Abstract
Aims: Delay reward discounting (DRD) measures the degree to which a person prefers smaller rewards soon or larger rewards later. People who smoke have been shown to have higher DRD. There are several ways of measuring DRD and the method used might influence the association between smoking and DRD. The key differences are the order that the items are presented in, the delays used, and the magnitude of the delayed amount.
Setting: An international online study running from September 2010 to June 2011.
Participants: N= 9454; 38% male, mean age = 23.1.
Design and Measurements: Users completed a multi-item DRD task. They were randomly presented the immediate rewards in an ascending, descending, or randomized order. The delays were between 1 week and 5 years. The delayed amounts were $1000 for all delays, and $100 for 1 month. Users also self-reported their smoking status.
Findings: A hyperbolic DRD function fit better than an exponential function. There were differences in the derived DRD function based on methodology used. Items presented in a randomized order, longer delays and smaller rewards showed steeper discounting. However, these did not interact with smoking status, as for all methodologies used daily smokers showed the steepest discounting, followed by non-daily smokers, then non-smokers.
Conclusions: Smokers discount more steeply irrespective of which method is used. However, the methods of assessing DRD influence the parameters, which means that parameters estimated with different methods cannot be compared.