Psychology is the study of
mind and
behavior.
[1][2] It is an
academic discipline and an
applied science which seeks to understand individuals and groups by establishing general principles and researching specific cases.
[3][4] 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 concepts such as
perception,
cognition,
attention,
emotion,
intelligence,
phenomenology,
motivation,
brain functioning,
personality, behavior, and
interpersonal relationships, including
psychological resilience,
family resilience, and other areas. Psychologists of diverse orientations also consider the
unconscious mind.
[5] 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",
[6] 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.
[7][8] 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
[9] such as
human development and aging,
sports,
health, and
the media, as well as in
forensic investigation and other aspects of
law.
Etymology
The word
psychology derives from Greek roots meaning study of the
psyche, or
soul (
ψυχή psukhē, "breath, spirit, soul" and -λογία
-logia, "study of" or "research").
[10] The
Latin word
psychologia was first used by the
Croatian humanist and
Latinist Marko Marulić in his book,
Psichiologia de ratione animae humanae in the late 15th century or early 16th century.
[11] 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."
[12]
History
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),
[13] addressed the workings of the mind.
[14] As early as the 4th century BC, Greek physician
Hippocrates theorized that
mental disorders had physical rather than supernatural causes.
[15]
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.
[16]
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.
[17]
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 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
Georg Friedrich Wilhelm Hegel and
Johann Friedrich 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.
[18] In England, early psychology involved
phrenology and the response to social problems including alcoholism, violence, and the country's well-populated mental asylums.
[19]
Beginning of experimental psychology
Wilhelm Wundt (seated) with colleagues in his psychological laboratory, the first of its kind.
Gustav Fechner began conducting psychology research in
Leipzig in the 1830s, studying
psychophysics and articulating the
principle that human perception of a stimulus varies logarithmically according to its intensity.
[20] Fechner's 1950
Elements of Psychophysics challenged Kant's stricture against quantitative study of the mind.
[18] 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.
[21] Paul Flechsig and
Emil Kraepelin soon created another influential psychology laboratory at Leipzig, this one focused on more on experimental
psychiatry.
[18]
Psychologists in Germany, Denmark, Austria, England, and the United States soon followed Wundt in setting up laboratories.
[22] 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.
[23] 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.
[17] 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.
[24]
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.
[25] 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][25] Dewey integrated psychology with social issues, most notably by promoting the cause
progressive education to assimilate immigrants and inculcate moral values in children.
[28]
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.
[29] 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 (contra
free will) viewpoint on human behavior.
[30]
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,
[31] and the Russian-Soviet
physiologist Ivan Pavlov, who discovered in dogs a learning process that was later termed "
classical conditioning" and applied to human beings.
[32]
Disciplinary consolidation
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
[22] Tokyo Imperial University led the way in bringing the new psychology to the East, and from Japan these ideas diffused into China.
[23][16]
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.
[22] 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.
[23]
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. Although pedology fell out of favor in 1936, psychology maintained its privileged position as an instrument of the Soviet state.
[30] 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.
[18]
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.
[22] The world federation of national psychological societies is the
International Union of Psychological Science, founded in 1951 under the auspices of
UNESCO, the United Nations cultural and scientific authority.
[33][22] Psychology departments have since proliferated around the world, based primarily on the Euro-American model.
[17][33] Since 1966, the Union has published the
International Journal of Psychology.
[22] Membership in the American Psychological Association increased from 5,000 in 1945 to 100,000 in the present day.
[25]
Behaviorism
An early researcher into psychological
conditioning was
Ivan Pavlov, known best for inducing dogs to salivate in the presence of a stimulus previous linked with food. As the star of psychology rose over the
Soviet Union, Pavlov became a leading figure and attracted many followers, who applied his theories to humans.
[30] In the United States, "
connectionism" studies were conducted by
Edward Lee Thorndike, who trapped animals in "puzzle boxes" and rewarded them for escaping. Like Pavlov, Thorndike focused narrowly on stimulus-response (S–R) pairings. He believed that the field of human psychology should focus on outward behavior, writing in 1911: "There can be no moral warrant for studying man's nature unless the study will enable us to control his acts."
