Brain scan studies show that watching pornography could quiet the primary visual cortex, an area of the brain responsible for processing incoming optical information, reports msnbc.
Researchers from the University of Groningen Medical Center in the Netherlands found that while movies and other visual stimuli normally increase blood flow to the primary visual cortex, watching erotic movies results in far less blood flowing through to this region.
Instead, the scientists suggest that while watching sex scenes, the blood may be flowing to other parts of the brain concerned with sexual arousal, meaning you're probably not taking in all of the visual details.
"If you look, for example, at your computer and you have to write something or whatever, then you have to look specifically and carefully at what you're doing because if you don't, it means you make mistakes," said Gert Holstege, study researcher and neurologist at the University.
"But the moment you are watching explicit sexual movies, that's not necessary, because you know exactly what's going on. It's not important that the door is green or yellow."
The research involved 12 heterosexual women who were all using hormonal birth control, which mitigates the monthly cyclical changes to libido and sexual arousal.
The women were made to watch three videos while their brain activity was being monitored by positron emission tomography (PET) scans, which detects changes in radioactivity levels based on the amount of blood flowing to certain brain regions.
Two of the videos were erotic "woman-friendly" clips: one showed foreplay, while the other depicted oral sex and vaginal intercourse. The third video was a nature documentary about Carribean marine life.
Results of the scans showed reduced blood flow to the primary visual cortex while the women were watching the high-intensity erotic video, suggesting that the brain is less focused on processing visual stimuli than on sexual arousal during this time.
"You have to realise that the brain wants to spare as much energy as possible, so if some part of the brain is not necessary at a high level of functioning, it immediately goes down," said Holstege.
Holstege explains that the brain is capable of being aroused or anxious, but never both. He has found that anxiety is greatly reduced in the brain during orgasm, which may be the reason women with low libidos often possess higher anxiety levels.
He says that scanning around for visual clues of danger will ultimately affect your level of focus on sexual arousal. The results of the study link anxiety with sexual dysfunction, and suggest that feeling safe is necessary to produce arousal.
"If you yourself are in a very dangerous situation, whatever the reason, you don't have sexual feelings, because you have to survive for yourself, not survive for the species," Holstege said.
"If you want to have sex, as a man, you need to produce a safe situation for the woman. That is what you want, that is the most important thing."
The results of the research were published in the online Journal of Sexual Medicine on April 10.