Psychology as empirical science

Most of us are amateur psychologists. We guess why a friend went quiet, why a child melts down at bedtime, or why we keep putting off one hard email. Some of those guesses are good. What they usually lack is a way to find out whether they are wrong.

That is the gap this lesson is about. Psychology is the scientific study of the mind and behavior (Spielman et al., 2020). The word that does the work in that definition is scientific. A psychologist is someone who takes a hunch about people and turns it into a question that the world can answer, even when the answer is no.

Psychology is empirical. Its knowledge rests on observation, including experiments, rather than on logic alone or on what an authority says (Spielman et al., 2020). Other people can look at the same evidence and check it.

That creates a real challenge, because no one can see a mind directly. So psychologists study the mind indirectly. They measure things that can be observed, such as behavior, body signals like heart rate, and people’s own reports, and then reason from those measurements back to mental processes (Spielman et al., 2020).

OpenStax gives a simple example. “A bird sings because it is happy” is not a testable idea, since we have no way to measure a bird’s happiness. We could study the bird’s brain activity while it sings instead, because that can be measured. With people, we can also just ask whether they sing when they are happy, because people can tell us (Spielman et al., 2020).

Psychology sits in two families of science at once. Every behavior has biological roots, so parts of psychology look like biology. But no person lives alone, and our behavior is shaped by the people around us, so psychology is also a social science (Spielman et al., 2020).

Common sense is not worthless. It is often where good questions come from. The trouble is that common sense contradicts itself. “Birds of a feather flock together,” but “opposites attract.” Without evidence, we can defend almost any belief after the fact.

History shows how confident people can be about things that are false. At various times people were sure that the sun circled a flat earth and that mental illness was caused by possession (Spielman et al., 2020). Research is what separates a fact, an observable reality, from an opinion, a personal judgment that may or may not be accurate (Spielman et al., 2020).

This is why psychology courses spend so much time on critical thinking: actively applying a set of skills to information in order to understand and evaluate it. Critical thinking includes healthy skepticism, noticing your own biases, asking good questions, and making careful observations (Spielman et al., 2020). When someone makes a claim, it helps to ask four questions. What is this person’s expertise? What might they gain if the claim is believed? Does the evidence support the claim? And what do other researchers think (Spielman et al., 2020)?

Intuition is fast, and it is often useful. But Myers and DeWall (2021) describe three habits of mind that make it feel more trustworthy than it really is.

The first is hindsight bias, the “I knew it all along” feeling. Once we learn how something turned out, the outcome seems obvious. Tell one group that research shows separation weakens romantic attraction, and they think of “out of sight, out of mind.” Tell another group that separation strengthens attraction, and they think of “absence makes the heart grow fonder.” Each group tends to find its result unsurprising (Myers & DeWall, 2021). Common sense explains things well after the fact. It predicts them much less well.

The second is overconfidence. We tend to think we know more than we do, and people are often surer of their answers than their accuracy justifies (Myers & DeWall, 2021).

The third is seeing order in random events. Random sequences often do not look random. Flip a coin enough times and you will get streaks of heads that seem to mean something, even though each flip is independent of the last (Myers & DeWall, 2021).

The cure is not cynicism. Myers and DeWall (2021) describe a scientific attitude with three parts: curiosity about how things work, skepticism that keeps asking “how do you know?”, and humility, a willingness to be surprised and to change your mind when the evidence says so.

Science moves in a circle. Ideas are tested against the real world, and what we observe leads to better ideas, which are tested again (Spielman et al., 2020).

The ideas come in two sizes. A theory is a well-developed set of ideas that explains something we observe. A theory is too broad to test all at once, so researchers pull out a hypothesis: a specific, testable prediction about what should happen if the theory is right. Hypotheses are often worded as if-then statements (Spielman et al., 2020).

Two kinds of reasoning keep the circle turning. In deductive reasoning, we start with a general idea and work out what should be true in a particular case, then check it. In inductive reasoning, we go the other way, from many observations to a general idea. Induction can be wrong even when every observation behind it is correct. If your favorite fruits all grow on trees, you might decide all fruit grows on trees, until you meet a strawberry (Spielman et al., 2020).

Figure 1.1 follows one question all the way around the circle: does a full night of sleep help you remember what you learned the day before?

A good hypothesis is falsifiable: it is possible to imagine a result that would show it is wrong (Spielman et al., 2020). “People recall more word pairs after eight hours of sleep than after five” is falsifiable, because the scores could come out equal or reversed. “Memory is mysterious” is not, because no result could count against it.

