Aronson and Mills
Aronson and Mills were the first to scientifically test the concept of Effort Justification which is really a form of cognitive dissonance.
They were first brought to our attention in the neuromarketing book by Robert B. Cialdini (Highly recommended by Theme Zoom) called Influence, the Psychology of Persuasion. You may read a few chapters about the topic of Effort Justification in Cialdini's book online.
A group of young women who volunteered to join a discussion group on the topic "Psychology of Sex" were asked to do a small reading test to make sure they were not too embarrassed to talk about sexual related topics with others. The mild-embarrassment condition subjects were asked to read aloud a list of sex related words such as "prostitute" or "virgin". The severe-embarrassment condition subjects were asked to read aloud a list of highly sexual words (e.g. "fuck", "cock") and to read two vivid descriptions of sexual activity taken from contemporary novels. All subjects then listened to a recording of a discussion about "Sexual Behavior in Animals" which was dull and unappealing. When asked to rate the group and its members, control and mild-embarrassment groups did not differ, but the severe-embarrassment group's ratings were significantly higher. This group, whose initiation process was more difficult (embarrassment = effort) had to increase their subjective value of the discussion group to resolve the dissonance.
Also See Russell Wright