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.And then this near the end on visual perception:
“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.
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?(via Friends of African Village Libraries)
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.