Cordula Vesper
Aarhus University, Linguistics, Cognitive Science and Semiotics, Faculty Member
When people engage in rhythmic joint actions, from simple clapping games to elaborate joint music making, they tend to increase their tempo unconsciously. Despite the rich literature on rhythmic performance in humans, the mechanisms... more
When people engage in rhythmic joint actions, from simple clapping games to elaborate joint music making, they tend to increase their tempo unconsciously. Despite the rich literature on rhythmic performance in humans, the mechanisms underlying joint rushing are still unknown. We propose that joint rushing arises from the concurrent activity of two separate mechanisms. the phase advance mechanism was first proposed in research on synchronously flashing fireflies and chorusing insects. When this mechanism is combined with a human-specific period correction mechanism, the shortened periods of individual intervals are translated into a tempo increase. In three experiments, we investigated whether joint rushing can be reliably observed in a joint synchronization-continuation drumming task. Furthermore, we asked whether perceptual similarities produced by the actions of different individuals modulate the joint rushing effect. The results showed that joint rushing is a robust phenomenon occurring in groups of different sizes. Joint rushing was more pronounced when the action effects produced by different individuals were perceptually similar, supporting the assumption that a phase advance mechanism contributed to rushing. Further control conditions ruled out the alternative hypothesis that rushing during rhythmic interactions can be explained by social facilitation or action mirroring effects. When humans engage in synchronized, rhythmic joint activities, they tend to increase their pace unconsciously. Even though this phenomenon appears to be ubiquitous and well known among musicians, dancers and their audiences 1-5 , it has hardly been addressed in research on timing mechanisms in humans (except for two recent studies 6,7). Thus, despite the rich literature on the cognitive and neural bases of rhythmic performance in humans 8,9 , the psychological mechanisms underlying joint rushing are still unknown. We argue that if joint rushing indeed emerges from human interaction in contrast to purely individual processes , then predominant models of inter-subjective sensorimotor synchronization are incomplete. Specifically, they do not consider how sounds produced during synchronous, rhythmic joint actions are integrated to result in specific patterns of tempo drift. Thus, the systematic study of joint rushing has potential to lead to more adequate models of inter-personal coordination by identifying missing components. In this article, we first present evidence that joint rushing is a robust phenomenon that emerges in interpersonal sensorimotor synchronization. As an explanation for joint rushing, we then propose a combination of two mechanisms, a period correction mechanism, which is a standard component of models of human sensorimotor synchronization 10 , with a phase advance mechanism, a mechanism that has been proposed to regulate rhythmic synchronicity in some firefly species and chorusing insects 11 .
In joint action, multiple people coordinate their actions to perform a task together. This often requires precise temporal and spatial coordination. How do co-actors achieve this? How do they coordinate their actions toward a shared task... more
In joint action, multiple people coordinate their actions to perform a task together. This often requires precise temporal and spatial coordination. How do co-actors achieve this? How do they coordinate their actions toward a shared task goal? Here, we provide an overview of the mental representations involved in joint action, discuss how co-actors share sensorimotor information and what general mechanisms support coordination with others. By deliberately extending the review to aspects such as the cultural context in which a joint action takes place, we pay tribute to the complex and variable nature of this social phenomenon.
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Joint Action is typically described as social interaction that requires coordination among two or more co-actors in order to achieve a common goal. In this article, we put forward a hypothesis for the existence of a neural-computational... more
Joint Action is typically described as social interaction that requires coordination among two or more co-actors in order to achieve a common goal. In this article, we put forward a hypothesis for the existence of a neural-computational mechanism of affective valuation that may be critically exploited in Joint Action. Such a mechanism would serve to facilitate coordination between co-actors permitting a reduction of required information. Our hypothesized affective mechanism provides a value function based implementation of Associative Two-Process (ATP) theory that entails the classification of external stimuli according to outcome expectancies. This approach has been used to describe animal and human action that concerns differential outcome expectancies. Until now it has not been applied to social interaction. We describe our Affective ATP model as applied to social learning consistent with an " extended common currency " perspective in the social neuroscience literature. We contrast this to an alternative mechanism that provides an example implementation of the so-called social-specific value perspective. In brief, our Social-Affective ATP mechanism builds upon established formalisms for reinforcement learning (temporal difference learning models) nuanced to accommodate expectations (consistent with ATP theory) and extended to integrate non-social and social cues for use in Joint Action.
