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Scientific Foundations of Psychology

The science of psychology is widely recognized as beginning in 1879 with Wilhelm Wundt’s founding of the first psychology lab, but it has a long prehistory in philosophy and physiology.

Theoretical Orientations

A wide variety of theoretical orientations have emerged throughout psychology’s history, each of which represents a distinctive approach to investigating behavior and mental processes.

Contemporary Psychology

Contemporary psychology consists of numerous specialized domains; today, there are many different types of psychologists.

Contributions to Psychology

Psychology would not be the science that it is today without the contributions of many talented men and women.

Research Methods in Psychology

The study of psychology relies on a diverse array of qualitative and quantitative research methods, including observations, case studies, surveys, and controlled experiments.

Psychological Research Design

Psychological research is carefully designed so that researchers can be confident about using results to draw conclusions about real-life phenomena by controlling variables, creating representative samples, controlling for internal and external validity, and operationalizing definitions and measurements.

Statistics in Psychological Research

Researchers use statistics to analyze and make sense of the data gathered in a research study, involving descriptive statistics and inferential statistics.

Ethical Principles in Psychological Research

Researchers must abide by established ethical principles and practices as well as by legal guidelines while conducting research involving human subjects.

René Descartes

A French philosopher and mathematician well known for his endorsement of mind-body dualism.

Mind-body dualism

Maintains that the mind and the body are distinct substances, each operating according to its own set of principles.

John Locke

An English philosopher and empiricist who believed that every human mind begins as a tabula rasa, or blank slate, which is shaped by individual experiences to become a unique person.

Empiricism

The idea that all knowledge comes from experience; embraced by philosophers such as Locke and Hume, it also remains influential in contemporary psychology and other experimental sciences.

David Hume

A Scottish empiricist and member of the Associationist School who proposed several principles of association.

Principles of association

Rules that govern the ways in which the mind connects one idea to another and constructs complex ideas out of simpler ones.

Evolution

The idea, developed by Darwin, that species change over time, adapting to their environments in order to maximize survival and reproductive success by means of natural selection.

Phrenology

The idea developed by German physiologists Gall and Spurzheim that personal traits could be revealed by measuring the size and location of bumps on a person’s skull; thoroughly discredited by subsequent research.

Psychophysics

A subfield of physiology created by the German scientists Weber and Fechner and concerned with the relationship between physical stimuli and the sensations they cause.

Introspection

A technique used by early scientific psychologists consisting of precise examination and description of an individual’s conscious experience, typically in response to stimuli presented by the researcher.

Structuralism

The theoretical approach developed in the late nineteenth century by Wundt and Titchener, which seeks to uncover the structures of consciousness through detailed descriptions of experience in laboratory settings.

Functionalism

Developed by William James in response to structuralism, an approach that emphasized the functions of the mind over its structures and focused on how aspects of consciousness allowed human beings to adapt to their environments.

Biological approach

An approach that maintains that all psychological phenomena have a biological basis; emphasizes neuroscience, genetics, and evolution in its explanations.

Eugenics

The controversial and discredited idea that the human species can be improved through selective breeding.

Behaviorism

A theoretical approach founded on the belief that psychology should only study observable and measurable behavior; behaviorists emphasize the impact of learning and other environmental forces on human and animal behavior.

Gestalt psychology

A response to structuralism developed by Max Wertheimer and others in the early twentieth century that sought to discover principles that organized the whole of perceptual experience.

Psychoanalysis

The therapeutic approach invented by Freud, premised on the idea that some symptoms are the results of conflicts and other problems in the unconscious mind.

Psychodynamic psychology

The collective term used to describe the approaches of Freud, Jung, Adler, Horney, and similar thinkers, which tend to rely on ideas about the unconscious; influential in the early development of clinical psychology.

Humanistic psychology

Developed in the mid-twentieth century by Maslow, Rogers, and others, an approach that emphasizes human freedom and self-development.

Cognitive revolution

The ascendance of the cognitive approach in psychology, which sought to investigate a wide variety of cognitive processes, including language, memory, and attention.

Sociocultural approach

A perspective that emphasizes how social and cultural contexts influence the development of human cognition and behavior.

Biological psychology/neuropsychology

Biological psychologists and neuropsychologists investigate how the brain and nervous system cause behavior.

Clinical psychology

Clinical psychologists specialize in helping people who suffer from psychological disorders.

