Psychology is the discipline concerned with behavior and mental processes and how they are affected by an organism's external and internal environment. An introductory psychology course can correct many misconceptions about human behavior.

Psychologists have many pseudoscientific competitors, such as astrologers and psychics. Psychology's methods and reliance on empirical evidence distinguish it from pseudoscience and “psychobabble.” Psychobabble is appealing because it confirms our beliefs and prejudices; in contrast, psychology often challenges them.

One benefit of studying psychology is the development of critical-thinking skills and attitudes. Critical thinking helps people evaluate competing findings on psychological issues that are personally and socially important.

Critical thinkers ask questions, define terms clearly, examine the evidence, analyze assumptions and biases, avoid emotional reasoning, avoid oversimplification, consider alternative interpretations, and tolerate uncertainty. Critical thinking is an evolving process rather than a once-and-for-all accomplishment.

Psychology's forerunners made some valid observations and had useful insights, but without rigorous empirical methods, they also made serious errors in the description and explanation of behavior, as in the case of phrenology.

The official founder of scientific psychology was Wilhelm Wundt, who formally established the first psychological laboratory in 1879, in Leipzig, Germany. His technique of trained introspection, although too subjective for a reliable methodology, illustrated the movement toward making psychology a science.

Structuralism emphasized the analysis of immediate experience into basic elements. It was soon abandoned, in part because of its reliance on introspection. Functionalism was inspired in part by the evolutionary theories of Charles Darwin; it emphasized the purpose of behavior. One of its leading proponents was William James. Sigmund Freud's theory of psychoanalysis emphasized unconscious causes of mental and emotional problems.

Four points of view predominate today in psychological science. The biological perspective emphasizes bodily events associated with actions, thoughts, and feelings, as well as genetic contributions to behavior. Within this perspective, a popular specialty, evolutionary psychology, is following in the footsteps of functionalism. The learning perspective emphasizes how the environment and a person's history affect behavior; within this perspective, behaviorists reject mentalistic explanations and social-cognitive learning theorists combine elements of behaviorism with the study of thoughts, values, and intentions. The cognitive perspective emphasizes mental processes in perception, problem solving, belief formation, and other human activities. The sociocultural perspective explores how social contexts and cultural rules affect an individual's beliefs and behavior.

Feminist psychology has influenced the questions researchers ask, the methods they use, and their awareness of sexist biases in the field. As members of minority groups entered psychology, they too raised awareness of issues specific to different groups by virtue of their ethnicity, culture, and sexual orientation. The result has been to make psychology more representative of all human beings.

Many psychologists conduct research and teach in colleges and universities, where they investigate a broad range of topics. Among the many psychological specialties are experimental, educational, developmental, industrial/organizational, psychometric, counseling, school, and clinical psychology.

Other psychologists provide mental health services (psychological practice). Psychotherapist is an unregulated term for anyone who does therapy, including people who have no credentials or training at all. Licensed therapists differ according to their training and approach. Clinical psychologists have a PhD, an EdD, or a PsyD; psychiatrists have an MD; psychoanalysts are trained in psychoanalytic institutes; and licensed clinical social workers (LCSWs) and marriage, family, and child counselors (MFCCs) may have various postgraduate degrees.

Some psychologists conduct research and apply findings in a variety of nonacademic settings. These professionals work to make their communities a better place to live, and to contribute to the mental, social, and physical health of people in those communities.