Effects of reward magnitude on running speed following a deprivation upshift

The running speed of rats trained in a straight alley under low deprivation (99%–101% ad-lib body weight) and then shifted to high deprivation (79%–81% ad-lib body weight) was compared with that of unshifted high-deprivation controls. Running speeds of shifted rats increased more rapidly, relative to unshifted controls, when reward magnitude was large (22.045-g pellets) as compared with small (2.045-g pellets). Thus the effect of a deprivation shift on instrumental performance was found to vary as a function of reward magnitude. Deprivation downshifts also produce more rapid and larger performance changes when large reward is used than when small reward is used. It seems that responsivity to changes in level of deprivation is an increasing function of reward magnitude.