Assignment Brief Definition Of Psychology

Not to be confused with Phycology, Physiology, or Psychiatry.

Psychology is the science of behavior and mind, including conscious and unconscious phenomena, as well as thought. It is an academic discipline of immense scope and diverse interests that, when taken together, seek an understanding of the emergent properties of brains, and all the variety of epiphenomena they manifest. As a social science it aims to understand individuals and groups by establishing general principles and researching specific cases.[1][2]

In this field, a professional practitioner or researcher is called a psychologist and can be classified as a social, behavioral, or cognitive scientist. Psychologists attempt to understand the role of mental functions in individual and social behavior, while also exploring the physiological and biological processes that underlie cognitive functions and behaviors.

Psychologists explore behavior and mental processes, including perception, cognition, attention, emotion (affect), intelligence, phenomenology, motivation (conation), brain functioning, and personality. This extends to interaction between people, such as interpersonal relationships, including psychological resilience, family resilience, and other areas. Psychologists of diverse orientations also consider the unconscious mind.[3] Psychologists employ empirical methods to infer causal and correlational relationships between psychosocial variables. In addition, or in opposition, to employing empirical and deductive methods, some—especially clinical and counseling psychologists—at times rely upon symbolic interpretation and other inductive techniques. Psychology has been described as a "hub science",[4] with psychological findings linking to research and perspectives from the social sciences, natural sciences, medicine, humanities, and philosophy.

While psychological knowledge is often applied to the assessment and treatment of mental health problems, it is also directed towards understanding and solving problems in several spheres of human activity. By many accounts psychology ultimately aims to benefit society.[5][6] The majority of psychologists are involved in some kind of therapeutic role, practicing in clinical, counseling, or school settings. Many do scientific research on a wide range of topics related to mental processes and behavior, and typically work in university psychology departments or teach in other academic settings (e.g., medical schools, hospitals). Some are employed in industrial and organizational settings, or in other areas[7] such as human development and aging, sports, health, and the media, as well as in forensic investigation and other aspects of law.

Etymology and definitions

The word psychology derives from Greek roots meaning study of the psyche, or soul (ψυχήpsychē, "breath, spirit, soul" and -λογία -logia, "study of" or "research").[8] The Latin word psychologia was first used by the Croatianhumanist and LatinistMarko Marulić in his book, Psichiologia de ratione animae humanae in the late 15th century or early 16th century.[9] The earliest known reference to the word psychology in English was by Steven Blankaart in 1694 in The Physical Dictionary which refers to "Anatomy, which treats the Body, and Psychology, which treats of the Soul."[10]

In 1890, William James defined psychology as "the science of mental life, both of its phenomena and their conditions". This definition enjoyed widespread currency for decades. However, this meaning was contested, notably by radical behaviorists such as John B. Watson, who in his 1913 manifesto defined the discipline of psychology as the acquisition of information useful to the control of behavior. Also since James defined it, the term more strongly connotes techniques of scientific experimentation.[11][12]Folk psychology refers to the understanding of ordinary people, as contrasted with that of psychology professionals.[13]


Main article: History of psychology

The ancient civilizations of Egypt, Greece, China, India, and Persia all engaged in the philosophical study of psychology. Historians note that Greek philosophers, including Thales, Plato, and Aristotle (especially in his De Anima treatise),[14] addressed the workings of the mind.[15] As early as the 4th century BC, Greek physician Hippocrates theorized that mental disorders had physical rather than supernatural causes.[16]

In China, psychological understanding grew from the philosophical works of Laozi and Confucius, and later from the doctrines of Buddhism. This body of knowledge involves insights drawn from introspection and observation, as well as techniques for focused thinking and acting. It frames the universe as a division of, and interaction between, physical reality and mental reality, with an emphasis on purifying the mind in order 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, includes theories of personality based on yin–yang balance, and analyzes mental disorder in terms of physiological and social disequilibria. Chinese scholarship focused on the brain advanced in the Qing Dynasty with the work of Western-educated Fang Yizhi (1611–1671), Liu Zhi (1660–1730), and Wang Qingren (1768–1831). Wang Qingren emphasized the importance of the brain as the center of the nervous system, linked mental disorder with brain diseases, investigated the causes of dreams and insomnia, and advanced a theory of hemispheric lateralization in brain function.[17]

