Sometimes the main reason for situational impotence is a gross anomaly in a patient's erotic preferences. However, those patients who for one reason or other try to adjust in their sexual interactions to the general norm tend to hide or underestimate their true erotic preferences. This makes it necessary sometimes to base our diagnosis on data other than a patient's verbal report. An overview on nonverbal diagnostic methods is presented, and one of them, the phallometric test, is described in more detail, including a discussion of its limitations.