Cross-model Transferability among Large Language Models on the Platonic Representations of Concepts

Understanding the inner workings of Large Language Models (LLMs) is a critical research frontier.Prior work has shown that a single LLM's concept representations can be captured as steering vectors (SVs), enabling the control of LLM behavior (e.g., towards generating harmful content).This paper takes a novel approach by exploring the intricate relationships between representations of concepts across different LLMs, drawing an intriguing parallel to the Plato's Allegory of the Cave.In particular, we introduce a linear transformation method to bridge these representations and present three key findings: 1) The representations of a same concept in different LLMs can be effectively aligned using simple linear transformations, enabling efficient cross-model transfer and behavioral control via SVs.2) This linear transformation generalizes across multiple concepts, facilitating alignment and control of SVs representing different concepts across LLMs.3) A weakto-strong transferability exists between LLMs, whereby SVs extracted from smaller LLMs can effectively control behaviors of larger LLMs.