Despite the rapid growth in our knowledge of the brain and nervous system in the past century, information in this field has still fallen far behind the needs of the rapidly growing science of psychology. Even today, the role of the brain and nervous system in the simplest sensory experiences or motor reactions is not completely understood, Our knowledge of what an organism can perceive, learn, remember, and do, is much greater than our understanding of how such proecesses occur. In recent years, however, psychological and physiological resarches have brought us some new discoveries and new concepts of the functioning of the brain and nervous system. Among these discoveries, the EEG (electroencephalograph) which has been utlized to study the relation between brain function and behavior is of particular importance.
In 1929, a German neuropsychiatrist, Hans Berger, demonstrated that the nervous system is not a mere standby system, active only when incoming sensory massages arouse it to activity, but that it is continuously active electrically (Hill and Parr, 1963). This pioneer work was largely ignored until similar investigations were carried out in Adrian’s laboratory at Cainbrige. Then, in 1934, Adrian and Metthews published their classic paper entitled “The Berger Rhythm; Potential Changes from the Occipital Lobes in Man” confirming to a large extent of Berger’s observations.
Adrian and Matthews described regular potential oscillations at approximately 10 cycles per second detected by electrodes applied to the scalp. They agreed with Berger’s conclusion that these waves were due to electrical activity of the cortex; they demonstrated, however, that these waves arose from the occipital lobes and not from the whole cortex as Berger had contended. Investigating the response of this activity (which became known. as alpha activity) to certain types of stimulation they concluded that the essential activity necessary for the disappearance of the rhythm is pattern vision, although certain other types of stimulation or activity such as unexpected touch stimuli, pressure on eyeballs, probem solving may cause a diminution. V
After Adrian and Matthews’s confirmation, investigators in Europe and America began to utilize their techniques in an attempt to solve the tangled. problem of brain function. The electroencephalographic experiments carried out so far have been concerned chiefly with the effect of light upon alpha activity. Investigators have studied the effect of variation in stimulus intensity and duration upon the alpha activity (Cruikshank, 1937; Jasper and Cruikshank, 1956), the effect of attention and external stimulation upon the alpha wave response to light (Jasper and Cruik.. shank, 1935; Thomas, 1962), the perseveration of the alpha blocking response to light (Jasper and Cruikshank, 1937; Travis and Knott, 1936, 1937), and have made electroencephalographic studies of conditioned learning (Jasper and Shagass, 1941; Knott and Henry, 1941; Travis and Egan, 1936). A review of these researches shows that few investigators have considered the phenomenon of orientation reflex (also entitled habituation) of the alpha wave response to a strong visual stimulation.
In this country, though it has been utilized recently for clinical purpose in several hospitals, electroencephalographic techniques has not yet been employed in psychological laboratory. The present series of experimental studies was undertaken to investigate the basic phenomena of various aspects of electroencephalogram in groups of normal human subjects in a rather simply equipped laboratory. Three related experiments were included in these stduies: (1) the effect of light stimulation upon occipital alpha rhythmic activity; (2) conditioned response formation of occipital alpha rhythm; and (3) orientation reflex of alpha rhythm to light stimulation
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Electroencephalographic Studies of Classical Conditioning in Man
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