Published in the medical journal Hormones and Behavior, the study was conducted by Dr. Kim Wallen, a psychologist, and former graduate student Heather Rupp.
A test group of 30 women and 15 men were shown photos of couples in various sexual situations. A tracking device was used to measure where their gaze landed initially, how long they viewed a particular area in the photo, and in what order their eyes scanned the photo.
Results suggested that men viewing the photos actually looked at the female subject’s faces first, looking for signs of arousal that would not be so obvious by viewing other body parts. Wallen and Rupp said men's increased attention to faces might be related to higher activation in the amygdala, a portion of the brain that processes emotional information and excitement.
“It's cryptic, but facial expression is one way of showing an indication of interest in and enjoyment of sex," Wallen told MSNBC.com.
Women, on the other hand, were more likely to look at the area of sexual activity first, and how long they lingered there seemed to be regulated by whether or not they were taking hormonal birth control. These women paid more attention to the overall picture and background details, while those not taking hormonal birth control seemed more interested in men’s private parts.
"Eye-tracking data suggested that what women paid most attention to was dependent on their hormonal state," Rupp said.