INTERFERENCE OF CONTROL BY STIMULUS POSITION IN ARBITRARY CONDITIONAL DISCRIMINATION TRAINING IN CAPUCHIN MONKEY (Sapajus sp.)

Abstract

The interference of the control by stimulus locations in conditional discrimination training has already been documented in the literature on stimulus control with animals. Subsequent studies suggested (1) variation of the position in which sample stimuli are presented and (2) increasing variation of comparison stimulus positions. The present study documents the interference of the control by stimulus position even in such condition of great variation of stimulus locations. Arbitrary zero-delay matching-to-sample was carried out with a capuchin monkey (Sapajus sp.). The position of sample and comparison stimuli, presented on the computer screen varied every trial among nine positions in a 3x3. During training, we observed systematic errors in trials in which correct comparison (S+) was located at Positions 8 and 9. Manipulations in the positions in which the stimuli were presented confirmed the interference of control by the position. It is possible that such kind of interference causes part of the difficulties in studies with the purpose of demonstrating generalized identity matching and equivalence class formation in non-human subjects. Keywords: stimulus control relations, arbitrary conditional discriminations, Sapajus sp.