Failure to Establish Errorless Discrimination in Monkeys

Abstract

A fading procedure similar to that reported by Terrace (1963) was used with monkeys to determine whether errorless discrimination learning could be obtained without prior establishment of a baseline of stimulus control before applying the training procedure. Four methods of training were used which differed with respect to when and how the non-reinforced stimulus (S—) was introduced. No animal learned without errors although all did acquire the discrimination. Furthermore, the fading procedure which was expected to result in errorless learning was no more effective than the other methods. These results suggest that establishing stimulus control before using a fading procedure is a necessary condition for errorless discrimination.