Distinctions in types of awareness appear in the ancient thought of India, influenced by Hinduism. A central idea of the Upanishads is the distinction between a person's transient mundane self and their eternal unchanging soul. Divergent Hindu doctrines, and Buddhism, have challenged this hierarchy of selves, but have all emphasized the importance of reaching higher awareness. Yoga is a range of techniques used in pursuit of this goal. Much of the Sanskrit corpus was suppressed under the British East India Company followed by the British Raj in the 1800s. However, Indian doctrines influenced Western thinking via the Theosophical Society, a New Age group which became popular among Euro-American intellectuals.[18]

Psychology was a popular topic in Enlightenment Europe. In Germany, Gottfried Wilhelm Leibniz (1646–1716) applied his principles of calculus to the mind, arguing that mental activity took place on an indivisible continuum—most notably, that among an infinity of human perceptions and desires, the difference between conscious and unconscious awareness is only a matter of degree. Christian Wolff identified psychology as its own science, writing Psychologia empirica in 1732 and Psychologia rationalis in 1734. This notion advanced further under Immanuel Kant, who established the idea of anthropology, with psychology as an important subdivision. However, Kant explicitly and notoriously rejected the idea of experimental psychology, writing that "the empirical doctrine of the soul can also never approach chemistry even as a systematic art of analysis or experimental doctrine, for in it the manifold of inner observation can be separated only by mere division in thought, and cannot then be held separate and recombined at will (but still less does another thinking subject suffer himself to be experimented upon to suit our purpose), and even observation by itself already changes and displaces the state of the observed object." Having consulted philosophers Hegel and Herbart, in 1825 the Prussian state established psychology as a mandatory discipline in its rapidly expanding and highly influential educational system. However, this discipline did not yet embrace experimentation.[19] In England, early psychology involved phrenology and the response to social problems including alcoholism, violence, and the country's well-populated mental asylums.[20]

Beginning of experimental psychology

Gustav Fechner began conducting psychophysics research in Leipzig in the 1830s, articulating the principle that human perception of a stimulus varies logarithmically according to its intensity.[21] Fechner's 1860 Elements of Psychophysics challenged Kant's stricture against quantitative study of the mind.[19] In Heidelberg, Hermann von Helmholtz conducted parallel research on sensory perception, and trained physiologist Wilhelm Wundt. Wundt, in turn, came to Leipzig University, establishing the psychological laboratory which brought experimental psychology to the world. Wundt focused on breaking down mental processes into the most basic components, motivated in part by an analogy to recent advances in chemistry, and its successful investigation of the elements and structure of material.[22]Paul Flechsig and Emil Kraepelin soon created another influential psychology laboratory at Leipzig, this one focused on more on experimental psychiatry.[19]

Psychologists in Germany, Denmark, Austria, England, and the United States soon followed Wundt in setting up laboratories.[23]G. Stanley Hall who studied with Wundt, formed a psychology lab at Johns Hopkins University in Maryland, which became internationally influential. Hall, in turn, trained Yujiro Motora, who brought experimental psychology, emphasizing psychophysics, to the Imperial University of Tokyo.[24] Wundt assistant Hugo Münsterberg taught psychology at Harvard to students such as Narendra Nath Sen Gupta—who, in 1905, founded a psychology department and laboratory at the University of Calcutta.[18] Wundt students Walter Dill Scott, Lightner Witmer, and James McKeen Cattell worked on developing tests for mental ability. Catell, who also studied with eugenicist Francis Galton, went on to found the Psychological Corporation. Wittmer focused on mental testing of children; Scott, on selection of employees.[25]

Another student of Wundt, Edward Titchener, created the psychology program at Cornell University and advanced a doctrine of "structuralist" psychology. Structuralism sought to analyze and classify different aspects of the mind, primarily through the method of introspection.[26]William James, John Dewey and Harvey Carr advanced a more expansive doctrine called functionalism, attuned more to human–environment actions. In 1890 James wrote an influential book, The Principles of Psychology, which expanded on the realm of structuralism, memorably described the human "stream of consciousness", and interested many American students in the emerging discipline.[26][27][28] Dewey integrated psychology with social issues, most notably by promoting the cause progressive education to assimilate immigrants and inculcate moral values in children.[29]

