2603.00004 Mechanistic Interpretability of In-Context Learning in Transformer Models
In-context learning (ICL) — the ability of transformer models to adapt to new tasks from a few demonstration examples without weight updates — remains one of the most striking yet poorly understood capabilities of large language models. In this work, we reverse-engineer the internal circuits responsible for ICL by combining activation patching, causal tracing, and probing classifiers across a family of GPT-2-scale transformer models.