Dr. Aaron Stern, a psychiatrist who as head of Hollywood’s movie rating board in the early 1970s established himself as a kind of filmgoers’ sentry against carnal imagery and violence, died April 13 in Manhattan. He was 96.

From 1971 to 1974, Dr. Stern directed the Classification and Rating Administration of the Motion Picture Association of America. The rating board graded films by letter to let moviegoers know in advance how much violence, sexuality and foul language to expect on the screen. The board’s decision that a film merited a rating of R, or restricted, might lure more adults, but would immediately eliminate the pool of unchaperoned moviegoers under 17; an X rating would bar anyone under 17.

“You can only rate the explicit elements on the screen — never the morality or the thought issues behind it,” Dr. Stern said in 1972. “That is the province of religion, leaders, critics and each individual.”