Prediction in joint action: what, when, and where

Sharing a bimanual task between two: evidence of temporal alignment in interpersonal coordination

In recent years, researchers have made many new discoveries in the field of social interaction and have attempted to understand the mechanisms of interpersonal coordination. This research is marked by two streams: On the one hand, there are attempts to explain spontaneous, incidental interpersonal coordination in terms of the behavioral dynamics perspective, and on the other, to explain instructed, intentional interpersonal coordination in terms of joint action. Other paradigms fall somewhere between incidental and intentional coordination, e.g. task sharing paradigms. The present study has two major objectives. First, we wanted to explore to what extent a dyadic scenario for bimanual coordination mimics typical signatures of bimanual coordination performance as obtained in the classical individual scenario. Second, if such mimicking is obtained, we wanted to investigate the kind of information on which the coordination between the two individuals may be grounded. To do so, we used a bimanual aiming task, which enabled us to assess measurements of two levels of coordination: global (operating over longer periods of time) and local (operating on each particular trial). In Experiment 1, this task was performed in an individual and in a dyadic setting. In the dyadic scenario, we observed strong global coordination and weak local coordination. In Experiment 2, we replicated this pattern and showed that different kinds of feedback had no impact on interpersonal coordination. Based on these findings, we propose that interpersonal coordination in a non-rhythmic choice response task is based on weak interpersonal coordination.

Joint action modulates motor system involvement during action observation in 3-year-olds

When we are engaged in a joint action, we need to integrate our partner’s actions with our own actions. Previous research has shown that in adults the involvement of one’s own motor system is enhanced during observation of an action partner as compared to during observation of an individual actor. The aim of this study was to investigate whether similar motor system involvement is present at early stages of joint action development and whether it is related to joint action performance. In an EEG experiment with 3-year-old children, we assessed the children’s brain activity and performance during a joint game with an adult experimenter. We used a simple button-pressing game in which the two players acted in turns. Power in the mu- and beta-frequency bands was compared when children were not actively moving but observing the experimenter’s actions when (1) they were engaged in the joint action game and (2) when they were not engaged. Enhanced motor involvement during action observation as indicated by attenuated sensorimotor mu- and beta-power was found when the 3-year-olds were engaged in the joint action. This enhanced motor activation during action observation was associated with better joint action performance. The findings suggest that already in early childhood the motor system is differentially activated during action observation depending on the involvement in a joint action. This motor system involvement might play an important role for children’s joint action performance.

Motor execution affects action prediction

Previous studies provided evidence of the claim that the prediction of occluded action involves real-time simulation. We report two experiments that aimed to study how real-time simulation is affected by simultaneous action execution under conditions of full, partial or no overlap between observed and executed actions. This overlap was analysed by comparing the body sides and the movement kinematics involved in the observed and the executed action. While performing actions, participants observed point-light (PL) actions that were interrupted by an occluder, followed by a test pose. The task was to judge whether the test pose depicted a continuation of the occluded action in the same depth angle. Using a paradigm proposed by Graf et al., we independently manipulated the duration of the occluder and the temporal advance of the test pose relative to occlusion onset (occluder time and pose time, respectively). This paradigm allows the assessment of real-time simulation, based on prediction performance across different occluder time/pose time combinations (i.e., improved task performance with decreasing time distance between occluder time and pose time is taken to reflect real-time simulation). The PL actor could be perceived as from the front or back, as indicated by task instructions. In Experiment 1 (front view instructions), evidence of action simulation was obtained for partial overlap (i.e., observed and performed action corresponded either in body side or movement kinematics), but not for full or no overlap conditions. The same pattern was obtained in Experiment 2 (back view instructions), ruling out a spatial compatibility explanation for the real-time pattern observed. Our results suggest that motor processes affect action prediction and real-time simulation. The strength of their impact varies as a function of the overlap between observed and executed actions.

Giving a helping hand: effects of joint attention on mental rotation of body parts

Research on joint attention has addressed both the effects of gaze following and the ability to share representations. It is largely unknown, however, whether sharing attention also affects the perceptual processing of jointly attended objects. This study tested whether attending to stimuli with another person from opposite perspectives induces a tendency to adopt an allocentric rather than an egocentric reference frame. Pairs of participants performed a handedness task while individually or jointly attending to rotated hand stimuli from opposite sides. Results revealed a significant flattening of the performance rotation curve when participants attended jointly (experiment 1). The effect of joint attention was robust to manipulations of social interaction (cooperation versus competition, experiment 2), but was modulated by the extent to which an allocentric reference frame was primed (experiment 3). Thus, attending to objects together from opposite perspectives makes people adopt an allocentric rather than the default egocentric reference frame.

