The Barnum Effect was generated to teach students about the ethics of deception in research and the feelings of subjects who are deceived. The Barnum Effect occurs when individuals are duped into believing invalid results of psychological tests. People are most accepting when given favorable feedback about themselves. They interpret evaluations as being uniquely descriptive even when the feedback is so general that it applies to virtually everybody. Twenty-eight female and 11 male students in research methods classes received feedback based on a bogus personality inventory. Subjects then rated the perceived validity of the interpretations. Students accepted the feedback, although seniors were more skeptical than were juniors or sophomores. A discussion was conducted of the ethics of deception based on students' own reactions to the knowledge that they were deceived. Students agreed that the approach was effective in helping them learn firsthand about the costs and benefits of deception in research. Men and women reacted in the same ways. The demonstration seems useful for a wide range of students. Appendices contain the test items from the inventory and the evaluation questions. A seven-item list of references is included. (SLD)