You prefer your mirror-image, how you look in a mirror, and your loved ones preferred the real-image photo.

For decades, psychologists have been studying this phenomenon, called the “mere exposure” principle, which says that people develop a preference for things that are more familiar (i.e., merely being exposed to something makes us view it more positively).

One of the pioneers in the field was Robert Zajonc (whose name now feels strangely likable …). When Zajonc exposed people to various stimuli—nonsense words, Chinese-type characters, photographs of faces—he found that the more they saw the stimuli, the more positive they felt about them.

In a fascinating application of this principle, psychologists studied people’s reactions to their own faces. To introduce the study, let’s talk about you for a moment. This may sound odd, but you’re actually not very familiar with your own face. The face you know well is the one you see in the mirror, which of course is the reverse image from what your loved ones see.

Knowing this, some clever researchers developed two different photographs of their subjects’ faces: One photo corresponded to their images as seen by everyone else in the world, and the other to their mirror images as seen by them.

As predicted by the mere-exposure principle, the subjects preferred the mirror-image photo, and their loved ones preferred the real-image photo. We like our mirror face better than our real face, because it’s more familiar!

The face-flipping finding is harmless enough, though weird and surprising. But what’s more troubling is that the mere-exposure principle also extends to our perception of truth.

When the participants were exposed to a particular statement three times during the experiment, rather than once, they rated it as more truthful. Repetition sparked trust.

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