[34] John B. Watson, teaching at Johns Hopkins, led a rising tide of sentiment in the United States against the idea that psychology had to study consciousness itself. From 1910–1913 the American Psychological Association went through a sea change of opinion, away from mentalism and towards "behavioralism", and in 191 Watson coined the term
behaviorism for this school of thought.
[35] Behaviorism, embraced and extended by
Clark L. Hull,
Edward C. Tolman,
Edwin Guthrie and many others, focused on the way organisms respond to environmental
stimuli eliciting
pain or
pleasure.
[25]
Behaviorism became a dominant school of thought in the midcentury United States, with
B.F. Skinner its leading intellectual. Skinner's behaviorism shared with its predecessors a philosophical inclination toward
positivism,
determinism, and the study of observable behavior.
[36][37] In lieu of probing an "unconscious mind" that underlies unawareness, behaviorists spoke of the "contingency-shaped behaviors" in which unawareness becomes outwardly manifest.
[36] Notable incidents in the history of behaviorism are John B. Watson's
Little Albert experiment which applied classical conditioning to the developing human child, and the clarification of the difference between classical conditioning and
operant (or instrumental) conditioning, first by Miller and Kanorski and then by Skinner.
[38][39] Skinner's version of behaviorism emphasized operant conditioning, through which behaviors are strengthened or weakened by their consequences.
Noam Chomsky delivered an influential critique of behaviorism on the grounds that it could not adequately explain the complex mental process of
language acquisition.
[40][41] Martin Seligman and colleagues discovered that the conditioning of dogs led to outcomes ("
learned helplessness") that opposed the predictions of behaviorism.
[42][43] Skinner's behaviorism did not die, perhaps in part because it generated successful practical applications.
[40]
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).
[44] Today the field of behaviorism is also commonly referred to as
behavior modification or
behavior analysis.
[44]
Psychoanalysis
Beginning in the 1890s, Austrian psychologists including
Josef Breuer Alfred Adler,
Otto Rank, and most prominently
Sigmund Freud, developed an influential school of thought and clinical practice called
psychoanalysis.
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 unconscious conflict.
[45] 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 mind as general aspects of psychological development. These were largely considered taboo subjects at the time, and Freud provided a catalyst for them to be openly discussed in polite society. Clinically,
Freud helped to pioneer the method of
free association and a therapeutic interest in
dream interpretation.
[46][47]
Freud had a significant influence on Swiss psychiatrist
Carl Jung, whose theories of
analytical psychology include such well-known concepts as the
collective unconscious. Modification of Jung's theories led to the
archetypal and
process-oriented schools. Other well-known psychoanalytic scholars of the mid-20th century include
Erik Erikson,
Melanie Klein,
D.W. Winnicott,
Karen Horney,
Erich Fromm,
John Bowlby, and Sigmund Freud's daughter,
Anna Freud. Throughout the 20th century, psychoanalysis evolved into diverse schools of thought which could be called
Neo-Freudian. Among these schools are
ego psychology,
object relations, and
interpersonal,
Lacanian, and
relational psychoanalysis.
Psychoanalytic theory and therapy were criticized by psychologists such as
Hans Eysenck, and by philosophers including
Karl Popper. Popper, a
philosopher of science, argued that psychoanalysis had been misrepresented as a scientific discipline,
[48] whereas Eysenck said that psychoanalytic tenets had been contradicted by
experimental data. By the end of 20th century, psychology departments in
American universities had become
scientifically oriented, marginalizing Freudian theory and dismissing it as a "desiccated and dead" historical artifact.
[49] Meanwhile, however, researchers in the emerging field of
neuro-psychoanalysis defended some of Freud's ideas on scientific grounds,
[50] while scholars of the
humanities maintained that Freud was not a "scientist at all, but ... an
interpreter."
[49]
Existential-humanistic theories
Psychologist Abraham Maslow in 1943 posited that humans have a hierarchy of needs, and it makes sense to fulfill the basic needs first (food, water etc.) before higher-order needs can be met.
[51]
Humanistic psychology was developed in the 1950s in reaction to both behaviorism and psychoanalysis.
