S. Glautier et al., Motivation for alcohol assessed by multiple variable interval schedule behaviour: effects of reward size and alcohol cues, BEHAV PHARM, 12(2), 2001, pp. 81-89
Altered motivation for drugs of abuse is a central feature of most definiti
ons of drug dependence and the impact of drug-related cues on motivation is
of current interest. However, since most studies of cue-reactivity have no
t used behavioural measures of motivation, their results are often difficul
t to interpret in motivational terms. In the current paper we describe two
experiments in which a behavioural technique, based on multiple variable in
terval (VI) schedules of reinforcement, was used to study motivation for al
cohol in human subjects. In both experiments, subjects attended for several
sessions and, during each session, were exposed to a 6-ply VI schedule (va
lues ranged from 1 to 720 s), during which they earned points that were lat
er exchanged for a preferred beer or lager, In Experiment 1 the procedure w
as validated by showing that changes in the magnitude of reinforcement alte
red behaviour appropriately. In Experiment 2 we found evidence that the pre
sence of an alcohol-related cue increased the value of alcohol rewards. The
results are discussed with reference to a model for the behavioural effect
s of drug-related cues in triggering relapse and a number of problems we fo
und in using the multiple variable interval schedule procedure. (C) 2001 Li
ppincott Williams & Wilkins.