Introduction to psychology

Psychology is an academic and applied field involving the study of the human mind, brain, and behavior. 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.

Psychology differs from anthropology, economics, political science, and sociology in seeking to capture explanatory generalizations about the mental function and overt behaviour of individuals, while the other disciplines rely more heavily on field studies and historical methods for extracting descriptive generalizations. In practice, however, there is quite a lot of cross-fertilization that takes place among the various fields. Psychology differs from biology and neuroscience in that it is primarily concerned with the interaction of mental processes and behavior, and of the overall processes of a system, and not simply the biological or neural processes themselves, though the subfield of neuropsychology combines the study of the actual neural processes with the study of the mental effects they have subjectively produced.

The word psychology comes from the ancient Greek ψυχή, psyche ("soul", "mind") and logy, study).

History


Rudolph Goclenius, a German scholastic philosopher, is credited with inventing the term 'psychology' (1590). The root of the word psychology (psyche) means "soul" in Greek, and psychology was sometimes considered a study of the soul (in a religious sense of this term). Psychology as a medical discipline can be seen in Thomas Willis' reference to psychology (the "Doctrine of the Soul") in terms of brain function, as part of his 1672 anatomical treatise "De Anima Brutorum" ("Two Discourses on the Souls of Brutes").

Until about the end of the 19th century, psychology was regarded as a branch of philosophy.

In 1879 Wilhelm Wundt founded a laboratory at the University in Germany in Leipzig specifically to focus on the study of psychology. William James later published his 1890 book, Principles of Psychology which laid many of the foundations for the sorts of questions that psychologists would focus on for years to come. Other important early contributors to the field include Hermann Ebbinghaus (a pioneer in studies on memory) and the Russian Ivan Pavlov (who discovered the learning process of classical conditioning).

Meanwhile, Sigmund Freud, who was trained as a neurologist and had no formal training in experimental psychology, had invented and applied a method of psychotherapy known as psychoanalysis. Freud's understanding of the mind was largely based on interpretive methods and introspection, but was particularly focused on resolving mental distress and psychopathology. Freud's theories were wildly successful, not least because they aimed to be of practical benefit to individual patients, but also because they tackled subjects such as sexuality and repression 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. Although it has become fashionable to discredit many of Freud's more outlandish theories, his application of psychology to clinical work and his more mainstream work has been massively influential.

Partly as a reaction to the subjective and introspective nature of psychology at the time, behaviourism began to become popular as a guiding psychological theory. Championed by psychologists such as John B. Watson, Edward Thorndike, and B.F. Skinner, behaviorists argued that psychology should be a science of behaviour, not the mind, they rejected the idea that internal mental states such as beliefs, desires, or goals, could be studied scientifically. In his paper "Psychology as the Behaviourist Views It" (1913), Watson argued that psychology "is a purely objective experimental branch of natural science", "introspection forms no essential part of its methods" and "The behaviourist recognizes no dividing line between man and brute".

Behaviourism was the dominant model in psychology for much of the early 20th century, largely due to the creation and successful application (not least of which in advertising) of conditioning theories as scientific models of human behaviour.

However, it became increasingly clear that although behaviourism had made some important discoveries, it was deficient as a guiding theory of human behaviour. Noam Chomsky's review of Skinner's book Verbal Behavior (that aimed to explain language acquisition in a behaviourist framework) is considered one of the major factors in the ending of behaviourism's reign. Chomsky demonstrated that language could not purely be learnt from conditioning, as people could produce sentences unique in structure and meaning that couldn't possibly be generated solely through experience of natural language, implying that there must be internal states of mind that behaviourism rejected as illusory. Similarly, work by Albert Bandura showed that children could learn by social observation, without any change in overt behaviour, and so must be accounted for by internal representations.

Humanistic psychology emerged in the 1950s and has continued as a reaction to positivist and scientific approaches to the mind. It stresses a phenomenological view of human experience and seeks to understand human beings and their behaviour by conducting qualitative research. The humanistic approach has its roots in existentialist and phenomenological philosophy and many humanist psychologists completely reject a scientific approach, arguing that trying to turn human experience into measurements strips it of all meaning and relevance to lived existence.

