Theory of mind

Etymology

The phrase was introduced by primatologists David Premack and Guy Woodruff in a 1978 paper asking whether chimpanzees possess a “theory of mind.” It became central to developmental psychology through “false-belief” tests measuring when children grasp that others can hold mistaken beliefs.

noun phrase · /THEER-ee uhv mynd/
The ability to attribute mental states — beliefs, desires, intentions — to others and grasp that they differ from your own.
What it names
The cognitive achievement that lets you model what someone else knows, wants, or believes, the foundation of empathy and deception alike.
Example
A child who understands that a playmate will look for a toy where he left it — not where it was secretly moved — has developed a theory of mind.
Related idea
Theory of mind is the general capacity to model other minds; empathy is the narrower sharing of another’s feelings, and metacognition turns the same modeling inward onto your own thoughts.