[52] By using
phenomenology,
intersubjectivity, and first-person categories, the humanistic approach sought to glimpse the whole person—not just the fragmented parts of the personality or cognitive functioning.
[53] Humanism focused on fundamentally and uniquely human issues, such as individual
free will, personal growth,
self-actualization,
self-identity,
death,
aloneness,
freedom, and
meaning. The humanistic approach was distinguished by its emphasis on subjective meaning, rejection of determinism, and concern for positive growth rather than pathology.
[citation needed] Some founders of the humanistic school of thought were American psychologists
Abraham Maslow, who formulated a
hierarchy of human needs, and
Carl Rogers, who created and developed
client-centered therapy.
Later,
positive psychology opened up humanistic themes to scientific modes of exploration.
In the 1950s and 1960s, largely influenced by the work of German philosopher
Martin Heidegger and Danish philosopher
Søren Kierkegaard, psychoanalytically trained American psychologist
Rollo May pioneered an
existential branch of psychology, which included
existential psychotherapy, a method of therapy that operates on the belief that inner conflict within a person is due to that individual's confrontation with the givens of existence. Swiss psychoanalyst
Ludwig Binswanger and American psychologist
George Kelly may also be said to belong to the existential school.
[54]
Existential psychologists differed from more "humanistic" psychologists in their relatively neutral view of
human nature and their relatively positive assessment of
anxiety.
[55] Existential psychologists emphasized the humanistic themes of death, free will, and meaning, suggesting that meaning can be shaped by
myths, or narrative patterns,
[56] and that it can be encouraged by an acceptance of the free will requisite to an
authentic, albeit often anxious, regard for death and other future prospects.
Austrian existential psychiatrist and
Holocaust survivor
Viktor Frankl drew evidence of meaning's therapeutic power from reflections garnered from his own
internment,
[57] and he created a variation of existential psychotherapy called
logotherapy, a type of
existentialist analysis that focuses on a
will to meaning (in one's life), as opposed to Adler's
Nietzschean doctrine of
will to power or Freud's
will to pleasure.
[58]
Cognitive revolution
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.
[59] In its early years, this development was seen as a
"revolution,"
[59] as cognitive science both responded to and reacted against then-popular theories, including
psychoanalytic and
behaviorist theories.
Noam Chomsky helped to launch a "
cognitive revolution" in psychology when he criticized the behaviorists' notions of "stimulus", "response", and "reinforcement". Chomsky argued that such ideas—which Skinner had borrowed from animal experiments in the laboratory—could be applied to complex human behavior, most notably language acquisition, in only a superficial and vague manner. The postulation that humans are born with the instinct or "
innate facility" for acquiring language posed a challenge to the position that all behavior, including language, is contingent upon learning and reinforcement.
[60] 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.
[61]
The
Müller–Lyer illusion. Psychologists make inferences about mental processes from shared phenomena such as optical illusions.
Meanwhile, technological advances helped to renew interest and belief in the mental states and representations—i.e., cognition—that had fallen out of favor with behaviorists. 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. With the rise of
computer science and
artificial intelligence, analogies were drawn between the processing of information by humans and information processing by machines. Research in cognition had proven practical since
World War II, when it aided in the understanding of weapons operation.
[62] By the late 20th century cognitivism had become the dominant
paradigm of psychology, and
cognitive psychology emerged as a popular branch.
Assuming both that the covert mind should be studied, and that the scientific method should be used to study it, cognitive psychologists set such concepts as
subliminal processing and
implicit memory in place of the psychoanalytic
unconscious mind or the behavioristic
contingency-shaped behaviors. Elements of behaviorism and cognitive psychology were synthesized to form the basis of
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.
Subfields
Psychology encompasses many subfields and includes different approaches to the study of mental processes and behavior:
Biological
MRI depicting the human brain. The arrow indicates the position of the
hypothalamus.
Biological psychology or
behavioral neuroscience is the study of the biological substrates of behavior and mental processes. There are different specialties within behavioral neuroscience. 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.
[63] 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.
Clinical
Clinical psychologists work with individuals, children, families, couples, or small groups.
