The Scientific Method
Psychology is the scientific study of behavior, mental states, and processes in humans and other animals. It is a rigorous scientific discipline with connections to biology, chemistry, neuroscience, and medicine. As scientists, psychologists use carefully collected data to explain thoughts, feelings, and behavior. They base their understanding of the world on hard evidence as chemists, biologists, and physicists do. The scientific method refers to a set of experimental and mathematical procedures used to develop, test, and modify ideas about how the world works. It involves a systematic approach to gathering and evaluating evidence, along with a commitment to discarding ideas that are not supported by evidence.
A scientific theory is an explanation of some aspect of the natural world backed by substantial evidence. It can be used to organize observations and predict events. Nonscientists often refer to a hunch or unsubstantiated idea as a theory. For example, a person might say, "I have a theory that trying teenagers as adults for their crimes will keep kids from committing crimes," or, "I have a theory that eating more fat will help me lose weight." However, scientific theories must be backed by a significant accumulation of evidence. Scientific theories are not tied to only one event or research finding. Rather, theories explain a broad set of observations. They do not reflect the mere opinion of one, or even many, scientists.
A hypothesis is a testable prediction that can be evaluated by observable data. In developing hypotheses, scientists prefer the simplest possible explanation. Over 500 years ago, British philosopher William of Occam (also spelled Ockham) argued that if there are two explanations for a phenomenon, the simpler explanation is likely accurate. This idea is called the principle of parsimony, or Occam's razor.
A scientific hypothesis must be falsifiable, meaning that it is capable of being proven wrong based on observation or experimentation. Hypotheses can be supported or refuted by evidence. For example, a researcher could test the hypothesis, "People who eat a moderate-fat diet for 12 weeks will lose more weight than people who eat a low-fat diet for 12 weeks." This hypothesis could be based on the scientifically supported theory that eating fat keeps people feeling full for longer. Many different studies, conducted with people of various ages, genders, and ethnicities, have shown that eating fat helps people feel full.
To test the hypothesis that a moderate-fat diet leads to more weight loss than a low-fat diet, the researcher would need to conduct an experiment. She may assign some participants to eat a moderate-fat diet and some to eat a low-fat diet for 12 weeks. If the moderate-fat group loses more weight, this would support the hypothesis. However, many more studies would be required before scientists would consider a moderate-fat diet superior to a low-fat diet for weight loss.
Replication means repeating a study to verify the original results. Replication of findings is a key part of the scientific method. To have confidence in a result, scientists need to reproduce findings across different samples and labs using a variety of measures and research designs. Not all findings can be replicated. Random chance, an unusual sample, poor research design, or faulty analyses can all lead to inaccurate findings.
One of the most famous replication failures involves a 1998 study linking autism to vaccines. British researcher Andrew Wakefield published an article suggesting that children in his study developed autism as a result of common childhood vaccines. Since then, many parents have decided not to vaccinate their children. Some children have died of preventable illnesses as a result. Across many attempts to replicate this work, studies have consistently shown that vaccines do not cause autism. Eventually, it became clear that Wakefield's study included numerous errors, omissions, and ethical lapses. As a result, the publisher retracted the study.Cycle of Scientific Inquiry
Following a Scientific Approach
Psychology requires a scientific approach to research because objective, evidence-based findings are more reliable than anecdotal assumptions. Most people see themselves as logical thinkers. Individuals generally believe their opinions are the result of critical thinking, an objective evaluation and analysis of a topic that considers the full range of evidence. However, psychological research indicates that people are often illogical and easily swayed by emotion.
Part of the challenge involved in objectivity lies in how human brains work. Humans excel at recognizing patterns and identifying causes of events. When early humans became ill after trying a new food, they quickly learned that it was toxic. However, the human skill of pattern recognition means people sometimes imagine connections between events.
An illusory correlation is the perception of a stronger relationship between events than actually exists. A soccer player may have a great game after eating oatmeal instead of eggs. This could lead her to see oatmeal as the best game-day breakfast. A person may have positive interactions with people of a specific religion. This may lead him to assume that all kind people share that religious belief.
Many superstitions and beliefs in psychic powers come from illusory correlations. For example, a student may decide to wear a specific sweatshirt for every psychology quiz because her grades were initially lower when she did not wear the sweatshirt and higher when she did. Illusory correlations arise partly because people are more likely to notice and remember surprising information. When a person gets a call from an old friend just after thinking of them, it feels significant. She is less likely to notice all the other possible combinations of thinking of and hearing from a friend. It simply is not surprising or noteworthy to have a day on which a long-lost friend fails to get in touch.
