Theory of mind
The theory of mind impairment describes a difficulty someone would have with perspective-taking. This is also sometimes referred to as "mind-blindness". This means that individuals with a theory of mind impairment would have a difficult time seeing phenomena from any other perspective than their own. Individuals who experience a theory of mind deficit have difficulty determining the intentions of others, lack understanding of how their behavior affects others, and have a difficult time with social reciprocity. Theory of Mind deficits have been observed in people with autism spectrum disorders, people with schizophrenia, people with nonverbal learning disorder, people with attention deficit hyperactivity disorder, persons under the influence of alcohol and narcotics, sleep-deprived persons, and persons who are experiencing severe emotional or physical pain. Theory of mind deficits have also been observed in deaf children who are late signers (i.e. are born to hearing parents), but the deficit is due to the delay in language learning, not any cognitive deficit, and therefore disappears once the child learns sign language.