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Psychology (Classical Greek: psyche = "soul" or "mind", logos = "study of") is an academic and applied field involving the study of behavior and its relationship to the mind and brain. Psychology also refers to the application of such knowledge to various spheres of human activity, including problems of individuals' daily lives and the treatment of mental illness. It is largely concerned with humans, although the behavior and mental processes of animals is also be part of psychological research, either as a subject in its own right (e.g. animal cognition and ethology), or as a way of gaining an insight into human psychology by means of comparison (including comparative psychology). Psychology is commonly defined as the science of behavior and mental processes. Although its name derives from the Greek word "psyche", psychology does not scientifically study the soul.

Psychology differs from sociology, anthropology, economics, and political science, in part, because it involves studying the behaviour of individuals (alone or in groups) rather than the behavior of the groups or aggregates themselves. Psychology differs from biology and neuroscience in that it is primarily concerned with the overall behavior of a system, and not simply the pattern of neural responses produced by the system.

Although psychological questions were asked in antiquity (see Aristotle's De Memoria et Reminiscentia or "On Memory and Recollection"), psychology emerged as a separate discipline only recently. The first person to call himself a "psychologist", Wilhelm Wundt, opened the first psychological laboratory in 1879.



Main article: History of psychology

Wilihem Wundt
Wilihem Wundt

The late 19th century marks the start of psychology as a scientific enterprise. The year 1879 is commonly seen as the start of psychology as an independent field of study, because in that year German scientist Wilhelm Wundt founded the first laboratory dedicated exclusively to psychological research in Leipzig, Germany. Other important early contributors to the field include Hermann Ebbinghaus (a pioneer in studies on memory), the Russian Ivan Pavlov (who discovered the learning process of classical conditioning), and the Austrian Sigmund Freud. Freud's influence has been enormous, though more as cultural icon than a force in (scientific) psychology. Freud's basic theories postulated the existence in humans of various unconscious and instinctive "drives", and that the "self" existed as a perpetual battle between the desires and demands of the internal id, ego, and superego.

The mid-20th century saw a rejection of Freud's theories among many psychologists as being too unscientific, as well as a reaction against Edward Titchener's abstract approach to the mind. This led to the formulation of behaviorism by John B. Watson, which was popularized by B.F. Skinner. Behaviorism proposed epistemologically limiting psychological study to overt behavior, since that could be quantified and easily measured. Scientific knowledge of the "mind" was considered too metaphysical, hence impossible to achieve. The final decades of the 20th century have seen the rise of a new interdisciplinary approach to studying human psychology, known collectively as cognitive science. Cognitive science again considers the "mind" as a subject for investigation, using the tools of evolutionary psychology, linguistics, computer science, philosophy, and neurobiology. This new form of investigation has proposed that a wide understanding of the human mind is possible, and that such an understanding may be applied to other research domains, such as artificial intelligence.

Principles of psychology

Mind and brain

Psychology does not necessarily refer to the brain or nervous system and can be framed purely in terms of phenomenological or information processing theories of the mind. Increasingly, though, an understanding of brain function is being included in psychological theory and practice, particularly in areas such as artificial intelligence, neuropsychology, and cognitive neuroscience.

Schools of thought

Various schools of thought have argued for a particular model to be used as a guiding theory by which all, or the majority, of human behavior can be explained. The popularity of these has waxed and waned over time. Some psychologists may think of themselves as adherents to a particular school of thought and reject the others, although most consider each as an approach to understanding the mind, and not necessarily as mutually exclusive theories. See psychological schools of thought for a comprehensive list.

Scope of psychology

Psychology is an extremely broad field, encompassing many different approaches to the study of behavior. Below are the major areas of inquiry that comprise psychology. A comprehensive list of the sub-fields and areas within psychology is given in the Related Topics section below.

Biological basis: the brain

Image of the human brain. The arrow indicates the position of the hypothalamus.
Image of the human brain. The arrow indicates the position of the hypothalamus.

