Sigmund Freud believed that human personality consisted of three components: the id, the ego, and the superego. The id is the part of the personality that includes such basic biological impulses or drives as eating, drinking, eliminating wastes, avoiding pain, attaining sexual pleasure, and aggression. The id operates on the "pleasure principle," seeking to satisfy these basic urges …
Components of identity include a sense of personal continuity and of uniqueness from other people. In addition to carving out a personal identity based on the need for uniqueness, people also acquire a social identity based on their membership in various groups—familial, ethnic, occupational, and others. These group identities, in addition to satisfying the need for affiliation, help people…
Imagination involves the synthetic combining of aspects of memories or experiences into a mental construction that differs from past or present perceived reality, and may anticipate future reality. Generally regarded as one of the "higher mental functions," it is not thought to be present in animals. Imagination may be fantastic, fanciful, wishful, or problem-solving, and may differ …
While the incest taboo is nearly universal and exists in nearly all societies, notions of kinship vary greatly from culture to culture. Thus, some cultures would consider sexual relations between first cousins incest, while others would not. The same premise holds true for inter-course between a stepfather and stepdaughter. The very rare exceptions to incest, such as those found in ancient Egyptia…
In experimental research, psychologists create two or more groups that are as similar as possible except for a single change that the psychologist makes from one group to the next. That single element that varies across groups is called the independent variable. In more complex research, the experimenter may include more than one independent variable. In one experiment dealing with eyewitness test…
The term "inferiority complex" was coined in the 1920s by French psychologist Alfred Adler, a one-time follower of Sigmund Freud who became disenchanted with Freud's emphasis on the influence of unconscious factors as motivators in human behavior. While Adler subscribed to the notion that underlying motivations play a part in directing personality, he introduced the notion of …
The information-processing theory is associated with the development of high-speed computers in the 1950s. Researchers—most notably Herbert Simon and his colleagues—demonstrated that computers could be used to simulate human intelligence. This development led to the realization that computer-oriented information-processing models could provide new insight into how the human mind rece…
The insanity defense allows a mentally ill person to avoid being imprisoned for a crime on the assumption that he or she was not capable of distinguishing right from wrong. Often, the sentence will substitute psychiatric treatment in place of jail time. The idea that some people with mental illness should not be held responsible for crimes they commit dates back to the Roman Empire, if not earlier…
Behavior is considered instinctive only if it occurs in the same form in all members of a species. Instincts must be unlearned and characteristic of a specific species. Animals provide the best examples of instinctive behavior. Birds naturally build nests without being taught and feed and protect their young in the exact same ways. Other animals, such as squirrels or dogs, behave in manners charac…
Our views of mental institutions are often colored by media's portrayal of them, such as in the movies One Flew Over the Cuckoo's Nest and Girl, Interrupted. With an emphasis on care and treatment, the best institutions offer emotionally disturbed people a better chance at life. They can learn new skills, improve behavioral and psychological problems, and develop healthier self-estee…
Instrumental behavior is a concept that grew out of the behavior therapy movement, originating in the 1950s with the work of H.J. Eysenck. Behavior therapy asserts that neuroses are not the symptoms of underlying disorders (as Sigmund Freud theorized), but are in fact disorders in and of themselves. Further, these disorders are learned responses to traumatic experiences in much the same way that a…
Several theories about intelligence emerged in the 20th century and with them debate about the nature of intelligence, whether it is hereditary, environmental or both. As methods developed to assess intelligence, theorizing occurred about the measurability of intelligence, its accuracy and this field known as psychometrics. As the 20th century drew to a close, publication of The Bell Curve by Rich…
Although intelligence quotient (IQ) tests are still widely used in the United States, there has been increasing doubt voiced about their ability to measure the mental capacities that determine success in life. IQ testing has also been criticized for being biased with regard to race and gender. In modern times, the first scientist to test mental ability was Alfred Binet, a French psychologist who d…
Holistic healthcare, the concept that the body is not just a collection of separate and distinct parts but rather an assemblage of interrelated components that form a unified whole, is at the root of interdisciplinary treatment. The holistic viewpoint is that mental health is related to and interdependent on physical well-being, and viceversa. An interdisciplinary treatment team has the ability to…
