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An anchored or moored floating object, other than a lightship, intended as an aid to navigation. Buoys are the most numerous of all engineered aids to navigation, with some 20,000 in United States waters alone.A great variety of buoys are in use.…

The internal structures and processes that are involved in the acquisition and use of knowledge, including sensation, perception, attention, learning, memory, language, thinking, and reasoning. The mental processes and behaviors that constitute…

Technology used to augment human mental capacity. In contrast, technology is widely used to augment human physical capabilities. We can move faster using cars, we can lift heavier weights using cranes, and we can even fly through the air using…

The ability to discriminate light on the basis of wavelength composition. Color vision is found in humans, in other primates, and in certain species of birds, fishes, reptiles, crustaceans, and insects. These animals have visual receptors that…

A learned response performed by a human or other animal to a signal that was previously associated with an event of consequence for that human or animal. A conditioned reflex, also known as a conditioned response, is an acquired response in which…

The state of being aware of one's own existence, of one's mental states, and of the impressions made upon one's senses. Consciousness is central to human existence, yet it has proved difficult to define and characterize. Typically, consciousness…

A syndrome characterized by a generalized decline in cognition that is severe enough to cause functional impairment in daily activities. Dementia is a term used to describe a collection of symptoms of severe cognitive decline. Individuals suffering…

A heterogeneous affective disorder involving a depressed mood and/or a loss of interest in daily activities. The most common form of affective disorder is depression (also termed clinical depression) [Fig. 1]. A major depressive episode is defined…

The study of age-related changes in behavior from birth to death. Developmental psychology is an important branch of psychological analysis that investigates the development and changes of behavior over an individual's lifetime (Fig. 1). In general,…

Disorders characterized by abnormal eating behaviors, extreme weight-control behaviors, and dysfunctional beliefs about eating, weight, and body shape. Individuals suffering from eating disorders display abnormal eating behaviors and extreme…

A term commonly associated with both behaviors and states of mind (known as feelings) that are not under the control of reason and disturb the flow of consciously directed behavior. Emotions influence human thinking and behavior (Fig. 1), and they…