🤖 AI Summary
This paper addresses the coupled dynamics between strategic user behavior and model evolution in learning platforms: conventional model optimization criteria often misalign with user incentives, triggering strategic responses, while existing research neglects dynamic interdependencies and collective effects among users. To tackle this, we propose a forward-looking multi-agent modeling framework that integrates behavioral-economic level-k reasoning with a novel collective reasoning mechanism, formally capturing users’ coupled decision-making under anticipatory modeling of peer behavior and system feedback. Theoretical analysis reveals two key findings: (i) level-k reasoning accelerates convergence without altering equilibrium outcomes; (ii) collective optimization reshapes the predictive evolution trajectory, substantially improving aggregate utility and delineating the feasibility boundary and marginal gains of coordinated action in large-scale learning systems.
📝 Abstract
On many learning platforms, the optimization criteria guiding model training reflect the priorities of the designer rather than those of the individuals they affect. Consequently, users may act strategically to obtain more favorable outcomes, effectively contesting the platform's predictions. While past work has studied strategic user behavior on learning platforms, the focus has largely been on strategic responses to a deployed model, without considering the behavior of other users. In contrast, look-ahead reasoning takes into account that user actions are coupled, and -- at scale -- impact future predictions. Within this framework, we first formalize level-$k$ thinking, a concept from behavioral economics, where users aim to outsmart their peers by looking one step ahead. We show that, while convergence to an equilibrium is accelerated, the equilibrium remains the same, providing no benefit of higher-level reasoning for individuals in the long run. Then, we focus on collective reasoning, where users take coordinated actions by optimizing through their joint impact on the model. By contrasting collective with selfish behavior, we characterize the benefits and limits of coordination; a new notion of alignment between the learner's and the users'utilities emerges as a key concept. We discuss connections to several related mathematical frameworks, including strategic classification, performative prediction, and algorithmic collective action.