Continuous dynamics of cooperation and competition in social decision-making

In recent research paper published in Communications Psychology, Lewen et al., (2025) introduced a novel and methodologically groundbreaking experimental paradigm i.e., the continuous Cooperation-Competition Foraging (CCF) Game. This paradigm was designed to capture how cooperation and competition emerge dynamically in continuous time and space during real social interactions. By overcoming the limitations of traditional discrete game tasks, the study embedded social decision-making within a naturalistic context by incorporating real-time perception-action coupling, face-to-face visual access, continuous movement, and immediate feedback. This approach offered a more ecologically valid representation of social behavior, aligning it more closely with real-world dynamics of social interactions.The most significant contribution of this work lies in its shift from "turn-based, discrete, symbolic" frameworks of classical game paradigms to a "continuous, embodied, interactive" perspective grounded in dynamical systems theory, a well-established framework for understanding how complex interacting processes evolve over time in cognitive and social behavior (Gordon et al., 2021;Priorelli et al., 2025;Schöner, 2023;Spivey, 2023;Yoo et al., 2021). In traditional paradigms such as the Prisoner's Dilemma, Ultimatum Game, or Public Goods Game, participants typically make binary or limited-choice decisions in discrete trials where decision-making and action are temporally separated, and there is a lack of real-time visible behavioral cues (Schilbach et al., 2013). Although such setups are conducive to modeling, they are limited in ecological validity and fail to capture continuous flow of information, bodily coordination, and real-time strategic adjustments inherent in real-world social interactions. In contrast, the CCF paradigm developed by Lewen et al., (2025) enabled participants to express their strategies through continuous movement trajectories and adjust their behavior on a millisecond-scale based on the actions of the partner they were interacting with, thus, embodying the concept of "decide-while-acting." This design more authentically replicates social decision-making processes observed in everyday life, offering a dynamic perspective rather than a static choice model. Notably, Lewen et al., (2025) demonstrated that dyads spontaneously converge toward relatively stable set-points along a cooperation-competition spectrum, forming cooperative, intermediate, and competitive groups. Rather than adopting extreme strategies, most dyads stabilized around intermediate patterns. Through computational modeling, the authors showed that weighted path minimization, combined with across-cycle predictors such as invitations and target history, predicted dyadic choices with high accuracy (87%). These findings suggest that social coordination emerges from a dynamic interplay between low-level sensorimotor coupling and higher-order strategic preferences.Taken together, Lewen et al. (2025) contribute not only a sophisticated and thoughtfully designed behavioral paradigm, but also a conceptually important framework for social neuroscience. By integrating real-time visual access, continuous behavioral exchange, immediate feedback, and ecologically relevant information such as action history, current position, and the partner's ongoing behavioral state, the CCF paradigm captures social decision-making in a way that is far closer to natural interactive contexts than traditional laboratory tasks. At the neuroscientific level, the paradigm is equally important because it renders social decision-making tractable not merely as a final choice outcome, but as a temporally extended process composed of transient interaction events and ongoing decision dynamics that can be related to neural activity. In this sense, the CCF paradigm offers a strong foundation for future work aimed at linking continuous social interaction with neural processes across multiple levels of analysis.A major strength of this study lies in its remarkably inventive experimental design, which is both technically ambitious and methodologically illuminating. At the center of the paradigm is a large transparent bidirectional display positioned between two participants seated face-to-face, such that the game unfolds on the screen while each participant can simultaneously see the other through it. This arrangement is far more demanding and resource-intensive than conventional computer-based social decision-making paradigms, but precisely for that reason it represents a remarkable methodological commitment to ecological validity. Rather than reducing social choice to isolated responses on separate screens, the design preserves a critical feature of real-world interaction: people make decisions while continuously monitoring one another's facial expressions, body posture, movement tendencies, and moment-to-moment behavioral adjustments. As a result, participants can modify their own choices online in light of the partner's visible reactions, making the unfolding decision process much closer to how cooperation and competition operate in everyday social life. In this sense, the transparent-screen setup is not merely an unusual or clever piece of apparatus. It is a genuinely original and highly informative design innovation that transforms the experimental situation itself, allowing social decisions to emerge under conditions of continuous mutual visibility, embodied responsiveness, and ongoing interpersonal exchange. Precisely because such transparent interactive displays remain rare in behavioral research, their use here is especially creative and consequential, opening a methodological space that most traditional paradigms simply cannot access.Beyond the ingenuity of the apparatus itself, a second and equally important advantage is that the interaction remains continuously structured and behaviorally informative throughout the task. The game unfolds in a shared two-dimensional space in which both agents, all targets, and the evolving payoff structure are visible to both participants at all times. Crucially, the task preserves continuity from one moment to the next: after a target is collected, new targets appear