Predictably Irrational: The Hidden Forces That Shape our Decisions

These two chapters focus on expectations. Chapter 10 examines how expectations change the way people appreciate and perceive experiences. Ariely explores how expectations influence all aspects of life. While he provides examples about how expectations impact a person’s view of drinks and food, he also focuses on less trivial items, like stereotypes. Stereotypes are not inherently bad. The brain creates stereotypes, or short-cuts, to help make sense of a complicated environment. Stereotypes become problematic when they “unfavorably influence both our perceptions and our behavior” (212). One particularly vivid example was when women and Asian-Americans were primed to think about their gender and race and then take a math exam. The women, who were reminded of their gender, did worse than Asian-Americans. The stereotype that women are bad at math impacted the results. These findings demonstrate that stereotypes influence behaviors. Moreover, this influence has real-world consequences: Such stereotypes are why fewer women go into STEM fields, which are higher paying than non-STEM fields. Not only do STEM fields have less gender diversity because of this stereotype, but the stereotype impacts women’s long-term economic outcomes.

Chapter 11 expands on the findings from Chapter 10 to look at how expectations affect sense perception and subjective and objective experiences. As one example, Ariely and colleagues conducted an experiment where they offered students the same energy drink at two different prices. Students who drank the pricier beverage self-reported less fatigue than those who drank the discounted beverage. To test the phenomenon’s persistence, Ariely and colleagues asked the same students to complete a series of anagrams, which are words or phrases spelled by rearranging other words or phrases. The students who drank the full-priced energy drink outperformed those who had the discounted drinks. This experiment highlights human irrationality: The energy drink is the same, yet its price influences how people perceive its benefits. However, through other experiments, Ariely found that when individuals stop to reflect about the relationship between quality and price of an item, they are less likely to assume the discounted item has fewer benefits. The key is taking the time to slow down and think before making a decision.

At the end of Chapter 11, Ariely encourages readers to ponder placebos’ morality. Placebos are ethically tricky, and, in medical research, using a placebo can mean that the experiment is sacrificing the wellbeing and perhaps life of participants in order to discover a treatment’s efficacy. However, research also makes trade-offs by not carrying out placebo experiments to determine efficacy.

Ariely shares his own personal story to underscore this point. During the first few months he was in the hospital, he tried to wear a Jobst suit, which is a compression suit meant to help burn victims’ skin heal. He recalls that “he suffered with this treatment for months—itching, aching, struggling to wear it, and tearing my new delicate skin while trying to put it on (and when this new thin skin tears, it takes a long while to heal)” (245). He eventually learned that the suit did not have any real benefits for him. While it might have been morally questionable to have burn victims test the efficacy of these suits relative to other methods and a placebo suit, it might have also saved him and other victims from suffering. To him, “my wasted suffering, and the suffering of other patients like me, is the real cost of not doing such [placebo] experiments” (246).