FACTORS INFLUENCING INHIBITORY STIMULUS CONTROL: DISCRIMINATION TRAINING AND PRIOR NON‐DIFFERENTIAL REINFORCEMENT1

Abstract
In Exp. I, shallow U‐shaped gradients of inhibition in the line‐orientation dimension were obtained from birds that had a vertical (0°) line on a green surround correlated with extinction and a blank green surround correlated with reinforcement. Birds that had massed extinction in the presence of the 0° line showed flat gradients. Thus, discrimination training, but not massed extinction, appears to generate inhibitory control. In Exp. II, as in studies of control by a stimulus correlated with punishment, non‐differential training across the line‐orientation dimension preceded further sessions. Steep inverted gradients about the 0° line were obtained after discrimination training with the 0° line correlated with extinction. Gradients obtained after massed extinction tended to be flat. Again, discrimination training was critical in obtaining negative gradients of stimulus control.