HOW blind and deaf people approach a cognitive test regarded as a milestone in human development has provided clues to how most of us deduce what others are thinking.
Understanding the mental states of others, and realising they can differ from our own, is known as theory of mind. It underpins empathy, communication and the ability to lie. But we don’t acquire ToM until around the age of 4, and how it develops is a mystery.
You can test for ToM via the false-belief test, in which two children are shown playing. One puts a toy under the bed…