An interest inventory is a testing instrument designed for the purpose of measuring and evaluating the level of an individual's interest in, or preference for, a variety of activities; also known as interest test. Testing methods include direct observation of behavior, ability tests, and self-reporting inventories of interest in educational, social, recreational, and vocational activities. …
Individuals who are quiet, reserved, thoughtful, and self-reliant are often referred to as "introverts." They are likely to prefer solitary work and leisure activities. In comparison with extroverts, who draw most of their energy from social interaction and respond to external stimuli immediately and directly, introverts tend to mull things over before formulating a reaction, and the…
Jealousy is a combination of emotional reactions, including fear, anger, and anxiety. Studies have shown that men and women tend to feel jealous for different reasons; for instance, physical attractiveness in a perceived rival is more likely to incite jealousy in a woman than in a man. Everyone occasionally experiences normal jealousy; caring about anyone or anything means that one will become unc…
When we try to compare two different objects to see if they are the same or different on some dimension (e.g., weight), the difference between the two that is barely big enough to be noticed is called the just noticeable difference (JND). Just noticeable differences have been studied for many dimensions (e.g., brightness of lights, loudness of sounds, weight, line length, and others). The human se…
According to the Federal Bureau of Investigation (FBI) and the Centers for Disease Control (CDC), the arrest rate of American juveniles (persons 18 years of age or younger) committing violent crimes increased from 137 percent in 1965 to 430 percent in 1990. While teenagers are the population most likely to commit crimes, their delinquency is related to the overall incidence of crime in society: te…
Kinesthesis refers to sensory input that occurs within the body. Postural and movement information are communicated via sensory systems by tension and compression of muscles in the body. Even when the body remains stationary, the kinesthetic sense can monitor its position. Humans possess three specialized types of neurons responsive to touch and stretching that help keep track of body movement and…
Psychologists have been interested in the factors that are important in behavior change and control since psychology emerged as a discipline. One of the first principles associated with learning and behavior was the Law of Effect, which states that behaviors that lead to satisfying outcomes are likely to be repeated, whereas behaviors that lead to undesired outcomes are less likely to recur. This …
In any group of people, there are those who step forward to organize people and events to achieve a specific result. In organized activities, leaders can be designated and, in informal contexts, such as a party, they may emerge naturally. What makes certain people into leaders is open to debate. Luella Cole and Irma Nelson Hall have written that leadership "seems to consist of a cluster …
The left-brain hemisphere neurologically controls the right side of the body and is connected to the right-brain hemisphere by an extensive bundle of over a million nerve fibers called the corpus callosum. Scientific study of the brain hemispheres dates back to the 1800s. In the 1860s, French physician Paul Broca (1824-1880) observed speech dysfunction in patients with lesions on the left frontal …
The term libido, which Sigmund Freud used as early as 1894 and as late as the 1930s, underwent changes as he expanded, developed, and revised his theories of sexuality, personality development, and motivation. In Freud's early works, it is associated specifically with sexuality. Libido is central to the theory of psychosexual development outlined in Three Essays on the Theory of Sexuality (…
Theories of localization first gained scientific credence in the 1860s with Paul Broca's discovery that damage to a specific part of the brain—the left frontal lobe—was associated with speech impairment. Other discoveries followed: in 1874, Carl Wernicke identified the part of the brain responsible for receptive speech (the upper rear part of the left temporal lobe, known as W…
One of the highly developed abilities that humans and other animals possess is the ability to determine where a sensory input originates. The capacity to localize a sound, for example, depends on two general mechanisms. The first is relevant for low frequency (i.e., low pitch) sounds and involves the fact that sound coming from a given source arrives at our ears at slightly different times. The se…
If a person with an internal locus of control does badly on a test, she is likely to blame either her own lack of ability or preparation for the test. By comparison, a person with an external locus of control will tend to explain a low grade by saying that the test was too hard or that the teacher graded unfairly. The concept of locus of control was developed by psychologist Julian Rotter, who dev…
Regarded as a universal human trait, the ability to think logically, following the rules of logical inference, has traditionally been defined as a higher cognitive skill. The field of cognitive child psychology was dominated for more than half a century by the Swiss philosopher and psychologist Jean Piaget, whose studies are considered fundamental. Piaget identified four stages of cognitive develo…
