Modeling User Exploration Saturation: When Recommender Systems Should Stop Pushing Novelty

TL;DR

This paper investigates how fairness-driven exploration in recommender systems reaches a saturation point where additional novelty no longer benefits users, highlighting the need for user-specific adaptation.

Contribution

It empirically analyzes exploration saturation across users, revealing variability and diminishing returns, and emphasizes adaptive strategies over fixed exploration levels.

Findings

Users with limited history reach saturation earlier.

Fairness-induced exploration shows diminishing returns.

Uniform exploration can disadvantage certain users.

Abstract

Fairness-aware recommender systems often mitigate bias by increasing exposure to under-represented or long-tail content, commonly through mechanisms that promote novelty and diversity. In practice, the strength of such interventions is typically controlled using global hyperparameters, fixed regularization weights, heuristic caps, or offline tuning strategies. These approaches implicitly assume that a single level of exploration is appropriate across users, contexts, and stages of interaction. In this work, we study exploration saturation as a user-dependent phenomenon arising from fairness- and novelty-driven recommendation strategies. We define exploration saturation as the point at which further increases in exploration no longer improve user utility and may instead reduce engagement or perceived relevance. Rather than proposing a new fairness-aware algorithm or optimizing a specific objective, we empirically analyze how increasing exploration affects users across varied recommendation models. Through longitudinal experiments using MovieLens-1M and Last.fm datasets, our results indicate that fairness-induced exploration exhibits diminishing or non-monotonic returns and varies substantially across users. In particular, users with limited interaction histories tend to reach saturation earlier, suggesting that uniform fairness or novelty pressure can disproportionately disadvantage certain users. These findings reveal a trade-off between fairness and user experience, suggesting that recommendation systems should adapt not only to relevance but also to the amount of fairness-driven exploration applied to individual users.