According to incentive salience theory, conditioned stimuli (CS+) associated with drug reinforcement acquire the capacity to elicit a conditioned attentional orienting response, which controls drug-seeking and drug-taking behaviour. We sought evidence for this proposal by measuring visual attentional orienting towards smoking pictures presented briefly in the periphery of the visual field, versus control pictures likewise presented, in smokers versus non-smokers. In each trial, smokers and non-smokers responded manually to a dot probe stimulus that appeared in a location previously occupied by either a smoking picture or a control picture. Attentional bias scores were calculated by subtracting the median reaction time (RT) in the former condition from the median RT in the latter condition. In two experiments, light-smokers (smokers of fewer than 20 cigarettes/day) produced a mean bias score that was significantly greater than that of heavy-smokers (smokers of 20 or more cigarettes/day) and non-smokers. In addition, when smokers from the two experiments were pooled, a significant quadratic relationship was found between cigarettes/day and the attentional bias for the smoking stimuli. These findings are consistent with incentive salience theories and dual-process theories of addiction.
aLaboratory of Experimental Psychology, School of Biological Sciences, University of Sussex, Falmer, Brighton
bDepartment of Psychology, University of Southampton, Highfield, Southampton
cDepartment of Experimental Psychology, University of Cambridge, Cambridge, UK
Sponsorship: This study was supported by a Medical Research Council (MRC) UK studentship to L.C.H. (G78/5065), an MRC Programme Grant (9537855) and a Wellcome Trust Research Grant (061162). B.P.B. and K.M. hold a Wellcome Trust Project Grant (057076).
Correspondence and requests for reprints to Dr Lee Hogarth, Laboratory of Experimental Psychology, School of Biological Sciences, University of Sussex, Falmer, Brighton, BN1 9QG, UK.
Received 4 October 2002 Accepted as revised 16 January 2003