Clinical psychology includes the study and application of psychology for the purpose of understanding, preventing, and relieving psychologically based distress or
dysfunction and to promote subjective
well-being and personal development. Central to its practice are psychological assessment and
psychotherapy, although clinical psychologists may also engage in research, teaching, consultation, forensic testimony, and program development and administration.
[64] Some clinical psychologists may focus on the clinical management of patients with
brain injury—this area is known as
clinical neuropsychology. In many countries, clinical psychology is a regulated
mental health profession.
The work performed by clinical psychologists tends to be influenced by various therapeutic approaches, all of which involve a formal relationship between professional and client (usually an individual, couple, family, or small group). The various therapeutic approaches and practices are associated with different theoretical perspectives and employ different procedures intended to form a therapeutic alliance, explore the nature of psychological problems, and encourage new ways of thinking, feeling, or behaving. Four major theoretical perspectives are
psychodynamic,
cognitive behavioral,
existential–humanistic, and systems or
family therapy. There has been a growing movement to integrate the various therapeutic approaches, especially with an increased understanding of issues regarding culture, gender, spirituality, and sexual orientation. With the advent of more robust research findings regarding psychotherapy, there is evidence that most of the major therapies are about of equal effectiveness, with the key common element being a strong therapeutic alliance.
[65][66] Because of this, more training programs and psychologists are now adopting an
eclectic therapeutic orientation.
[67][68][69][70][71]
Cognitive
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.
Computational models are sometimes used to simulate phenomena of interest. Computational models provide a tool for studying the functional organization of the mind whereas neuroscience provides measures of brain activity.
Comparative
The common
chimpanzee can use
tools. This chimpanzee is using a stick in order to get food.
Comparative psychology refers to the scientific study of the behavior and mental processes of non-human animals, especially as these relate to the phylogenetic history, adaptive significance, and development of behavior. Research in this area addresses many issues, uses many methods, and explores the behavior of many species, from insects to primates. It is closely related to other disciplines that study animal behavior such as
ethology.
[72] Research in comparative psychology sometimes appears to shed light on human behavior, but some attempts to connect the two have been quite controversial, for example the
Sociobiology of
E. O. Wilson.
[73] Animal models are often used to study neural processes related to human behavior, e.g. in
cognitive neuroscience.
Developmental
Developmental psychologists would engage a child with a book and then make observations based on how the child interacts with the object.
Mainly focusing on the development of the human mind through the life span,
developmental psychology seeks to understand how people come to perceive, understand, and act within the world and how these processes change as they age. This may focus on cognitive, affective,
moral, social, or neural development. Researchers who study children use a number of unique research methods to make observations in natural settings or to engage them in experimental tasks. Such tasks often resemble specially designed games and activities that are both enjoyable for the child and scientifically useful, and researchers have even devised clever methods to study the mental processes of infants. In addition to studying children, developmental psychologists also study
aging and processes throughout the life span, especially at other times of rapid change (such as
adolescence and
old age). Developmental psychologists draw on the full range of psychological theories to inform their research.
Educational and school
An example of an item from a cognitive abilities test used in educational psychology.
Educational psychology is the study of how humans learn in
educational settings, the effectiveness of educational interventions, the psychology of teaching, and the
social psychology of
schools as organizations. The work of child psychologists such as
Lev Vygotsky,
Jean Piaget,
Bernard Luskin, and
Jerome Bruner has been influential in creating
teaching methods and educational practices. Educational psychology is often included in teacher education programs in places such as North America, Australia, and New Zealand.
School psychology combines principles from
educational psychology and
clinical psychology to understand and treat students with learning disabilities; to foster the intellectual growth of
gifted students; to facilitate
prosocial behaviors in adolescents; and otherwise to promote safe, supportive, and effective learning environments. School psychologists are trained in educational and behavioral assessment, intervention, prevention, and consultation, and many have extensive training in research.
