theory of mind

Theory of mind is the everyday skill of modelling what other people know, believe, want, and intend, including beliefs that are false. The classic test: Anna hides a marble in a basket and leaves; someone moves it to a box; where will Anna look when she returns? A child who has it answers the basket, because she tracks Anna's belief, not the true location. To follow a story, hold a useful conversation, or be a good assistant, a model needs some grip on this, since meaning so often depends on what each person believes.

Modern models handle many such tasks impressively, tracking who knows what across a passage and tailoring an answer to a listener's perspective. Whether this is genuine mind-modelling or skilled pattern-matching on the mountains of human social text they read is fiercely debated, and the truth is probably some of both. The practical takeaway is that the ability is real but uneven: it can be brittle under small changes to a well-known puzzle, so it is safer to treat the model as simulating perspective-taking than as truly understanding another mind.