Thinking. Modern psychologists do not agree on any one definition of the term, but all agree that thinking is a mental activity involving the use of symbols, such as words or images. Most other mental processes involve primarily direct responses to stimuli. In perceiving, for example, a person is aware of an object or event that is currently presented to his senses. In recalling what he has perceived, or in anticipating something, he uses such symbols as words or images to represent objects and events. Recalling and anticipating are, therefore, forms of thinking. Among other forms of thinking are dreaming, daydreaming, and problem solving. (It was once believed that all thinking is conscious, but psychologists now recognize as thinking some mental activities of which the person may not be consciously aware.)
Thought is a term sometimes used to describe the product of thinking, such as a recollection, opinion, or decision. It is also used as a synonym for thinking.
In the past, psychologists and philosophers believed that thinking was an exclusively human type of behavior. However, studies of animal behavior begun in the late 1800's show that certain animals other than humans are capable of some forms of thinking.
The development of automation, especially in regard to automatic control systems, has led some researchers to claim that the term thinking can be properly applied to the activity of such machines as computers. Others believe that the thought processes of humans and other thinking animals are fundamentally different from the “artificial thinking” of machines, whose action depends entirely upon programs worked out by human intelligence.
Thinking is primarily a function of the nervous system, and especially of the cerebral cortex, or gray matter of the brain. If the cerebral cortex is damaged, thinking ability is impaired.
There is also a relation between specific areas of the cortex and certain thought processes. For example, direct electrical stimulation of the cortex of the temporal (side) lobes of a person's brain brings about the recall of past experiences, although no way has been found to determine what material will be recalled. Injury to the same cortical area decreases or destroys memory. This localization is more pronounced in humans than in other animals. However, even in humans the entire cerebral cortex seems to be involved to some extent in any thought process.
