During this study, 22 young adults (11 men and 11 women) played numerous 24-second intervals of the game while being hooked up to a functional magnetic resonance imaging, or fMRI, machine. fMRI is designed to produce a dynamic image showing which parts of the brain are working during a given activity.
Study participants were instructed to click as many balls as possible; they weren't told that they could gain or lose territory depending on what they did with the balls. Reiss said all participants quickly learned the point of the game, and the male and female participants wound up clicking on the same number of balls. The men, however, wound up gaining a significantly greater amount of space than the women. That's because the men identified which balls - the ones closest to the "wall" - would help them acquire the most space if clicked.
"The females 'got' the game, and they moved the wall in the direction you would expect," said Reiss, who is director of the Center for Interdisciplinary Brain Sciences Research. "They appeared motivated to succeed at the game. The males were just a lot more motivated to succeed."
After analyzing the imaging data for the entire group, the researchers found that the participants showed activation in the brain's mesocorticolimbic center, the region typically associated with reward and addiction. Male brains, however, showed much greater activation, and the amount of activation was correlated with how much territory they gained. (This wasn't the case with women.) Three structures within the reward circuit - the nucleus accumbens, amygdala and orbitofrontal cortex - were also shown to influence each other much more in men than in women. And the better connected this circuit was, the better males performed in the game.
|Contact: Michelle Brandt|
Stanford University Medical Center