Simple discrimination and matching-to-sample with objects in Infant and Adult Capuchin Monkeys. Discriminations with objects in Infant and Adult Capuchin Monkeys.

Abstract

This study sought to confirm the acquisition of repeated shifts of simple discrimination (RSSD) and identity matching-to-sample (IDMTS) using three-dimensional stimuli in adult capuchin monkeys (Sapajus, spp.). We also investigated the possibility that this acquisition can occur in infant capuchins. Two infants (M26 and M28) and two adults (M27 and M18) were given RSSD training, interspersing trials in which only one stimulus was presented (S+) with trials in which two or more stimuli were presented simultaneously. The reinforcement rate was then reduced in single stimulus trails so the procedure became similar to an IDMTS procedure. IDMTS training began with two samples and two comparisons, increasing to four samples and four comparisons. Subjects M26, M28, M27, and M18 completed the RSSD training in 80, 94, 103, and 22 sessions, respectively. In the IDMTS task, M26, M27, M28, and M18 needed 100, 36, 78, and 26 sessions to reach the criterion, respectively. The performance of the four subjects was compared to studies that used two-dimensional stimuli with regard to experimental history and the RSSD procedure used in this study.