It is generally stated that the ability to reproduce previously learned material decreases with the passing of time and that the most rapid forgetting occurs immediately after learning. In most cases a negatively accelerated curve has been obtained when efficiency of retention is plotted against successive increments of time. Experimental studies, however, have yielded a significant number of deviating cases in which an initial rise in the curve of retention precedes a negatively accelerated section.Ebbinghaus (5), in 1885, made the first experimental attempt to plot the memorial history of an acquired material by taking retention tests at successive points in time and plotting the amount retained against the time unit. The curve of retention, as traced by Ebbinghaus, shows a descent which is initially rapid and which then becomes less and less rapid as time elapses. Ebbinghaus obtained his curve with the use of only one subject, with only one type of material, nonsense syllables, and with only the relearning method of measuring the amounts retained. The general trend of the curve, however, has received experimental substantiation by many investigators who have varied the conditions extensively. Radossawljewitsch ( 14), Finkenbinder (6), Luh (10), Bean (2), and Strong (17), varied the experimental conditions both in regard to the character of the material for which retention was tested and in the methods in terms of which retention was measured. They made use of nonsense syllables, poetry, consonants, abstract words and typewriting, and they measured retention by the methods of anticipation, recognition, 385

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The use of electric shock in learning experiments has been almost entirely confined to the procedure of administering the shocks only when certain particular acts, usually errors, occur during learning. Seldom has electric shock been used as the condition motivating the learning. In those studies involving a comparison of hunger and punishment, electric shocks have been used frequently as the form of punishment but were usually administered for errors only during the process of learning which was motivated by some other condition, e.g., hunger. Muenzinger and Fletcher (2, p. 87) have recently reported a study in which escape-from-shock was compared with hunger as the condition motivating the formation of a visual discrimination habit. Their results show "... greater effectiveness of shock alone over food alone." Further, that "the combination of the two methods of motivation, food and shock, produced the same learning efficiency as shock alone."The present study was conducted to determine the relative efficiency with which white rats master a difficult maze problem under the following conditions of motivation and practice: (a) hunger motivation; (b) hunger motivation with shocks administered in blind alleys as punishment for errors; (c) escape-fromshock motivation; (d) escape-from-shock and hunger motivation combined; (e) escape-from-shock motivation when the practice trials are massed instead of distributed as in the preceding conditions.