Originally a
mentalist was an adherent or advocate of a mentalistic school of psychology or psychiatry. Someone who believes that some mental phenomena cannot be explained by physical laws (i.e. telepathy and
mind reading).
While a psychic may claim to observe an underlying spiritual reality and report on it, in a process known as a "psychic reading," a mentalist, by contrast, might claim the ability to manipulate that reality in order to create a different manifestation.
The term "mentalist" also refers to "psychic" entertainers whose illusions feature the apparent ability to read minds, foretell the future, and see distant and hidden objects. This branch of magic is referred to as "
mentalism".
"
Mentalist" has more recently become a tongue-in-cheek insult for when someone is behaving oddly or wackily, thanks to tv series "
Alan Partridge" and "The Office".