Mark decided that participants in this study will not be at risk, and therefore, he didn't bother the IRB with his proposal. His study investigates the number of discomfort people is willing to put up with in order to earn a large sum of money. He recruits students by posting ads about a "contest in which you can earn $1000." Everyone who shows up is told that they must do whatever he tells them to do for the next several hours and that the last person to comply will earn the money. He then makes the participants eat disgusting food combinations, rub permanent markers on their own faces, and mail insulting messages to their professors. After two hours he stops the "contest," informs everyone that it was actually an experiment, and explains that there is no prize money. Before participants leave, he gets them to sign an informed consent form to acknowledge that they "were free to leave at any time."