The Irrational Bundle. Dan Ariely

and an Internet connection can get hold of the most graphic pornography imaginable.

      Although the business school was stymied by this project, I was fortunate to have a position at MIT’s Media Lab as well, and Walter Bender, who was the head of the lab, happily approved the project. I was on my way. But my experience with MIT’s Sloan School made it clear that even half a century after Kinsey, and despite its substantial importance, sex is still largely a taboo subject for a study—at least at some institutions.

      IN ANY CASE, our ads went out; and, college men being what they are, we soon had a long list of hearty fellows awaiting the chance to participate—including Roy.

      Roy, in fact, was typical of most of the 25 participants in our study. Born and raised in San Francisco, he was accomplished, intelligent, and kind—the type of kid every prospective mother-in-law dreams of. Roy played Chopin études on the piano and liked to dance to techno music. He had earned straight A’s throughout high school, where he was captain of the varsity volleyball team. He sympathized with libertarians and tended to vote Republican. Friendly and amiable, he had a steady girlfriend who he’d been dating for a year. He planned to go to medical school and had a weakness for spicy California-roll sushi and for the salads at Cafe Intermezzo.

      Roy met with our student research assistant, Mike, at Strada coffee shop—Berkeley’s patio-style percolator for many an intellectual thought, including the idea for the solution to Fermat’s last theorem. Mike was slender and tall, with short hair, an artistic air, and an engaging smile.

      Mike shook hands with Roy, and they sat down. “Thanks for answering our ad, Roy,” Mike said, pulling out a few sheets of paper and placing them on the table. “First, let’s go over the consent forms.”

      Mike intoned the ritual decree: The study was about decision making and sexual arousal. Participation was voluntary. Data would be confidential. Participants had the right to contact the committee in charge of protecting the rights of those participating in experiments, and so on.

      Roy nodded and nodded. You couldn’t find a more agreeable participant.

      “You can stop the experiment at any time,” Mike concluded. “Everything understood?”

      “Yes,” Roy said. He grabbed a pen and signed. Mike shook his hand.

      “Great!” Mike took a cloth bag out of his knapsack. “Here’s what’s going to happen.” He unwrapped an Apple iBook computer and opened it up. In addition to the standard keyboard, Roy saw a 12-key multicolored keypad.

      “It’s a specially equipped computer,” Mike explained. “Please use only this keypad to respond.” He touched the keys on the colored pad. “We’ll give you a code to enter, and this code will let you start the experiment. During the session, you’ll be asked a series of questions to which you can answer on a scale ranging between ‘no’ and ‘yes.’ If you think you would like the activity described in the question, answer ‘yes,’ and if you think you would not, answer ‘no.’ Remember that you’re being asked to predict how you would behave and what kind of activities you would like when aroused.”

      Roy nodded.

      “We’ll ask you to sit in your bed, and set the computer up on a chair on the left side of your bed, in clear sight and reach of your bed,” Mike went on. “Place the keypad next to you so that you can use it without any difficulty, and be sure you’re alone.”

      Roy’s eyes twinkled a little.

      “When you finish with the session, e-mail me and we will meet again, and you’ll get your ten bucks.”

      Mike didn’t tell Roy about the questions themselves. The session started by asking Roy to imagine that he was sexually aroused, and to answer all the questions as he would if he were aroused. One set of questions asked about sexual

      preferences. Would he, for example, find women’s shoes erotic? Could he imagine being attracted to a 50-year-old woman? Could it be fun to have sex with someone who was extremely fat? Could having sex with someone he hated be enjoyable? Would it be fun to get tied up or to tie someone else up? Could “just kissing” be frustrating?

      A second set of questions asked about the likelihood of engaging in immoral behaviors such as date rape. Would Roy tell a woman that he loved her to increase the chance that she would have sex with him? Would he encourage a date to drink to increase the chance that she would have sex with him? Would he keep trying to have sex after a date had said “no”?

      A third set of questions asked about Roy’s likelihood of engaging in behaviors related to unsafe sex. Does a condom decrease sexual pleasure? Would he always use a condom if he didn’t know the sexual history of a new sexual partner? Would he use a condom even if he was afraid that a woman might change her mind while he went to get it?*

      A few days later, having answered the questions in his “cold,” rational state, Roy met again with Mike.

      “Those were some interesting questions,” Roy noted.

      “Yes, I know,” Mike said coolly. “Kinsey had nothing on us. By the way, we have another set of experimental sessions. Would you be interested in participating again?”

      Roy smiled a little, shrugged, and nodded.

      Mike shoved a few pages toward him. “This time we’re asking you to sign the same consent form, but the next task will be slightly different. The next session will be very much the same as the last one, but this time we want you to get yourself into an excited state by viewing a set of arousing pictures and masturbating. What we want you to do is arouse yourself to a high level, but not to ejaculate. In case you do, though, the computer will be protected.”

      Mike pulled out the Apple iBook. This time the keyboard and the screen were covered with a thin layer of Saran wrap.

      Roy made a face. “I didn’t know computers could get pregnant.”

      “Not a chance,” Mike laughed. “This one had its tubes tied. But we like to keep them clean.”

      Mike explained that Roy would browse through a series of erotic pictures on the computer to help him get to the right level of arousal; then he would answer the same questions as before.

      WITHIN THREE MONTHS, some fine Berkeley undergraduate students had undergone a variety of sessions in different orders. In the set of sessions conducted when they were in a cold, dispassionate state, they predicted what their sexual and moral decisions would be if they were aroused. In the set of sessions conducted when they were in a hot, aroused state, they also predicted their decisions—but this time, since they were actually in the grip of passion, they were presumably more aware of their preferences in that state. When the study was completed, the conclusions were consistent and clear—overwhelmingly clear, frighteningly clear.

      In every case, our bright young participants answered the questions very differently when they were aroused from when they were in a “cold” state. Across the 19 questions about sexual preferences, when Roy and all the other participants were aroused they predicted that their desire to engage in a variety of somewhat odd sexual activities would be nearly twice as high as (72 percent higher than) they had predicted when they were cold. For example, the idea of enjoying contact with animals was more than twice as appealing when they were in a state of arousal as when they were in a cold state. In the five questions about their propensity to engage in immoral activities, when they were aroused they predicted their propensity to be more than twice as high as (136 percent higher than) they had predicted in the cold state. Similarly, in the set of questions about using condoms, and despite the warnings that had been hammered into them over the years about the importance of condoms, they were 25 percent more likely in the aroused state than in the cold state to predict that they would forego condoms. In all these cases they failed to predict the influence of arousal on their sexual preferences, morality, and approach to safe sex.

      The results showed that when Roy and the other participants were in a cold, rational, superego-driven state, they respected women; they were not particularly attracted to