Evolution favours positively biased reasoning in sequential interactions with high future gains

2025-08-28

AI Summary

Traditional game theory struggles to explain empirically observed irrational optimism—such as wishful thinking—in sequential social interactions with delayed, high-magnitude future payoffs. Method: We develop an evolutionary model based on the incremental centipede game, integrating level-k reasoning and bounded rationality to simulate the coevolution of unbiased, positively biased (e.g., optimistic), and negatively biased strategies. Contribution/Results: Positive cognitive biases consistently dominate under natural selection, while fully rational strategies decline; longer game horizons further reinforce this bias. Population-level reasoning depth stabilizes at a finite, empirically realistic level. Crucially, we demonstrate for the first time that wishful thinking may constitute an adaptive mechanism for coping with uncertainty in delayed-reward environments. Moreover, biased strategies can coexist stably with non-reasoning agents, yielding a novel evolutionary stable equilibrium—challenging classical assumptions about rationality’s selective advantage.

Technology Category

• Game Theory and Economic Paradigms: Mechanism Design
• Reasoning under Uncertainty: Sequential Decision Making
• Multiagent Systems: Mechanism Design

Application Category

• Economics, Online Markets and Human Computation: Incentives in network design for Web infrastructures and ecosystems
• Web Mining and Content Analysis: Models for Web evolution
• Social Networks and Social Media: Media and governance, opinion dynamics, filter bubbles, polarization

Abstract

Empirical evidence shows that human behaviour often deviates from game-theoretical rationality. For instance, humans may hold unrealistic expectations about future outcomes. As the evolutionary roots of such biases remain unclear, we investigate here how reasoning abilities and cognitive biases co-evolve using Evolutionary Game Theory. In our model, individuals in a population deploy a variety of unbiased and biased level-k reasoning strategies to anticipate others' behaviour in sequential interactions, represented by the Incremental Centipede Game. Positively biased reasoning strategies have a systematic inference bias towards higher but uncertain rewards, while negatively biased strategies reflect the opposite tendency. We find that selection consistently favours positively biased reasoning, with rational behaviour even going extinct. This bias co-evolves with bounded rationality, as the reasoning depth remains limited in the population. Interestingly, positively biased agents may co-exist with non-reasoning agents, thus pointing to a novel equilibrium. Longer games further promote positively biased reasoning, as they can lead to higher future rewards. The biased reasoning strategies proposed in this model may reflect cognitive phenomena like wishful thinking and defensive pessimism. This work therefore supports the claim that certain cognitive biases, despite deviating from rational judgment, constitute an adaptive feature to better cope with social dilemmas.

Problem

• Evolutionary origins of cognitive biases in reasoning
• Co-evolution of biased reasoning and bounded rationality
• Adaptive advantages of positive bias in social dilemmas

Innovation

• Evolutionary Game Theory models biased reasoning
• Positively biased strategies favor uncertain high rewards
• Bounded rationality co-evolves with cognitive biases