Illusory Correlations
| Event | llusory Correlation | Reasons for Illusory Correlation | Possible Factual Explanations |
|---|---|---|---|
| Woman is pickpocketed while visiting Barcelona | She decides people in Barcelona are criminally-minded. | For her, being pickpocketed and visiting Barcelona are both rare events. Having them occur together links them in her mind. | Pickpockets target tourists in cities around the world; this is not true only of Barcelona. Even so, most tourists do not get pickpocketed. She may have simply been unlucky. |
| Man hears about a pitbull attack on the news | He decides all pitbulls are violent and people should not be allowed to keep them as pets. | The few pitbulls that attack people get news coverage. The many pitbulls that do not harm people do not get news coverage. | The pitbull mentioned on the news may have been provoked or trained to be aggressive. Not all pitbulls are prone to aggression. |
Illusory correlations suggest a stronger relationship between variables than actually exists, leading to assumptions that are based on personal experience rather than scientific data.
People are also easily swayed by emotions and personal stories. Anecdotal evidence, personal stories about specific experiences and incidents, often feel more compelling than dull numeric data drawn from many people's experiences. Unfortunately, anecdotal evidence is less reliable than large data sets. A person may have a compelling story about how their depression vanished after they switched to an organic diet, but that does not mean organic food cured them. The change of seasons, a new exercise habit, or a decrease in stress may have solved their problem. Perhaps they were never clinically depressed in the first place.
Psychologists have found that biases influence people's perceptions and reasoning. Confirmation bias occurs when people seek out or interpret information in ways that support an existing belief. For example, people who believe that ultra low-fat diets are the healthiest option tend to read articles supporting that belief. If they read an article challenging that belief, they are likely to criticize the evidence for the new idea or challenge the competence of the researchers.Pop Psychology and Pseudoscience
People who have not studied psychology often assume that only common sense is needed to understand why people think, feel, and act as they do. It is easy to wrongly assume that what is true of one's own personal experience is true of all people.
Many books and television shows present pop psychology ideas rather than scientifically accurate information. Pop psychology, short for "popular psychology," refers to ideas about psychology that are perpetuated in the media and through other social channels but that are not rooted in science. Often, the popular media oversimplifies the causes of complex problems and promises easy solutions. For example, many books and shows promote the power of positive thinking. They suggest that simply thinking positively will result in health, wealth, and happiness. Optimism can predict well-being, but books and talk shows often dramatically overstate the benefits. For example, self-help books often guarantee that the reader will find happiness, career success, and romance with a few simple life changes. Books promising quick fixes to complex problems misrepresent psychological knowledge. Often, these works are pure pseudoscience—a collection of beliefs or practices that appear to be scientific but are not supported by evidence.
Pseudoscientific information is widespread and often discovered by individuals seeking help for psychological or other health-related problems. For example, a person who is searching for treatment options for depression may find information about thought field therapy. This seemingly revolutionary treatment promises to rapidly cure depression, anxiety, and chronic pain. Some providers promise to quickly correct people's "thought fields" over the phone. However, this approach is not supported by research. Relying on unsupported claims or treatments may waste a person's time or money.
Some pseudoscientific treatments, such as rebirthing therapy, can cause direct harm. This controversial treatment uses pillows and blankets to mimic the physical experience of being born. It is intended to help adopted children attach to their caregivers. In extreme circumstances, rebirthing therapy can result in death, as in the case of 10-year-old Candace Newmaker in Colorado in 2000. There is no research evidence supporting this treatment, and it has been widely discredited by the scientific community.
Many pseudoscientific claims come with clear warning signs. Claims that are substantiated by a single study or treatment options reported exclusively in the popular media are likely to be pseudoscience. Legitimate treatments are generally tested by multiple independent labs and reported in scientific journals rather than only through the media. Individuals should also be wary of interventions that claim to rely on unknown forms of energy, ancient knowledge, or exclusive techniques. Alarmist or overly assertive marketing tactics are also red flags. Similarly, treatments that sound too good to be true or those that "doctors don't want you to know about" are unlikely to work. Evidence-based treatments will be familiar to professionals.