Abstract
Background and Aims: Alcohol choice is governed by its subjective value, which can be experimentally modified. However, less is known about the moment-to-moment dynamics through which experimental manipulations of value influence observable choice behaviour. We tested whether an experimental manipulation intended to elevate alcohol value would alter computational parameters of value-based decision-making (VBDM) and alcohol choice, and whether these outcomes would mediate ad libitum alcohol consumption. Design: Pre-registered, randomised between-subjects experiment comparing two personalised experimental conditions: alcohol value (exposure to alcohol memories and multisensory alcohol cues) vs. control (exposure to non-alcohol memories and multisensory soft-drink cues), conducted over two separate sessions with baseline measures included as covariates. Setting: University laboratory in the United Kingdom (UK). Participants: 129 adults (63% male; mean age = 44 years; mean Alcohol Use Disorders Identification Test [AUDIT] score = 16) who regularly consume alcohol (mean Estimated Weekly Alcohol Consumption [EWAC] = 42 UK units/week), randomised to alcohol value (n = 65) or control (n = 64) conditions. Measurements: At baseline and post-exposure, participants completed self-reported measures of alcohol craving and a value-based decision-making (VBDM) task where they chose between pairs of previously rated alcohol-related and non-alcohol images. A drift-diffusion model was fitted to behavioural data to estimate evidence accumulation rates (value sensitivity) and response thresholds (response caution). Participants also completed a concurrent choice task (alcohol vs. non-alcohol) that measured percentage alcohol relative to non-alcohol reward (enlargement; index of relative alcohol value), and a taste test to measure alcohol consumption. Findings: Some indices of subjective craving were responsive to the experimental manipulation, but there were no significant between-group differences at post-manipulation (ps ≥ .17). Baseline-adjusted analyses showed that response thresholds for non-alcohol decisions were higher in the alcohol value condition compared to control (p = .03, d = 0.40); however, Bayesian analysis quantified only anecdotal evidence for this effect (BF10 = 1.84). Other VBDM parameters, percentage alcohol choice, and alcohol consumed were unaffected by the manipulation (ps ≥ .19, BF10s ≤ 0.40). Furthermore, no value indices (computational or percentage choice) mediated the effect of the experimental manipulation on alcohol consumed. Conclusions: A personalised experimental manipulation intended to elevate alcohol value had modest effects on self-reported craving, but did not alter computational parameters of VBDM, relative alcohol choice, or ad-libitum alcohol consumption.