With the discovery of mirror neurons and similar systems in humans, neuroscience has shown us that when we see the actions, sensations and emotions of others, we activate brain regions as if we were doing similar actions, were touched in similar ways or made similar facial expressions. In short, our brain mirrors the states of the people we observe. Intuitively, we have the impression that while we mirror, we feel what is going on in the person we observe. We empathize with him or her.
When the person we see has the exact same body and brain as we do, mirroring would tell us what the other feels. Whenever the other person is different in some relevant way, however, mirroring will mislead us. Imagine a masochist receiving a whiplash. Your mirror system might make you feel his pain — because you would feel pain in his stead. What he actually feels though is pleasure. You committed the mirror fallacy of incorrectly feeling that he would have felt what you would have felt — not what he actually felt.
The world is full of such fallacies: we feel dolphins are happy just because their face resembles ours while we smile or we attribute pain to robots in sci-fi movies. We feel an audience is Japan failed to like a presentation we gave because their poise would be our boredom. Labeling them, and realizing that the way we interpret the social world is through projection might help us reappraise these situations and beware.