Control of variation by reward probability.
Two bar-press experiments with rats tested the rule that reducing expectation of reward increases the variation from which reward selects. Experiment 1 used a discrete-trial random-interval schedule, with trials signaled by light or sound. One signal always ended with reward; the other signal ended with reward less often. The 2 signals were randomly mixed. Bar-press duration (how long the bar was held down) varied more during the signal with the lower probability of reward. Experiment 2 closely resembled Experiment 1 but used a random-ratio schedule rather than a random-interval schedule. Again, bar-press duration varied more during the signal with the lower probability of reward. The results support the rule--the first well-controlled comparisons to do so.
Gharib
Afshin
A
Department of Psychology, Dominican University of California, USA.
Gade
Christopher
C
Roberts
Seth
S
D000818:Animals; D003214:Conditioning, Classical; D007858:Learning; D011897:Random Allocation; D051381:Rats; D011916:Rats, Inbred F344; D012055:Reinforcement Schedule