Main articles: Behavioral neuroscience, Cognitive neuroscience, Neuropsychology

Since all behavior is rooted in the brain, it is sensible to study how the brain functions in order to understand behavior. This is the approach taken in behavioral neuroscience, cognitive neuroscience, and Neuropsychology. Neuropsychology is the branch of psychology that aims to understand how the structure and function of the brain relate to specific psychological processes. Often neuropsychologists are employed as scientists to advance scientific or medical knowledge. Neurospychology is particularly concerned with the understanding of brain injury in an attempt to work out normal psychological function.

The approach of cognitive neuroscience to studying the link between brain and behavior is to use brain imaging tools, such as fMRI, to observe which areas of the brain are active during a particular behavioral task.

Information processing: the mind

Neural network with two layers.
Neural network with two layers.

Main articles: Cognitive psychology, Cognitive science

The nature of thought is another core interest in psychology. Cognitive psychology is primarily concerned with the process by which perception results in behavior. Cognitive psychology uses information processing as a framework for understanding the mind. Perception, learning, problem solving, memory, attention, language and emotion are all well researched areas. Cognitive psychology is based on a school of thought known as cognitivism, whose adherents argue for an information processing model of mental function, informed by positivism and experimental psychology. Techniques and models from cognitive psychology are widely applied and form the mainstay of psychological theories in many areas of both research and applied psychology.

Cognitive science is very closely related to cognitive psychology, but differs in some of the research methods used, and has a slightly greater emphasis on explaining mental phenomena in terms of both behavior and neural processing.

Both areas used computational models to simulate phenomena of interest. Since mental events cannot directly be observed, computational models provide a tool for studying the functional organization of the brain and behavior. Such models allow cognitive psychologists to better understand the information processing requirements of behavior and explain hypotheses obtained from behavioral experiments.

Change over time: development

A baby thinking
A baby thinking

Main articles: Developmental psychology, Educational psychology

Largely 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 perceptions change as they age. This may focus on intellectual, cognitive, neural, social, or moral development. Researchers who study children use a number of unique research methods to engage them in experimental tasks. These tasks often resemble specially designed games and activities that are both enjoyable for the child and scientifically useful. In addition to studying children, developmental psychologists also study other times of rapid change (such as adolescence and old age).

Educational psychology largely seeks to apply much of this knowledge and understand how learning can best take place in educational situations. Because of this, the work of child psychologists such as Lev Vygotsky, Jean Piaget and Jerome Bruner has been influential in creating teaching methods and educational practices.

Mental health

Main articles: Clinical psychology, Health psychology

Clinical psychology is the application of psychology to the understanding, treatment, and assessment of psychopathology, behavioural or mental health issues. It has traditionally been associated with counselling and psychotherapy, although modern clinical psychology may take an eclectic approach, including a number of therapeutic approaches. Typically, although working with many of the same clients as psychiatrists, clinical psychologists do not prescribe psychiatric drugs. Some clinical psychologists may focus on the clinical management of patients with brain injury. This area is known as clinical neuropsychology.

In recent years and particularly in the United States, a major split has been developing between academic research psychologists in universities and some branches of clinical psychology. Many academic psychologists believe that these clinicians use therapies based on discredited theories and unsupported by empirical evidence of their effectiveness. From the other side, these clinicians believe that the academics are ignoring their experience in dealing with actual patients. The disagreement has resulted in the formation of the American Psychological Society by the research psychologists as a new body distinct from the American Psychological Association.

Whereas clinical psychology focuses on mental health and neurological illness, health psychology is concerned with the psychology of a much wider range of health-related behaviour including healthy eating, the doctor-patient relationship, a patient's understanding of health information, and beliefs about illness. Health psychologists may be involved in public health campaigns, examining the impact of illness or health policy on quality of life or in research into the psychological impact of health and social care.

