What Our Eyes Are Saying

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  • By Robin Westen

    Most of us know the adage, “The eyes are the windows to the soul.” Well, now science is backing up this poetic description. Several studies show our eyes actually do reveal what’s going on in our minds. Let’s take a look at what the eyes can reveal:
  • Concentration If you ask someone for the name of the president of the United States, chances are you won’t see much change in pupil size, but ask someone to solve a complex equation, and unless they’re adept in math, their pupils will open wide. That’s because research shows the harder our brain works, the more our pupils dilate. In one study as participants were given increasingly tough tasks to complete, their pupils got larger.
  • Information Overload Keep watching a friend’s eyes closely while you tell a long-winded story. When their pupils get small, you’ll know you’ve gone too far. Research shows when our minds are loaded to 125% of capacity and we turn off, our pupils visibly constrict.
  • Interest The size of pupils can also signal whether someone is interested in what you’re saying. Subjects in a study listened to excerpts from three books: one was erotic, another involved mutilation, while a third was neutral. Their pupils widened at first for all three, but only remained wide for the passages that were erotic or involved mutilation.
  • Illness Doctors and paramedics flash a light in patients' eyes to check if their brains are working normally. They use the acronym PERRL: Pupils should be Equal, Round and Reactive to Light. If a brain isn’t functioning normally, the PERRL test reveals it.
  • Arousal Both men and women's pupils expand when they are sexually aroused. In one study, subjects were shown pictures of landscapes, buildings and nudes. When nude photos were exhibited their pupil size increased.
  • Distress Just as pupils increase in size when folks are interested or turned on, they constrict when they’re disgusted. In one study when people were shown pictures of injured children, first their pupils dilated because of the shock -- and then they constricted to try and avoid the troubling images.
  • Political Leanings In a decades-old study, scientists showed people pictures of Lyndon Johnson, George Wallace and Martin Luther King, Jr. Liberals' pupils dilated when they saw fellow liberals Johnson and King but constricted when they saw conservative Wallace. Conservatives showed the opposite pattern.
  • Pain When researchers fired small electric shocks into their subjects’ fingertips, prompting their pain sensors (photo at left), the patients' pupils dilated.
  • Effects of Drugs and Medicine Some drugs, like alcohol and opioids, cause the pupils to constrict. Others, like amphetamine, cocaine, LSD and mescaline cause them to dilate. Police officers know this and some use it as one way of checking if someone is on drugs.

    About the Author

    Robin Westen is ThirdAge's Medical Director. Check for her daily updates. Her latest book, co-authored with Dr. Alyssa Dweck, is "V is for Vagina."