Some of the founding theorists behind this school of thought were Abraham Maslow who formulated a hierarchy of human needs, Carl Rogers who created and developed client-centred therapy, and Fritz Perls who helped create and develop Gestalt therapy.

The rise of computer technology also promoted the metaphor of mental function as information processing. This, combined with a scientific approach to studying the mind, as well as a belief in internal mental states, led to the rise of cognitivism as the dominant model of the mind.

Links between brain and nervous system function were also becoming common, partly due to the experimental work of people like Charles Sherrington and Donald Hebb, and partly due to studies of people with brain injury (see cognitive neuropsychology). With the development of technologies for accurately measuring brain function, neuropsychology and cognitive neuroscience have become some of the most active areas in contemporary psychology.

With the increasing involvement of other disciplines (such as philosophy, computer science and neuroscience) in the quest to understand the mind, the umbrella discipline of cognitive science has been created as a means of focusing such efforts in a constructive way.

However, many psychologists have not been happy with what they perceive as 'mechanical' models of the mind and human nature. Coming full circle, Transpersonal psychology and the Analytical Psychology of Carl Jung seek to return psychology to its spiritual roots. Others, such as Serge Moscovici and Gerard Duveen, argue that behaviour and thought are essentially social in nature and seek to embed psychology in a broader social scientific study that incorporates the social meaning of experience and behaviour.

Mind and brain
Psychology (literally, the study of the human mind) describes and attempts to explain consciousness, behaviour and social interaction. Empirical psychology is primarily devoted to describing human experience and behaviour as it actually occurs. In the past 20 years or so psychology has begun to examine the relationship between consciousness and the brain or nervous system. It is still not clear in what ways these interact: does consciousness determine brain states or do brain states determine consciousness - or are both going on in various ways - or is consciousness some sort of complicated 'illusion' which bears no direct relationship to neural processes? An understanding of brain function is increasingly 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.

Scope of psychology
Psychology is an extremely broad field, encompassing many different approaches to the study of mental processes and behavior. Below are the major areas of inquiry that comprise psychology. A comprehensive list of the sub-fields and areas within psychology can be found at the list of psychological topics and list of psychology disciplines.

Biological basis: the brain
Main articles: Behavioral neuroscience, Cognitive neuroscience, Neuropsychology, Evolutionary psychology

Because all behavior is controlled by the central nervous system, 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 behavioral and psychological processes. Often neuropsychologists are employed as scientists to advance scientific or medical knowledge. Neuropsychology 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 neuroimaging tools, such as fMRI, to observe which areas of the brain are active during a particular task.



Information processing: the mind
Main articles: Cognitive psychology, Cognitive science

The nature of thought is another core interest in psychology. Cognitive psychology studies cognition, the mental processes underlying behavior. It 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 associated with a school of thought known as cognitivism, whose adherents argue for an information processing model of mental function, informed by positivism and experimental 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 use computational models to simulate phenomena of interest. Because mental events cannot directly be observed, computational models provide a tool for studying the functional organization of the mind. Such models give cognitive psychologists a way to study the "software" of mental processes independent of the "hardware" it runs on, be it the brain or a computer.

Change over time: development
Main articles: Developmental psychology, Educational psychology, Evolutionary developmental psychology

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 intellectual, cognitive, neural, social, or moral 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 small 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). Urie Bronfenbrenner's theory of development in context (The Ecology of Human Development - ISBN 0-674-22456-6) is influential in this field, as are those mentioned in "Educational psychology" immediately below, as well as many others. Developmental psychologists draw on the full range of theorists in scientific psychology to inform their research.

Educational psychology largely seeks to apply much of this knowledge to understanding 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..

Personality
Personality psychology studies enduring psychological patterns of behavior, thought and emotion, commonly called an individual's personality. Theories of personality vary between different psychological schools. Trait theories attempts to break personality down into a number of traits, by use of factor analysis. The number of traits have varied between theories. One of the first, and smallest, models was that of Hans Eysenck, which had three dimensions: extraversion&mdash;introversion, neuroticism&mdash;emotional stability, and psychoticism. Raymond Cattell proposed a theory of 16 personality factors. The theory that has most empirical evidence behind it today may be the "Big Five" theory, proposed by Lewis Goldberg and others.

