Some determinants of inhibitory stimulus control

Interspersed reinforcement and extinction during discrimination learning generate a U-shaped gradient of inhibition about the stimulus correlated with extinction. The present work showed that extinction is not a necessary determinant of inhibitory stimulus control. In Exp. I, a reduction in the rate of reinforcement, through a shift from a multiple variable-interval 1-min variable-interval 1-min schedule to a multiple variable-interval 1-min variable-interval 5-min schedule, resulted in a post-discrimination line orientation gradient of inhibition about the stimulus correlated with the variable-interval 5-min schedule. In Exp. II, the rates of reinforcement, correlated with a pair of stimuli, were held constant during a shift from a multiple variable-interval 1-min variable-interval 1-min schedule to a multiple variable-interval 1-min differential-reinforcement-of-low-rate schedule. Inhibitory stimulus control about the stimulus correlated with the differential reinforcement of low rate was obtained. In both experiments, a reduction in the rate of responding during one stimulus and behavioral contrast during the other stimulus preceded the observation of inhibitory stimulus control.     

Stimulus control in the goldfish after massed extinction

Compared with the data of goldfish trained only with stimuli correlated with reinforcement, interspersed reinforcement-stimulus and extinction-stimulus trials resulted in sharper stimulus control and a marked reduction in the percentage of key-presses emitted in the presence of stimuli located near the extinction stimulus on the test dimension. If non-reinforced trials were not interspersed with reinforced trials, there was no sharpening of stimulus control and less reduction in key presses in the presence of stimuli near the extinction stimulus on the test dimension.