Anthropic has built something close to a mind-reading tool for its own AI. What it found sits somewhere between a breakthrough and an unsettling party trick.
Anthropic researchers now have the clearest view yet of what a large language model does while it thinks. In a paper published on the company’s Transformer Circuits site, they describe a hidden region inside Claude that holds a small set of unspoken words: the concepts the model is reasoning with, but has not said out loud. If Claude were a person, and it is not, you might call these its private thoughts.
The team built a tool they call the Jacobian lens to read that region, which they named the J-space. MIT Technology Review, which first reported the work, described the findings as ranging from the mundane to the unnerving. That is a fair summary.
A workspace that looks a little like a mind
The comparison Anthropic reaches for is a bold one. In humans, only a sliver of brain activity is consciously accessible at any moment. Neuroscientists sometimes call this a “global workspace”: a shared space that a thought enters when it becomes available for reasoning, for report, and for deliberate control.
