The social psychological experiment of Festinger and Carlsmith done in 1959 provides insight into why we do things that are contrary to our normal beliefs.
In the study experimenters tell the participants that they are doing a study in which they will see how your expectations affect the experience of the task. They are told that there are two groups, one that has been told what to expect from the experience, but that they are part of the group that has not been given an expectation.
The task that they are given is extremely boring, for half an hour they are to move spoons around in a box, and for another half hour they are to move pegs around a board. After they have completed the task the experimenter tells them that other participants have found the task quite interesting. Then the experimenter explains that there has been a mistake, that the next participant was supposed to have been given an expectation of the task and had not been. They offer the participant either $1 or $20 to tell the next person that the task was interesting.
Afterwords, the participant is to fill out a survey ranking how interesting the task was to them. The results discovered that those who were paid $1 ranked the task as interesting, and those who were paid $20 ranked the task as boring.
This result is called the power of cognitive dissonance. It's the way we deal with two thoughts that contradict each other. In this case, how we rationalize telling someone something was interesting that we actually found boring. For those paid $20 dollars it was easy to lie (in 1959 $20 was much more money). The money, in their mind, was worth lying to the next person and so they felt little guilt doing it. For the person paid only $1, however, their brain needed to rationalize a reason for lying and the person therefore convinced themselves that the task was more interesting then it actually was.
This theory applies to many situations in which people can convince themselves to believe something they would have otherwise found false; to think something unimportant is important, or something boring is interesting.
This experiment is a simplification of how people resolve cognitive dissonance through rationalizations. What are some other situations in which people might do this? How much does money play a roll in the outcome? Could there have been another "reward" such as a feeling of inclusion and would that make the experiment more valid? Are we more likely to rationalize because of monetary gain or social pressures?