A number of studies have been made on experimental extinction as a function of various aspects of training, such as the number of reinforcements employed (5,6). However, no study has determined This relationship is presumably a functional behavioral law and is important as such. Moreover, at the present time it has the additional importance that it is required to mediate the determination of drive (D) as a function of the number of hours of food privation, i.e., D = /(A) .
METHODSubjects.-The Ss were 199 albino rats purchased from the Albino Farms, Redbank, New Jersey. At the beginning of training they 1 The present study is a portion of a thesis presented to the Faculty of the Graduate School of Yale University in partial fulfillment of the requirements for the degree of Doctor of Philosophy. The investigation also represents a part of the coordinated research program of the Institute of Human Relations. The writer is deeply indebted to Professors Clark L. Hull and Mark A. May for their generous 'advice arid criticism.