Your Next Token Prediction: A Multilingual Benchmark for Personalized Response Generation
Shiyao Ding, Takayuki Ito
TL;DR
The paper introduces Your Next Token Prediction (YNTP), a multilingual benchmark for personalized response generation that captures token-level decisions across daily conversations with MBTI-grounded NPCs. It formalizes the task as predicting a user’s next-token responses conditioned on context and user background, and it evaluates prompt-based and parameter-efficient tuning methods on English, Chinese, and Japanese data gathered from a five-day multi-NPC dialogue system. The study provides six evaluation metrics spanning semantic fidelity and stylistic consistency, and reports that few-shot prompting, especially when augmented with MBTI inference, yields substantial gains, with LoRA offering niche advantages in style and history tracking. By releasing a 100-user multilingual dataset and establishing baseline results, the work advances user-aligned language modeling and highlights practical trade-offs between external prompting and internal personalization for real-world personalized AI assistants.
Abstract
Large language models (LLMs) excel at general next-token prediction but still struggle to generate responses that reflect how individuals truly communicate, such as replying to emails or social messages in their own style. However, real SNS or email histories are difficult to collect due to privacy concerns. To address this, we propose the task of "Your Next Token Prediction (YNTP)", which models a user's precise word choices through controlled human-agent conversations. We build a multilingual benchmark of 100 dialogue sessions across English, Japanese, and Chinese, where users interact for five days with psychologically grounded NPCs based on MBTI dimensions. This setup captures natural, daily-life communication patterns and enables analysis of users' internal models. We evaluate prompt-based and fine-tuning-based personalization methods, establishing the first benchmark for YNTP and a foundation for user-aligned language modeling. The dataset is available at: https://github.com/AnonymousHub4Submissions/your-next-token-prediction-dataset-100
