Psychology

Psychology is the scientific study of the mind and behavior. It looks at both humans and animals, exploring conscious and unconscious thoughts, feelings, and motives. This wide-ranging field connects the natural and social sciences. Some psychologists focus on how the brain works, linking their work to neuroscience, while others study how people and groups behave.

Professionals in this area are called psychologists. They may study how mental processes affect individual and social behavior, or examine the physiological and neurobiological bases of thinking and acting. Psychology is an interdisciplinary field, with researchers exploring topics like perception, cognition, emotion, intelligence, motivation, brain functioning, and personality.

Psychologists also look at interpersonal relationships, psychological resilience, and family resilience. They use empirical methods to understand connections between different mental and social factors. While many psychologists help treat mental health issues through psychotherapy, others conduct research in universities, work in industrial and organizational settings, or study topics like human development, sports, health, and education. Overall, psychology aims to help improve society in many different ways.

Etymology and definitions

The word psychology comes from the Greek word psyche, meaning spirit or soul, and -logia, meaning "study" or "research". People started using the word psychology during the Renaissance, and it has been used to talk about the mind and behavior ever since.

William James once described psychology as the science of mental life. Others, like John B. Watson, saw it as a way to study behavior through experiments. Today, psychology is a scientific field that explores how our minds and behaviors work.

History

Main article: History of psychology

For a chronological guide, see Timeline of psychology.

The ancient civilizations of Egypt, Greece, China, India, and Persia all engaged in the philosophical study of psychology. In Ancient Egypt the Ebers Papyrus mentioned thought disorders. Greek philosophers, including Thales, Plato, and Aristotle, addressed the workings of the mind. As early as the 4th century BCE, the Greek physician Hippocrates theorized that mental disorders had physical rather than supernatural causes. In 387 BCE, Plato suggested that the brain is where mental processes take place, and in 335 BC, Aristotle suggested that it was the heart.

In China, the foundations of psychological thought emerged from the philosophical works of ancient thinkers like Laozi and Confucius, as well as the teachings of Buddhism. Chinese philosophy emphasized purifying the mind to increase virtue and power. An ancient text known as The Yellow Emperor's Classic of Internal Medicine identifies the brain as the nexus of wisdom and sensation, and includes theories of personality based on balance. Chinese scholarship advanced during the Qing dynasty.

Psychology was of interest to Enlightenment thinkers in Europe. In Germany, Gottfried Wilhelm Leibniz applied his principles of calculus to the mind. Christian Wolff identified psychology as its own science. Immanuel Kant advanced the idea of anthropology as a discipline, with psychology an important subdivision.

Beginning of experimental psychology

Philosopher John Stuart Mill believed that the human mind was open to scientific investigation. Gustav Fechner began conducting research in the 1830s. Fechner's achievement was to show that mental processes could be measured by experimental methods. In Heidelberg, Hermann von Helmholtz conducted parallel research on sensory perception, and trained physiologist Wilhelm Wundt. Wundt, in turn, came to Leipzig University, where he established the psychological laboratory that brought experimental psychology to the world.

James McKeen Cattell, a professor of psychology at the University of Pennsylvania and Columbia University, was the first professor of psychology in the United States.

The German psychologist Hermann Ebbinghaus pioneered the experimental study of memory. In the early 20th century, Wolfgang Kohler, Max Wertheimer, and Kurt Koffka co-founded the school of Gestalt psychology. The approach of Gestalt psychology is based upon the idea that individuals experience things as unified wholes.

Psychologists in Germany, Denmark, Austria, England, and the United States soon followed Wundt in setting up laboratories. G. Stanley Hall founded a psychology lab that became internationally influential. The lab was located at Johns Hopkins University.

Another student of Wundt, the Englishman Edward Titchener, created the psychology program at Cornell University and advanced "structuralist" psychology. William James, John Dewey, and Harvey Carr advanced the idea of functionalism, an expansive approach to psychology. In 1890, James wrote an influential book, The Principles of Psychology.