Researchers in such fields as developmental psychology use longitudinal studies to study changes in individual or group behavior over an extended period of time by repeatedly monitoring the same subjects. In longitudinal research, results are recorded for the same group of subjects, referred to as a cohort, throughout the course of the study. An example of a longitudinal study might be an examinat…
There are many kinds of loss and each has its own kind of grief. People lose loved ones like spouses, partners, children, family members, and friends. Even pet losses can cause grief. Job or property loss can be painful. Mourning is the conventional cultural behavior for those experiencing a loss. Grief reactions are those personal reactions to a loss, independent of expected cultural standards. E…
Cannabis, in the form of marijuana, hashish (a dried resinous material that seeps from cannabis leaves and is more potent than marijuana), or other cannabinoids, is probably the most often used illegal substance in the world. In the United States, marijuana use became widespread among young people in the 1960s. By 1979, 68 percent of young adults between the ages of 18 and 25 had experimented with…
Mental images are created by the brain from memories, imagination, or a combination of both. In the 1990s, scientists were gaining knowledge of how the brain forms these visual pictures without input from the eyes. According to researchers at Harvard University, the brain may generate these mental pictures in the area of the brain responsible for vision. Stephen Kosslyn, a psychologist, used posit…
In Erik Erikson's influential scheme of human development, middle age is the period in which an individual is presented with the developmental task of choosing between ego stagnation (self-interest) and generativity, the capacity to care for others and make a positive contribution to society by being productive in work, parenting, or other activities. Carl Jung characterized the middle year…
Military psychology, when defined broadly, can include a vast array of activities in psychological research, assessment, and treatment. Military psychologists may be either soldiers or civilians. The field can encompass every aspect of the human mind that interests the military., but researchers focus on the psychology of military organization, military life, and the psychology of combat. Military…
The basic coding procedure common to most mnemonic strategies is to mentally associate, in some manner, items of new or unfamiliar information with various interconnected parts of a familiar, known whole. Mnemonic devices range from the very simple to the remarkably complex. An example of a very simple mnemonic device is the use of the acronymic word HOMES to remember the names of the Great Lakes …
The study of motivation is concerned with the influences that govern the initiation, direction, intensity, and persistence of behavior. Three categories of motives have been recognized by many researchers: primary or biological (hunger and the regulation of food intake); stimulus-seeking (internal needs for cognitive, physical, and emotional stimulation, or intrinsic and extrinsic rewards); and le…
Narcissism is the personality trait that features an exaggerated sense of the person's own importance and abilities. People with this trait believe themselves to be uniquely gifted and commonly engage in fantasies of fabulous success, power, or fame. Arrogant and egotistical, narcissistics are often snobs, defining themselves by their ability to associate with (or purchase the services of) …
A narcotic is a depressant that produces a stuporous state in the person who takes it. Narcotics, while often inducing a state of euphoria or feeling of extreme well being, are powerfully addictive. The body quickly builds a tolerance to narcotics, so that greater doses are required to achieve the same effect. Because of their addictive qualities, most countries have strict laws regarding the prod…
The nature-nurture controversy is an age-old dispute among behavioral psychologists, philosophers, theologians, and theorists of consciousness as to the source of the creation ofhuman personality: Does it develop primarily from biology (nature), or from the environments in which we are raised (nurture)? People have been pondering the role of nature and environmentsince the time of Hippocrates (c. …
Tales of near-death experiences (NDEs) are not unusual. Out-of-body experiences, the sensation of moving through a tunnel toward a light, the review of the events of one's life, and pleasurable glimpses of other worlds are relatively consistent features of people's "near death" reports. In fact, research suggests that almost one fifth of Americans report having almost d…
Negativism is a behavior characterized by the tendency to resist direction from others, and the refusal to comply with requests. Negativism appears and wanes at various stages of a person's development. Active negativism, that is, behavior characterized by doing the opposite of what is being asked, is commonly encountered with young children. For example, a parent may ask a toddler to come …
Nerves form the network of connections that receive signals, known as sensory input, from the environment and within the body and transmit the body's responses, or instructions for action, to the muscles, organs, and glands. The central nervous system, comprised of the brain and spinal cord, sends information throughout the body over the network of nerves known collectively as the periphera…
The nervous system is responsible for the perception of external and internal conditions and the body's response to them. It has two major divisions: the central and peripheral nervous systems. The central nervous system (CNS), consisting of the brain and the spinal cord, is that part of the nervous system that is encased in bone; the brain is located in the cranial cavity of the skull, and…
