New York ? He wasn’t grief-stricken, he was acting, Joaquin Phoenix says of tabloid reports that he had a breakdown while filming the upcoming Johnny Cash biopic.

Phoenix banged his head on a bedpost during a scene related to Cash’s brother’s death, prompting speculation that he was reacting to the 1993 death of his brother, River.

The 30-year-old actor tells Newsweek he was just trying to get into the emotional state of his character.

His brother River Phoenix died of a drug overdose outside a Los Angeles nightclub when he was 23.

Suggesting that he’d use his personal life for “Walk the Line,” says Phoenix, “kind of makes me sick.”

“I don’t need to pull from my experience for a character, and I’ve never understood why actors would, except for lack of ability, imagination or research,” he says. “I had all three things, so this is a little frustrating to me, because it denies my work and the research that I did.”

“Walk the Line,” scheduled for release in November, traces Cash’s rise from the son of an Arkansas farmer to the “Man in Black.” It co-stars Reese Witherspoon as Cash’s wife, June Carter.