress that has been made toward understanding different forms of collective-level agency in joint action, including the sense that agency is shared among co-actors and the sense that co-actors are acting as a single unit; and synthesizes evidence concerning the relationships between different measures of implicit agency and individual- versus collective-level agency in joint action. The review concludes by highlighting numerous outstanding questions and promising avenues for future research.

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.

Processing and utilization of auditory action effects in individual and social tasks

The influence of action-effect integration on motor control and sensory processing is often investigated in arrangements featuring human-machine interactions. Such experiments focus on predictable sensory events produced through participants' interactions with simple response devices. Action-effect integration may, however, also occur when we interact with human partners. The current study examined the similarities and differences in perceptual and motor control processes related to generating sounds with or without the involvement of a human partner. We manipulated the complexity of the causal chain of events between the initial motor and the final sensory event. In the self-induced condition participants generated sounds directly by pressing a button, while in the interactive condition sounds resulted from a paired reaction-time task, that is, the final sound was generated indirectly, by relying on the contribution of the partner. Auditory event-related potentials (ERPs) and force application patterns were similar in the two conditions, suggesting that social action effects produced with the involvement of a second human agent in the causal sequence are processed, and utilized as action feedback in the same way as direct consequences of one's actions. The only reflection of a processing difference between the two conditions was a slow, posterior ERP waveform that started before the presentation of the auditory stimulus, which may reflect differences in stimulus expectancy or task difficulty.

Implicit Agency in Observed Actions: Evidence for N1 Suppression of Tones Caused by Self-made and Observed Actions

Every day we make attributions about how our actions and the actions of others cause consequences in the world around us. It is unknown whether we use the same implicit process in attributing causality when observing others' actions as we do when making our own. The aim of this research was to investigate the neural processes involved in the implicit sense of agency we form between actions and effects, for both our own actions and when watching others' actions. Using an interval estimation paradigm to elicit intentional binding in self-made and observed actions, we measured the EEG responses indicative of anticipatory processes before an action and the ERPs in response to the sensory consequence. We replicated our previous findings that we form a sense of implicit agency over our own and others' actions. Crucially, EEG results showed that tones caused by either self-made or observed actions both resulted in suppression of the N1 component of the sensory ERP, with no difference in suppression between consequences caused by observed actions compared with self-made actions. Furthermore, this N1 suppression was greatest for tones caused by observed goal-directed actions rather than non-action or non-goal-related visual events. This suggests that top–down processes act upon the neural responses to sensory events caused by goal-directed actions in the same way for events caused by the self or those made by other agents.

Rhythm in joint action: psychological and neurophysiological mechanisms for real-time interpersonal coordination

Human interaction often requires simultaneous precision and flexibility in the coordination of rhythmic behaviour between individuals engaged in joint activity, for example, playing a musical duet or dancing with a partner. This review article addresses the psychological processes and brain mechanisms that enable such rhythmic interpersonal coordination. First, an overview is given of research on the cognitive-motor processes that enable individuals to represent joint action goals and to anticipate, attend and adapt to other's actions in real time. Second, the neurophysiological mechanisms that underpin rhythmic interpersonal coordination are sought in studies of sensorimotor and cognitive processes that play a role in the representation and integration of self- and other-related actions within and between individuals' brains. Finally, relationships between social-psychological factors and rhythmic interpersonal coordination are considered from two perspectives, one concerning how social-cognitive tendencies (e.g. empathy) affect coordination, and the other concerning how coordination affects interpersonal affiliation, trust and prosocial behaviour. Our review highlights musical ensemble performance as an ecologically valid yet readily controlled domain for investigating rhythm in joint action.

Tickle me, I think I might be dreaming! Sensory attenuation, self-other distinction, and predictive processing in lucid dreams

The contrast between self- and other-produced tickles, as a special case of sensory attenuation for self-produced actions, has long been a target of empirical research. While in standard wake states it is nearly impossible to tickle oneself, there are interesting exceptions. Notably, participants awakened from REM (rapid eye movement-) sleep dreams are able to tickle themselves. So far, however, the question of whether it is possible to tickle oneself and be tickled by another in the dream state has not been investigated empirically or addressed from a theoretical perspective. Here, we report the results of an explorative web-based study in which participants were asked to rate their sensations during self-tickling and being tickled during wakefulness, imagination, and lucid dreaming. Our results, though highly preliminary, indicate that in the special case of lucid control dreams, the difference between self-tickling and being tickled by another is obliterated, with both self- and other produced tickles receiving similar ratings as self-tickling during wakefulness. This leads us to the speculative conclusion that in lucid control dreams, sensory attenuation for self-produced tickles spreads to those produced by non-self dream characters. These preliminary results provide the backdrop for a more general theoretical and metatheoretical discussion of tickling in lucid dreams in a predictive processing framework. We argue that the primary value of our study lies not so much in our results, which are subject to important limitations, but rather in the fact that they enable a new theoretical perspective on the relationship between sensory attenuation, the self-other distinction and agency, as well as suggest new questions for future research. In particular, the example of tickling during lucid dreaming raises the question of whether sensory attenuation and the self-other distinction can be simulated largely independently of external sensory input.

Action-based effects on music perception

The classical, disembodied approach to music cognition conceptualizes action and perception as separate, peripheral processes. In contrast, embodied accounts of music cognition emphasize the central role of the close coupling of action and perception. It is a commonly established fact that perception spurs action tendencies. We present a theoretical framework that captures the ways in which the human motor system and its actions can reciprocally influence the perception of music. The cornerstone of this framework is the common coding theory, postulating a representational overlap in the brain between the planning, the execution, and the perception of movement. The integration of action and perception in so-called internal models is explained as a result of associative learning processes. Characteristic of internal models is that they allow intended or perceived sensory states to be transferred into corresponding motor commands (inverse modeling), and vice versa, to predict the sensory outcomes of planned actions (forward modeling). Embodied accounts typically refer to inverse modeling to explain action effects on music perception (Leman, 2007). We extend this account by pinpointing forward modeling as an alternative mechanism by which action can modulate perception. We provide an extensive overview of recent empirical evidence in support of this idea. Additionally, we demonstrate that motor dysfunctions can cause perceptual disabilities, supporting the main idea of the paper that the human motor system plays a functional role in auditory perception. The finding that music perception is shaped by the human motor system and its actions suggests that the musical mind is highly embodied. However, we advocate for a more radical approach to embodied (music) cognition in the sense that it needs to be considered as a dynamical process, in which aspects of action, perception, introspection, and social interaction are of crucial importance.