When a woman says, “You turn me on,” it may be her brain that’s talking, as well as her hormones.

A new study shows looking at erotic images causes a rapid increase in women’s electrical brainwave activity, effectively turning their brains on.

The brains’ electrical activity fired about 20 percent faster when study participants viewed erotic images than when they looked at other types of images, researchers found.

"That surprised us," says researcher Andrey P. Anokhin, PhD, research assistant and professor of psychiatry at Washington University School of Medicine in St. Louis, in a news release. "We believed both pleasant and disturbing images would evoke a rapid response, but erotic scenes always elicited the strongest response."

"Usually men subjectively rate erotic material much higher than women," says Anokhin. "So, based on those data, we would expect lower responses in women, but that was not the case. Women have responses as strong as those seen in men."

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Erotic Images Turn the Brain On

In the study, published in the journal Brain Research, researchers placed electrodes on the scalps of 264 women to measure brainwave activity as they viewed a series of 55 color slides. The images varied from water skiers to snarling dogs to partially-clad couples in sensual poses.

Results showed that when the women viewed erotic pictures, their brains produced electrical responses that were stronger and quicker than responses produced by the other types of images, regardless of how pleasant or disturbing the other images were.

When volunteers viewed erotic images, their electrical brainwave activity began firing within 160 milliseconds -- about 20 percent faster than the electrical response prompted by other images.

Researchers also found that the erotic images were processed in different brain structures than those used for other images.

The results suggest that different brain circuits may be involved in processing erotic images than in other types of everyday images, the researchers say.

In addition, Anokhin says the fact that this study showed women’s brains exhibited such a quick response to erotic pictures suggests that, perhaps for evolutionary reasons, our brains are programmed to preferentially respond to erotic material.

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By Jennifer Warner, reviewed by Louise Chang, MD

SOURCES: Anokhin, A. Brain Research, May 18, 2006 online edition. News release, Washington University School of Medicine.