Document Type



Recent research has demonstrated that food-pellet
reinforcement upcoming in the second half of an experimental
session can increase operant response rates for low-concentration
liquid-sucrose reinforcers in the first half. The present study
investigated whether an upcoming reinforcer other than food
pellets could produce a similar increase (Experiment 1) and
whether a decrease in responding would be observed by
worsening the upcoming conditions of reinforcement (Experiment
2). Experiment 1 demonstrated that rats' rates of lever pressing for
1 or 5% liquid-sucrose reinforcers delivered by a random-interval
60-s schedule during the first half of a 50-min session were
similarly increased by the delivery of food or sucrose pellets in the
second half. Experiment 2 demonstrated that rates of lever
pressing for 5% liquid-sucrose reinforcers in the first half of the
session were increased and decreased by upcoming food-pellet
and 1 % liquid-sucrose reinforcement, respectively. The results
from both experiments represent induction (i.e., a direct
relationship between rate of responding and the upcoming
conditions of reinforcement). They suggest that the induction may
be both general (i.e., not limited to specific upcoming reinforcers)
and symmetrical (i.e., manifesting in either an increase or a
decrease in responding), the latter of which provides a potential
link to the study of behavioral contrast.