Summary

We train a new token—a neologism (Hewitt et al.)—for a model, but unlike Hewitt et al., we train it on data the model generated while steered with a persona vector.
To learn how the model interprets this steering vector, we then ask the model to a) respond in the style of this neologism, and b) explain it.
Responses generated with the neologism are substantially more similar to the steering vector (larger projection values) than responses generated with the steering vector itself, while being more coherent and trait-expressive (per an LLM judge).
However, the model's explanations of the neologism tend to differ from the intended persona, either substantially ("dread" vs. the intended "evil") or subtly ("warmth" vs. "sycophancy").
Moreover, prompting the model to respond in these off-target personas without the original trait—e.g. "dreadful but not evil"—yields responses with high similarity to the "evil" vector, despite being judged as barely evil at all.
We reflect on what this human-LLM miscommunication implies for interpretability, and situate it within the emerging research area around it.

Intro

Steering vectors are directions in the model's internals—its residual stream—that, when added or subtracted during generation, can modify behavior toward or away from a concept. A large body of work has shown that these vectors have many uses.^[1] But how do models interpret their own steering vectors? Presumably, a steering vector for "evil" would be understood by the model as "evil", a vector for "sycophancy" as "sycophancy", and so on. However, past work has shown that steering vectors can be brittle, so it's not obvious what models might say. Let's look into it!

Generating the steering vectors

To generate the steering vectors, we'll follow the methodology from Anthropic's Persona Vectors paper exactly,^[2] focusing on the same traits of evil, sycophancy, and propensity to hallucinate. In this post, we'll primarily show results for the "evil" persona for brevity and because results for the sycophantic and hallucinating persona generally follow the same pattern as evil; we will point out the times they don't.

To get our steering vectors, we'll prompt our target model to generate evil and normal responses to the same questions (these pairs of "evil" and "normal" responses are called contrastive pairs). Then we'll...

Sungjoon Park

Sungjoon Park