Effect of Hours of Food Deprivation on Maze and Discrimination Learning in White Rats

Abstract

The purpose of this study was to investigate an effect of hunger motivation on performance in maze and discrimination learning situations.In Experiment I, 26 male white rats were divided into 3 groups of 2, 21, 45 hours of food deprivation, and trained a pattern of turnings (RLLR or LRRL) in 4 unit V-shaped maze (Fig. 1). Rats run six trials a day. Running time was the shortest in 45 h group and the tardest in 2 h group (Fig. 2). Maze learning was more facilitated in 21 h and 45 h group (Fig. 3). Number of errors was the least in 45 h group (Fig. 4). It was found in the analysis of errors that the course of learning progressed in the order as follows; first at the 4th choice point (nearest goal), next at the 2nd point, third at the 1st point, last at the 3rd point. And this course was shown earliest in 45 h group. (Fig. 5).In Experiment II, 21 male rats were divided into 3 groups similar to Exp. I, and trained to choose positive (white) one from among six doors (others black) in the hexagonal multiple choice discrimination apparatus (Fig. 6, Fig. 9). Rats were given six trials a day, and the position of positive door was changed every trial. Reaction time was shorter in 21 h and 45 h group, and longer in 2 h group (Fig. 7). During the first training day the percentage of no-error trials was the lowest in 2 h group, but its discrimination performance became much improved during successive training days (Fig. 8), and it reached earliest the learning criterion of six no-error trials. According to the analysis of errors, it appeared that 2 h group could choose, with less errors, the positive door presented back or side in relation to the direction of a rat when placed on floor (Fig. 9, Table 1).In brief, 45 h high motivation group was superior to others in maze learning, while 2 h low motivation group was superior to others in discrimination learning. These incongruent results seem to be derived from the difference in task situations. Presumably, high hunger motivation invigorated the dominant approach response exclusively. It is supposed that this affected profitably the process of extinguishing errors in maze performance, but interfered the process in discrimination performance.