A different strain of experimentalism emerged in South America, under the leadership of Horacio G. Piñero at the University of Buenos Aires. In Russia, researchers emphasized the biological basis for psychology, beginning with Ivan Sechenov's essay, "Who Is to Develop Psychology and How?" Sechenov advanced the idea of brain reflexes. The Russian-Soviet physiologist Ivan Pavlov discovered a learning process that was later termed "classical conditioning" and applied the process to human beings.

Consolidation and funding

One of the earliest psychology societies was La Société de Psychologie Physiologique in France. The first meeting of the International Congress of Psychology took place in Paris in August 1889. The American Psychological Association (APA) was founded soon after, in 1892.

American psychology gained status upon the U.S.'s entry into World War I. Subsequently, the Rockefeller family began to provide funding for behavioral research. In the 1910s and 1920s, the eugenics movement influenced American psychology.

During World War II and the Cold War, the U.S. military and intelligence agencies became leading funders of psychology. University of Michigan psychologist Dorwin Cartwright reported that university researchers began large-scale propaganda research in 1939–1941.

In Germany after World War I, psychology held institutional power through the military. After the war, new institutions were created.

After the Russian Revolution, the Bolsheviks promoted psychology as a way to engineer the "New Man" of socialism. Consequently, university psychology departments trained large numbers of students.

Twentieth-century Chinese psychology originally modeled itself on U.S. psychology. After the Chinese Communist Party gained control of the country, the Stalinist Soviet Union became the major influence.

Women in psychology

Main articles: List of women psychologists and Female psychology

1900–1949

Women in the early 1900s began to make key contributions to the field of psychology. In 1923, Anna Freud, the daughter of Sigmund Freud, built on her father's work to psychoanalyze children.

Functional periodicity, the belief that women are mentally and physically impaired during menstruation, impacted women's rights. Leta Stetter Hollingworth worked to prove this hypothesis incorrect. She recorded both women's and men's performances on tasks for three months. No evidence was found of decreased performance due to a woman's menstrual cycle.

New theories emerged in the first half of the 1900s, marking a turning point in women's recognition in the field of psychology. In addition to the contributions made by Leta Stetter Hollingworth and Anna Freud, Mary Whiton Calkins invented the paired associates technique of studying memory. Karen Horney developed the concept of "womb envy" and neurotic needs. Psychoanalyst Melanie Klein impacted developmental psychology with her research of play therapy.

1950–1999

Women in the second half of the 20th century continued to do research that had large-scale impacts on the field of psychology. Mary Ainsworth's work centered around attachment theory. Because of her work, Ainsworth became one of the most cited psychologists of all time. Mamie Phipps Clark was another woman in psychology that changed the field with her research.

As the field of psychology developed in the latter half of the 20th century, women in the field advocated for their voices to be heard and their perspectives valued.

The latter half of the 20th century further diversified the field of psychology, with women of color reaching new milestones. In 1962, Martha Bernal became the first Latina woman to get a Ph.D. in psychology. In 1969, Marigold Linton, the first Native American woman to get a Ph.D. in psychology, founded the National Indian Education Association. In 1971, the Network of Indian Psychologists was established by Carolyn Attneave.

21st century

In the 21st century, women have gained greater prominence in psychology, contributing significantly to a wide range of subfields. Many have taken on leadership roles and directed influential research labs. However, gender disparities persist, disadvantaging women in pay and representation in senior academic positions. The number of women pursuing education and training in psychological science has reached a record high. In the United States, estimates suggest that women make up about 78% of undergraduate students and 71% of graduate students in psychology.

Disciplinary organizations

See also: List of psychology organizations

In 1920, Édouard Claparède and Pierre Bovet started an organization called the International Association of Applied Psychology. Today, there are at least 65 international groups focused on different parts of psychology. The International Union of Psychological Science (IUPsyS) was created in 1951 and connects psychology groups from many countries.

