Alien abduction is the phenomenon claimed by people reporting that they or their patients have been kidnapped by extraterrestrial beings and subjected to physical and/or psychological experimentation. Most scientists and mental health professionals explain these experiences by factors such as suggestibility, sleep paralysis, deception, and psychopathology. Skeptic Robert Sheaffer sees similarity between some of the aliens described by abductees and those depicted in science fiction films, in particular Invaders From Mars (1953).