I was going to begin this post with the common saying, “The eyes are the windows of the soul,” but I couldn’t find the originator of the line to give him or her credit. It turns out that human beings have been saying variations of this truism almost as long as we have been putting things down in writing, and probably long before then as well. So I got to thinking about the ubiquitous nature of this saying. I think it suggests a powerful shared insight we humans have for recognizing and relating to other intelligent beings.

Our ancestors got it right

As I look for practical applications of neuroscience, I sometimes stumble upon things we believe at some instinctual level that we can now say we “know” because of evidence uncovered in a living brain. One example of this is the way we talk about inspiration and creativity as a sudden flash of light or a light bulb turning on. It turns out that this is not just a pretty metaphor; it is pretty much what happens if you leave out the quantum physics going on at the sub-atomic level of your brain’s activity. As a learning professional, I’m also aware of the enormous amount of information that comes to the brain directly through our eyes. In fact, about 30% of the human brain is dedicated to processing visual information. Compare that to about 8% for sound and you get a sense of the importance of our eyes – and the neural network behind them.

Eye contact is an important visual cue

It makes perfect sense to me that we recognize our eyes as windows by which we let the outside world into our mind. But windows go both ways. We often speak of being able to look into someone’s eyes to determine if they are telling the truth, or to fall in love with them. In fact, a recent study showed that when two people stare into each other’s eyes for several minutes their brains literally get on the same frequency, generating a deep feeling of intimacy and bonding. Several studies have indicated that when two people are communicating effectively their brains gradually adopt the same modulation and frequency. A great deal of that communication is coming through visual channels. In this video from a neuroscience conference in Amsterdam in 2013, several pairs of strangers sit quietly and use the visual feedback to synchronize their brains. They are literally “in sync.” The phrase “in sync” is another example of a common phrase that seems to express a neural activity perfectly.

Our brains use visual patterns to interpret the world

I’ve written before about visual illusions, which work because our brain is so good at seeing patterns that it sometimes sees patterns even when they aren’t “really” there. Because we recognize certain behavior patterns in ourselves, we’re able to empathize with others and recognize those same patterns. In fact, the human brain is so good at interpreting facial expressions that scientists have used this same process to develop a machine learning program to do the same thing.

Eyes and “cuteness”

As we move closer and closer to the day when a fully-functioning robot can be said to be “intelligent,” artificial intelligence researchers have been building robots with at least one key facial feature – eyes. As you look at these human-mimicking machines, you will notice something special about these “eyes.” Most are over-sized when compared to the proportions on a human adult’s face. The reason for this is explained by evolution. The babies of humans and other mammals are born virtually defenseless and need the protection from the adults in order to survive. As this video compilation of “cute baby animals” will demonstrate, we have evolved to recognize over-size eyes as “cute.” By giving our babies over-size eyes we are hard-wiring ourselves to be attracted to them and want to care for them. Your brain extends this same “cuteness” formula to baby animals, photos and drawings and even inanimate objects that give the appearance of having eyes. So one way to make us more comfortable with robots and other AIs is to give them cute eyes.

Eyes and “intelligence”

We’ve also developed a tendency to interpret certain eye characteristics as a shortcut for assessing intelligence. While so far this doesn’t seem to have been validated by any research that I’ve been able to find, we humans often talk about a “brightness” in the eyes as indicative of intelligence. If this trait is anything like some of the other truisms that neuroscience has proven to be actually true, we may soon expand our definition of intelligence to include other animals and – eventually – inanimate “artificial” intelligences as well. Take a moment and look deep into the eyes of an animal in your life. Chances are you’ll feel a certain amount of connection. Now stare at a stone or a chair. Not the same, is it? We seem to have an innate sense of aliveness and with that, a general impression of whether the alive creature is capable of communicating with us. We humans tend to measure everything in terms of ourselves, so one way to determine if something is “intelligent” is to see if it interacts with us. Of course, if beings from another planet ever visit Earth, they may apply a similar standard to us. I wonder if we’ll pass?