A NEUROPSYCHOLOGICAL APPROACH TO THINKING

The study of thinking presents a prominent and interesting problem in human behavior but it has not been investigated experimentally extensively, until recently. Prior to this decade relatively few important studies on the thinking process were reported, e.g., Duncker ( 5 ) , Luchins ( 24 ) , Maier ( 2 5-27 ) , and Wertheimer (37). The dearth of research in this area possibly may be attributed to the experimental psychologist's desire to be objective and to circumvent any processes which are covert. Whatever the reason may be for the retardation, it seems apparent that to understand human behavior it will be necessary to understand the process of thinking. However, more emphasis has been devoted recently to thinking, as indicated by an increase in the number of relevant books and articles, e.g., Bruner, Goodnow, and Austin (3), Galanter and Gerstenhaber ( 8 ) , Guetzkow (9 ) , Guilford ( 10 ) , Humphrey ( 17), and Johnson ( 18), to mention a few. Thinking has sometimes been defined narrowly, sometimes broadly. Those who define it narrowly separate it from such phenomena as learning, problem solving, and reasoning, whereas the broad definition would consider these as different aspects of the same problem. It seems appropriate to maintain a distinction between learning and thinking but to consider thinking, reasoning, and problem-solving behavior as involving the same set of operations. The distinction between learning and thinking is based on the difference between content and process. Learning always involves the "residue" or "trace" of previous experience whereas thinking is a process in which the "residues" are manipulated. However, this distinction is of academic interest only inasmuch as thinking and learning are so intimately intertwined that it is difficult to investigate one irrespective of the other. It is postulated that thinking is a process which is common to learning and so-called problem-solving and reasoning situations and is practiced by the organism through all waking states, even though sometimes on a very low habitual level. It even appears in dreams but at a very low level wherein the neurophysiological substratum which is responsible for integrated thinking and behavior is usually functioning well below the optimum level. Even though it seems certain that some modification of the brain is involved in behavior, there has been great reluctance on the part of most psychologists to incorporate neurological concepts in theory building. However, the stimulating neuropsychological theory propounded by Hebb ( 13 ) , research on the brain stem reticular activation system (23, 29), and further advances in the recording of electrical activity of brain tissue in the last decade have