Hi, I thought you may like this Mentalrobics exercise from Braingle.com:
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Memory Conformity

Two people who witness the same event may have different memories about what happened. This is because people pay attention to different things, and because memories fade and become distorted. If these people are allowed to talk, they can seriously distort each other's memory of what happened. This phenomenon is called "memory conformity." People who experience the same thing naturally want their memories to be the same, and as a result they can be talked out of their true memory and convinced to believe something that is false.

This frequently happens to married couples or family members who are trying to remember something that happened in the past. If the two people disagree on a particular detail, one person can often be convinced that their memory is wrong even if it isn't.
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For more mind exercises: http://www.braingle.com/mind/