Life, death and a ticket to the movies
We all have one, a particular moment of movie violence that forces us to recoil and turn away from the screen in revulsion. For many film fans the sickening scene in Quentin Tarantino's Reservoir Dogs when tough-guy actor Michael Madsen - Mr Blonde in the movie - slices off a young policeman's ear and then threatens to set him alight is a prime example.
Others cite Oliver Stone's Natural Born Killers as an illustration of movie-makers' ability to produce scene after scene of gut-wrenching, gaze-averting action.
Such episodes of wanton cruelty have sparked animated political debate in the United States over whether explicit film scenes are linked to spiralling real-life violence and all the social and economic costs that entails.
They have also led to a series of multi-million dollar lawsuits over so-called copycat crimes which victims claim were spawned by the movies.
As the argument rages between right-wing moralists and the libertarian left, no one has come up with a concrete causal link between what we watch over our box of popcorn and what happens on the street.
But now, renowned Californian film academic, Dr Nicholas Browne of the University of California, Los Angeles' (UCLA) Department of Film and Television - school to such movie luminaries as Godfather director Francis Ford Coppola and Alex Cox, director of the cult Repo Man - is hoping to shed new light on the subject.