Why do mirrors reverse left and right, not up and down? © iStock

Why do mirrors reverse left and right, not up and down?

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Truth is, mirrors only reverse front to back...

Asked by: Dave Ford, Birmingham

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Mirrors don’t reverse left and right either – that’s just our interpretation of what happens. Your reflection in the mirror is actually reversed front to back – if you have a mole on left side of your face, it still appears on the left side of the reflection. But we are used to seeing the faces of other people and we instinctively perform the mental rotation because we know that they have turned through 180 degrees to face us. The image in the mirror is reflected, not rotated, so when we rotate it back in our head, it appears reversed.


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Authors

Robert is a science writer and visiting professor of science at Aston University.

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