For the bubbleheaded young Narcissus of myth, the mirror spun a fatal fantasy, and the beautiful boy chose to die by the side of a reflecting pond rather than leave his “beloved” behind. For the aging narcissist of Shakespeare’s 62nd sonnet, the mirror delivered a much-needed whack to his vanity, the sight of a face “beated and chopp’d with tann’d antiquity” underscoring the limits of self-love.
Whether made of highly polished metal or of glass with a coating of metal on the back, mirrors have fascinated people for millennia: ancient Egyptians were often depicted holding hand mirrors. With their capacity to reflect back nearly all incident light upon them and so recapitulate the scene they face, mirrors are like pieces of dreams, their images hyper-real and profoundly fake. Mirrors reveal truths you may not want to see. Give them a little smoke and a house to call their own, and mirrors will tell you nothing but lies.
To scientists, the simultaneous simplicity and complexity of mirrors make them powerful tools for exploring questions about perception and cognition in humans and other neuronally gifted species, and how the brain interprets and acts upon the great tides of sensory information from the external world. They are using mirrors to study how the brain decides what is self and what is other, how it judges distances and trajectories of objects, and how it reconstructs the richly three-dimensional quality of the outside world from what is essentially a two-dimensional snapshot taken by the retina’s flat sheet of receptor cells. They are applying mirrors in medicine, to create reflected images of patients’ limbs or other body parts and thus trick the brain into healing itself. Mirror therapy has been successful in treating disorders like phantom limb syndrome, chronic pain and post-stroke paralysis.
“In a sense, mirrors are the best ‘virtual reality’ system that we can build,” said Marco Bertamini of the University of Liverpool. “The object ‘inside’ the mirror is virtual, but as far as our eyes are concerned it exists as much as any other object.” Dr. Bertamini and his colleagues have also studied what people believe about the nature of mirrors and mirror images, and have found nearly everybody, even students of physics and math, to be shockingly off the mark.
Other researchers have determined that mirrors can subtly affect human behavior, often in surprisingly positive ways. Subjects tested in a room with a mirror have been found to work harder, to be more helpful and to be less inclined to cheat, compared with control groups performing the same exercises in nonmirrored settings. Reporting in the Journal of Personality and Social Psychology, C. Neil Macrae, Galen V. Bodenhausen and Alan B. Milne found that people in a room with a mirror were comparatively less likely to judge others based on social stereotypes about, for example, sex, race or religion.
“When people are made to be self-aware, they are likelier to stop and think about what they are doing,” Dr. Bodenhausen said. “A byproduct of that awareness may be a shift away from acting on autopilot toward more desirable ways of behaving.” Physical self-reflection, in other words, encourages philosophical self-reflection, a crash course in the Socratic notion that you cannot know or appreciate others until you know yourself.
The mirror technique does not always keep knees from jerking. When it comes to socially acceptable forms of stereotyping, said Dr. Bodenhausen, like branding all politicians liars or all lawyers crooks, the presence of a mirror may end up augmenting rather than curbing the willingness to pigeonhole.
The link between self-awareness and elaborate sociality may help explain why the few nonhuman species that have been found to recognize themselves in a mirror are those with sophisticated social lives. Our gregarious great ape cousins — chimpanzees, bonobos, orangutans and gorillas — along with dolphins and Asian elephants, have passed the famed mirror self-recognition test, which means they will, when given a mirror, scrutinize marks that had been applied to their faces or bodies. The animals also will check up on personal hygiene, inspecting their mouths, nostrils and genitals.
Yet not all members of a certifiably self-reflective species will pass the mirror test. Tellingly, said Diana Reiss, a professor of psychology at Hunter College who has studied mirror self-recognition in elephants and dolphins, “animals raised in isolation do not seem to show mirror self-recognition.”
For that matter, humans do not necessarily see the face in the mirror either. In a report titled “Mirror, Mirror on the Wall: Enhancement in Self-Recognition,” which appears online in The Personality and Social Psychology Bulletin, Nicholas Epley and Erin Whitchurch described experiments in which people were asked to identify pictures of themselves amid a lineup of distracter faces. Participants identified their personal portraits significantly quicker when their faces were computer enhanced to be 20 percent more attractive. They were also likelier, when presented with images of themselves made prettier, homelier or left untouched, to call the enhanced image their genuine, unairbrushed face. Such internalized photoshoppery is not simply the result of an all-purpose preference for prettiness: when asked to identify images of strangers in subsequent rounds of testing, participants were best at spotting the unenhanced faces.
How can we be so self-delusional when the truth stares back at us? “Although we do indeed see ourselves in the mirror every day, we don’t look exactly the same every time,” explained Dr. Epley, a professor of behavioral science at the University of Chicago Graduate School of Business. There is the scruffy-morning you, the assembled-for-work you, the dressed-for-an-elegant-dinner you. “Which image is you?” he said. “Our research shows that people, on average, resolve that ambiguity in their favor, forming a representation of their image that is more attractive than they actually are.”
When we look in the mirror, our relative beauty is not the only thing we misjudge. In a series of studies, Dr. Bertamini and his colleagues have interviewed scores of people about what they think the mirror shows them. They have asked questions like, Imagine you are standing in front of a bathroom mirror; how big do you think the image of your face is on the surface? And what would happen to the size of that image if you were to step steadily backward, away from the glass?
People overwhelmingly give the same answers. To the first question they say, well, the outline of my face on the mirror would be pretty much the size of my face. As for the second question, that’s obvious: if I move away from the mirror, the size of my image will shrink with each step.
Both answers, it turns out, are wrong. Outline your face on a mirror, and you will find it to be exactly half the size of your real face. Step back as much as you please, and the size of that outlined oval will not change: it will remain half the size of your face (or half the size of whatever part of your body you are looking at), even as the background scene reflected in the mirror steadily changes. Importantly, this half-size rule does not apply to the image of someone else moving about the room. If you sit still by the mirror, and a friend approaches or moves away, the size of the person’s image in the mirror will grow or shrink as our innate sense says it should.
What is it about our reflected self that it plays by such counterintuitive rules? The important point is that no matter how close or far we are from the looking glass, the mirror is always halfway between our physical selves and our projected selves in the virtual world inside the mirror, and so the captured image in the mirror is half our true size.
Rebecca Lawson, who collaborates with Dr. Bertamini at the University of Liverpool, suggests imagining that you had an identical twin, that you were both six feet tall and that you were standing in a room with a movable partition between you. How tall would a window in the partition have to be to allow you to see all six feet of your twin?
The window needs to allow light from the top of your twin’s head and from the bottom of your twin’s feet to reach you, Dr. Lawson said. These two light sources start six feet apart and converge at your eye. If the partition is close to your twin, the upper and lower light points have just begun to converge, so the opening has to be nearly six feet tall to allow you a full-body view. If the partition is close to you, the light has nearly finished converging, so the window can be quite small. If the partition were halfway between you and your twin, the aperture would have to be — three feet tall. Optically, a mirror is similar, Dr. Lawson said, “except that instead of lighting coming from your twin directly through a window, you see yourself in the mirror with light from your head and your feet being reflected off the mirror into your eye.”
This is one partition whose position we cannot change. When we gaze into a mirror, we are all of us Narcissus, tethered eternally to our doppelgänger on the other side.