The second part of the study involved 81 undergraduates who studied five films, one violent, one R-rated for sex, and three features: "Brokeback Mountain," about two gay cowboys; "American History X," a violent film dealing with brutal racism, and "Notebook," a love story.
Each participant was instructed to imagine watching one of the movies with a spouse, parents, first date, and two same-sex friends.
"By far the most uncomfortable combination was watching the sexual movie with one's parents," the study concluded. Not surprisingly, the men largely felt ok watching a violent film, and the women enjoyed the love story. And most would hate to see a raunchy downer on a first date.
"You go to a movie on a first date and you say, oh, I didn't realize this was so sexual," Harris said. "You don't really enjoy it very much under those circumstances whereas seeing it with someone else would be fine."
Even bad movies, or movies about bad things, might be beneficial, he added.
"'American History X' was a very, very grim movie about racist skinheads," he said. "I heard about it when it came out, but I didn't want to see it. I happened to see it later at a conference and it was just horribly grim and wrenching and depressing, but I remember thinking I was glad I saw it.
"It gave me some insight into that mindset, that subculture, but I never want to see it again," he said. "Once was enough. But I think I'm a little better person for having seen it once."
Some of Harris' earlier research suggests that some experiences may be nearly universal.
"About 10 years ago we asked 265 college students to think about a movie they saw as a child or a teen that really scared them," he said. "We asked them what they remembered experiencing emotionally. I didn't know how many people actually have those kind of memories, but 100 percent of our sample could do that. Everybody had that kind of experience."
Some said they couldn't sleep with the light off, and many were terrified of spiders after seeing "Arachnophobia."
"They had very vivid and very specific memories," he said.
Some films can have an immediate impact, especially if you see it with the right person. Harris said a friend of his, who stuttered, went to "The King's Speech" with his son, about 30, who also stutters.
"For them, that was just an extremely powerful experience," Harris said. "It brought them closer together as father and son. They talked about it together long afterward, and the father said it was one of the best things for their relationship in a long time."
So movies, and who we watch them with, can "tap into very powerful emotions."
Incidentally, I asked Harris which film he thinks will win the Oscar this year for best picture. He said it looks like a toss-up between "Social Network" and "The King's Speech."
But then he slipped and let the truth out. He's for George VI, or was that Colin Firth?