A different strain of experimentalism, with more connection to physiology, emerged in South America, under the leadership of Horacio G. Piñero at the University of Buenos Aires.[30] Russia, too, placed greater emphasis on the biological basis for psychology, beginning with Ivan Sechenov's 1873 essay, "Who Is to Develop Psychology and How?" Sechenov advanced the idea of brain reflexes and aggressively promoted a deterministic viewpoint on human behavior.[31]

Wolfgang Kohler, Max Wertheimer and Kurt Koffka co-founded the school of Gestalt psychology (not to be confused with the Gestalt therapy of Fritz Perls). This approach is based upon the idea that individuals experience things as unified wholes. Rather than breaking down thoughts and behavior into smaller elements, as in structuralism, the Gestaltists maintained that whole of experience is important, and differs from the sum of its parts. Other 19th-century contributors to the field include the German psychologist Hermann Ebbinghaus, a pioneer in the experimental study of memory, who developed quantitative models of learning and forgetting at the University of Berlin,[32] and the Russian-Soviet physiologistIvan Pavlov, who discovered in dogs a learning process that was later termed "classical conditioning" and applied to human beings.[33]

Consolidation and funding

One of the earliest psychology societies was La Société de Psychologie Physiologique in France, which lasted 1885–1893. The first meeting of the International Congress of Psychology took place in Paris, in August 1889, amidst the World's Fair celebrating the centennial of the French Revolution. William James was one of three Americans among the four hundred attendees. The American Psychological Association was founded soon after, in 1892. The International Congress continued to be held, at different locations in Europe, with wider international participation. The Sixth Congress, Geneva 1909, included presentations in Russian, Chinese, and Japanese, as well as Esperanto. After a hiatus for World War I, the Seventh Congress met in Oxford, with substantially greater participation from the war-victorious Anglo-Americans. In 1929, the Congress took place at Yale University in New Haven, Connecticut, attended by hundreds of members of the American Psychological Association[23] Tokyo Imperial University led the way in bringing the new psychology to the East, and from Japan these ideas diffused into China.[17][24]

American psychology gained status during World War I, during which a standing committee headed by Robert Yerkes administered mental tests ("Army Alpha" and "Army Beta") to almost 1.8 million GIs.[34] Subsequent funding for behavioral research came in large part from the Rockefeller family, via the Social Science Research Council.[35][36] Rockefeller charities funded the National Committee on Mental Hygiene, which promoted the concept of mental illness and lobbied for psychological supervision of child development.[34][37] Through the Bureau of Social Hygiene and later funding of Alfred Kinsey, Rockefeller foundations established sex research as a viable discipline in the U.S.[38] Under the influence of the Carnegie-funded Eugenics Record Office, the Draper-funded Pioneer Fund, and other institutions, the eugenics movement also had a significant impact on American psychology; in the 1910s and 1920s, eugenics became a standard topic in psychology classes.[39]

During World War II and the Cold War, the U.S. military and intelligence agencies established themselves as leading funders of psychology—through the armed forces and in the new Office of Strategic Services intelligence agency. University of Michigan psychologist Dorwin Cartwright reported that university researchers began large-scale propaganda research in 1939–1941, and "the last few months of the war saw a social psychologist become chiefly responsible for determining the week-by-week-propaganda policy for the United States Government." Cartwright also wrote that psychologists had significant roles in managing the domestic economy.[40] The Army rolled out its new General Classification Test and engaged in massive studies of troop morale. In the 1950s, the Rockefeller Foundation and Ford Foundation collaborated with the Central Intelligence Agency to fund research on psychological warfare.[41] In 1965, public controversy called attention to the Army's Project Camelot—the "Manhattan Project" of social science—an effort which enlisted psychologists and anthropologists to analyze foreign countries for strategic purposes.[42][43]

