" " Dilated pupils are perceived as more feminine than undilated pupils. Mark Mainz/Getty Images

Italian women in the Middle Ages were a step ahead of science. Recognizing the beauty endowed by wide-open pupils, they would dilate their own eyes with belladonna [source: Gowin]. (Incidentally, the word "belladonna" means "beautiful woman" in Italian.) Unfortunately, the plant secreted not only the chemical atropine, which draws back the irises, but also a toxin that would poison them [source: Swaminathan].

Although belladonna wasn't an optimal dilating agent, the come-hither effect of large pupils was a scientifically valid assumption.



In 1965, pupillometry pioneer and psychologist Hess asked men to compare the attractiveness of images of women with average-sized pupils to drawings in which the women's pupil sizes were enhanced. Consistently, men ranked the doe-eyed gazes as prettier, since the subtle ocular opening unconsciously signals sexual attraction on the woman's part [source: Murphy]. In response to attraction, the brain secretes norepinephrine [source: Fisher]. That chemical then flexes the eyeball's dilator muscles [source: Gowin]. Therefore, men may unwittingly read pupil dilation as an advertisement of interest.

Studying women's preferences for male pupil sizes wasn't so predictable, however. Researchers have found that some women prefer men with medium-sized pupils, apparently because they were perceived as not being oversexed and more likely to be dependable partners in raising offspring. But others were drawn to men with large pupils. Those women told the researchers that they had a tendency to get involved with "bad boy" types [source: Murphy].

Monthly menstrual cycles also appear to hold sway over female pupil preferences. During the follicular phase, which culminates with ovulation, desire for doe-eyes peaks [source: Caryl et al].

But there seems to be a common pattern: The more physiologically primed for sex they are, the more males and females both innately keep an eye out for dilated pupils. Given that evolutionary phenomenon, the eyes are less the windows to one's soul than the windows one's bedroom.

Belladonna Knockoff Deadly nightshade, aka belladonna, contains atropine, which naturally stimulates pupil dilation — and can ruin people's vision. Since atropine has long been identified as a toxin, optometrists use a synthetic derivative to dilate patients' pupils before examining their eyes [source: Swaminathan].

Last editorial update on Mar 26, 2018 03:44:52 pm.

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