The
classical experiment in cognitive dissonance involves getting participants to do a
boring and
meaningless task, and then to try and convince someone (in fact a member of the experimenting team) that the task was in fact
interesting. The participants are paid either a
token amount, a
larger amount or
no money. Later they are asked about their opinions of the task.
People who were paid the large amount have an obvious external justification for their actions (the action is describing the task as interesting, not merely doing it), and they will have little dissonance in telling you that it was boring. Those paid little have a lower external justification, and so are forced to internalise it and conclude that the task was in fact interesting.
Hence the cognitive dissonance method for dating involves picking people you'd want to date and making them write a short essay on why they want to go out with you, for a very low fee. Come back to them a few days later and they should have internalised their beliefs and will want to go out with you.