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Previous research has identified a number of coordination processes that enable people to perform joint actions. But what determines which coordination processes joint action partners rely on in a given situ-ation? The present study... more
Previous research has identified a number of coordination processes that enable people to perform joint actions. But what determines which coordination processes joint action partners rely on in a given situ-ation? The present study tested whether varying the shared visual information available to co-actors can trigger a shift in coordination processes. Pairs of participants performed a movement task that required them to synchronously arrive at a target from separate starting locations. When participants in a pair received only auditory feedback about the time their partner reached the target they held their movement duration constant to facilitate coordination. When they received additional visual information about each other's movements they switched to a fundamentally different coordination process, exaggerating the curvature of their movements to communicate their arrival time. These findings indicate that the availability of shared perceptual information is a major factor in determining how individuals coordinate their actions to obtain joint outcomes.
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People performing joint actions coordinate their individual actions with each other to achieve a shared goal. The current study investigated the mental representations that are formed when people learn a new skill as part of a joint... more
People performing joint actions coordinate their individual actions with each other to achieve a shared goal. The current study investigated the mental representations that are formed when people learn a new skill as part of a joint action. In a musical transfer-of-learning paradigm, piano novices first learned to perform simple melodies in the joint action context of coordinating with an accompanist to produce musical duets. Participants then performed their previously learned actions with two types of auditory feedback: while hearing either their individual action goal (the melody) or the shared action goal (the duet). As predicted, participants made more performance errors in the individual goal condition than in the shared goal condition. Further experimental manipulations indicated that this difference was not due to different coordination requirements in the two conditions or perceptual dissimilarities between learning and test. Together, these findings indicate that people form representations of shared goals in contexts that promote minimal representations, such as when learning a new action together with another person.
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How is coordination achieved in asymmetric joint actions where co-actors have unequal access to task information? Pairs of participants performed a non-verbal tapping task with the goal of synchronizing taps to different targets. We... more
How is coordination achieved in asymmetric joint actions where co-actors have unequal access to task information? Pairs of participants performed a non-verbal tapping task with the goal of synchronizing taps to different targets. We tested whether 'Leaders' knowing the target locations would support 'Followers' without this information. Experiment 1 showed that Leaders tapped with higher amplitude that also scaled with specific target distance, thereby emphasizing differences between correct targets and possible alternatives. This strategic communication only occurred when Leaders' movements were fully visible, but not when they were partially occluded. Full visual information between co-actors also resulted in higher and more stable behavioral coordination than partial vision. Experiment 2 showed that Leaders' amplitude adaptation facilitated target prediction by independent Observers. We conclude that fully understanding joint action coordination requires b...
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When two or more people perform actions together such as shaking hands, playing ensemble music or carrying an object together, they often naturally adjust the spatial and temporal parameters of their movements to facilitate smooth task... more
When two or more people perform actions together such as shaking hands, playing ensemble music or carrying an object together, they often naturally adjust the spatial and temporal parameters of their movements to facilitate smooth task performance. This paper reviews recent findings from experiments with human participants to demonstrate ways in which individuals strategically modulate their own action performance to support a task partner in predicting their actions and thereby facilitate coordination. Based on this evidence, it is discussed how strategic action modulation (“action signaling”) might be a useful approach also for robotic systems to assist human users, thereby reducing cognitive load and flexibly supporting the acquisition of new skills.
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How do people imagine performing actions together? The present study investigated motor imagery of joint actions that requires integrating one's own and another's part of an action. In two experiments, individual participants imagined... more
How do people imagine performing actions together? The present study investigated motor imagery of joint actions that requires integrating one's own and another's part of an action. In two experiments, individual participants imagined jumping alone or jointly next to an imagined partner. The joint condition required coordinating one's own imagined actions with an imagined partner's actions to synchronize landing times. We investigated whether the timing of participants' own imagined jumps would reflect the difference in jump distance to their imagined partner's jumps. The results showed that participants' jump imagery was indeed modulated to achieve coordination with an imagined task partner, confirming prior findings from a performance task. Moreover, when manipulating both target distance and target size, the same violation of Fitts' law reported for individual jumping was present in imagery of joint jumping. These findings link research on motor imagery and joint action, demonstrating that individuals are able to integrate simulations of different parts of a joint action.
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What kinds of processes and representations make joint action possible? In this paper, we suggest a minimal architecture for joint action that focuses on representations, action monitoring and action prediction processes, as well as ways... more
What kinds of processes and representations make joint action possible? In this paper, we suggest a minimal architecture for joint action that focuses on representations, action monitoring and action prediction processes, as well as ways of simplifying coordination. The architecture spells out minimal requirements for an individual agent to engage in a joint action. We discuss existing evidence in support of the architecture as well as open questions that remain to be empirically addressed. In addition, we suggest possible interfaces between the minimal architecture and other approaches to joint action. The minimal architecture has implications for theorising about the emergence of joint action, for human-machine interaction, and for understanding how coordination can be facilitated by exploiting relations between multiple actions and between actions and the environment.