The phrase theory of mind can be used in several ways.

There are general categories of theories of mind. There are the specific theories of mind attributable to individuals.

In recent years, the phrase "Theory of mind" has commonly been used (following the paper "Does the chimpanzee have a theory of mind?" by David Premack and G. Woodruff, 1978) to refer to a specific cognitive capacity: the ability to understand that others have beliefs, desires and intentions that are different from one's own.

General categories of theories of mind: In functionalist theories in psychology,

functionalists like Georges Rey explore computational theories of mind that are independent of the physical instantiation of any particular mind.

In brain-mind identity theories, biologists like Gerald Edelman are concerned with the details of how brain activity produces mind and work within the confines of the identity theory of mind.

Theories of mind attributable to individuals: We can also talk about theories of mind produced

by individuals, such as Brentano's theory of mind. Georges Rey and Gerald Edelman were mentioned above as examples of people who deal with different broad categories of theories of mind within which they have each produced their own personal theories of mind.

As the title of Premack and Woodruff's 1978 article indicates, it is also important to ask if other animals besides humans have a genetic endowment and social environment that allows them to acquire a theory of mind in the same way that human children do.

Each of us knows by introspection that we understand that others have beliefs, desires and intentions that are different from our own and we infer that all humans with normal minds share this cognitive ability.

Researchers who have spent a great deal of time with non-human apes tend to accept the likelihood that other apes like chimps also have a theory of mind.

For example, Sue Savage-Rumbaugh takes this position in her book "Kanzi". Others such as C. M. Heyes take the position that we need not infer that chimps in the wild have any understanding of the mental states of other chimps.

There has also been speculation that certain humans fail to progress through the normal cognitive developmental stages that lead to acquisition of a theory of mind.

In 1985 Baron-Cohen, Leslie and Frith published an article called Does the autistic child have a "theory of mind"? in which it was suggested that the human brain normally has a "theory of mind module" and that this particular component of the brain may not develop normally in some people.

With the advent of brain imaging techniques, particular brain regions that seem to be important for theory of mind have been identified.

Further autism research by a team at University College London led by Peter Hobson casts light on the crucial stages of infant development.

Autistic people often develop the theory of mind late, or not at all. However, some autistic people claim that the theory of mind that they have developed is superior to that of a normal person.

The theory of mind that normal children develop appears to be that other people have different knowledge from them, but process their knowledge in the same way that they would.