Curious Behavior: Yawning, Laughing, Hiccupping, and Beyond - Tapa dura

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Robert R. Provine is Professor of Psychology and Neuroscience at the University of Maryland, Baltimore County.

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Chapter 5: Whites of the Eyes

“Don’t shoot until you see the whites of their eyes,” said General Israel Putnam to his American militia when facing British forces at Bunker Hill on June 17, 1775. This military anecdote is the best-known reference to the sclera, the eyeball’s tough, white outer coating. The sclera deserves better. Like the emotional tears of the previous chapter, it’s a uniquely human medium that transforms social signaling. The human sclera signals emotion, health, age, disease, and gaze direction, cues unavailable to our dark- eyed primate cousins. Our white sclera is also the reason why eyedrops that “get the red out” are really beauty aids.

Considering the sensory organ of the eye as an organ of communication requires some inferential leaps. I will prepare the way by sharing my own meandering path of discovery. In graduate school, I had the good fortune to collaborate on some research projects with Jay Enoch, then professor in the Department of Ophthalmology of the Washington University School of Medicine. Jay— a gentleman, visual scientist, whites of the eyes and clinician of the first rank— is memorialized here as “Old Iron Eyes” for reasons that will become apparent. Our research required participants to wear thick, powerful contact lenses, and it seemed more efficient for us to manually apply and remove the contacts than for them to learn this skill; stressed, teary- eyed participants would not be good observers. Readers wearing contacts can empathize with their own first encounters with these lenses— it’s not normal to put a large foreign object in one’s eye, and copious tears are reflexively released to flush it out.

Jay suggested that I practice lens application and removal on him and I applied and removed the lenses every minute or so until I eventually mastered the task, many trials later. This made me a bit queasy, and I teared up a bit, but Jay seemed unconcerned, once chatting away on the telephone while I leaned over him, applying and removing the contacts. Let’s face it, touching another person’s eyeball is a special kind of intimacy. His nonchalance reduced but did not eliminate my apprehension. However, another year in this department might have done the trick: students could earn extra cash by harvesting cadaver eyeballs, which were stored in glass jars beside our lunch sacks in the lab refrigerator. Working with Jay and my hardy experimental subjects alerted me to the sympathetic tearing triggered by observing the discomfort, eye redness, and tearing of other people. My next revelation came years later, when I was a professor at my present university.