Effects of Deprivation and Testing Procedures on Preference for Stimuli Correlated with Food Reinforcement Under Higher Deprivation Conditions in Mice

A number of recent studies have found that organisms appear to prefer stimuli correlated with food reinforcement under higher food deprivation levels relative to stimuli correlated with food under lower deprivation levels. This has led some researchers to assume a general relation between food deprivation level and preference regardless of procedural details. The purpose of the present study was to evaluate the generality of the relation between food deprivation magnitude and preference by using mice as subjects and employing three different deprivation methods and three different preference test procedures. Experiment 1 employed an hours-deprived deprivation method. A pre-feeding deprivation method was assessed in Experiment 2. Experiment 3 imposed deprivation through food rationing. In each experiment, three groups of mice were exposed to three different preference test procedures. Robust preference for high deprivation stimuli was not observed in any of the experiments, but the greatest degree of preference was observed under the hours-deprived and food rationing deprivation methods with discrete-trial preference tests. The results suggest that the degree of discriminability between the stimuli correlated with reinforcement as well as between high and low deprivation conditions affects the extent to which preference for high deprivation stimuli is exhibited. This means that the relationship between motivation and preference depends in part upon the features of the procedure by which this relation is studied

Data

Raw data on responses/response rates for all subject

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

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