cs.CLOct 19, 2026

No Matter Who You Are: Addressivity and Sycophancy in Large Language Models

Authors: Seungjong Sun, Hyunmin Jun, Minsik Yoon, Eungu Lee, Choongwon Kang, Young Seok Woo, Jang Hyun Kim

Organizations: Department of Human-Artificial Intelligence Interaction, Sungkyunkwan University · Department of Applied Artificial Intelligence, Sungkyunkwan University · Department of Interaction Science, Sungkyunkwan University

Abstract

Sycophancy, where an LLM becomes overly agreeable, deferential, or flattering toward the user, has been identified as a major failure mode. While post-training has been implicated as a cause, how it internally gives rise to sycophantic behavior remains insufficiently understood. Post-training transforms the model's output from text completion into utterances directed toward an addressee, thereby giving the output addressivity. We hypothesize that the accompanying pressure to follow the addressee's instructions and align with their preferences links this addressivity to sycophancy. To test this, we use Sparse Autoencoders to extract addressivity directions from pre-trained and post-trained models and examine their relationship with sycophancy. Steering models with addressivity directions can amplify or suppress sycophancy, and this effect is observed only in post-trained models. Furthermore, comparing the internal mechanisms of both model types confirms that the association between addressivity and sycophancy is strengthened through post-training. Finally, through a controlled post-training experiment, we find that models are sycophantic not toward a specific addressee but toward any recognized addressee, suggesting that the presence of an addressee, rather than the addressee's identity, is what elicits sycophancy.

Figures & tables

Appendix figures & tables22 assets

Supplementary material from the paper’s appendix.

Appendix

Explore similar work

CardsList
  1. Not Your Typical Sycophant: The Elusive Nature of Sycophancy in Large Language Models

    Jan 21, 2026Shahar Ben-Natan, Oren TsurLLM EvaluationLLM Sycophancy

  2. SyPS: Measuring Sycophancy Prompt Sensitivity in Large Language Models

    Aug 24, 2026Lijia Huang, Yao Fu, Sihao RenLLM SycophancyLLM Evaluation