The effect of periodicity of reinforcement on food accumulation

Abstract

Recent studies on food accumulation have shown that the rate of food-procuring responses increases by delaying the delivery of food (i.e., an increasing delay gradient). However, these studies have only delivered the food periodically, which could lead to the establishment of a behavior sequence between successive food deliveries. Therefore, the increasing delay gradient could be due to the establishment of different behavior sequences, composed of more food-procuring responses as the delay of reinforcement is lengthened. The present study investigated whether the increasing delay gradient occurs when the establishment of a behavior sequence is hindered by eliminating the periodicity of reinforcement from a situation of food accumulation. The periodicity of reinforcement was eliminated by using a variable delay in Experiment 1 and a variable inter-trial interval in Experiment 2. It was found that the increasing delay gradient occurred both with periodic and aperiodic reinforcement, which may imply that it does not depend on the establishment of a behavior sequence. In contrast, the increasing delay gradient was attributed to the temporal distribution of the food-procuring period within the inter-reinforcement time.