Interaction with others

Main articles: Social psychology, Personality psychology

Social psychology is the study of the nature and causes of human social behavior, with an emphasis on how people think towards each other and how they relate to each other. Social Psychology aims to understand how we make sense of social situations. For example, this could involve the influence of others on an individual's behaviour (e.g., conformity or persuasion), the perception and understanding of social cues, or the formation of attitudes or stereotypes about other people. Social cognition is a common approach and involves a mostly cognitive and scientific approach to understanding social behaviour.

Personality psychology includes theories of career development.

Applied psychology

Main articles: Applied psychology, Industrial and organizational psychology, Forensic psychology, Human factors

The basic premise of applied psychology is the use of psychological principles and theories to overcome practical problems in other fields, such as business management, product design, ergonomics, nutrition, and clinical medicine. Applied psychology includes the areas of industrial/organizational psychology, human factors, forensic psychology, as well as many other areas.

Industrial and organizational

Industrial and organizational psychology focuses to varying degrees on the psychology of the workforce, customer, and consumer, including issues such as the psychology of recruitment, selecting employees from an applicant pool which overall includes training, performance appraisal, job satisfaction, work behaviour, stress at work and management.

Forensic psychology

Forensic psychology is the area concerned with the application of psychological methods and principles to legal questions and issues. Most typically, this involves a clinical analysis of a particular individual and an assessment of some specific psycho-legal question. Forensic psychology refers to any application of psychological principles, methods or understanding to legal questions or issues. In addition to the applied practices, it also includes academic or empircal research on topics involving law and human behavior.

Human factors

Human factors is the study of how cognitive and psychological processes affect our interaction with tools and objects in the environment. The goal of research in human factors is to better design objects by taking into account the limitations and biases of human behavior.

Research methods

Psychology is conducted both scientifically and non-scientifically, but is to a large extent wholly rigorous. Mainstream psychology is based largely on positivism, using quantitative studies and the scientific method to test and disprove hypotheses, often in an experimental context. Psychology tends to be eclectic, drawing on scientific knowledge from other fields to help explain and understand behaviour. However, not all psychological research methods strictly follow the empirical positivism philosophy. Qualitative research utilizes interpretive techniques and is descriptive in nature, enabling the gathering of rich clinical information unattainable by classical experimentation. Some psychologists, particularly adherents to humanistic psychology, may go as far as completely rejecting a scientific approach, viewing psychology more as an art rather than a rigid science. However, mainstream psychology has a bias towards the scientific method, which is reflected in the dominance of cognitivism as the guiding theoretical framework used by most psychologists to understand thought and behaviour.

The testing of different aspects of psychological function is a significant area of contemporary psychology. Psychometric and statistical methods predominate, including various well-known standardised tests as well as those created ad hoc as the situation or experiment requires.

Academic psychologists may focus purely on research and psychological theory, aiming to further psychological understanding in a particular area, while other psychologists may work in applied psychology to deploy such knowledge for immediate and practical benefit. However, these approaches are not mutually exclusive and most psychologists will be involved in both researching and applying psychology at some point during their work. Clinical psychology, among many of the various discipline of psychology, aims at developing in practicing psychologists knowledge of and experience with research and experimental methods which they will continue to build up as well as employ as they treat individual with psychological issues or use psychology to help others.

Where an area of interest is considered to need specific training and specialist knowledge (especially in applied areas), psychological associations will typically set up a governing body to manage training requirements. Similarly, requirements may be laid down for university degrees in psychology, so that students acquire an adequate knowledge in a number of areas. Additionally, areas of practical psychology, where psychologists offer treatment to others, may require that psychologists be licensed by government regulatory bodies as well.

Controlled experiments

Main article: Experimental psychology

The majority of psychological research is conducted in the laboratory under controlled conditons. This method of research relies completely on the scientific method to determine the basis of behavor. Common measurements of behavior include reaction time and various psychometric measurements. Experiments are conducted to test a particular hypothesis.

