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…
Night terrors, known medically as pavor nocturnus, are episodes that apparently occur during the non-dreaming stages of sleep in some children. Episodes of night terrors are most common in the preschool and early school years. Night terrors usually occur within an hour or two after the child has fallen asleep, and generally do not recur with any frequency or regularity. Many children experience on…
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 …
In testing, norms are figures describing the frequency with which particular scores appear. They provide information about whether a score is above or below average and about what percentage of the persons tested received that score. Norms may apply to tests of mental ability or achievement, such as IQ tests or SATs. They are also used in personality assessment to measure variables such as anxiety…
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…
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…
Occupational therapists help persons with both physical and emotional problems as well as learning difficulties. Although occupational therapy was initially associated with reintegrating veterans of First and Second World Wars into the work force, the term "occupation" used in the context of this profession actually refers to any activity with which persons occupy their time. Occupat…
Sigmund Freud first suggested the existence of what he would later call the Oedipus complex in The Interpretation of Dreams (1900). In this work, he describes a subconscious feelings in children of intense competition and even hatred toward the parent of the same sex, and feelings of romantic love toward the parent of the opposite sex. He felt that if these conflicting feelings were not successful…
Operant conditioning is an elaboration of classical conditioning. Operant conditioning holds that human learning is more complex than the model developed by Ivan Pavlov (1849-1936) and involves human intelligence and will operating (thus its name) on its environment rather than being a slave to stimuli. The Pavlovian model of classical conditioning was revolutionary in its time but eventually came…
Depending on the population, 2-6% of children have oppositional-defiant disorder. Oppositional-defiant disorder is similar to conduct disorder, without the more severe behavior components of aggression, property destruction, deceit, and theft. Oppositional-defiant children often go on to develop conduct disorder. Many children, especially during transitional periods such as preschool and adolescen…
In general, any disorder that is caused by a known pathological condition of an organic structure may be categorized as an organic disorder, or more specifically, as an organic mental disorder, or a psychological disorder. An example is delirium, a disorder that is caused by a known physical dysfunction of the brain. Most psychologists and psychiatrists now believe that virtually all serious, or p…
Arthur Otis was born in Denver, Colorado, and educated at Stanford University. He served on the faculty of Stanford University, and held various consulting and research positions at several U.S. government agencies. He was also an editor of tests in mathematics for an educational publishing company. Otis introduced and developed the Otis Group Intelligence Scale, which is considered to be the earl…
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 …
Paired-associate (PA) learning was invented by Mary Whiton Calkins in 1894 and involves the pairing of two items (usually words)—a stimulus and a response. For example, words such as calendar (stimulus) and shoe (response) may be paired, and when the learner is prompted with the stimulus, he responds with the appropriate word (shoe). The study of PA learning has been important for a number …
Feelings of fear and panic are common to all species, and humans are certainly no exception. Psychologically speaking, however, panic can be an obtrusive, life-altering phenomena for many people who suffer panic attacks. Such attacks occur commonly in people suffering from various phobias. People suffering from agoraphobia, for instance, can expect to suffer panic attacks when out in public. While…
Paranoia is an ever-present feeling of suspicion that others cannot be trusted. Such feelings are not based on fact or reality; insecurity and low self-esteem often exaggerate these emotions. Typically, paranoia is not seen in children, but in most cases it begins to develop in late adolescence and early adulthood. Most people experience feelings of paranoia, usually in response to a threatening s…
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…
The study of paranormal activities and phenomena has been riddled with controversy since its conception. It is claimed that some people, utilizing senses beyond the ordinary, exhibit powers that cannot be explained by traditional science. Skeptics of the paranormal point to the fact that in over a century since the first serious studies of the paranormal began, usually dated to the opening of the …
Of the many different relationships we form over the course of the life span, the relationship between parent and child is among the most important. Not surprisingly, students of child development have devoted considerable attention to the parent-child relationship, in order to understand how it develops and functions over the lifespan. Among the many questions researchers examine are those concer…
Parkinson's disease is a degenerative disorder of the central nervous system named for James Parkinson (1755-1824), the physician who first described it in 1817. This disorder is also called paralysis agitans, shaking palsy, or parkinsonism. Typically, the symptoms of Parkinson's disease begin to appear in late middle life, and the course of the disease is slowly progressive over 20 …
Formerly listed among the personality disorders in the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders, the passive-aggressive personality type has been described by a number of psychologists and psychiatrists, including Karen Horney, Karl Menninger, and Wilhelm Reich (1897-1957). Its main distinguishing feature is indirect resistance to the demands …
Ivan Pavlov was born into an impoverished family in the rural village of Ryazan, Russia. He won a government scholarship to the University of St. Petersburg and studied medicine at the Imperial Medical Academy, receiving his degree in 1883. In 1890, Pavlov was appointed to a professorship at the St. Petersburg Military Academy and a few years later joined the faculty of the University of St. Peter…
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 acceptance is measured by the quality rather than the quantity of a child or adolescent's relationships. While the number of friends varies among children and over time as a child develops, peer acceptance is often established as early as preschool. Factors such as physical attractiveness, cultural traits, and disabilities affect the level of peer acceptance, with a child's degr…
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…
Peers are the individuals with whom a child or adolescent identifies, who are usually but not always of the same age-group. Peer pressure occurs when the individual experiences implicit or explicit persuasion, sometimes amounting to coercion, to adopt similar values, beliefs, and goals, or to participate in the same activities as those in the peer group. Although it is usually conceived of as prim…
Wilder G. Penfield and his wife. (The Library of Congress. Reproduced with permission.) Wilder Graves Penfield was born in Spokane, Washington, on January 26, 1891. He was one of three children born to Charles Samuel and Jean (Jefferson) Penfield. His father was a physician and died when Penfield was very young. To support herself and her family, Penfield's mother became a writer and…
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…