A different, but well known, approach to personality is that of Sigmund Freud, whose structural theory of personality divided personality into the ego, superego, and id. Freud's theory of personality has been criticized by many, including many mainstream psychologists.

Interaction with others
Main articles: Social psychology, Community 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 behavior (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 behavior.

A related area is community psychology, which examines psychological and mental health issues on the level of the community rather than using the individual as the unit of measurement. "Sense of community" has become its conceptual center (Sarason, 1986; Chavis & Pretty, 1999).

Study of nonhuman animals in psychology
Psychology as a science is primarily concerned with humans, although the behavior and mental processes of  animals is also an important part of psychological research, either as a subject in its own right (e.g., animal cognition and ethology), or with strong emphasis about evolutionary links, and somewhat more controversially, as a way of gaining an insight into human psychology by means of comparison (including comparative psychology) or via animal models of emotional and behavior systems as seen in neuroscience of psychology (e.g., affective neuroscience and social neuroscience).

Mental health
Main articles: Clinical psychology, Health psychology

Clinical psychology is the application of psychology to the understanding, treatment, and assessment of psychopathology, behavioral 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 behavior 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.

The majority of work performed by clinical psychologists tends to be done inside a Cognitive-Behaviorial therapy (CBT) framework. CBT is an umbrella term that refers to a number of therapies which focus on changing cognitions and/or behaviors, rather than changing behavior exclusively, or discovering the unconscious causes of psychopatholgy (as in the psychodynamic school). The two most famous CBT therapies are Aaron T. Beck's cognitive therapy and Albert Ellis's rational emotive behaviour therapy (with cognitive therapy being, by far, the most extensively studied therapy in contemporary clinical psychology).

Applied psychology
Main articles: Applied psychology, Industrial and organizational psychology, Ecological psychology, Environmental psychology, Forensic psychology, Human factors, Traffic psychology, health psychology

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, health 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 behavior, stress at work and management.

Applications of industrial psychology include improving human performance and satisfaction in the workplace, as well as the improvement of organizational performance. The primary purpose of industrial psychologists is integration of psychometric research into applications that achieve these ends. (Bradberry and Greaves, 2005)

Forensic psychology
Forensic psychology is the area concerned with the application of psychological methods and principles to the legal arena. Most typically, forensic psychology involves a clinical analysis of a particular individual and an assessment of some specific psycho-legal question. Typically, referrals to forensic practices constitute assessments for individuals that have ostensibly suffered neurologic insult(s). These patients have sought legal recourse, and the job of the forensic psychologist is to demonstrate that there is or is not (depending on their employ by either the prosecution or defense) a cause-and-effect relation between the accident and the subsequent (again, ostensible) neurologic change. A job required of the forensic psychologist in any case is the detection of malingering, although this is not exclusive to forensics. Malingering, or the detection of 'faking' (this term is used somewhat liberally) is particularly germane to a forensic assessment, for obvious reasons. In addition to such applied practices, it also includes academic or empirical research on topics involving the relationship of law to human mental processes and behavior (see also: Legal Psychology).

Health psychology
Health psychology is the application of psychological theory and research to health, illness and health care.

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 mental processes and behavior.

School Psychology
School Psychology is the area of discipline in order to help children and youth succeed academically, socially, and emotionally. They collaborate with educators, parents, and other professionals to create safe, healthy, and supportive learning environments for all students that strengthen connections between home and school (NASPonline.com, 2006).

Research methods


Research in psychology is conducted in broad accord with the standards of scientific method, encompassing both qualitative ethological and quantitative statistical modalities to generate and evaluate explanatory hypotheses with regard to psychological phenomena. Where research ethics and the state of development in a given research domain permits, investigation may be pursued by experimental protocols. Psychology tends to be eclectic, drawing on scientific knowledge from other fields to help explain and understand psychological phenomena. Qualitative psychological research utilizes a broad spectrum of observational methods, including action research, ethography, ethnography, exploratory statistics, structured and unstructured interviews, and participant observation, to enable the gathering of rich information unattainable by classical experimentation. Research in humanistic psychology is more typically pursued by ethnographic, historical, and historiographic methods.

