attention deficit hyperactivity disorder (ADHD), formerly called hyperkinesis or minimal brain dysfunction, a chronic, neurologically based syndrome characterized by any or all of three types of behavior: hyperactivity, distractibility, and impulsivity. Hyperactivity refers to feelings of restlessness, fidgeting, or inappropriate activity (running, wandering) when one is expected to be quiet; distractibility to heightened distraction by irrelevant sights and sounds or carelessness and inability to carry simple tasks to completion; and impulsivity to socially inappropriate speech (e.g., blurting out something without thinking) or striking out. Unlike similar behaviors caused by emotional problems or anxiety, ADHD does not fluctuate with emotional states. While the three typical behaviors occur in nearly everyone from time to time, in those with ADHD they are excessive, long-term, and pervasive and create difficulties in school, at home, or at work. ADHD is usually diagnosed before age seven. It is often accompanied by a learning disability.

The cause of ADHD is unknown, although there appears to be a genetic component in some cases. Intake of sugars, preservatives, and artificial flavorings is no longer considered to be a factor. It has been shown that people with ADHD have less activity in areas of the brain that control attention. Treatment usually includes behavioral therapy and emotional counseling combined with medications such as methylphenidate hydrochloride (Ritalin) or dextroamphetamine (Dexedrine) that correct neurochemical imbalances in the brain, but a long-term study has questioned the effectiveness of such medications. Symptoms may decrease after adolescence, although they often persist into adulthood.

formerly hyperactivity

Behavioral syndrome in children, whose major symptoms are inattention and distractibility, restlessness, inability to sit still, and difficulty concentrating on one thing for any period of time. It occurs in about 5percnt of all schoolchildren, and it is three times more common in boys than in girls. It can adversely affect learning, though many children with ADD can learn to control their behaviour sufficiently to perform satisfactorily in school. It appears to be caused by a combination of genetic and environmental factors. Certain aspects of the syndrome may persist into adulthood. Treatment usually entails counseling and close parental supervision, and it may also include prescription medication.

Learn more about attention deficit (hyperactivity) disorder (ADD or ADHD) with a free trial on Britannica.com.

In psychology, the act or state of applying the mind to an object of sense or thought. Wilhelm Wundt was perhaps the first psychologist to study attention, distinguishing between broad and restricted fields of awareness. He was followed by William James, who emphasized active selection of stimuli, and Ivan Pavlov, who noted the role attention plays in activating conditioned reflexes. John B. Watson sought to define attention not as an “inner” process but rather as a behavioral response to specific stimuli. Psychologists today consider attention against a background of “orienting reflexes” or “preattentive processes,” whose physical correlates include changes in the voltage potential of the cerebral cortex and in the electrical activity of the skin, increased cerebral blood flow, pupil dilation, and muscular tightening. Seealso attention deficit disorder.

Learn more about attention with a free trial on Britannica.com.