Dynamic structure of joint-action stimulus-response activity

The Dynamical Hypothesis in Situ: Challenges and Opportunities for a Dynamical Social Approach to Interpersonal Coordination

Over the past three decades, Van Gelder's dynamical hypothesis has been instrumental in reconceptualizing the ways in which perception-action-cognition unfolds over time and in context. Here, I examine how the dynamical approach has enriched the theoretical understanding of social dynamics within cognitive science, with a particular focus on interpersonal coordination. I frame this review around seven principles in dynamical systems: three that are well-represented in interpersonal coordination research to date (emergent behavior, context-sensitive behavior, and attractors) and four that could be useful opportunities for future growth (hysteresis, sensitivity to initial conditions, equifinality, and reciprocal compensation). In addition to identifying specific promising lines of theoretical inquiry, I focus on the significant potential afforded by computationally intensive science-especially in naturally occurring data or trace data. Building on the foundation laid over the past three decades, I argue that looking to increasingly situated and naturalistic settings (and data) is not only necessary to realize the full commitment to the dynamical hypothesis but is also critical to building parsimonious and principled theories of social phenomena.

Human-like behavioral variability blurs the distinction between a human and a machine in a nonverbal Turing test

Variability is a property of biological systems, and in animals (including humans), behavioral variability is characterized by certain features, such as the range of variability and the shape of its distribution. Nevertheless, only a few studies have investigated whether and how variability features contribute to the ascription of humanness to robots in a human-robot interaction setting. Here, we tested whether two aspects of behavioral variability, namely, the standard deviation and the shape of distribution of reaction times, affect the ascription of humanness to robots during a joint action scenario. We designed an interactive task in which pairs of participants performed a joint Simon task with an iCub robot placed by their side. Either iCub could perform the task in a preprogrammed manner, or its button presses could be teleoperated by the other member of the pair, seated in the other room. Under the preprogrammed condition, the iCub pressed buttons with reaction times falling within the range of human variability. However, the distribution of the reaction times did not resemble a human-like shape. Participants were sensitive to humanness, because they correctly detected the human agent above chance level. When the iCub was controlled by the computer program, it passed our variation of a nonverbal Turing test. Together, our results suggest that hints of humanness, such as the range of behavioral variability, might be used by observers to ascribe humanness to a humanoid robot.

Reaction time coupling in a joint stimulus-response task: A matter of functional actions or likable agents?

Shaping one owns actions by observing others’ actions is driven by the deep-rooted mechanism of perception-action coupling. It typically occurs automatically, expressed as for example the unintentional synchronization of reaction times in interactive games. Theories on perception-action coupling highlight its benefits such as the joint coordination of actions to cooperatively perform tasks properly, the learning of novel actions from others, and the bonding with likable others. However, such functional aspects and how they shape perception-action coupling have never been compared quantitatively. Here we tested a total of hundred-fifteen participants that played a stimulus-response task while, in parallel, they observed videos of agents that played the exact same task several milliseconds in advance. We compared to what degree the reaction times of actions of agents, who varied their behavior in terms of functionality and likability in preceding prisoner dilemma games and quizzes, shape the reaction times of human test participants. To manipulate functionality and likability, we varied the predictability of cooperative behavior and correctness of actions of agents, respectively, resulting in likable (cooperative), dislikable (uncooperative), functional (correct actions), and dysfunctional (incorrect actions) agents. The results of three experiments showed that the participants’ reaction times correlated most with the reaction times of agents that expressed functional behavior. However, the likability of agents had no effects on reaction time correlations. These findings suggest that, at least in the current computer task, participants are more likely to adopt the timing of actions from people that perform correct actions than from people that they like.

Joint Simon effect in movement trajectories

In joint action literature it is often assumed that acting together is driven by pervasive and automatic process of co-representation, that is, representing the co-actor's part of the task in addition to one's own. Much of this research employs joint stimulus-response compatibility tasks varying the stimuli employed or the physical and social relations between participants. In this study we test the robustness of co-representation effects by focusing instead on variation in response modality. Specifically, we implement a mouse-tracking version of a Joint Simon Task in which participants respond by producing continuous movements with a computer mouse rather than pushing discrete buttons. We have three key findings. First, in a replication of an earlier study we show that in a classical individual Simon Task movement trajectories show greater curvature on incongruent trials, paralleling longer response times. Second, this effect largely disappears in a Go-NoGo Simon Task, in which participants respond to only one of the cues and refrain from responding to the other. Third, contrary to previous studies that use button pressing responses, we observe no overall effect in the joint variants of the task. However, we also detect a notable diversity in movement strategies adopted by the participants, with some participants showing the effect on the individual level. Our study casts doubt on the pervasiveness of co-representation, highlights the usefulness of mouse-tracking methodology and emphasizes the need for looking at individual variation in task performance.

