eye collage

Looking and listening.

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Answering Listener Questions, From Earwax To Eye Gaze

March 28, 2017

Let's start things off with a quick quiz: 

Walt Whitman sang this electric; Catholics believe in its resurrection, as well as the soul’s; and John Mayer thinks yours is wonderland.

What am I talking about? The body, of course.

That's where the Curiosity Desk shone its spotlight this week – in particular on two questions from listeners about how the body works.

Waxing About The Ears
The first question came courtesy of John Goldthwait from Hanover, Mass.

"I’ve wondered for years what this rather bizarre stuff is that comes out of ears. So, if you can tell me what ear wax is and what its function is I would find it very interesting."

For answers, I headed down to Mass. Eye and Eye, where otology specialist Dr. David Jung took a few minutes out of his day to shed some light, and dispel some myths.

"There’s a very common misconception among many people – including my wife, who should know better – that earwax is quote, unquote dirty," he said. "Nothing could be further from the truth."

In fact, the main function of ear wax, also called cerumen, is to keep the ear clean. It’s largely comprised of two substances.

The first are oily secretions from modified sweat glands in our ears that produce the moist base for the earwax. The second component is dead skin cells. Like much of the body, the ear canal is covered in skin, and skin sloughs off. But unlike other areas, that dead skin needs to be carried away, otherwise the ear would quickly become blocked. Thanks to the wax and some specialized ear hairs "all of that kind of gets worked out of the ear and allows the ear to remain healthy," explained Dr. Jung.

Cerumen also keeps the ear canal lubricated, and provides a line of defense against bacteria and water. While Dr. Jung says he sees patients who produce too much, or not enough earwax, both are usually easily treatable. More common are problems that arise when people try to clear out the ear canal themselves. His advice? Step away from the Q-tips.

"Earwax is healthy," he explained. "Do not clean it. Your body knows best. It will clean itself."

A diagram of the ear from a 1918 edition of Gray's Anatomy
Caption
Photo Credit: Bartleby.com: Gray's Anatomy, Plate 907

 

What Are You Looking At?
We turned from ears to eyes thanks to Joan Chisholm from Wakefield who has, for years, been curious about why we look where we look.

"I wonder why humans look at eyes when we speak to each other instead of looking at mouths, which seems to be the logical thing to do because it's the source of sound."

In the words of Matthew Peterson, a brain and cognitive post-doctoral researcher at MIT, understanding why we look where we look is "very complex."

For starters, it turns out we’re not even very good at knowing where we're actually looking when we're looking at others. Peterson once did a study where he tracked the eyes of 50 people who he asked to look at faces on a screen, and then click on the exact spot where they were looking.

"Forty-nine out of the 50 either clicked on the eyes or the mouth," he said. None of them were. "When you actually look at the data, only one person actually clicked where they were looking."

Peterson says that everyone has a unique home base: A spot on the face where they tend to look when they look at others. For a very few it is the eyes or the mouth, but for the majority of people it’s actually a more featureless, central area.

"People’s gaze is generally directed, definitely, at the face," said Peterson. "But it’s actually directed a little bit below the eyes, about a third to halfway between the eyes and the nose tip."

Peterson says there’s a reason why we think we look at the eyes more than we actually do. The brain is constantly using what we see (not to mention what we hear, smell, and feel), to help it both make sense of what is happening and make decisions about what to do in response.

"It happens to be that that information that we use...the cues we can use to make those decisions...they’re really highly concentrated in the eye region," he explained. "So even if we're not looking at the eyes directly, we're using the eyes."

Complicating matters is the fact that the eye is moving subtly all the time, some 1-4 times per second, often darting between our home base and other areas on the face. And those movements can be situation dependent. For example, put two people in a loud environment and ask them to converse, and they'll likely spend more time looking at each others mouths than they would in a quiet room.   

Add to all that the fact that we don't simply use our eyes to take signals in, but also to send them out. 

"If I am looking really direct strong eye contact to you for a long time that might be a signal of dominance or aggression," said Peterson. "If I’m looking at you and my pupils get larger it’s a sign of arousal, for instance. So it’s a receiver but also a transmitter, which of course makes it all the more complicated but all the more interesting I think."

Of Babies And Beagles
Unlike adults, newborns look almost exclusively at the eyes, at least for the first few months to year of their lives. 

"There seems to be an automatic mechanism in the brain that guides newborn's eye movements - or gaze - to the eyes," said Peterson.

Peterson says the thought among researchers is that, given the limited number of things that a developing brain can do, the eyes appear to be the best place for babies to begin to get a baseline understanding of the face, and find answers to fundamental questions about it such as, "What do faces look like? How are they organized and structured? Where are their features? Where is the information?"

Unlike many other animals, man's best friend seems to be biologically conditioned to look us in the eyes. 

"Dogs of course have been selectively bred to be highly social and highly collaborative and cooperative in humans," Peterson noted. 

Peterson pointed to a study that found that when dogs look humans in the eyes, it triggered a release of oxytocin - a hormone sometimes referred to as the "love hormone" that plays a crucial role in bonding.  

"The same thing happens with humans," he said. "When we make eye contact with another human ... we also get a squirt of oxytocin." 

That same "reward" for eye contact spurred in humans' and dog's brains is not seen in the brains of wolves, the animal from which dogs are descended. 

Our thanks to John Goldthwait and Joan Chisholm for their questions that led to this story. If there is something you have been itching to know more about, email The Curiosity Desk.


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