Human attention has become a scarce and strategically contested resource in digital environments. Content providers increasingly engage in excessive competition for visibility, often prioritizing attention-grabbing tactics over substantive quality. Despite extensive empirical evidence, however, there is a lack of theoretical models that explain the fundamental dynamics of the attention economy. Here, we develop a minimal mathematical framework to explain how content quality and audience attention coevolve under limited attention capacity. Using an evolutionary game approach, we model strategic feedback between providers, who decide how much effort to invest in production, and consumers, who choose whether to search selectively for high-quality content or to engage passively. Analytical and numerical results reveal three characteristic regimes of content dynamics: collapse, boundary, and coexistence. The transitions between these regimes depend on how effectively audiences can distinguish content quality. When audience discriminability is weak, both selective attention and high-quality production vanish, leading to informational collapse. When discriminability is sufficient and incentives are well aligned, high- and low-quality content dynamically coexist through feedback between audience selectivity and providers' effort. These findings identify two key conditions for sustaining a healthy information ecosystem: adequate discriminability among audiences and sufficient incentives for high-effort creation. The model provides a theoretical foundation for understanding how institutional and platform designs can prevent the degradation of content quality in the attention economy.

翻译：在数字环境中，人类注意力已成为稀缺且具有战略竞争性的资源。内容提供者日益陷入对可见度的过度竞争，往往优先采用吸引注意力的策略而非实质性质量。尽管存在大量实证证据，但目前仍缺乏解释注意力经济基本动态的理论模型。本文建立了一个最小化的数学框架，用以解释在有限注意力容量下内容质量与受众注意力如何协同演化。通过演化博弈方法，我们建模了提供者（决定投入多少精力进行生产）与消费者（选择是否主动搜寻高质量内容还是被动参与）之间的策略性反馈。解析与数值结果揭示了内容动态的三种特征状态：崩溃态、边界态与共存态。状态间的转变取决于受众区分内容质量的有效程度。当受众辨别能力较弱时，选择性关注与高质量生产均会消失，导致信息崩溃。当辨别能力充分且激励措施协调良好时，高质量与低质量内容通过受众选择性与提供者努力之间的反馈实现动态共存。这些发现确定了维持健康信息生态系统的两个关键条件：受众具备足够的辨别能力，以及存在对高投入创作的充分激励。该模型为理解制度与平台设计如何防止注意力经济中内容质量退化提供了理论基础。