The American Psychological Association is the largest group for psychologists, with over 100,000 members. It has many smaller groups, or divisions, that focus on specific areas of psychology. Other groups, like the Interamerican Psychological Society, help share psychology ideas across regions.

Major schools of thought

Biological

Psychologists study biology as the foundation of thoughts and feelings. Behavioral neuroscience looks at how biological processes affect behavior in humans and animals. This includes studying how mental functions connect to specific areas of the brain. Important discoveries came from people whose brains were damaged, showing how different parts control different abilities.

Modern behavioral neuroscience began in the 1870s when researchers found areas of the brain linked to speech. Today, scientists use animals to understand learning and memory, and use imaging tools to see brain activity in humans. The biopsychosocial model shows how biology, psychology, and environment all work together to affect behavior.

Behaviorist

Behaviorism focuses on how behavior is learned through interactions with the environment. Early behaviorists studied how animals and humans learn from rewards and punishments. They found that neutral signals can become triggers for certain responses through repeated pairing with meaningful events.

John B. Watson introduced behaviorism, and B.F. Skinner expanded it with ideas about reinforcement and punishment. Noam Chomsky later questioned behaviorism, pointing out it couldn't fully explain complex mental processes like language. Behaviorism remains useful today in applications like helping people change habits.

Cognitive

Cognitive psychology studies mental processes such as perception, attention, memory, and problem-solving. Researchers use models of information processing to understand how the mind works. The field grew in the 1950s when new technologies allowed better study of mental states.

Cognitive psychology looks at how people think, including biases and errors in thinking. It also explores how learning happens through observation, not just rewards. Cognitive science brings together psychology, computer science, and neuroscience to understand the mind.

Social

Social psychology examines how people influence each other's thoughts, feelings, and actions. It studies topics like conformity, persuasion, and stereotypes. Social psychologists also look at group behavior and leadership.

Psychoanalytic

Psychoanalysis explores the unconscious mind and its effects on daily life. Started by Sigmund Freud, it includes techniques like free association and dream interpretation. Over time, many different psychoanalytic approaches developed.

Existential-humanistic

Humanistic psychology focuses on personal growth, free will, and self-understanding. It emerged in the 1950s as an alternative to behaviorism and psychoanalysis. Key figures include Abraham Maslow and Carl Rogers.

Positive psychology studies what makes people happy and well, building on humanistic ideas. Existential psychology looks at how people find meaning in life, especially when facing big questions about existence. Viktor Frankl developed logotherapy, emphasizing finding personal meaning even in difficult situations.

Main article: Cognitive neuroscience

Main articles: Behaviorism, Psychological behaviorism, and Radical behaviorism

Main article: Cognitive psychology

Main article: Social psychology

See also: Social psychology (sociology)

Main articles: Psychodynamics and psychoanalysis

Main articles: Existential psychology and Humanistic psychology

Themes

Personality psychology looks at lasting patterns in how people behave, think, and feel. Different theories explain these patterns in various ways. Some focus on traits, like how outgoing or anxious someone might be, while others look at deeper, hidden influences.

The idea of an unconscious mind—thoughts and feelings we aren’t aware of but that still affect us—has been important in psychology. Studies show that things we don’t consciously notice can still shape our actions and decisions.

Motivation explains why people start or continue doing things. It includes basic needs like hunger and thirst, as well as more complex desires such as wanting to belong or feel good about ourselves.

Developmental psychology studies how people’s thinking, feelings, and behaviors change throughout their lives. Researchers watch children in everyday settings and create fun activities to learn about their development. They also study how genes and environment together shape who we are.

Applications

Psychology has many different areas of study and practical uses. It helps us understand how people think, feel, and behave in various situations.

