Two people who had lost nearly all ability to understand or produce language sat down with a set of number puzzles. They had to work out the hidden rule that turned one list into another, then apply it to new examples. They performed as well as people whose language was intact, and they communicated the rules they had worked out through gestures or a sketch.
That result, published in the Proceedings of the National Academy of Sciences, is a pointed piece of evidence in a long argument about whether humans need words to think. The MIT team behind it says the answer is no.
