Google DeepMind has unveiled Gemma Scope 2, a comprehensive suite of interpretability tools designed for the Gemma 3 language models, which range from 270 million to 27 billion parameters. This suite aims to enhance AI safety and alignment by allowing researchers to trace model behavior back to internal features, rather than relying solely on input-output analysis. Gemma Scope 2 employs sparse autoencoders (SAEs) to break down high-dimensional activations into sparse, human-inspectable features, offering insights into model behaviors such as jailbreaks, hallucinations, and sycophancy. The suite includes tools like skip transcoders and cross-layer transcoders to track multi-step computations across layers, and it is tailored for models tuned for chat to analyze complex behaviors. This release builds on the original Gemma Scope by expanding coverage to the entire Gemma 3 family, utilizing the Matryoshka training technique to enhance feature stability, and addressing interpretability across all layers of the models. The development of Gemma Scope 2 involved managing 110 petabytes of activation data and training over a trillion parameters, underscoring its scale and ambition in advancing AI safety research. This matters because it provides a practical framework for understanding and improving the safety of increasingly complex AI models.
