Selective Attention: Distinctive Brain Electrical Patterns

When asked which body organ controls mental functions, the man-in-the-street would today answer unhesitatingly: the brain. Again, when asked which organ is most readily modified by experience, Le., where might memories be stored, the ready answer would be: the brain. But this recognition of the brain's importance has not always been so. As recently as the year 1800, our feelings were credited to circulating humors and our thoughts were attributed to airy spirits. True enough, today we know that humors, biologically active chemicals, do in fact control basic feelings, moods, and states of mind, but these biologically active chemicals work locally upon receptive sensitivities of brain tissue. And true enough, early nineteenth-century man had entrapped' the spirits of mind in the ventricles of the brain-the spirits (defined by Webster as "physical energy") had only to be moved a few centimeters 1"0 brain substance and become identified as electrical. Yet the change in man's view of himself that has been wr.ought by these specifications is impressive, as attested to by the contents of this volume., rt is really only in the past half century that the spirits of the mind have n~ate'rialized as the brain's electrical activities. In the late 1920s, electrical brain recordings were made possible; in the late I930s, potential changc:s were evoked in brain systems by abrupt sensory stimulation and monitored by loudspeaker. The laie 1940s saw the applkation of osdlloscopc:s to these studies and the general availability of recording devices such as the electroencephalograph. In the 1950s