The Mandela Effect: Evidence of Matrix, Alternate Dimensions, or Mass Delusion?

The Mandela Effect is variously seen as evidence that we are living in a matrix, that there are alternate/parallel dimensions, or that collective mis-remembering is a common cognitive effect.

Those not familiar with the Mandela Effect can learn more here: http://knowyourmeme.com/memes/the-mandela-effect.

Those who believe they have personally experienced a Mandela Effect (and especially a "flip-flop") often make this a serious study.

We'll do a quick overview of the idea, will collect personal experiences, and then will try and determine how and why changes might be occurring or be perceived to be occurring.