Negative Discriminative Stimulus as Punishing Consequence: A new approach to behavioural change

Abstract

The study and use of punishment in behavioural treatments has been restrained by ethical concerns. However, there remains a need to decrease harmful behaviour unable to be decreased by alternative methods. This thesis comprises four studies that collectively investigate a new approach to punishment. The first study investigated whether a negative discriminative stimulus will function as a punishing consequence. Pigeons were trained on a multiple schedule to discriminate between a positive discriminative stimulus (S+) signalling the presence of food in one component, and a negative discriminative stimulus (S-), signalling the absence of food in an alternate component. Once learned, every five responses on average to S+ produced S-for a duration of 1.5 s. In addition, responses to S+ produced food. There was a decrease in S+ response rate when responses produced S-, compared to when they did not. In addition, when responses to one of two concurrently available S+ alternatives produced S-, the proportion of choice to that alternative decreased compared with when responses to either alternative did not produce S-. Therefore, the contingent S-stimulus punished response rate and shifted choice. The second study investigated whether a contingent S-stimulus would punish responding for money in humans. There was no reliable effect of the contingent S-stimulus on response rate. The third and fourth studies investigated the ability of a negative discriminative stimulus to shift suboptimal choice processes. The third study replicated and extended a study by Vaughan (1981).Then, using Vaughan’s procedure, the fourth study investigated whether a negative discriminative stimulus would shift suboptimal choice in pigeons. Interruption of the suboptimal choice process was observed in five of six pigeons, but was not consistent across repeated cycles. Together these findings provide a foundation for continued investigation of the use of a negative discriminative stimulus as a punishing consequence. If a contingent S-stimulus is found to function reliably as a punisher, this approach has the potential to assist in the development of safe interventions to reduce or eliminate harmful behaviour in humans.