In Germany after World War I, psychology held institutional power through the military, and subsequently expanded along with the rest of the military under the Third Reich.[19] Under the direction of Hermann Göring's cousin Matthias Göring, the Berlin Psychoanalytic Institute was renamed the Göring Institute. Freudian psychoanalysts were expelled and persecuted under the anti-Jewish policies of the Nazi Party, and all psychologists had to distance themselves from Freud and Adler.[44] The Göring Institute was well-financed throughout the war with a mandate to create a "New German Psychotherapy". This psychotherapy aimed to align suitable Germans with the overall goals of the Reich; as described by one physician: "Despite the importance of analysis, spiritual guidance and the active cooperation of the patient represent the best way to overcome individual mental problems and to subordinate them to the requirements of the Volk and the Gemeinschaft." Psychologists were to provide Seelenführung, leadership of the mind, to integrate people into the new vision of a German community.[45]Harald Schultz-Hencke melded psychology with the Nazi theory of biology and racial origins, criticizing psychoanalysis as a study of the weak and deformed.[46]Johannes Heinrich Schultz, a German psychologist recognized for developing the technique of autogenic training, prominently advocated sterilization and euthanasia of men considered genetically undesirable, and devised techniques for facilitating this process.[47] After the war, some new institutions were created and some psychologists were discredited due to Nazi affiliation. Alexander Mitscherlich founded a prominent applied psychoanalysis journal called Psyche and with funding from the Rockefeller Foundation established the first clinical psychosomatic medicine division at Heidelberg University. In 1970, psychology was integrated into the required studies of medical students.[48]

After the Russian Revolution, psychology was heavily promoted by the Bolsheviks as a way to engineer the "New Man" of socialism. Thus, university psychology departments trained large numbers of students, for whom positions were made available at schools, workplaces, cultural institutions, and in the military. An especial focus was pedology, the study of child development, regarding which Lev Vygotsky became a prominent writer.[31] The Bolsheviks also promoted free love and embranced the doctrine of psychoanalysis as an antidote to sexual repression.[49] Although pedology and intelligence testing fell out of favor in 1936, psychology maintained its privileged position as an instrument of the Soviet state.[31] Stalinist purges took a heavy toll and instilled a climate of fear in the profession, as elsewhere in Soviet society.[50] Following World War II, Jewish psychologists past and present (including Vygotsky, A. R. Luria, and Aron Zalkind) were denounced; Ivan Pavlov (posthumously) and Stalin himself were aggrandized as heroes of Soviet psychology.[51] Soviet academics was speedily liberalized during the Khrushchev Thaw, and cybernetics, linguistics, genetics, and other topics became acceptable again. There emerged a new field called "engineering psychology" which studied mental aspects of complex jobs (such as pilot and cosmonaut). Interdisciplinary studies became popular and scholars such as Georgy Shchedrovitsky developed systems theory approaches to human behavior.[52]

Twentieth-century Chinese psychology originally modeled the United States, with translations from American authors like William James, the establishment of university psychology departments and journals, and the establishment of groups including the Chinese Association of Psychological Testing (1930) and the Chinese Psychological Society (1937). Chinese psychologists were encouraged to focus on education and language learning, with the aspiration that education would enable modernization and nationalization. John Dewey, who lectured to Chinese audiences in 1918–1920, had a significant influence on this doctrine. Chancellor T'sai Yuan-p'ei introduced him at Peking University as a greater thinker than Confucius. Kuo Zing-yang who received a PhD at the University of California, Berkeley, became President of Zhejiang University and popularized behaviorism.[53] After the Chinese Communist Party gained control of the country, the Stalinist USSR became the leading influence, with Marxism–Leninism the leading social doctrine and Pavlovian conditioning the approved concept of behavior change. Chinese psychologists elaborated on Lenin's model of a "reflective" consciousness, envisioning an "active consciousness" (tzu-chueh neng-tung-li) able to transcend material conditions through hard work and ideological struggle. They developed a concept of "recognition" (jen-shih) which referred the interface between individual perceptions and the socially accepted worldview. (Failure to correspond with party doctrine was "incorrect recognition".)[54] Psychology education was centralized under the Chinese Academy of Sciences, supervised by the State Council. In 1951 the Academy created a Psychology Research Office, which in 1956 became the Institute of Psychology. Most leading psychologists were educated in the United States, and the first concern of the Academy was re-education of these psychologists in the Soviet doctrines. Child psychology and pedagogy for nationally cohesive education remained a central goal of the discipline.[55]

