I’m hustling along the sidewalk, late for work, lost in ruminations about my eight o’clock meeting and how to sidestep my vindictive boss. But I’m also dodging the hustling oncomers, scanning their faces, weaving by them. Suddenly I stop scanning, take a second look at that face, at the unmistakable combination of her eyes slanting over that angle of her mouth and the arc of her chin. I slow down. A wave washes through me. With my whole body I know that face, my first high school love, that mesmerizing face I gazed into so deeply, for what I were sure was a lifetime of gazing. Is this that face with thirty years of aging? My hand flits up to scratch just behind the ear, right where the fusiform area of my brain is lighting up like crazy. Do I stop or hurry on? Got to be her! But the same area of your brain lights up when I imagine a face. Maybe my subconscious has been longing for her and I’ve imagined her coming to my rescue again after all these years. I look again. But she’s gone.
Evolution has made sure we’re endowed with a talent for face recognition. In fact, for most of us our brains devote more space to face recognition than to recognition of any other object, such as hands, fire, animals, or words on a page. In the region of the visual cortex of our brains where we identify objects, there’s a special section devoted to faces in the inferior temporal cortex, called the fusiform area . Picture six discrete “face patches” of neurons, each about three milliliters in diameter, lined up in a row, each linked to the others. Together they figure out if an object is a face, what its shape and orientation are, and whether it’s recognizable. This news on how we see faces comes partly from Eric Kandel’s Age of Insight, 2012, chapter 17.
When I see you, your face takes a place in my brain. Later when I miss seeing you and can only imagine you, that same place may light up in my brain. If I love you or fear you, your place in my brain is different than if I just saw you once in the checkout line. Long ago nature gave us a Facebook, because without it we wouldn’t stand a chance of surviving. Know thine enemy, beware of strangers, covet your loved ones. The more recent arrival of the other kind of Facebook is pretty cool, but so far not essential to survival.
For most of us when we’re looking at a hand or a house or abstract art, this fusiform area stays quiet. But a few lines in the right relationships to each other are all we need to excite the Facebook in our brains. Our experience with the caricatures of cartoon faces is confirmed by laboratory experiments with macaque monkeys looking at various options for facial representation: the necessary elements of a face are simple and include just a round or oval outline with two marks for eyes and below them a mark for a mouth. The face area does not light up for two eyes only, or a mouth only, or two eye marks and a mouth mark without the enclosing circle or oval. Monkeys and we are terrible at recognizing faces when they’re upside down. Try it. It will remind you of how rarely you’ve needed to recognize the face of a person who’s standing on his head. Evolution has its efficiencies.
The middle two face patches in your fusiform area activate more intensely when the facial features are exaggerated (within the limits of what we recognize as a face). Cartoons and the clown face and primitive ceremonial masks and the distortions of Picasso can trigger a more emotional response than the accurate representation of the face. The instantaneous recognition of a face as friend or enemy, familiar or strange, colored with the right emotional value, allows us to navigate every day through potentially treacherous and nourishing relationships, the sidewalk of life.
Unless you’re born with an aversion to faces. Some infants avoid looking at faces, are wired to feel intense anxiety with eye contact, and at the extreme develop autistic behaviors. Because of this avoidance their fusiform areas may develop alternative capacities for recognition, depending on their chosen fascination at critical stages of brain development: trucks, numbers, beetles, historical dates. Autism research is now exploring this possibility of an inborn aversion to eye contact, which could guide a new approach to early interventions for autism spectrum disorders, summarized briefly in Richard Davidson’s, The Emotional Life of Your Brain, 2012.
Though nature’s Facebook is not as easy to find and share as Mark Zuckerberg’s, he could learn a few things from her about how we recognize and represent faces.