without resetting the positions of the agents or the remaining items, so the shared spatial situation continues to evolve rather than restarting from scratch. This absence of clearly demarcated trial boundaries is methodologically important, because it allows interaction history to accumulate and shape subsequent decisions. Participants do not repeatedly return to a neutral starting point; instead, each new movement and choice is made against the background of prior coordination, hesitation, concession, or defection. In this way, strategy formation becomes path-dependent, making it possible to observe how cooperative tendencies are built up, stabilized, disrupted, or repaired over time. Under these conditions, each action unfolds through continuous mutual responsiveness: participants can monitor one another's movements, adjust to changing spatial relations, and coordinate their behavior moment by moment rather than making isolated choices in discretized rounds. This makes the task closer to a naturalistic "decide-while-acting" situation, in which action and social evaluation unfold together in real time. Just as importantly, this continuous mutual visibility generates process-level behavioral evidence that conventional round-based paradigms cannot provide. Because movements were tracked at high temporal resolution, the study could analyze invitations, leader-follower dynamics, miscoordination, curved trajectories, and other within-trial interaction patterns, thereby opening access to the microdynamics of social decisionmaking rather than only its final outcomes.The target and payoff structure is another particularly insightful feature of the design. At every moment, participants faced one single target worth 7 cents to one player alone and two joint targets that required cooperation but distributed payoffs asymmetrically as 5/2 and 2/5. This is an elegant solution because the total joint payoff of the cooperative and non-cooperative options is held constant, avoiding a trivial incentive bias toward either target type, while the asymmetry within the cooperative options creates the conditions under which one participant can accept a less favorable immediate outcome for the partner's benefit. In turn, this makes prosocial intent behaviorally legible and allows the study to capture whether such short-term concessions are later reciprocated, thereby revealing how reciprocal cooperation can be established and maintained over repeated interactions.Equally important, the design preserves a genuinely graded strategic space rather than reducing social choice to a forced opposition between cooperation and competition. Because the task repeatedly confronts participants with alternatives that differ in coordination demands and payoff distribution, it allows stable cooperation, partial cooperation, opportunistic defection, and dynamically shifting strategies to emerge within the same framework. This is methodologically important because it prevents behavior from being artificially compressed into a binary classification and instead makes it possible to study how social preferences vary in degree, consistency, and temporal stability. In this way, the experiment is informative not only about whether cooperation occurs, but about how cooperative tendencies are sustained, weakened, or strategically revised over time.For future behavioral research, the CCF paradigm offers an excellent template for studying social decision-making. Its high temporal resolution, continuous interaction without repeated trial resets, face-to-face visibility, and carefully balanced incentive structure enable researchers to track the realtime unfolding of social decision-making while linking these dynamics to observable outcomes within a single framework, including choices, movement trajectories, coordination signals, finegrained interaction behaviors such as position holding, waiting, hesitation, and reciprocal adjustment, as well as latent social motives. For that reason, the present design should be regarded not merely as a clever task for one specific study, but as a methodological model for how social decision-making experiments can move beyond static, trial-based paradigms toward richer and more ecologically grounded forms of interaction.A central contribution of the CCF paradigm introduced in the target article (Lewen et al., 2025) is that it makes social decision-making more tractable for neuroscience by transforming it from a discrete outcome into a temporally extended and behaviorally annotated process. By enabling continuous, face-to-face interaction while generating high-temporal-resolution behavioral measures and model-based estimates of target choice, choice certainty, and spatiotemporal coordination, the paradigm creates quantifiable variables that can be aligned with neural activity. The study therefore does more than demonstrate that cooperation and competition can be examined in a more naturalistic format; it provides a behavioral and computational framework rich enough to support future neural analyses of naturalistic social interaction.First, this design is especially promising for event-locked social neuroscience, because it reveals interaction events that are largely inaccessible in conventional discrete, trial-based paradigms. In standard economic games, neural activity is typically aligned to coarse markers such as stimulus onset, button press, or feedback (Batten et al., 2024;Guo et al., 2022;Numano et al., 2026;Wang et al., 2021). By contrast, the present paradigm identifies fine-grained social events within continuous interaction, including invitations to cooperate, failed invitations, leader-follower episodes, concurrent approaches to the same target, movement-based hesitation or redirection, and overt breakdowns of coordination in which the two agents commit to different targets. This feature opens the door to asking more specific neural questions: which brain signals a cooperative the or of an a competitive for a single target, or a from an cooperative In that sense, the paradigm could neuroscience to move beyond such as toward the neural of that and more importantly, the paradigm is well positioned to support the study of decision formation as a continuous neural process. 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