Influence of perceived emotion and gender on social motor coordination

Theorists have long postulated that facial properties such as emotion and sex are potent social stimuli that influence how individuals act. Yet extant scientific findings were mainly derived from investigations on the prompt motor response upon the presentation of affective stimuli, which were mostly delivered by means of pictures, videos, or text. A theoretical question remains unaddressed concerning how the perception of emotion and sex would modulate the dynamics of a continuous coordinated behaviour. Conceived in the framework of dynamical approach to interpersonal motor coordination, the present study aimed to address this question by adopting the coupled-oscillators paradigm. Twenty-one participants performed in-phase and anti-phase coordination with two avatars (male and female) displaying three emotional expressions (neutral, happy, and angry) at different frequencies (100% and 150% of the participant's preferred frequency) by executing horizontal rhythmic left-right oscillatory movements. Time to initiate movement (TIM), mean relative phase error (MnRP), and standard deviation of relative phase (SDRP) were calculated as indices of reaction time, deviation from the intended pattern of coordination, and coordination stability, respectively. Results showed that in anti-phase condition at 150% frequency, MnRP was lower with the angry and the female avatar. In addition, coordination was found to be more stable with the male avatar than the female one when both displaying neutral emotion. But the happy female avatar was found to elicit more stable coordination than the neutral female avatar. These results implied that individuals are more relaxed to coordinate with the female than the male, and the sensorimotor system becomes more flexible to coordinate with an angry person. It is also suggested social roles influence how people coordinate, and individuals attend more to interact with a happy female. In sum, the present study evidenced that social perception is embodied in the interactive behaviour during social interaction.

Response Coordination Emerges in Cooperative but Not Competitive Joint Task

Effective social interactions rely on humans' ability to attune to others within social contexts. Recently, it has been proposed that the emergence of shared representations, as indexed by the Joint Simon effect (JSE), might result from interpersonal coordination (Malone et al., 2014). The present study aimed at examining interpersonal coordination in cooperative and competitive joint tasks. To this end, in two experiments we investigated response coordination, as reflected in instantaneous cross-correlation, when co-agents cooperate (Experiment 1) or compete against each other (Experiment 2). In both experiments, participants performed a go/no-go Simon task alone and together with another agent in two consecutive sessions. In line with previous studies, we found that social presence differently affected the JSE under cooperative and competitive instructions. Similarly, cooperation and competition were reflected in co-agents response coordination. For the cooperative session (Experiment 1), results showed higher percentage of interpersonal coordination for the joint condition, relative to when participants performed the task alone. No difference in the coordination of responses occurred between the individual and the joint conditions when co-agents were in competition (Experiment 2). Finally, results showed that interpersonal coordination between co-agents implies the emergence of the JSE. Taken together, our results suggest that shared representations seem to be a necessary, but not sufficient, condition for interpersonal coordination.

Are You Keeping an Eye on Me? The Influence of Competition and Cooperation on Joint Simon Task Performance

Social interaction plays an important role in human life. While there are instances that require cooperation, there are others that force people to compete rather than to cooperate, in order to achieve certain goals. A key question is how the deployment of attention differs between cooperative and competitive situation; however, empirical investigations have yielded inconsistent results. By manipulating the (in-)dependence of individuals via performance-contingent incentives, in a visual go–nogo Simon task the current study aimed at improving our understanding of complementary task performance in a joint action context. In the independent condition each participant received what s/he achieves; in the cooperative condition each participant received the half of what both achieved, and in the competitive condition participants were instructed that the winner takes it all. Extending previous findings, we found sequential processing adjustments of the Simon effect as a function of the interdependency (i.e., competition, cooperation) and transition between (i.e., go–nogo requirements) interacting individuals. While sequential processing adjustments of the Simon effect in both the competition and cooperation condition were unaffected when alternating between responsible actors (i.e., nogo–go transition), sequential processing adjustments were enlarged under competition for repeating responsibilities of one and the same actor (i.e., go–go transitions). In other words, the prospect of performance-contingent reward in a competitive context exclusively impacts flexible behavioral adjustments of one’s own actions. Rather than fostering the consideration and differentiation of the other actor, pushing one’s own performance to the limit appears to be the suitable strategy in competitive instances of complementary tasks. Therefore, people keep their eyes on themselves when aiming at beating a co-actor and emerging as the winner.

Long-range correlations and patterns of recurrence in children and adults' attention to hierarchical displays

In order to make sense of a scene, a person must pay attention to several levels of nested order, ranging from the most differentiated details of the display to the integrated whole. In adults, research shows that the processes of integration and differentiation have the signature of self-organization. Does the same hold for children? The current study addresses this question with children between 6 and 9 years of age, using two tasks that require attention to hierarchical displays. A group of adults were tested as well, for control purposes. To get at the question of self-organization, reaction times were submitted to a detrended fluctuation analysis and a recurrence quantification analysis. H exponents show a long-range correlations (1/f noise), and recurrence measures (percent determinism, maximum line, entropy, and trend), show a deterministic structure of variability being characteristic of self-organizing systems. Findings are discussed in terms of organism-environment coupling that gives rise to fluid attention to hierarchical displays.