The relationship between addiction and reward bundling: An experiment comparing smokers and non-smokers

Aims: Previous studies indicate that addicts show reduced preference for more delayed versus more immediate rewards compared to non-addicts. This may reflect a lower propensity to view such decisions in terms of the larger sequences to which they typically belong (e.g. smoking is a frequently repeated act). Therefore, this study aims to test whether, in a sequence of decisions involving smaller, sooner (SS) versus larger, later (LL) rewards, suggesting or forcing people with a propensity to addiction to make the decision for the series as a whole would increase LL preference. It is hypothesized that people without a propensity to addiction should benefit less from being encouraged to think of reward sequences because they already tend to take that view. Conclusion: Thirty regular smokers (as exemplars of addicted individuals) and 30 non-smokers chose between small short-term and larger long-term monetary rewards over a sequence of four decisions spaced 2 weeks apart. Subjects were divided into three groups: one who made each decision independently with no suggestion that they be considered as a series ('free'), a group to whom it was suggested from the start that they consider each decision as part of the series ('suggested') and a group who were told that their very first choice in the series would be used for the remaining decisions ('forced'). All subjects were paid the amounts they had chosen. Setting: A laboratory room at the University of Cape Town (UCT). Participants: UCT undergraduate volunteers.Analyses The proportion of LL choices in each subgroup was evaluated by χ² tests and a probit model. Findings: Smokers increased their preference for LL rewards when 'bundling' of individual decisions into a sequence was either suggested or forced. This preference increased with repeated experience. Non-smokers showed neither pattern. Conclusions: The propensity of smokers to prefer small short-term rewards over larger delayed rewards may be mitigated, over a sequence of decisions of this kind, by encouraging or forcing them to think of the sequence as a whole. If replicated, this finding may form the basis of an intervention that could attenuate the choice patterns characteristic of addiction.