Disciplinary organization


In 1920, Édouard Claparède and Pierre Bovet created a new applied psychology organization called the International Congress of Psychotechnics Applied to Vocational Guidance, later called the International Congress of Psychotechnics and then the International Association of Applied Psychology.[23] The IAAP is considered the oldest international psychology association.[56] Today, at least 65 international groups deal with specialized aspects of psychology.[56] In response to male predominance in the field, female psychologists in the U.S. formed National Council of Women Psychologists in 1941. This organization became the International Council of Women Psychologists after World War II, and the International Council of Psychologists in 1959. Several associations including the Association of Black Psychologists and the Asian American Psychological Association have arisen to promote non-European racial groups in the profession.[56]

The world federation of national psychological societies is the International Union of Psychological Science (IUPsyS), founded in 1951 under the auspices of UNESCO, the United Nations cultural and scientific authority.[23][57] Psychology departments have since proliferated around the world, based primarily on the Euro-American model.[18][57] Since 1966, the Union has published the International Journal of Psychology.[23] IAAP and IUPsyS agreed in 1976 each to hold a congress every four years, on a staggered basis.[56]

The International Union recognizes 66 national psychology associations and at least 15 others exist.[56] The American Psychological Association is the oldest and largest.[56] Its membership has increased from 5,000 in 1945 to 100,000 in the present day.[26] The APA includes 54 divisions, which since 1960 have steadily proliferated to include more specialties. Some of these divisions, such as the Society for the Psychological Study of Social Issues and the American Psychology–Law Society, began as autonomous groups.[56]

The Interamerican Society of Psychology, founded in 1951, aspires to promote psychology and coordinate psychologists across the Western Hemisphere. It holds the Interamerican Congress of Psychology and had 1000 members in year 2000. The European Federation of Professional Psychology Associations, founded in 1981, represents 30 national associations with a total of 100,000 individual members. At least 30 other international groups organize psychologists in different regions.[56]

In some places, governments legally regulate who can provide psychological services or represent themselves as a "psychologist".[58] The American Psychological Association defines a psychologist as someone with a doctoral degree in psychology.[59]

See also: List of psychology organizations


Early practitioners of experimental psychology distinguished themselves from parapsychology, which in the late nineteenth century enjoyed great popularity (including the interest of scholars such as William James), and indeed constituted the bulk of what people called "psychology". Parapsychology, hypnotism, and psychism were major topics of the early International Congresses. But students of these fields were eventually ostractized, and more or less banished from the Congress in 1900–1905.[23] Parapsychology persisted for a time at Imperial University, with publications such as Clairvoyance and Thoughtography by Tomokichi Fukurai, but here too it was mostly shunned by 1913.[24]

As a discipline, psychology has long sought to fend off accusations that it is a "soft" science. Philosopher of science Thomas Kuhn's 1962 critique implied psychology overall was in a pre-paradigm state, lacking the agreement on overarching theory found in mature sciences such as chemistry and physics.[60] Because some areas of psychology rely on research methods such as surveys and questionnaires, critics asserted that psychology is not an objective science. Skeptics have suggested that personality, thinking, and emotion, cannot be directly measured and are often inferred from subjective self-reports, which may be problematic. Experimental psychologists have devised a variety of ways to indirectly measure these elusive phenomenological entities.[61][62][63]

Divisions still exist within the field, with some psychologists more oriented towards the unique experiences of individual humans, which cannot be understood only as data points within a larger population. Critics inside and outside the field have argued that mainstream psychology has become increasingly dominated by a "cult of empiricism" which limits the scope of its study by using only methods derived from the physical sciences.[64] Feminist critiques along these lines have argued that claims to scientific objectivity obscure the values and agenda of (historically mostly male)[34] researchers. Jean Grimshaw, for example, argues that mainstream psychological research has advanced a patriarchal agenda through its efforts to control behavior.[65]