Cognitive psychology

Cognitive psychologists are interested in thinking and other cognitive processes, such as perception, memory, language use, reasoning, and decision making.

Community psychology

Community psychologists help build collaborative relationships among community members, organizations, and other groups to solve social problems. They study how individuals relate to their communities and the effect those communities have on the individual.

Counseling psychology

Though similar in some respects to clinical psychologists, counseling psychologists tend to assist individuals with less severe problems. They often help people looking for guidance in navigating through ordinary difficulties in life.

Developmental psychology

Developmental psychologists focus on human development throughout the course of life.

Educational psychology

Educational psychologists investigate how a variety of factors, such as ability, motivation, and classroom setting, affect students.

Environmental psychology

Environmental psychologists study the interactions between people and the natural environment and explore issues such as the impact of environmental stress on psychological health and productivity.

Experimental psychology

Experimental psychologists design and oversee empirical research projects to gain insights into psychological processes.

Evolutionary psychology

Evolutionary psychologists understand behavior and cognition through the lens of fitness, adaptation, and other evolutionary concepts.

Forensic psychology

Forensic psychologists are usually trained in both psychology and the law; they can provide valuable expertise within the judicial system, assessing defendants and inmates, advising judges, and conducting research on issues relevant to the justice system, such as jury behavior and eyewitness testimony.

Gerontological psychology/gerontology

Gerontology is the study of aging and the elderly; gerontological psychologists assess cognitive functioning in older people and assist in determining how much assistance an older person needs on a daily basis, as well as conducting research and teaching.

Health psychology

Health psychologists examine health and illness in the context of biological, psychological, and social factors.

Human factors psychology

Human factors specialists, also known as engineering psychologists, typically investigate how human beings can work safely and effectively with machines.

Industrial and organizational psychology

Industrial and organizational psychologists apply psychological principles and research methods to the workplace and are interested in improving productivity, health, and the quality of work life.

Personality psychology

Personality psychologists investigate how our personalities develop and how they affect the ways in which we think, feel, and act.

Psycholinguistics

Psycholinguists study language acquisition and other psychological processes that involve language.

Psychometrics

Psychometricians study the theories and techniques of psychological measurement. Some design tests that measure intelligence, attitudes, personality traits, and other psychological characteristics.

Rehabilitation psychology

Rehabilitation psychologists work with people affected by injuries, disabilities, and other medical conditions, helping clients adapt to their new situations, including adjusting to work and pain management.

School psychology

The majority of school psychologists work for school systems and provide a wide range of services, such as diagnosis, assessment, intervention, prevention, health promotion, and program development.

Social psychology

Social psychologists study group behavior, as well as the impact of other people on the behavior of individuals.

Sport psychology

Sport psychologists are generally knowledgeable in the areas of psychology, physiology, and kinesiology. These specialists focus on optimizing the performance of athletes.

Alfred Adler

Austrian medical doctor and psychotherapist who was one of the first practitioners of family counseling and an advocate of the psychodynamic approach.

Jerome S. Bruner

American cognitive psychologist who developed a theory of cognitive growth; influential in educational psychology.

Mary Whiton Calkins

Student of William James best known for self-psychology, an introspective psychology that understands the self as a conscious organism that functions and has experiences and drives.

Noam Chomsky

Linguist and cognitive psychologist who views language acquisition as an innate human characteristic and argues for a universal grammar underlying all language.

Charles Darwin

British naturalist whose scientific theory of evolution by natural selection became the foundation of modern evolutionary studies. He influenced both the early functionalists and more contemporary evolutionary psychologists.

Dorothea Dix

Best known for investigating and exposing the atrocious conditions suffered by the mentally ill in state institutions and spearheading a reform movement for the humane treatment of mental patients.

Gustav Fechner

One of the founders of psychophysics, he examined quantitative relations between sensations and the stimuli producing them.

Sigmund Freud

Austrian founder of psychoanalysis, a form of therapy that focuses on the unconscious. He also developed the structural model of personality that distinguishes between id, ego, and superego, and a stage theory of psychosexual development.

Franz Joseph Gall

Founder of phrenology who maintained that different functions were localized in different parts of the brain.

G. Stanley Hall

First president of the American Psychological Association and student of William James; also influential in the study of child development.

Hermann von Helmholtz

Conducted research on the nervous system, eye, and ear; advanced the trichromatic theory of color vision; and was the first to measure the speed of a nerve impulse.

