Thanks to that whole "mental" part, mental illnesses are often heavily influenced by the cultures and societies in which people live. Case in point: The way people with schizophrenia interpret their own hallucinations has changed over the course of the 20th century, keeping pace with changes in technology. Where people once believed that demons were speaking to them, they came to think of those voices as emanating from secret phonographs. Today, people with schizophrenia are likely to imagine hidden cameras taping them for a reality show. The paranoid delusions are always there, but the context changes.