Drug expectancy is necessary for stimulus control of human attention, instrumental drug-seeking behaviour and subjective pleasure

Abstract

It has been suggested that drug-paired stimuli (S+) control addictive behaviour by eliciting an explicit mental representation or expectation of drug availability. The aim of the present study was to test this hypothesis by determining whether the behavioural control exerted by a tobacco-paired S+ in human smokers would depend upon the S+ eliciting an explicit expectation of tobacco. In each trial, human smokers (n=16) were presented with stimuli for which attention was measured with an eyetracker. Participants then reported their cigarette reward expectancy before performing, or not, an instrumental tobacco-seeking response that was rewarded with cigarette gains if the S+ had been presented or punished with cigarette losses if the S- had been presented. Following training, participants rated the pleasantness of stimuli. The S+ only brought about conditioned behaviour in an aware group (those who expected the cigarette reward outcome when presented with the S+). This aware group allocated attention to the S+, performed the instrumental tobacco-seeking response selectively in the presence of the S+ and rated the S+ as pleasant. No conditioned behaviour was seen in the unaware group (those who did not expect the cigarette reward outcome in the presence of the S+). Drug-paired stimuli control selective attention, instrumental drug-seeking behaviour and positive emotional state by eliciting an explicit expectation of drug availability.