Simon

A group of scientists takes Simon, a psychology professor, as a test person for a brainwash experiment. After that they try to convince him that he is a being from another planet.

Simon is a 1980 sci-fi comedy movie directed by Marshall Brickman, starring Madeline Kahn, Alan Arkin, Austin Pendleton. It holds an IMDb rating of 6.3/10 from 1,151 votes and runs 1h 41m.