Alien abduction, sometimes also called abduction phenomenon, alien abduction syndrome or UFO abduction, is a personally held belief in which the alleged “abductee” describes “subjectively real experiences” of being secretly kidnapped by non-human entities (aliens) and subjected to physical and psychological experimentation. Most scientists and mental health professionals explain these experiences by factors such as suggestibility (e.g. false memory syndrome), sleep paralysis, deception, and psychopathology. Skeptic Robert Sheaffer sees similarity between the aliens depicted in science fiction films, in particular Invaders From Mars (1953), and some of those reported to have actually abducted people. People claiming to have been abducted are usually called “abductees” or “experiencers”.