Abstract

Cooperative interaction often unfolds in real time, with individuals choosing not only what to do but also when to commit. This temporal feature gives rise to an endogenous decision order and can fundamentally alter the dynamics of social dilemmas. Here, we examine how endogenous decision timing shapes human cooperation by comparing two-player social dilemmas across three timing structures: simultaneous, assigned-order sequential, and real-time choices. Across two experiments (N=718), pairs achieved mutual cooperation most often when they interacted in real time. This advantage was not explained by greater cooperation among first movers. Instead, second movers reciprocated cooperation more reliably when the move order emerged endogenously. A belief-dependent reciprocity model captured these patterns, suggesting that real-time interaction can change the meaning of early cooperation for humans. Because players can strategically wait and observe whether the other player acts first, choosing to cooperate early in real time is more demanding than cooperating as an assigned first mover. Voluntary early cooperation thus provides a stronger signal of the first mover’s cooperative intent and increases second movers’ willingness to reciprocate. Real-time interaction facilitates mutual cooperation not by increasing prosociality per se, but by changing the signalling value of actions under strategic uncertainty.

Short Bio

Nobuyuki Hanaki is a professor and the director of the Institute of Social and Economic Research, the University of Osaka. He is also a Visiting Distinguished Research Professor of Economics at the University of Limassol in Cyprus and a member of the Academic Advisory Board of the School of Business at Hang Seng University of Hong Kong. His main research interest lies in understanding the aggregate consequences of interactions among heterogeneous decision makers. He employs mathematical and computational modeling, as well as controlled laboratory experiments, in his research. Results of his research have been published in leading journals such as the Economic Journal, Management Science, Nature Communications, Journal of Political Economy: Microeconomics, Experimental Economics, Games and Economic Behavior, European Economic Review, Journal of Economic Behavior and Organization, and Journal of Economic Dynamics and Control.

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