Feature microscope

Inside the model, every word becomes a long list of numbers that nobody can read. A sparse autoencoder (SAE) translates them into … features: small concepts the model has learned, such as “the word ball” or “right after the word named”. Everything runs in your browser.

How to use it

  1. Click a word in the analyzed text below. You see the features active on it and a graph of why the model wrote that word.
  2. Click a feature to see where else it fires, in thousands of real stories.
  3. Type your own text and press Analyze, or search for a feature by word.

Click a token to see the features active on it.

Features most active in this text

    Find a feature

      How to read this: the SAE was trained on the residual stream entering block ? of the model. Each feature has a label made automatically from its strongest examples: "ball" means it fires on that token, after "named" on the token after it, before "said" on the token before it. The percentage is how many of those examples agree, so a low percentage means the label does not explain the feature well. Labels and examples come from a script (python -m glassbox.features), not from a person.

      The first position (the start-of-story token) is skipped, as in training. Shading shows activation relative to the feature's strongest validation example.