[74]
Evolutionary
Evolutionary psychology examines psychological
traits—such as
memory,
perception, or
language—from a
modern evolutionary perspective. It seeks to identify which human psychological traits are evolved
adaptations, that is, the functional products of
natural selection or
sexual selection. Evolutionary psychologists suggest that
psychological adaptations evolved to solve recurrent problems in human ancestral environments. By focusing on the evolution of psychological traits and their adaptive functions, it 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).
Industrial–organizational
Industrial and organizational psychology (I–O) applies psychological concepts and methods to optimize human potential in the workplace. Personnel psychology, a subfield of I–O psychology, applies the methods and principles of psychology in selecting and evaluating workers. I–O psychology's other subfield,
organizational psychology, examines the effects of work environments and management styles on worker motivation,
job satisfaction, and productivity.
[75]
Personality
Personality psychology is concerned with enduring patterns of
behavior,
thought, and
emotion—commonly referred to as
personality—in individuals. Theories of personality vary across different psychological schools and orientations. They carry different assumptions about such issues as the role of the
unconscious and the importance of childhood experience. According to Freud, personality is based on the dynamic interactions of the
id, ego, and super-ego.
[76] Trait theorists, in contrast, attempt to analyze personality in terms of a discrete number of key traits by the statistical method of
factor analysis. The number of proposed traits has varied widely. An early model, proposed by
Hans Eysenck, suggested that there are three traits which comprise human personality:
extraversion–introversion,
neuroticism, and
psychoticism.
Raymond Cattell proposed a theory of
16 personality factors.
Increasingly, web-based surveys are being used in research for its convenience and also to get a wide range of participants. Similar methodology is also used in applied setting, such as clinical assessment and
personnel assessment.
Longitudinal studies
Longitudinal studies are often used in psychology to study developmental trends across the life span, and in
sociology to study life events throughout lifetimes or generations. The reason for this is that unlike
cross-sectional studies, longitudinal studies track the same people, and therefore the differences observed in those people are less likely to be the result of cultural differences across generations. Because of this benefit, longitudinal studies make observing changes more accurate and they are applied in various other fields.
Because most longitudinal studies are observational, in the sense that they observe the state of the world without manipulating it, it has been argued that they may have less power to detect causal relationships than do experiments. They also suffer methodological limitations such as from selective attrition because people with similar characteristics may be more likely to drop out of the study making it difficult to analyze.
Some longitudinal studies are
experiments, called
repeated-measures experiments. Psychologists often use the
crossover design to reduce the influence of
confounding covariates and to
reduce the number of subjects.
Observation in natural settings
Phineas P. Gage survived an accident in which a large iron rod was driven completely through his head, destroying much of his brain's left frontal lobe, and is remembered for that injury's reported effects on his personality and behavior.
[80]
Just as
Jane Goodall studied
chimpanzee social and family life by careful observation of chimpanzee behavior in the field, psychologists conduct observational studies of ongoing human social, professional, and family life.
Sometimes the participants are aware they are being observed, and other times the participants do not know they are being observed. Strict ethical guidelines must be followed when covert observation is being carried out.
Qualitative and descriptive research
Artificial neural network with two layers, an interconnected group of nodes, akin to the vast network of neurons in the human brain.
Research designed to answer questions about the current state of affairs such as the thoughts, feelings, and behaviors of individuals is known as
descriptive research. Descriptive research can be qualitative or quantitative in orientation.
Qualitative research is descriptive research that is focused on observing and describing events as they occur, with the goal of capturing all the richness of everyday behavior and with the hope of discovering and understanding phenomena that might have been missed if only more cursory examinations have been made.
Neuropsychological methods
Neuropsychological research methods are employed in studies that examine the relation of mental activity and behavior to the structure and function of the
brain. These methods include testing (e.g., the various
Wechsler scales,
Wisconsin Card Sorting Test),
functional neuroimaging, and
transcranial magnetic stimulation.
Computational modeling
The experimenter (E) orders the teacher (T), the subject of the experiment, to give what the latter believes are painful electric shocks to a learner (L), who is actually an actor and
confederate. The subject believes that for each wrong answer, the learner was receiving actual electric shocks, though in reality there were no such punishments. Being separated from the subject, the confederate set up a tape recorder integrated with the electro-shock generator, which played pre-recorded sounds for each shock level etc.
