Just as the surgeons never compared radical mastectomy with other procedures, when you rely on personal experience to decide what is true, you usually don’t have a systematic comparison group because you’re observing only one “patient”: yourself. Perhaps you try tapping on your eyebrows to calm yourself in an anxious moment—and it seems to work! But how would you have felt if you’d tried something different? That salt lamp you’ve been using seems to reduce your stress, but what would have happened without it? Maybe you would have felt fine anyway. You might think visiting a rage room makes you calm down when you’re angry, but would you have felt even better if you had gone to the gym? What if you had done nothing and just let a little time pass

For instance, suppose you’re considering buying a new car. You want the most reliable one, so after consulting Consumer Reports, you decide on a Honda Fit, a top-rated car based on objective road testing and a survey of 1,000 Fit owners. But then you hear about your cousin’s Honda Fit, which is always in the shop. Why not rely on your own experience—or that of someone you know and trust—as a source of information?

Thinking like a psychologist means thinking like a scientist, and thinking like a scientist involves thinking about the empirical basis for what we believe.

In the natural world, a mother provides both food and contact comfort at once, so when the baby clings to her, it is impossible to tell why. To test the alternative theories, Harlow had to separate the two influences—food and contact comfort. The only way he could do so was to create “mothers” of his own. He built two monkey foster “mothers”—the only mothers his lab-reared baby monkeys ever had. One of the mothers was made of bare wire mesh with a bottle of milk built in. This wire mother offered food, but not comfort. The other was covered with fuzzy terrycloth and was warmed by a lightbulb suspended inside, but she had no milk. This cloth mother offered comfort, but not food.

Empiricists do not base conclusions on intuition, on casual observations of their own experience, or on what other people—even people with PhDs—say. Empiricism, also referred to as the empirical method or empirical research, involves using evidence from the senses (sight, hearing, touch) or from instruments that assist the senses (such as thermometers, timers, photographs, and questionnaires) as the basis for conclusions. Empiricists aim to be systematic and rigorous and to make their work independently verifiable by other observers.

What do you gain by being a critical consumer of information? Imagine, for example, that you are a correctional officer at a juvenile detention center and you hear of a crime-prevention program called Scared Straight. The program targets teenagers who are at risk for becoming involved in the criminal justice system. They visit prisons, where selected inmates describe the stark, violent realities of prison life (Figure 1.2). The idea is that when teens hear about how tough it is in prison, they will be scared into the “straight,” law-abiding life. The program makes intuitive sense, and your employer is considering a partnership between the residents of your detention center and the state prison system.

Some psychology students are fascinated by the research process and intend to become producers of research. Perhaps they hope to get a job studying brain anatomy, documenting the behavior of dolphins or monkeys in their natural habitats, administering personality questionnaires, observing children in a school setting, or analyzing data. They expect to write up their results and present them at research meetings. These students dream about working as research scientists or professors. Other psychology students may not want to work in a lab, but they do enjoy reading about the structure of the brain, the natural behavior of dolphins or monkeys, the personalities of their fellow students, or the behavior of children in a school setting. They are interested in being consumers of research information—reading about research so they can later apply it to their work, hobbies, relationships, or personal growth. In practice, psychologists engage in both roles. When they are planning their research and creating new knowledge, they study the work of others who have gone before them. Research producers and consumers also share a commitment to empiricism—answering psychological questions with direct, formal observations—and to communicating with others about what they have learned.