A systematic review and meta-analysis of test-retest reliability and stability of delay and probability discounting.

In this meta-analysis, we describe a benchmark value of delay and probability discounting reliability and stability that might be used to (a) evaluate the meaningfulness of clinically achieved changes in discounting and (b) support the role of discounting as a valid and enduring measure of intertemporal choice. We examined test-retest reliability, stability effect sizes (dz; Cohen, 1992), and relevant moderators across 30 publications comprising 39 independent samples and 262 measures of discounting, identified via a systematic review of PsychInfo, PubMed, and Google Scholar databases. We calculated omnibus effect-size estimates and evaluated the role of proposed moderators using a robust variance estimation meta-regression method. The meta-regression output reflected modest test-retest reliability, r = .670, p < .001, 95% CI [.618, .716]. Discounting was most reliable when measured in the context of temporal constraints, in adult respondents, when using money as a medium, and when reassessed within 1 month. Testing also suggested acceptable stability via nonsignificant and small changes in effect magnitude over time, dz = 0.048, p = .31, 95% CI [-0.051, 0.146]. Clinicians and researchers seeking to measure discounting can consider the contexts when reliability is maximized for specific cases.

Effect of nicotine expectancy and nicotine dose reduction on cigarette demand, withdrawal alleviation, and puff topography.

BACKGROUND: Current FDA plans include proposed nicotine reduction mandates by the end of 2023. Most research on reduced nicotine cigarettes has been dose-blinded, while a mandate would be known to the public. Few laboratory studies have examined specifically how low nicotine content labeling impacts behavioral response. The purpose of this within-subject, balanced-placebo, human laboratory study was to evaluate the main and interactive effects of nicotine dose expectancy and dose reduction on cigarette reinforcement, withdrawal alleviation, and puff topography. METHODS: Participants who smoke daily (N=21; 9 female) completed one practice and four experimental sessions in which expectancy (labeled "average" versus "very low" nicotine) and nicotine dose (0.80mg versus 0.03mg yield) were manipulated. Participants in acute withdrawal sampled experimental cigarettes followed by withdrawal alleviation and puff topography measures. Cigarette demand was measured using an incentivized purchase task. Analyses evaluated main and interactive effects of expectancy and nicotine dose. RESULTS: Nicotine dose manipulation produced expected physiological effects (e.g., heart rate increases) and both reduced nicotine dose and expectation manipulations reduced perceived nicotine content. Expectation of reduced nicotine alone or in combination with reduced nicotine dose did not alter demand, withdrawal alleviation, or topography. Effective withdrawal alleviation was observed in all conditions. CONCLUSIONS: These data inform nicotine regulation policy by suggesting limited compensatory harms caused by reduced nicotine expectations. The minimal acute effects of reduced nicotine expectancy or exposure on demand suggests that reduced nicotine standards are likely to generate their greatest public health benefit through the slowing of newly initiating cigarette smoking.