Major schools of thought


Psychologists generally consider the organism the basis of the mind, and therefore a vitally related area of study. Psychiatrists and neuropsychologists work at the interface of mind and body.[66] Biological psychology, also known as physiological psychology,[67] or neuropsychology is the study of the biological substrates of behavior and mental processes. Key research topics in this field include comparative psychology, which studies humans in relation to other animals, and perception which involves the physical mechanics of sensation as well as neural and mental processing.[68] For centuries, a leading question in biological psychology has been whether and how mental functions might be localized in the brain. From Phineas Gage to H. M. and Clive Wearing, individual people with mental issues traceable to physical damage have inspired new discoveries in this area.[67] Modern neuropsychology could be said to originate in the 1870s, when in France Paul Broca traced production of speech to the left frontal gyrus, thereby also demonstrating hemispheric lateralization of brain function. Soon after, Carl Wernicke identified a related area necessary for the understanding of speech.[69]

The contemporary field of behavioral neuroscience focuses on physical causes underpinning behavior. For example, physiological psychologists use animal models, typically rats, to study the neural, genetic, and cellular mechanisms that underlie specific behaviors such as learning and memory and fear responses.[70]Cognitive neuroscientists investigate the neural correlates of psychological processes in humans using neural imaging tools, and neuropsychologists conduct psychological assessments to determine, for instance, specific aspects and extent of cognitive deficit caused by brain damage or disease. The biopsychosocial model is an integrated perspective toward understanding consciousness, behavior, and social interaction. It assumes that any given behavior or mental process affects and is affected by dynamically interrelated biological, psychological, and social factors.[71]

Evolutionary psychology examines cognition and personality traits from an evolutionary perspective. This perspective suggests that psychological adaptations evolved to solve recurrent problems in human ancestral environments. Evolutionary psychology offers complementary explanations for the mostly proximate or developmental explanations developed by other areas of psychology: that is, it focuses mostly on ultimate or "why?" questions, rather than proximate or "how?" questions. "How?" questions are more directly tackled by behavioral genetics research, which aims to understand how genes and environment impact behavior.[72]

The search for biological origins of psychological phenomena has long involved debates about the importance of race, and especially the relationship between race and intelligence. The idea of white supremacy and indeed the modern concept of race itself arose during the process of world conquest by Europeans.[73]Carl von Linnaeus's four-fold classification of humans classifies Europeans as intelligent and severe, Americans as contented and free, Asians as ritualistic, and Africans as lazy and capricious. Race was also used to justify the construction of socially specific mental disorders such as drapetomania and dysaesthesia aethiopica—the behavior of uncooperative African slaves.[74] After the creation of experimental psychology, "ethnical psychology" emerged as a subdiscipline, based on the assumption that studying primitive races would provide an important link between animal behavior and the psychology of more evolved humans.[75]


Psychologists take human behavior as a main area of study. Much of the research in this area began with tests on mammals, based on the idea that humans exhibit similar fundamental tendencies. Behavioral research ever aspires to improve the effectiveness of techniques for behavior modification.

Early behavioral researchers studied stimulus–response pairings, now known as classical conditioning. They demonstrated that behaviors could be linked through repeated association with stimuli eliciting pain or pleasure. Ivan Pavlov—known best for inducing dogs to salivate in the presence of a stimulus previous linked with food—became a leading figure in the Soviet Union and inspired followers to use his methods on humans.[31] In the United States, Edward Lee Thorndike initiated "connectionism" studies by trapping animals in "puzzle boxes" and rewarding them for escaping. Thorndike wrote in 1911: "There can be no moral warrant for studying man's nature unless the study will enable us to control his acts."[76] From 1910–1913 the American Psychological Association went through a sea change of opinion, away from mentalism and towards "behavioralism", and in 1913 John B. Watson coined the term behaviorism for this school of thought.[77] Watson's famous Little Albert experiment in 1920 demonstrated that repeated use of upsetting loud noises could instill phobias (aversions to other stimuli) in an infant human.[12][78]Karl Lashley, a close collaborator with Watson, examined biological manifestations of learning in the brain.[67]

Embraced and extended by Clark L. Hull, Edwin Guthrie, and others, behaviorism became a widely used research paradigm.[26] A new method of "instrumental" or "operant" conditioning added the concepts of reinforcement and punishment to the model of behavior change. Radical behaviorists avoided discussing the inner workings of the mind, especially the unconscious mind, which they considered impossible to assess scientifically.[79] Operant conditioning was first described by Miller and Kanorski and popularized in the U.S. by B. F. Skinner, who emerged as a leading intellectual of the behaviorist movement.[80][81]

