In psychology and philosophy, theory of mind (often abbreviated to ToM) is the capacity to understand other individuals by ascribing mental states to them. A theory of mind includes the understanding that others' beliefs, desires, intentions, emotions, and thoughts may be different from one's own. Possessing a functional theory of mind is crucial for success in everyday human social interactions. People utilize a theory of mind when analyzing, judging, and inferring other people's behaviors.
Theory of mind was first conceptualized by researchers evaluating the presence of theory of mind in animals. Today, theory of mind research also investigates factors affecting theory of mind in humans, such as whether drug and alcohol consumption, language development, cognitive delays, age, and culture can affect a person's capacity to display theory of mind.