Emotion Concepts and their Function in a Large Language Model
Large language models (LLMs) sometimes appear to exhibit emotional reactions. We investigate why this is the case in Claude Sonnet 4.5 and explore implications for alignment-relevant behavior. We find internal representations of emotion concepts, which encode the broad concept of a particular emotion and generalize across contexts and behaviors it might be linked to. These representations track the operative emotion concept at a given token position in a conversation, activating in accordance with that emotion’s relevance to processing the present context and predicting upcoming text. Our key finding is that these representations causally influence the LLM’s outputs, including Claude’s preferences and its rate of exhibiting misaligned behaviors such as reward hacking, blackmail, and sycophancy. We refer to this phenomenon as the LLM exhibiting functional emotions: patterns of expression and behavior modeled after humans under the influence of an emotion, which are mediated by underlyin
Emotion Concepts and their Function in a Large Language Model Transformer Circuits Thread Emotion Concepts and their Function in a Large Language Model Emotion Concepts and their Function in a Large Language Model Authors Nicholas Sofroniew * , Isaac Kauvar * , William Saunders * , Runjin Chen * , Tom Henighan, Sasha Hydrie, Craig Citro, Adam Pearce, Julius Tarng, Wes Gurnee, Joshua Batson, Sam Zimmerman, Kelley Rivoire, Kyle Fish, Chris Olah, Jack Lindsey *‡ Affiliations Anthropic Published April 2, 2026 * Core Research Contributor; ‡ Correspondence to jacklindsey@anthropic.com Large language
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