Compared to the young of other mammals, human infants are precocious in some ways—notably sensory development—and relatively helpless in others, such as physical strength and mobility. At birth, the average American infant weighs approximately 7.5 pounds (3.37 kg), although a baby born 28 weeks after conception may weigh as little as two pounds (0.9 kg). The average length of an Amer…
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…
Bärbel Inhelder is permanently linked to Jean Piaget as a remarkable instance of scientific collaboration. Inhelder started working with Piaget in the early 1930s; by the 1940s, as she recalled, Piaget told her he needed her "to counter his tendency toward becoming a totally abstract thinker." Piaget never lost sight of his epistemological goals, while Inhelder was much more o…
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. …
Persons with this disorder experience episodes of aggressive or violent behavior that result in assault of a person or animal or the destruction of property. These intense episodes occur spontaneously, not in response to provocation or threat, and individuals often express regret as soon as the episode ends. Usually he or she does not exhibit aggressive tendencies between episodes. This disorder c…
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…
William James was born in New York City to a wealthy, educated family that included the future novelist, Henry James, his younger brother. The family traveled extensively in Europe and America in James's youth. James studied chemistry, physiology, and medicine at Harvard College, but was unable to settle on a career, his indecision intensified by physical ailments and depression. In 1872, a…
Born in Paris on May 28, 1859, Pierre Janet spent his childhood and youth in that city. His bent for natural sciences led him to pursue studies in physiology at the Sorbonne at the same time that he was studying philosophy, for which he received a master's degree in 1882. Janet then left Paris for Le Havre and for seven years taught philosophy there in the lycée. Janet, however, want…
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…
Arthur R. Jensen (AP/Wide World Photos. Reproduced with permission.) Arthur Jensen was born in San Diego, California, and attended the University of California at Berkeley, San Diego State College, and Columbia University. He completed a clinical internship at the University of Maryland's Psychiatric Institute in 1956, after which he won a two-year postdoctoral research fellowship wi…
In collaboration with Dr. William Howell Masters, psychologist and sex therapist Virginia E. Johnson pioneered the study of human sexuality under laboratory conditions. She and Masters published the results of their study as a book entitled Human Sexual Response in 1966, causing an immediate sensation. As part of her work at the Reproductive Biology Research Foundation in St. Louis and later at th…
One of the goals of 19th-century American scientists was to determine why some people engaged in undesirable or antisocial behavior. A family from Ulster County in upstate New York provided a great deal of material for speculation about the origins of such behavior. The family was referred to as the Jukes family (the actual family name was kept anonymous). One of the initial researchers of the Juk…
Carl Jung was born in Switzerland, the son of a Swiss Reform pastor. Having decided to become a psychiatrist, he enrolled in medical school at the University of Basel, from which he received his degree in 1900. Serving as an assistant at the University of Zurich Psychiatric Clinic, Jung worked under psychiatrist Eugen Bleuler (1857-1939), a psychiatrist renowned for his work on schizophrenia. Jung…
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…
Jerome Kagan is one of the major developmental biologists of the twentieth century. He has been a pioneer in re-introducing physiology as a determinate of psychological characteristics. The Daniel and Amy Starch Professor of Psychology at Harvard University, Kagan has won numerous awards, including the Hofheimer Prize of the American Psychiatric Association (1963) and the G. Stanley Hall Award of …
The history of intelligence testing in the United States has been troublesome from the beginning. Although psychologists attempted to conduct legitimate research and apply psychological knowledge to the study of intelligence, some of the early work was quite unscientific and led to dubious results. One case involved the descendants of an anonymous man referred to as Martin Kallikak. This man produ…
George Alexander Kelly, originator of personal construct theory of personality, was born on farm near Perth Kansas. He was the only child of Elfleda Merriam Kelly and Theodore Vincent Kelly. Kelly's father trained for the Presbyterian ministry but gave that up and moved to the farm soon after wedding Kelly's mother. When Kelly was four, his family moved to Eastern Colorado to make a …
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…
Alfred Charles Kinsey was a well-known entomologist, specializing in the study of gall wasps, when his increasing interest in human sexuality led him in a entirely new scientific direction. Appalled by the lack of reliable scientific information on human sexual practices and problems, Kinsey began conducting extensive interviews, first with his students and then with larger populations. Kinsey�…
Persons with this disorder, popularly referred to as kleptomaniacs, experience a recurring urge to steal that they are unable to resist. They do not steal for the value of the item, for its use, or because they cannot afford the purchase. The individual knows that it is wrong to steal. Stolen items are often thrown or given away, secretly returned to the store from which they were taken, or hidden…
Working with Max Wertheimer and Wolfgang Köhler, Kurt Koffka helped establish the theories of Gestalt psychology. It was Koffka who promoted this new psychology in Europe and introduced it to the United States. He was responsible for systematizing Gestalt psychology into a coherent body of theories. He extended Gestalt theories to developmental psychology, and his ideas about perception, in…