The effect of periodic reinforcement of bar-pressing in the presence of a discriminative stimulus.

Abstract

Two groups of rats were trained in a Skinner box to respond to a positive stimulus (light or darkness). The sequence for the experimental group was 2 min. of the negative stimulus and 1 min. of the positive stimulus, a reinforcement being given, however, only to the first response after the 1 min. of positive stimulus. The control group received 3 min. of the negative stimulus and was reinforced only when the positive stimulus was presented at the end of the 3 min. duration of the negative stimulus, the reinforced response terminating the positive stimulus. Rate of responding in the experimental group decreased for the 2 min. of negative stimulation and increased for the 3 min., giving an index of discrimination. Differences between the experimental and control group during the 3rd minute of the cycle were highly significant, the experimental group responding at the higher rate. (PsycINFO Database Record (c) 2006 APA, all rights reserved)