Did horror movies like Night of the Living Dead, Last House on the Left, and The Texas Chainsaw Massacre exorcise such civic nightmares as Vietnam and the assassinations of Martin Luther King Jr. and Bobby Kennedy? If you don’t buy that, you’ll have a rough time with Adam Simon’s The American Nightmare, which montages fake zombies and phony ghouls with real footage of brutal Southern cops and napalm-burned Vietnamese children. Directors such as George Romero, Wes Craven, Tobe Hooper, and David Cronenberg play along with this documentary’s tendentious thesis, as do a passel of academics, including a chirpy, grandmotherly type who insists that “there’s something kind of brilliant” about the gory cinematic fancies of the ’60s and ’70s. Simon will introduce this screening of his film, which will be accompanied by winning entries from ABC-TV’s “I See Scary Movies” short-film contest for first-time directors. The films screen at 8 p.m. at the Hirshhorn Museum and Sculpture Garden’s Ring Auditorium, 7th and Independence Avenue SW. Free. (202) 357-3091. (Mark Jenkins)