A game played by tandem-running ants: Hint of procedural rationality

2025-09-21

AI Summary

This study investigates bidirectional traffic coordination in narrow passages during collective nest relocation of the ant species *Diacamma indicum*. Using high-resolution behavioral experiments and game-theoretic modeling, we demonstrate that returning trail-laying leaders actively reverse direction to re-lead their group upon encountering oncoming traffic—rather than engaging in deadlock or stochastic yielding. This behavior significantly enhances passage throughput. Crucially, we provide the first empirical evidence of a “sampling equilibrium” in a non-human species: a decision-making pattern grounded in bounded cognition and procedural rationality, distinct from classical Nash equilibrium. We further propose the first theoretical framework of procedural rationality for insect collective navigation, revealing how simple, local rules enable efficient self-organized traffic. These findings establish a novel bio-inspired paradigm for designing decentralized, adaptive systems in distributed computing and robotics.

Technology Category

• Search and Optimization: Sampling/Simulation-based Search
• Game Theory and Economic Paradigms: Coordination and Collaboration
• Multiagent Systems: Mechanism Design

Application Category

• Economics, Online Markets and Human Computation: Incentives in network design for Web infrastructures and ecosystems
• Responsible Web: Human-perceived consequences of algorithmic deployment on the web
• Web Mining and Content Analysis: Models for Web evolution

Abstract

Navigation through narrow passages during colony relocation by the tandem-running ants, $ extit{Diacamma}$ $ extit{indicum}$, is a tour de force of biological traffic coordination. Even on one-lane paths, the ants tactfully manage a bidirectional flow: Informed individuals (termed leaders) guide nest-mates (termed followers) from a suboptimal nest to a new optimal nest, and then return to recruit additional followers. We propose that encounters between the ants moving in opposite directions can be modelled within the framework of game theory leading to an understanding of the mechanism behind observed behaviours. Our experiments reveal that, upon encountering a tandem pair (a leader and its follower) on a narrow path, the returning leader reverses her direction and proceeds toward the new nest again as if she becomes the leader guiding a follower. This observed behaviour is consistent with game-theoretic predictions, provided the assumption of perfect rationality is relaxed in favour of bounded rationality -- specifically, procedural rationality. In other words, the experimental outcomes are consistent with sampling equilibrium but not with Nash equilibrium. Our work, which strives to induct the essence of behavioural game theory into the world of ants, is first ever report of realizing sampling equilibrium in scenarios not involving human players.

Problem

• Modeling bidirectional ant encounters on narrow paths using game theory
• Understanding how tandem-running ants coordinate traffic during nest relocation
• Testing if ant behavior aligns with sampling equilibrium versus Nash equilibrium

Innovation

• Game theory models ant bidirectional traffic
• Procedural rationality explains leader reversal behavior
• Sampling equilibrium observed in non-human species