Principles of Reinforcement: The Effect of Deprivation Level, Reinforcer Quality, and Response Requirement on Ratio Schedule Performance

Predictions of Killeens (1994) mathematical principles of reinforcement (MPR) were tested with domestic hens as subjects in a series of experiments that manipulated deprivation level, reinforcer quality, and response requirement. In Experiment 1 hens experienced 3 levels of food deprivation, and were run at either, 100%, 90% or 80% of a free-feeding body weight and key pecks were reinforced according to an ascending series of random ratios. In Experiment 2, hens either pecked a key or pushed a "door", each at two different force levels, and responses were reinforced according to an ascending series of fixed ratios. In Experiment 3, key pecks will be reinforced with either wheat or corn according to an ascending series of random ratios. Data collection is ongoing. Thus far, response rates were typically higher when the animals were the more food deprived and when the response requirement was modest, and were generally fastest at smaller ratios and slowest at larger ratios. On random ratios as the ratio requirement increased response rate increased to a peak and then decreased with further increases in the ratio requirement. MPR described the hens' performance adequately, however, there were deviations from predictions of the model, and these will be discussed.