Three experiments (N = 60) were performed to assess the reliability and generality of Wright's finding of a learned drive based on hunger. While some support was found in Exp. I, this result could not be replicated successfully in two other sr~dies. In all three studies Ss' performance on the first consummatory test was contrary to the learned drive hypothesis.It is generally assumed that drives may be learned. While there is subscantial evidence to support this assumption in the case of drives based on pain, the bulk of the evidence is negative when appetitional needs are used (Cofer & Appley, 1964). Recently, Wright (1965) has reported that rats consumed greater amounts of liquid food in boxes where they were previously hungry than in boxes where they were previously satiated. Wright attributed his positive result to the use of a within-S type of design. The purpose of the present experiments was to assess the reliability and generality of Wright's finding. Because our studies employed dry rather than lquid food, [hey represent systematic replications (Sidman, 1960) rather than replications of the original investigation. METHOD SubjectsSs were 60 naive male Holtzman albino rats which were about 70 days of age at the start of each study. The 20 Ss in each study were assigned randomly and equally to the four treatments described below. ApparatusThe apparatus consisted of 20 boxes: 10 were 9 in. X 10 in. X 7.5 in., had hardware cloth attached to the wooden floors, and were painted white; 10 others were 6 in. X 15 in. X 7.5., had coarse sandpaper on the floors, and were black. ProcedureThe training and test procedures of Exps. I and I11 duplicated those of Wright. On Days 1 to 10 Ss were fed Purina pellets for 1 hr. daily in their living c a g e s . V n Days 11 to 34 S was placed in one empty goal box for 1 hr. D~u i n g a randomly-selected half of these days S was put into a high-drive box (e.g., black). S was then recurred to its home cage and 30 min. later fed for 1 hr.

Three experiments were done on delayed reinforcement and extinction using a within-group design in training. Entering one alley of a Grice discrimination apparatus led to immediate reward, while entering the other led to 40-sec. delays either on 50% of the trials (Exps. I and II) or on 100% of the trials (Exp. III). Half of Ss were extinguished in the non-delay alley, half in the delay alley. Half of Ss in each extinction group were extinguished without delay-box confinement, half with 40-sec. delay-box confinement on 50% of the trials (Exps. I and II) or 100% of the trials (Exp. III). In all three experiments Ss learned to discriminate between the delay and non-delay alleys. In Exp. I Ss ran significantly faster in extinction in the non-delay alley. The same trend was evident in Exps. II and III. Thus, the results were in the opposite direction to those which have been found in between-group studies. In Exp. III Ss with 100% delay-box confinement in extinction ran slower (.10 > p > .05) than Ss without confinement.

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Delay of reward as a secondary reinforcer 1