William James

A founder of functionalism known for the James-Lange theory of emotion. He established one of the first psychological laboratories in the United States and wrote the first psychology textbook, The Principles of Psychology (1890).

Carl Jung

Psychodynamic thinker best known for developing the theory of archetypes and the collective unconscious, as well as the distinction between introverted and extraverted personalities.

Abraham Maslow

Humanistic psychologist best known for his hierarchy of needs.

Ivan Pavlov

Russian physiologist most famous for his work on classical conditioning, who influenced the behaviorists.

Jean Piaget

Swiss psychologist best known for his stage theory of cognitive development.

Carl Rogers

Humanistic psychologist who developed client centered therapy.

B.F. Skinner

American behaviorist best known for operant conditioning theory and the “Skinner box,” an apparatus used in learning experiments.

Edward Titchener

Student of Wundt, credited with bringing structuralism to the United States; instrumental in the establishment of experimental psychology.

Lev S. Vygotsky

Russian psychologist who advocated for the sociocultural approach and is known for the zone of proximal development and other ideas about cognitive development.

Margaret Floy Washburn

First woman to receive a Ph.D. in psychology; best known for her book The Animal Mind (1908), which advocated for the scientific study of mental phenomena (contrary to the behaviorists).

Ernst H. Weber

One of the founders of psychophysics, he is known for the concept of the just-noticeable difference.

Max Wertheimer

Founder of Gestalt psychology, who emphasized the study of perception as a whole.

Wilhelm Wundt

German structuralist who founded the first psychological laboratory; widely recognized as the “father of psychology.”

John B. Watson

Founder of behaviorism, known for his contributions to classical conditioning theory and his Little Albert experiment.

Quantitative research

Research that uses operational measurements and statistical techniques to reach conclusions on the basis of numerical data, such as correlational studies and experiments.

Qualitative research

Research that does not rely on numerical representations of data, such as naturalistic observations, unstructured inter- views, and case studies.

Correlation coefficient

A number (symbolized by r) between −1 and +1, which represents the strength and direction of the correlation between two variables. The closer the coefficient is to −1 or +1, the stronger the correlation between the variables.

Positive correlation

An r value above 0, which indicates that two variables have a direct relationship: when one variable increases, the other also increases.

Negative correlation

An r value below 0, which indicates that two variables have an inverse relationship: when one variable increases, the other decreases.

Naturalistic observation

A research method, typically qualitative in nature and usually covert and undisclosed, that attempts to document behavior as it spontaneously occurs in a real-world setting.

Structured observation

A type of observational research typically conducted in a laboratory setting, where the researcher can control some aspects of the environment.

Coding

The classification of behaviors into discrete categories, used especially in structured observations to achieve a level of consistency in recording and describing observations.

Inter-rater reliability

A statistical measure of the degree of agreement between different codings of the same phenomena.

Participant observation

A mostly qualitative research method in which the researcher becomes a member of a studied group, either overtly or covertly.

Hawthorne effect

A phenomenon in which research subjects tend to alter their behavior in response to knowledge of being observed.

Longitudinal study

A research design that examines how individuals develop by studying the same sample over a long period of time.

Cross-sectional study

A research design conducted at a single point in time, comparing groups of differing ages to arrive at conclusions about development.

Case study

A research design involving an in-depth and detailed examination of a single subject, or case, usually an individual or a small group.

Survey

A mostly quantitative research method involving a list of questions filled out by a group of people to assess attitudes or opinions.

Surveyor bias

A distortion of data that can occur when survey questions are written in a way that prompts respondents to answer a certain way.

Nonresponse bias

A distortion of data that can occur in surveys with a low response rate.

Experiments

Deliberately designed proce- dures used to test research hypotheses.

Hypothesis

A proposed, testable explanation for a phenomenon, often constructed in the form of a statement about the relationship between two or more variables.

Controlled experiment

A research design for testing a causal hypothesis, in which all aspects of the study are deliberately controlled and only independent variables are manipulated to isolate their effects on dependent variables.

Field experiment

Experiments conducted out in the real world, with fewer controls than would be found in a lab.

Natural experiment/quasi-experiment

An experiment that does not involve the direct manipulation of variables, in which researchers rely on natural variations and advanced statistics to draw conclusions.

Independent variables

Factors manipulated in an experiment to test their effects on one or more dependent variables.

Dependent variables

The factors measured as outcomes or results in an experiment.