In preceding papers Spiesman and one of us (E. G.)1 have reported the effect of hyperpnea, lack of oxygen and excess of carbon dioxide on several cortical and subcortical processes. Since it is known that a reduction in the oxygen tension in the inspired air leads to characteristic mental symptoms2 and since similar symptoms were observed in our experiments with carbon dioxide and hyperpnea,3 it seemed desirable to investigate the influence of these factors on certain measurable cortical processes which are associated with what are ordinarily termed psychic phenomena. A suitable method should allow one to study quantitatively the alteration of the fundamental process and furthermore should also reveal the qualitative changes which will occur under experimental conditions. We thought that the method of studying associations would fit our purpose best for the following reasons:
Association processes may be considered to be fundamental in practically any type