Agree with Hitmaker. See;
http://www.guardian.co.uk/notesandqueries/query/0,
5753,-19877,00.html
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Mirrors
don't reverse left to right, they reverse front to back. Consider this, when you look at yourself in a mirror, it appears to you that your reflection is another person who looks just like you standing behind a piece of glass, at the same distance from the glass as yourself and facing you. To get there, you reason, that person walked behind the glass and - here's the important bit - turned 180 degrees about the vertical axis to face you. Now his/her left hand should be opposite your right hand, and vice versa. In fact this assumption is wrong. Your reflection didn't do a 180 degree turn. It was reversed front to back with no rotation at all. Your brain mentally subtracts the 180 degree turn that you assume must have happened from the observed front to back reversal and what do you get? An apparent left to right reversal!