As an example of a psychological experiment, one may want to test people's perception of different tones. Specifically, one could ask the following question: is it easier for people to discriminate one pair of tones from another depending upon their frequency? To answer this, one would want to disprove the hypothesis that all tones are equally discriminable, regardless of their frequency. (See hypothesis testing for an explanation of why one would disprove a hypothesis rather than attempt to prove one.) A task to test this hypothesis would have a participant seated in a room listening to a series of tones. If the participant would make one indication (by pressing a button, for example) if they thought the tones were two different sounds, and another indication if they thought they were the same sound. The proportion of correct responses would be the measurement used to describe whether or not all the tones were equally discriminable. The result of this particular experiment would probably indicate better discrimination of certain tones based on the human threshold of hearing.

Correlational studies

A correlational study uses statistics to determine if one variable is likely to co-occur with another variable. For example, one might be interested in whether or not an individual smokes is correlated with their change of getting lung cancer. One way to answer this would be to simply take a group of people who smoke and measure the proportion of those that get lung cancer within a certain time. In this particular case, one would probably find a high correlation (since tobacco has a deletarious effect on the lungs). However, we cannot know for certain that smoking is the cause of lung cancer. It could be that those more prone to cancer are also more likely to take up smoking. A third alternative is that some other variable caused both conditons. This is a major limitation of correlational studies, and it is exemplified by the fact that correlation does not imply causation.

Longitudinal studies

A longitudinal study is a research method which observes a particular population over time. For example, one might wish to study specific language impairment (SLI) by observing a group of individuals with the condition over a period of time. This method has the advantage of seeing how a condition can affect individuals over long time scales. However, since individual differences between members of the group are not controlled, it may be difficult to draw conclusions about the populations.

Neuropsychological methods

Neuropsychology is synonymous to patient study. It comprises broadly two different domains. One is acquired and the other is developmental. Neuropsychological study with acquired patients investigates the cognitive processing in certain cortical area by analyzing the behavioral consequence of lesion in the area. Since patients had no disability prior to the damage, the possibility of inherent disability shall be discounted. On the other hand, developmental neuropsychology investigates abnormally developing children in order to investigate cognitive development and neural development.

Computational modeling

Computational modeling is a tool often used in cognitive psychology to simulate a particular behavior using a computer. This method has several advantages. Since modern computers are extremely fast, many simulations can be run in a short time, allowing for a great deal of statistical power. Modeling also allows psychologists to visualise hypotheses about the functional organization of mental events that couldn't be directly observed in a human.

Several different types of modeling are used to study behavior. Connectionism uses neural nets to simulate the brain. Another method is symbolic modeling, which represents different mental objects using variables and rules. Other types of modeling include dynamic systems and stochastic modeling.

Criticisms of psychology

Psychology has always been a controversial discipline. Some criticisms of psychology have been made on ethical and philosophical grounds. Some have argued that by subjecting the human mind to experimentation and statistical study, psychologists objectify persons. Because it treats human beings as things, as objects that can be examined by experiment, psychology is sometimes portrayed as dehumanizing. It has been argued that ultimately, quantitative psychological research ignores or downplays what is most essential about being human.

Another common criticism of psychology concerns its fuzziness as a science. Since it relies on "soft" methods such as statistical analysis and questionnaires, some have said, psychology is not as scientific as it claims to be. Many believe that the mind is not amenable to quantitative scientific research, and as support for their criticism cite the vast theoretical diversity of psychology, a discipline which agrees on very little about how the mind works. This criticism, however, cannot be applied universally to psychology, as some areas within the discipline, such as behaviorism or neuropsychology, advocate only the scientific method. In defending their discipline, psychologists will often point out that astronomy's claim to being a science is also open to argument because it's theories are largely untestable, being only open to observation (philosophically, a scientific theory must be falsifiable: testable and able to be proven false if it is really false). This criticism does not reflect the vast majority of the type of research conducted in modern psychology.

Related topics

For a comprehensive list of psychological topics on wikipedia, please see the list of psychological topics. See List of psychologists for a full list of famous and influential psychologists. See List of publications in psychology for important publications in psychology.

Areas related to psychology:

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