SAE Feature Extraction: Seeing Model Representations Through the Residual Stream

Anthropic’s research team trained sparse autoencoders (SAEs) with up to 34 million features in Claude 3 Sonnet, extracting interpretable feature representations. The research shows causal effects on model output behavior, providing internal signals and potential tools that can be studied for AI safety governance, though faithfulness still requires validation.

Toy Models of Superposition: Feature Compression in Neural Networks

Open your IDE. You observe a single hidden-layer neuron. It responds to both “Python” and “error handling.” This is not a bug; it is feature-level compression. Anthropic’s Toy Models research reveals how feature sparsity drives “superposition,” explaining how models store more concepts under capacity constraints.

Chinchilla: Model/Data Ratios on a Budget

When compute is limited, should you buy a bigger model or feed it more data? Chinchilla gave a counterintuitive answer in 2022: at a fixed training budget, a 70B model trained on 1.4T tokens outperformed a 280B model trained on 300B tokens, using the same compute. That points to an approximate 1:20 parameter-to-token ratio in that setup. If you’re planning an LLM training run, this paper offers a practical way to think about model size, data volume, and where your next dollar creates more learning.