Relative Strength of Conditioned Reinforcers as a Function of Deprivation at the Time of Reinforcement

Abstract

Several studies have indicated that stimuli correlated with food function as relatively more effective conditioned reinforcers when the relevant motivating operation (food deprivation) is imposed. However, results from previous research have been inconclusive with regards to the relative efficacy of conditioned reinforcers as a function of motivating operations at the time of the stimulus-reinforcer correlation. The present study examined preferences for conditioned reinforcers as a function of the level of deprivation at the time of the stimulus-reinforcer correlation in mice. Under 24 hours of food deprivation, food delivery was correlated with a tone (high deprivation stimulus). Under 12 hours of food deprivation, food delivery was correlated with a different tone (low deprivation stimulus). A series of conditioned reinforcement tests were then performed to determine subjects' preference for either the high or low deprivation stimulus when under 18, 12, and 24 hours of deprivation. Subjects exhibited a strong preference for the high deprivation stimulus in the first conditioned reinforcement test under 18 hours of deprivation, but subsequent tests showed shifts in preference. We suggest that extinction effects may have been responsible for these results and recommend that future research on this phenomenon utilize procedures that eliminate or minimize those effects.