Noam Chomsky delivered an influential critique of radical behaviorism on the grounds that it could not adequately explain the complex mental process of language acquisition.[82][83][84]Martin Seligman and colleagues discovered that the conditioning of dogs led to outcomes ("learned helplessness") that opposed the predictions of behaviorism.[85][86] Skinner's behaviorism did not die, perhaps in part because it generated successful practical applications.[82]Edward C. Tolman advanced a hybrid "cognitive behaviorial" model, most notably with his 1948 publication discussing the cognitive maps used by rats to guess at the location of food at the end of a modified maze.[87]

The Association for Behavior Analysis International was founded in 1974 and by 2003 had members from 42 countries. The field has been especially influential in Latin America, where it has a regional organization known as ALAMOC: La Asociación Latinoamericana de Análisis y Modificación del Comportamiento. Behaviorism also gained a strong foothold in Japan, where it gave rise to the Japanese Society of Animal Psychology (1933), the Japanese Association of Special Education (1963), the Japanese Society of Biofeedback Research (1973), the Japanese Association for Behavior Therapy (1976), the Japanese Association for Behavior Analysis (1979), and the Japanese Association for Behavioral Science Research (1994).[88] Today the field of behaviorism is also commonly referred to as behavior modification or behavior analysis.[88]




The Stroop effect refers to the fact that naming the color of the first set of words is easier and quicker than the second.

Cognitive psychology studies cognition, the mental processes underlying mental activity. Perception, attention, reasoning, thinking, problem solving, memory, learning, language, and emotion are areas of research. Classical cognitive psychology is associated with a school of thought known as cognitivism, whose adherents argue for an information processing model of mental function, informed by functionalism and experimental psychology.

On a broader level, cognitive science is an interdisciplinary enterprise of cognitive psychologists, cognitive neuroscientists, researchers in artificial intelligence, linguists, human–computer interaction, computational neuroscience, logicians and social scientists. Computer simulations are sometimes used to model phenomena of interest.

Starting in the 1950s, the experimental techniques developed by Wundt, James, Ebbinghaus, and others re-emerged as experimental psychology became increasingly cognitivist—concerned with information and its processing—and, eventually, constituted a part of the wider cognitive science.[89] Some called this development the cognitive revolution because it rejected the anti-mentalist dogma of behaviorism as well as the strictures of psychoanalysis.[89]

Social learning theorists, such as Albert Bandura, argued that the child's environment could make contributions of its own to the behaviors of an observant subject.[90]

Technological advances also renewed interest in mental states and representations. English neuroscientist Charles Sherrington and Canadian psychologist Donald O. Hebb used experimental methods to link psychological phenomena with the structure and function of the brain. The rise of computer science, cybernetics and artificial intelligence suggested the value of comparatively studying information processing in humans and machines. Research in cognition had proven practical since World War II, when it aided in the understanding of weapons operation.[91]

A popular and representative topic in this area is cognitive bias, or irrational thought. Psychologists (and economists) have classified and described a sizeable catalogue of biases which recur frequently in human thought. The availability heuristic, for example, is the tendency to overestimate the importance of something which happens to come readily to mind.

Elements of behaviorism and cognitive psychology were synthesized to form cognitive behavioral therapy, a form of psychotherapy modified from techniques developed by American psychologist Albert Ellis and American psychiatrist Aaron T. Beck. Cognitive psychology was subsumed along with other disciplines, such as philosophy of mind, computer science, and neuroscience, under the cover discipline of cognitive science.


Main article: Social psychology

See also: Social psychology (sociology)

Social psychology is the study of how humans think about each other and how they relate to each other. Social psychologists study such topics as the influence of others on an individual's behavior (e.g. conformity, persuasion), and the formation of beliefs, attitudes, and stereotypes about other people. Social cognition fuses elements of social and cognitive psychology in order to understand how people process, remember, or distort social information. The study of group dynamics reveals information about the nature and potential optimization of leadership, communication, and other phenomena that emerge at least at the microsocial level. In recent years, many social psychologists have become increasingly interested in implicit measures, mediational models, and the interaction of both person and social variables in accounting for behavior. The study of human society is therefore a potentially valuable source of information about the causes of psychiatric disorder. Some sociological concepts applied to psychiatric disorders are the social role, sick role, social class, life event, culture, migration, social, and total institution.


