Interaction between the variety of negative stimuli and the type of go/no-go procedure

Abstract Two experiments were carried out in order to compare the speed of acquisition of visual simple discriminations by pigeons depending on whether the negative stimuli could vary trial by trial (varied condition) or it was always the same stimulus (constant condition). In the first experiment, the subjects were randomly assigned to the conditions and then exposed to a go/no-go procedure in which “no-go” trials were also reinforced. Subsequently, the subjects changed from one condition to the other and were exposed to a new discrimination. In the second experiment, two discriminations were arranged in the same way as in the previous experiment, but, this time, “no-go” trials were not reinforced. In Experiment 1, the acquisition was slower in the varied condition. In Experiment 2, this effect was only observed when the subjects were exposed to the varied condition in the second discrimination. These results suggest, on one hand, that the variety of negative stimuli is an important variable to be considered. And, on the other hand, that the resulting effect on acquisition might be strongly sensitive to the kind of procedure that is used.