Falsifiability is one of the fairest criticisms of Sigmund Freud. Many of his ideas were rich and influential, but it is hard to imagine any observation that would disprove the id, the ego, and the superego (Spielman et al., 2020). Compare the James-Lange theory of emotion, which says that feeling an emotion depends on noticing your body’s arousal. That theory makes a risky prediction: people who cannot feel their body’s arousal should feel little emotion. Researchers tested it by studying people with spinal cord injuries. Their emotions were sometimes less intense, but they still felt emotion (Chwalisz et al., 1988). The theory had to be revised, and that is science working the way it should.

Because claims must survive tests like this, and because other scientists repeat the tests, the knowledge that science finally accepts has usually been checked many times (Spielman et al., 2020).

One study rarely settles anything. Search the internet on almost any topic and you will find studies that seem to disagree. Often what you are seeing is the scientific community in the middle of reaching a consensus, and that can take years (Spielman et al., 2020).

OpenStax uses technology in education as an example. One study found that a smartphone app for surgery residents raised their engagement and their test scores. Another found that technology use among undergraduates had negative effects on sleep, communication, and time management. Until much more research is done, there is no clear consensus on how technology affects learning (Spielman et al., 2020).

Research matters outside the lab, too. Imagine you are a governor deciding whether to keep funding early intervention programs for young children from low-income backgrounds or with special needs. The programs sound appealing, but you would want evidence that they work. A large body of research shows that, in general, they do, although not every program is equally effective and many effects are strongest in the short term (Spielman et al., 2020). Reading that research is how a careful governor would decide which programs deserve the money.

Psychologists report their work in scientific journals, and most follow a format set out by the American Psychological Association (American Psychological Association, 2020; Spielman et al., 2020). Unlike a magazine story written for the general public, a journal article is written for other researchers, and it is built so that a reader can check every step.

Before publication, the article goes through peer review. Several experts on the topic, usually anonymous, read the draft. They look for a strong reason for the study, a clear description of how it was done, evidence that it was ethical, and flaws in the design or statistics. The editor then decides whether to publish it as it is, which is rare, to ask for revisions, or to reject it (Spielman et al., 2020).

Knowing the parts of an article turns a wall of text into a map. Figure 1.2 lays out a report of the sleep-and-memory study from Figure 1.1 and shows which stage of the research cycle each part records.

People have asked questions about the mind for thousands of years, but until the late 1800s those questions belonged to philosophy (Spielman et al., 2020). Psychology became its own science when researchers started bringing the mind into the laboratory.

Wilhelm Wundt opened a psychology laboratory at the University of Leipzig in 1879. He studied conscious experience with a trained form of self-observation called introspection, and with instruments that measured reaction times to a thousandth of a second. His student Edward Titchener developed structuralism, which tried to break experience into its basic parts. The weakness was that introspection stayed subjective, and trained observers often disagreed (Spielman et al., 2020).

In the United States, William James took a different path. Influenced by Darwin, he asked what the mind is for: how mental activity helps a living creature adapt to its world. That approach became functionalism (Spielman et al., 2020).

Then came several strong schools. Sigmund Freud focused on the unconscious mind and early childhood experience, and his psychoanalytic approach shaped clinical work for decades. Gestalt psychologists such as Max Wertheimer showed that we often perceive wholes, like a melody, rather than a sum of parts. Behaviorism, championed by John B. Watson and later B. F. Skinner, built on Ivan Pavlov’s work on conditioned reflexes. It argued that psychology should study only observable behavior, and it did much to make psychology an experimental science. Humanistic psychology, led by Abraham Maslow and Carl Rogers, pushed back against the determinism of both Freud and behaviorism and stressed each person’s potential for growth (Spielman et al., 2020).

By the 1950s, linguistics, neuroscience, and computer science had revived interest in the mind itself. This cognitive revolution owed much to the linguist Noam Chomsky, and in 1967 Ulric Neisser published the first textbook called Cognitive Psychology (Spielman et al., 2020). Figure 1.3 lines these moments up in order.

Early psychology was built mostly by White, Western men, and it carried their blind spots. Women and people of color had a hard time entering the field, and for years most research participants were men (Spielman et al., 2020). Even so, many people pushed the doors open.