Psychoanalysis comprises a method of investigating the mind and interpreting experience; a systematized set of theories about human behavior; and a form of psychotherapy to treat psychological or emotional distress, especially conflict originating in the unconscious mind.[92] This school of thought originated in the 1890s with Austrian medical doctors including Josef Breuer (physician), Alfred Adler (physician), Otto Rank (psychoanalyst), and most prominently Sigmund Freud (neurologist). Freud's psychoanalytic theory was largely based on interpretive methods, introspection and clinical observations. It became very well known, largely because it tackled subjects such as sexuality, repression, and the unconscious. These subjects were largely taboo at the time, and Freud provided a catalyst for their open discussion in polite society.[49] Clinically, Freud helped to pioneer the method of free association

Wilhelm Wundt (seated) with colleagues in his psychological laboratory, the first of its kind.
MRI depicting the human brain. The arrow indicates the position of the hypothalamus.
The Müller–Lyer illusion. Psychologists make inferences about mental processes from shared phenomena such as optical illusions.

Random assignment refers to the use of chance procedures in psychology experiments to ensure that each participant has the same opportunity to be assigned to any given group.

Study participants are randomly assigned to different groups, such as the experimental group, or treatment group. Random assignment might involve such tactics as flipping a coin, drawing names out of a hat, rolling dice, or assigning random numbers to participants.

It is important to note that random assignment differs from random selection. While random selection refers to how participants are randomly chosen to represent the larger population, random assignment refers to how those chosen participants are then assigned to experimental groups.

How Does Random Assignment Work in a Psychology Experiment?

To determine if changes in one variable lead to changes in another variable, psychologists must perform an experiment. Researchers often begin by forming a testable hypothesis predicting that one variable of interest will have some impact on another variable.

The variable that the experimenters will manipulate in the experiment is known as the independent variable while the variable that they will then measure is known as the dependent variable. While there are different ways to look at relationships between variables, and experiment is the best way to get a clear idea if there is a cause-and-effect relationship between two or more variables.

Once researchers have formulated a hypothesis, conducted background research, and chosen an experimental design, it is time to find participants for their experiment. How exactly do researchers decide who will be part of an experiment? As mentioned previously, this is often accomplished through something known as random selection.

In order to generalize the results of an experiment to a larger group, it is important to choose a sample that is representative of the qualities found in that population. For example, if the total population is 51 percent female and 49 percent male, then the sample should reflect those same percentages. Choosing a representative sample is often accomplished by randomly picking people from the population to be participants in a study. Random selection means that everyone in the group stands and equal chance of being chosen.

Once a pool of participants has been selected, it is time to assign them into groups. By randomly assigning the participants into groups, the experimenters can be sure that each group will be the same before the independent variable is applied.

Participants might be randomly assigned to the control group, which does not receive the treatment in question. Or they might be randomly assigned to the experimental group, which does receive the treatment. Random assignment increases the likelihood that the two groups are the same at the outset, that way any changes that result from the application of the independent variable can be assumed to be the result of the treatment of interest.

An Example of Random Assignment

Imagine that a researcher is interested in learning whether or not drinking caffeinated beverages prior to an exam will improve test performance. After randomly selecting a pool of participants, each person is randomly assigned to either the control group or the experimental group. The participants in the control group consume a placebo drink prior to the exam that does not contain any caffeine. Those in the experimental group, on the other hand, consume a caffeinated beverage before taking the test. Participants in both groups then take the test and the researcher compares the results to determine if the caffeinated beverage had any impact on test performance.

A Word From Verywell

Random assignment plays an  important role in the psychology research process. Not only does this process help eliminate possible sources of bias, it also makes it easier to generalize the results of a population to a larger population.

Random assignment helps ensure that members of each group in the experiment are the same, which means that the groups are also likely more representative of what is present in the larger population. Through the use of this technique, psychology researchers are able to study complex phenomena and contribute to our understanding of the human mind and behavior.


Alferes, VR. Methods of Randomization in Experimental Design. Los Angeles: SAGE; 2012.

Nestor, PG & Schutt, RK. Research Methods in Psychology: Investigating Human Behavior. Los Angeles: SAGE; 2015.

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