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 individuals with psychological issues or use psychology to help others.

When an area of interest requires specific training and specialist knowledge, especially in applied areas, psychological associations normally establish 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 behavior. 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 a person's smoking is correlated with that individual's chance of getting lung cancer. One way to answer this would simply be to take a group of people who smoke and measure the proportion of those who get lung cancer within a certain time. In this particular case, one would probably find a high correlation. (Tobacco is already known to have a deleterious effect on the lungs). Based on this correlation alone, 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, 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 involves the study of both healthy individuals and patients, typically who have suffered either brain injury or mental illness.

Cognitive neuropsychology and cognitive neuropsychiatry study neurological or mental impairment in an attempt to infer theories of normal mind and brain function. This typically involves looking for differences in patterns of remaining ability (known as 'functional dissociations') which can give clues as to whether abilities are comprised of smaller functions, or are controlled by a single cognitive mechanism.

In addition, experimental techniques are often used which also apply to studying the neuropsychology of healthy individuals. These include behavioural experiments, brain-scanning or functional neuroimaging - used to examine the activity of the brain during task performance, and techniques such as transcranial magnetic stimulation, which can safely alter the function of small brain areas to investigate their importance in mental operations.

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
Although modern mainstream psychology largely attempts to be a scientific endeavor, the field has a history of controversy. 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, ignoring or downplaying what is most essential about being human.

Another common criticism of psychology concerns its fuzziness as a science. Since some areas of psychological research rely on "soft" methods such as surveys and questionnaires, some have said, those areas of psychology are not as scientific as they claim to be. Furthermore, methods such as introspection and so-called expert analysis are commonplace, methods which are open to subjectivity and rely on speculation have caused many to dispute whether psychology should even be classified as a science, since objectivity, validity, and rigour are key attributes one rule for empiricism and science.

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 that involves significant disagreement about how the mind works.

One approach calling itself critical psychology takes almost an opposite approach. Rather than scientific validity being the standard against which psychology research should be judged, critical psychology uses philosophical, analytical, political, economic and social theories such as Marxism, constructionism, discourse analysis and qualitative approaches to criticize mainstream psychology, claiming among other things that it serves as a bulwark of an unjust or unsatisfying status quo when it should, instead, use its methods and knowledge base to critique and change societal norms.

Another criticism levelled at psychology and cognitive science is that the philosophical underpinnings of research are flawed. See Functionalism (psychology) and Pragmatism for more.

Another criticism of modern psychology is that it ignores spirituality, the soul, and spiritual concepts such as original sin. Not surprisingly, these arguments are made mostly by pious individuals, religious leaders (such as the Pope) and evangelists. These groups agree with the functionalists and pragmatics, in saying that the philosophical underpinnings of research are flawed, but they believe that the error of psychology is in its failure to acknowledge the crucial role that the soul plays in human behavior.

There is also a criticism from empirical psychology researchers concerning the gap between research and practice in psychology. A recent trend has seen the growth of dubious or unvalidated therapies such as NLP, Rebirthing, and Primal Therapy being promoted by some psychotherapy bodies. Psychologists are concerned about this and bodies such as the Scientific Review of Mental Health Practices have been set up to raise awareness and research in this area.

Related areas

 * Aging
 * Artificial consciousness
 * Cognitive science
 * Complex systems
 * Computer science
 * Counseling
 * Discourse analysis
 * Economics
 * Education


 * Emotion
 * Ethology
 * Game theory
 * Hypnotherapy
 * Linguistics
 * Marketing
 * Moral value
 * Multilevel model
 * Neuroscience


 * Philosophy of mind
 * Philosophy of psychology
 * Psychoanalysis
 * Psychodynamics
 * Psycholinguistics
 * Psychology of religion
 * Sociology
 * Structural equation modeling
 * Systems theory

Related topics

 * Aristotle, On the Soul
 * Tabula rasa
 * Empiricism
 * Rationalism
 * Scientific method