The role of temporal prediction abilities in interpersonal sensorimotor synchronization

Musical ensemble performance is a form of joint action that requires highly precise yet flexible interpersonal action coordination. To maintain synchrony during expressive passages that contain tempo variations, musicians presumably anticipate the sounds that will be produced by their co-performers. Our previous studies revealed that individuals differ in their ability to predict upcoming event timing when finger tapping in synchrony with tempo-changing pacing signals (i.e., the degree to which inter-tap intervals match vs. lag behind inter-onset intervals in the pacing signal varies between individuals). The current study examines the influence of these individual differences on synchronization performance in a dyadic tapping task. In addition, the stability of individual prediction tendencies across time is tested. Individuals with high or low prediction tendencies were invited to participate in two experimental sessions. In both sessions, participants were asked (1) to tap alone with a tempo-changing pacing signal and (2) to tap synchronously in dyads comprising individuals with similar or different prediction tendencies. Results indicated that individual differences in prediction tendencies were stable over several months and played a significant role in dyadic synchronization. Dyads composed of two high-predicting individuals tapped with higher accuracy and less variability than low-predicting dyads, while mixed dyads were intermediate. Prediction tendencies explained variance in dyadic synchronization performance over and above individual synchronization ability. These findings suggest that individual differences in temporal prediction ability may potentially mediate the interaction of cognitive, motor, and social processes underlying musical joint action.

Communicative interactions improve visual detection of biological motion

BACKGROUND

In the context of interacting activities requiring close-body contact such as fighting or dancing, the actions of one agent can be used to predict the actions of the second agent. In the present study, we investigated whether interpersonal predictive coding extends to interactive activities--such as communicative interactions--in which no physical contingency is implied between the movements of the interacting individuals.

METHODOLOGY/PRINCIPAL FINDINGS

Participants observed point-light displays of two agents (A and B) performing separate actions. In the communicative condition, the action performed by agent B responded to a communicative gesture performed by agent A. In the individual condition, agent A's communicative action was substituted with a non-communicative action. Using a simultaneous masking detection task, we demonstrate that observing the communicative gesture performed by agent A enhanced visual discrimination of agent B.

CONCLUSIONS/SIGNIFICANCE

Our finding complements and extends previous evidence for interpersonal predictive coding, suggesting that the communicative gestures of one agent can serve as a predictor for the expected actions of the respondent, even if no physical contact between agents is implied.

Tempo rubato : animacy speeds up time in the brain

Background

How do we estimate time when watching an action? The idea that events are timed by a centralized clock has recently been called into question in favour of distributed, specialized mechanisms. Here we provide evidence for a critical specialization: animate and inanimate events are separately timed by humans.

Methodology/Principal Findings

In different experiments, observers were asked to intercept a moving target or to discriminate the duration of a stationary flash while viewing different scenes. Time estimates were systematically shorter in the sessions involving human characters moving in the scene than in those involving inanimate moving characters. Remarkably, the animate/inanimate context also affected randomly intermingled trials which always depicted the same still character.

Conclusions/Significance

The existence of distinct time bases for animate and inanimate events might be related to the partial segregation of the neural networks processing these two categories of objects, and could enhance our ability to predict critically timed actions.

Toward You

Humans spend most of their time interacting with other people. It is the motor organization subtending these social interactions that forms the main theme of this article. We review recent experimental studies testing whether it is possible to differentiate the kinematics of an action performed by an agent acting in isolation from the kinematics of the very same action performed within a social context. The results indicate that social context shapes action planning and that in the context of a social interaction, flexible online adjustments take place between partners. These observations provide novel insights on the social dimension of motor planning and control.

The performance and observation of action shape future behaviour

The observation of other people's actions plays an important role in shaping the perceptual, cognitive, and motor processes of the observer. It has been suggested that these social influences occur because the observation of action evokes a representation of that response in the observer and that these codes are subsequently accessed by other cognitive systems to modify future behaviour. In the case of social search and movement tasks, the observation-evoked response code is thought to activate the same mechanisms that are activated following internally-generated response codes. In support of this hypothesis, the present study revealed that the magnitudes of the between-person inhibition of return (IOR) effects were correlated with within-person IOR effects. These findings provide substantial support for the link between observation-evoked response codes and social cognitive effects.