Neurons are the basic working unit of the nervous system, sending, receiving, and storing signals through a unique blend of electricity and chemistry. The human brain has more than 100 billion neurons. Neurons that receive information and transmit it to the spinal cord or brain are classified as afferent or sensory; those that carry information from the brain or spinal cord to the muscles or gland…
The word neurosis means "nerve disorder," and was first coined in the late eighteenth century by William Cullen, a Scottish physician. Cullen's concept of neurosis encompassed those nervous disorders and symptoms that do not have a clear organic cause. Sigmund Freud later used the term anxiety neurosis to describe mental illness or distress with extreme anxiety as a defining f…
Communication at the synapses between neurons relies on chemicals called neurotransmitters. Secreted from a part of one neuron (the axon) into the synaptic gap between two others, neurotransmitters diffuse across this space and combine with specific proteins on the surface of the receiving cell, triggering an electrochemical response in the target cell. Afterward, neurotransmitters are either dest…
Nightmares—frightening dreams—are experienced by most everyone at one time or another. Nightmares are thought to be caused by a central nervous system response, and are related to other parasomnias such as sleepwalking. In children, nightmares begin between the ages of 18 months and three years and increase in frequency and intensity around the ages of four and five years. Children t…
For statistical purposes, normal means whatever is average for a given group of people ("the norm"). Therefore, the term normal does include those group members who deviate significantly from the measures of central tendency (the mean, the median, or the mode) of a given distribution. The term normal is fundamentally statistical and quantitative. In testing and measuring, for example…
An example of the bell-shaped curve of a normal distribution. Psychological research involves measurement of behavior. This measurement results in numbers that differ from one another individually but that are predictable as a group. One of the common patterns of numbers involves most of the measurements being clustered together near the mean of the distribution, with fewer cases occurring …
Individuals who are 20 percent overweight are considered slightly obese. Those who are 40 percent above standard weight are moderately obese, while those 50 percent above it are morbidly obese. Persons who exceed desired weight levels by 100 pounds (45 kg) or more are hyperobese. Obesity is a serious health problem in the United States. Studies suggests that between 10 and 20 percent of Americans …
Obsessive-compulsive disorder (OCD) is classified as a mental illness, and is characterized by the recurrence of intrusive, anxiety-producing thoughts (obsessions). The person with obsessive-compulsive disorder repeatedly and consistently tries to suppress these thoughts through the performance of certain irrational, often ritualistic, behaviors (compulsions). Although there are marked similaritie…
The terms "overachiever" and "underachiever," most often applied to school and academia, both refer to gaps between academic performance and IQ test scores. Generally, these terms are not used by either educators or psychologists. However, clinical psychologist Marilyn Sorenson in her book, Breaking the Chain of Low Self-Esteem, maintains that people with low self-estee…
Pain is a complex phenomenon that scientists are still struggling to understand. Its purpose is to alert the body of damage or danger to its system, yet scientists do not fully understand the level and intensity of pain sometimes experienced by people. Long-lasting, severe pain does not serve the same purpose as acute pain, which triggers an immediate physical response. Pain that persists without …
To diagnose an individual with a paraphilia, the psychologist or other diagnostician must confirm recurrent, intense, sexually arousing feelings, fantasies, or behaviors over a period of at least six months. According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV), it is not uncommon for an individual to have more than one paraphilia. Bestiality is a term that describes sexu…
Pedophilia is a subcategory of a larger group of sexual disorders commonly classified as paraphilias. These are defined as recurrent, intense, aphrodisiac fantasies, sexual urges, or behaviors, over a period of at least six months, which involve non-human objects, the suffering or humiliation of oneself or one's partner, or children or other non-consenting partners. If these recurrent fanta…
Peer mediation is a form of conflict resolution based on integrative negotiation and mediation. Disputing parties converse with the goal of finding a mutually satisfying solution to their disagreement, and a neutral third party facilitates the resolution process. The salient feature of peer mediation as opposed to traditional discipline measures and other forms of conflict resolution is that, outs…
Psychologists have identified two general ways in which humans perceive their environment. One involves what is called "top-down" processing. In this mode, what is perceived depends on such factors as expectations and knowledge. That is, sensory events are interpreted based on a combination of what occurs in the external world and on existing thoughts, experience, and expectations. W…