• Margaret Floy Washburn became the first woman to earn a PhD in psychology, in 1894. Her textbook The Animal Mind was the standard in its field for more than 20 years (Spielman et al., 2020).
• Mary Whiton Calkins completed every requirement for a Harvard PhD, and William James argued for her, but Harvard refused to grant the degree because she was a woman. She went on to study memory, and in 1905 she became the first woman elected president of the American Psychological Association (Spielman et al., 2020).
• Francis Cecil Sumner became the first African American to earn a PhD in psychology, in 1920, and helped found the psychology department at Howard University. He is sometimes called the “Father of Black Psychology” (Spielman et al., 2020).
• Inez Beverly Prosser became the first African American woman to earn a PhD in psychology, in 1933. Her research compared segregated and integrated schools (Spielman et al., 2020).
• Mamie Phipps Clark and Kenneth Clark studied Black children’s preferences for dolls of different skin colors. Their work was instrumental in Brown v. Board of Education, the case that ended legal school segregation (Spielman et al., 2020).

The field also spread beyond Europe and the United States. Horatio Piñero founded some of the first experimental psychology laboratories in South America, in Buenos Aires. In India, Gunamudian David Boaz and Narendra Nath Sen Gupta established the first independent psychology departments, at the University of Madras and the University of Calcutta (Spielman et al., 2020).

Membership changed slowly. When the American Psychological Association was founded in 1892, every member was a White man. By 1946, nearly a quarter of American psychologists were women, and psychology had become a popular degree at the nation’s historically Black colleges and universities (Spielman et al., 2020).

A related problem is who gets studied. Much of psychology’s research has come from people in WEIRD societies: Western, educated, industrialized, rich, and democratic. Those samples differ from much of the world in perception, cooperation, and moral reasoning, so findings from them do not automatically apply to everyone (Henrich et al., 2010). Asking “who was in the study?” is part of thinking scientifically.

The old schools did not simply disappear. Today they live on as perspectives, different angles for asking questions about the same behavior (Myers & DeWall, 2021). No single perspective is the whole truth. A biological explanation and a social explanation can both be right, because they describe different levels of the same event. Many psychologists combine those levels in a biopsychosocial approach, which looks at biological, psychological, and social-cultural influences on a behavior together (Myers & DeWall, 2021).

Take a student who freezes during a big exam, even though they knew the material the night before. Figure 1.4 shows how each perspective would frame that moment, and what a researcher from each tradition might measure.

Modern psychology is wide. The American Psychological Association, the largest organization of psychologists in the world, has 54 divisions, each devoted to a specialty (Spielman et al., 2020). A few of the major areas:

• Biopsychology studies how the nervous system and body shape behavior. Evolutionary psychology asks how behavior might have been shaped by natural selection, though proving that a human trait was naturally selected is very hard (Spielman et al., 2020).
• Cognitive psychology studies thinking: attention, memory, problem solving, and language.
• Developmental psychology studies change across the whole lifespan, from infancy to old age.
• Social psychology studies how we think about, influence, and relate to one another.
• Personality psychology studies the patterns of thought and behavior that make each person distinct.
• Clinical and counseling psychology assess and treat psychological problems and support well-being. Other applied areas include health, industrial-organizational, sport, and forensic psychology (Spielman et al., 2020).

Clinical psychology gets the most attention in movies and on television, and many people assume it is all of psychology (Spielman et al., 2020). It is one important branch of a much larger tree.

Most careers as a psychologist require graduate school. A research or university career usually means a PhD, which typically takes five to six years of graduate study and ends with a dissertation: a long report of original research, defended before a committee of experts (Spielman et al., 2020). Many new PhDs then spend a year or two in postdoctoral training, broadening their research skills under supervision, before they apply for faculty jobs.

People who mainly want to practice therapy can instead earn a PsyD, a doctor of psychology degree that puts less emphasis on research and more on applying psychology in clinical settings. With either degree, only people who meet their state’s requirements and pass a licensing exam can call themselves licensed clinical or counseling psychologists (Spielman et al., 2020).

A clinical psychologist is not the same as a psychiatrist. Both can provide therapy. A clinical psychologist holds a PhD or PsyD and can give and interpret psychological tests. A psychiatrist is a medical doctor (MD) and can prescribe medication (Spielman et al., 2020).

A master’s degree opens other doors, such as professional counseling, school psychology, and consulting work in industry. A bachelor’s degree in psychology leads to careers well beyond psychology. Graduates often work in management, sales, social work, and human resources, and the MCAT, the admission test for medical school, now includes a section on the psychological foundations of behavior (Spielman et al., 2020).

Whatever the path, what unites every branch of psychology is the method: careful questions, testable predictions, and evidence that others can check. The next lesson looks closely at how that evidence is gathered, and at the duties researchers owe the people who make it possible.