A movie date, it turns out, can be more than a picture show.
A psychologist at the University of Michigan has found that certain movies can crank up our hormone levels and perhaps alter our behavior.
A romantic flick such as The Bridges of Madison County can increase our biochemical readiness to cuddle. But a violent The Godfather II can fire up a guy's testosterone, unleashing his assertive instincts and his libido.
"Movies, like good books, arouse our emotions," said Oliver C. Schultheiss, an assistant professor of psychology at the University of Michigan at Ann Arbor. "Clearly there is something going on that's not just the cold, cognitive mind, but the warm, feeling body that's involved, too."
Schultheiss didn't set out to study movies themselves. He just wanted to find out whether movies could be a motivational tool - a reliable way to get subjects into a specified mental state in order to measure their hormonal responses.
Turns out they can.
"Movies are a complex social stimulation ... devised for us by the masters in their art," he said. "They're perfect for research. They draw you in and get a grip on your emotions if they're done well."
Schultheiss rounded up 60 undergraduates and sat them down to watch 30-minute movie clips.
A third watched Meryl Streep, a lonely Iowa housewife, cuddle up to rugged photographer Clint Eastwood in the unabashedly romantic Bridges. Another third watched Al Pacino playing a young Vito Corleone clawing his way up through the local Mafia by cornering and murdering his neighborhood's reigning Godfather.
The rest - a control group - watched a National Geographic documentary on the Amazon rain forest.
Saliva tests before and after the movies revealed no changes in hormonal levels among the students who watched the documentary.
But tests on the young men and women who watched the romantic Bridges clip showed that progesterone levels among both male and female students shot up as much as 10 percent.
Progesterone is a hormone shared by both sexes. While its role in women's reproduction is well understood, scientists aren't sure how it affects behavior.
"It's a psychological no-man's land," Schultheiss said.
However, progesterone is known to reduce anxiety and prevent panic attacks. Schultheiss' own research also shows links between high progesterone and what psychologists call "affiliation motivation." That's a subconscious need to fit in and be close to others.
Separate psychological tests, called "Picture Story Exercises," confirmed that the romantic Bridges had aroused the affiliation motivation of both male and female students.
The findings were more complicated for the students who watched Godfather.
Men who had high testosterone levels before the film clip saw those levels jump as much as 30 percent afterward. Men and women who started with lower levels for their genders saw little change.
Research has shown that male testosterone enhances aggression, assertiveness and more benign forms of dominance. Less is known about how it affects women, Schultheiss said. But it has been shown to enhance libido in both sexes.
Curiously, women with relatively high testosterone before the movie experienced declines afterward - suggesting they find violent films a true turn-off.
Schultheiss's results also suggest a possible biochemical link between violent movies and aggression among men.
For males high in "dominance" or "power" motivation and testosterone, Schultheiss said, violent movies "will probably crank up the testosterone even further, and thereby fan the flames of aggression and assertiveness."
On the other hand, drag a man to a chick flick, he said, "and I think it will help the guy increase his affiliation motivation. ... [T]hey're much more likely to get into a romantic mood."
But there's a catch: "It probably doesn't last more than one to two hours at most," Schultheiss said.
After that, romance might require the same old stimuli it always has.
Schultheiss' study will appear later this year in the journal 'Hormones and Behavior.'
An article in yesterday's editions about the effect of motion pictures on hormones incorrectly identified the actor who played young Vito Corleone in The Godfather, Part II. The part was played by Robert De Niro.The Sun regrets the error.