[81]
Computational modeling[82] is a tool often used in
mathematical psychology and
cognitive psychology to simulate a particular behavior using a computer. This method has several advantages. Since modern computers process information extremely quickly, many simulations can be run in a short time, allowing for a great deal of statistical power. Modeling also allows psychologists to visualize hypotheses about the functional organization of mental events that couldn't be directly observed in a human.
Several types of modeling are used to study behavior.
Connectionism uses
neural networks to simulate the brain. Another method is symbolic modeling, which represents many mental objects using variables and rules. Other types of modeling include
dynamic systems and
stochastic modeling.
Animal studies
Animal experiments aid in investigating many aspects of human psychology, including perception, emotion, learning, memory, and thought, to name a few. In the 1890s, Russian physiologist
Ivan Pavlov famously used dogs to demonstrate
classical conditioning.
Non-human primates, cats, dogs, pigeons,
rats, and other
rodents are often used in psychological experiments. Ideally, controlled experiments introduce only one
independent variable at a time, in order to ascertain its unique effects upon dependent variables. These conditions are approximated best in laboratory settings. In contrast, human environments and genetic backgrounds vary so widely, and depend upon so many factors, that it is difficult to control important variables for human subjects. Of course, there are pitfalls in generalizing findings from animal studies to humans through animal models.
[83]
Criticism
Replication crisis
Psychology has recently found itself at the center of a "replication crisis" due to some research findings proving difficult to replicate. Replication failures are not unique to psychology and are found in all fields of science.
However, several factors have combined to put psychology at the center of the current controversy. Much of the focus has been on the area of social psychology, although other areas of psychology such as clinical psychology have also been implicated.
Firstly, questionable researcher practices (QRP) have been identified as common in the field. Such practices, while not intentionally fraudulent, involve converting undesired statistical outcomes into desired outcomes via the manipulation of statistical analyses, sample size or data management, typically to convert non-significant findings into significant ones.
[84] Some studies have suggested that at least mild versions of QRP are highly prevalent.
[85] False positive conclusions, often resulting from the
pressure to publish or the author's own
confirmation bias, are an inherent hazard in the field, requiring a certain degree of
skepticism on the part of readers.
[86]
Secondly, psychology and social psychology in particular, has found itself at the center of several recent scandals involving outright fraudulent research. Most notably the admitted data fabrication by
Diederik Stapel[87] as well as allegations against others. However, most scholars acknowledge that fraud is, perhaps, the lesser contribution to replication crises.
Third, several effects in psychological science have been found to be difficult to replicate even before the current replication crisis. For example the scientific journal
Judgment and Decision Making has published several studies over the years that fail to provide support for the
unconscious thought theory. Replications appear particularly difficult when research trials are pre-registered and conducted by research groups not highly invested in the theory under questioning.
These three elements together have resulted in renewed attention for replication supported by
Kahneman. Scrutiny of many effects have shown that several core beliefs are hard to replicate. A recent special edition of the journal Social Psychology focused on replication studies and a number of previously held beliefs were found to be difficult to replicate.
[88] A 2012 special edition of the journal Perspectives on Psychological Science also focused on issues ranging from publication bias to null-aversion that contribute to the replication crises in psychology
[89]
Scholar James Coyne has recently written that many research trials and meta-analyses are compromised by poor quality and conflicts of interest that involve both authors and professional advocacy organizations, resulting in many false positives regarding the effectiveness of certain types of psychotherapy.
[90]
It is important to note that this replication crisis does not mean that psychology is unscientific. Rather, this process is a healthy if sometimes acrimonious part of the scientific process in which old ideas or those that cannot withstand careful scrutiny are pruned.
[91] The consequence is that some areas of psychology once considered solid, such as
social priming, have come under increased scrutiny due to failed replications.
[92]
Theory
Criticisms of psychological research often come from perceptions that it is a "soft" science. Philosopher of science
Thomas Kuhn's 1962 critique
[93] implied psychology overall was in a pre-paradigm state, lacking the agreement on overarching theory found in mature sciences such as
chemistry and
physics.