Psychological testing

Psychological testing has a long history, starting with ancient exams for government jobs in China. Over time, scientists developed ways to measure mental abilities more accurately. Today, these tests are used in schools, workplaces, and many other places to help understand people's skills and abilities.

Mental health care

Mental health care focuses on helping people with emotional and mental challenges. Psychologists work with individuals and families to provide support and guidance. They use different methods, such as talking therapies, to help people manage their feelings and improve their lives.

Education

Educational psychology studies how people learn and how to teach effectively. It helps educators create better learning environments and teaching methods. This field draws on ideas from famous psychologists who explored how children develop and learn.

Work

Industrial and organizational psychology applies psychological ideas to help improve workplaces. It helps companies hire the right people, create good work environments, and support employee well-being. This field studies how people behave at work and how to make jobs more satisfying and productive.

Military and intelligence

Psychologists also work with military forces to support soldiers' mental health and provide guidance. They help with screening, counseling, and treating mental health issues that can arise from military service.

Health, well-being, and social change

Psychologists contribute to improving public health and well-being. They help people adopt healthier habits, support policies that benefit communities, and study how work environments affect health. Their research has helped change laws and practices to create safer, healthier workplaces and societies.

Research methods

Main articles: Psychological research and List of psychological research methods

Psychology uses many ways to study how the mind and behavior work. One common method is quantitative research, which uses numbers and statistics to test ideas. Psychologists often do experiments in labs where they can control many factors. They might change one thing to see how it affects another, like studying how learning happens.

Another method is qualitative research, which looks at people's thoughts and feelings more closely. This can include interviews or watching people in real-life situations. Both types of research help psychologists understand more about how we think, feel, and act.

Controlled experiments

Main article: Experiment

In controlled experiments, researchers change one factor to see its effect on another. This helps them understand cause-and-effect relationships. Sometimes, they cannot randomly assign people to groups, so they study existing groups instead.

Other types of studies

Further information: Video recall

Psychologists also use surveys to ask people about their attitudes or feelings. They might use paper surveys, phone calls, or online forms. Observational studies watch people over time to see how things change. Some studies happen once, while others follow the same group for years.

Direct brain observation/manipulation

A tool called the electroencephalogram (EEG) measures brain activity using sensors on the head. Newer tools like functional magnetic resonance imaging (fMRI) show which parts of the brain are active during certain tasks. These help scientists learn about how the brain and mind work together.

Computer simulation

Computers help psychologists simulate how people think and behave. This lets them test ideas quickly and see patterns that might be hard to notice otherwise.

Animal studies

Animals are sometimes used in research to understand human behavior. For example, Ivan Pavlov used dogs to study how learning works. While this can give useful clues, it’s important to remember that animals aren’t exactly like humans.

Qualitative research

Qualitative research looks at people’s thoughts and feelings in detail. Methods include interviews and watching people in their everyday lives. This helps psychologists understand experiences that numbers alone might miss.

Program evaluation

This involves checking whether programs or policies are working as intended. It looks not just at success, but also at costs, possible improvements, and unintended results.

Contemporary issues

Metascience studies how science itself can be improved. It has found that some psychology research has problems, like being hard to repeat or using statistics incorrectly. This has led to calls for better ways to check and share research results.

Researchers have noticed that most psychology studies are done with people from Western, educated, industrialized, rich, and democratic countries, called "WEIRD" societies. These groups make up only a small part of the world’s population, so findings might not apply to everyone. Scientists are now trying to include more diverse groups in their studies to make their results more useful worldwide.

Ethics

Ethical standards in psychology have developed over time. Some past studies are now seen as unethical and break important rules for research. Today, psychologists must get permission from people before including them in studies and ensure that participants know what they are agreeing to.

Key ethical principles include doing good and not causing harm, being honest, treating everyone fairly, and respecting people's rights and privacy. These rules help psychologists act in ways that protect those they work with and maintain trust in the field. Universities have special committees that review research to make sure it follows these ethical guidelines and protects participants.