Researchers in behavioral science are using mirrors to study cognition.

Elephants and other social animals can recognize their own reflections.

By NATALIE ANGIER

Mirrors have fascinated people ever since the deluded young Narcissus of myth chose to die by the side of a reflecting pond rather than leave his “beloved” behind.
But to scientists, mirrors are powerful tools for exploring questions about perception and cognition in humans and other neuronally gifted species. They are also 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, a researcher at 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.”
Other researchers have determined that mirrors can subtly affect human behavior, often in surprisingly positive ways. 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.
But 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 generalize.
The few nonhuman species that have been found to recognize themselves in a mirror are those with sophisticated social lives. Great apes - chimpanzees, bonobos, orangutans and gorillas - along with dolphins and Asian elephants, will, when given a mirror, scrutinize marks that have been applied to their faces or bodies. The animals also will check up on personal hygiene, inspecting their mouths, nostrils and genitals.
However, 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 in New York who has studied mirror selfrecognition in elephants and dolphins, “animals raised in isolation do not seem to show mirror self-recognition.”
Humans do not necessarily see the face in the mirror, either. In a report 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 face. But when asked to identify images of strangers in subsequent tests, participants were best at spotting the unenhanced faces.
“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 scruffymorning 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 .”
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 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?
To the first question most people 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, and the size of that outlined oval will not change: it will remain half the size of your face, even as the background scene reflected in the mirror changes.
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.
But no matter what size we appear, when we gaze into a mirror, we are all of us Narcissus, tethered eternally to our doppelganger on the other side.