Because some areas of psychology rely on research methods such as surveys and
questionnaires, critics have asserted that psychology is not an objective science. Other concepts that psychologists are interested in, such as
personality,
thinking, and
emotion, cannot be directly measured
[94] and are often inferred from subjective self-reports, which may be problematic.
[95][96]
Some critics view
statistical hypothesis testing as misplaced. Research
[which?] has documented that many psychologists confuse
statistical significance with
practical importance. Statistically significant but practically unimportant results are common with large samples.
[97] Some psychologists have responded with an increased use of
effect size statistics, rather than sole reliance on the
Fisherian p < .05 significance criterion (whereby an observed difference is deemed "
statistically significant" if an effect of that size or larger would occur with 5% -or less-
probability in
independent replications, assuming the truth of the
null-hypothesis of no difference between the treatments).
[citation needed]
Sometimes the debate comes from within psychology, for example between laboratory-oriented researchers and practitioners such as clinicians. In recent years, and particularly in the U.S., there has been increasing
debate about the nature of therapeutic effectiveness and about the relevance of empirically examining psychotherapeutic strategies.
[98]
Practice
Psychology Wiki snap shot
Some observers perceive a gap between scientific theory and its application—in particular, the application of unsupported or unsound clinical practices.
[99] Critics say there has been an increase in the number of mental health training programs that do not instill scientific competence.
[100] One skeptic asserts that practices, such as "
facilitated communication for infantile autism"; memory-recovery techniques including
body work; and other therapies, such as
rebirthing and
reparenting, may be dubious or even dangerous, despite their popularity.
[101] In 1984, Allen Neuringer made a similar point
[vague] regarding the experimental analysis of behavior.
[102]
Ethical standards
Current ethical standards of psychology would not permit some studies to be conducted today. These human studies would violate the
Ethics Code of the American Psychological Association, the Canadian Code of Conduct for Research Involving Humans, and the
Belmont Report. Current ethical guidelines state that using non-human animals for scientific purposes is only acceptable when the harm (physical or psychological) done to animals is outweighed by the benefits of the research.
[103] Keeping this in mind, psychologists can use certain research techniques on animals that could not be used on humans.
- An experiment by Stanley Milgram raised questions about the ethics of scientific experimentation because of the extreme emotional stress suffered by the participants. It measured the willingness of study participants to obey an authority figure who instructed them to perform acts that conflicted with their personal conscience.[104]
- Harry Harlow drew condemnation for his "pit of despair" experiments on rhesus macaque monkeys at the University of Wisconsin–Madison in the 1970s.[105] The aim of the research was to produce an animal model of clinical depression. Harlow also devised what he called a "rape rack", to which the female isolates were tied in normal monkey mating posture.[106] In 1974, American literary critic Wayne C. Booth wrote that, "Harry Harlow and his colleagues go on torturing their nonhuman primates decade after decade, invariably proving what we all knew in advance—that social creatures can be destroyed by destroying their social ties." He writes that Harlow made no mention of the criticism of the morality of his work.[107]
University psychology departments have ethics committees dedicated to the rights and well-being of research subjects. Researchers in psychology must gain approval of their research projects before conducting any experiment to protect the interests of human participants and laboratory animals.
[108]
Systemic bias
In 1959 statistician Theodore Sterling examined the results of psychological studies and discovered that 97% of them supported their initial hypotheses, implying a possible
publication bias.
[109][110][111] Similarly, Fanelli (2010)
[112] found that 91.5% of psychiatry/psychology studies confirmed the effects they were looking for, and concluded that the odds of this happening (a positive result) was around five times higher than in fields such as
space- or
geosciences. Fanelli argues that this is because researchers in "softer" sciences have fewer constraints to their conscious and unconscious biases.
In 2010, a group of researchers reported a systemic bias in psychology studies towards WEIRD ("western, educated, industrialized, rich and democratic") subjects.
[113] Although only 1/8 people worldwide fall into the WEIRD classification, the researchers claimed that 60–90% of psychology studies are performed on WEIRD subjects. The article gave examples of results that differ significantly between WEIRD subjects and tribal cultures, including the
Müller-Lyer illusion.
