Analysis of Stimulus Control that results from Manipulation of the Number of Choices in Discriminative Training with Capuchin Monkeys (Sapajus Sp.)

Abstract

Previous studies evaluated the effect of presenting multiple copies of an S- on simple simultaneous discrimination S+/S- train­ing. The present study evaluated whether some control by the nominal features of the stimuli develops in this kind of procedure, in addition to control by the singularity of the S+ (Experiment I). The present study also qualitatively evaluated stimulus control relations produced in this kind of procedure (Experiment II). In Experiment I, capuchin monkeys (Sapajus sp.) underwent discriminative training with three different trial types (two, four, and nine choices). A stimulus control test evaluated whether performance could be maintained when the discriminations learned in the three different trial types where presented in a two-choice procedure. The results showed clear control by the nominal features of the stimuli. In Experiment II, a mask procedure was used to identify the established stimulus control relations (select and/or reject control). The results showed solid reject control for both subjects, with select control also present for one of the subjects. The present study contributes to the research area by presenting a more detailed analysis of stimulus control that is ap­plicable to several studies on the manipulation of the number of choices in discriminative training.