Value-based decision-making and behavioural economic constructs that distinguish people with and without cannabis use history

Behavioural economic accounts posit distorted valuation processes underlie cannabis decisions; however, less is known about the moment-to-moment dynamics through which value influences observable choice behaviour. This study explored whether value-based decision-making and behavioural economic constructs distinguish people with and without cannabis use history. Sixty participants were recruited, half with history of cannabis use (cannabis group), and half without (control group). Participants completed a value-based decision-making task (choosing between previously rated cannabis-related and cannabis-unrelated images). A drift-diffusion model was fitted to behavioural data (choice and response time patterns) to estimate reinforcer-specific parameters, including evidence accumulation rates and response thresholds. Compared to controls, participants with cannabis use history had higher cannabis evidence accumulation rates (p = .023). Exploratory analyses revealed higher self-report cannabis demand across most indices (all except Pmax; ps ≤ .042). However, groups did not differ in cannabis-unrelated evidence accumulation rates or response thresholds for either decision type (ps ≥ .186). Notably, controls showed higher cannabis-unrelated than cannabis evidence accumulation rates (p = .001). People with a history of cannabis use ascribe a higher value to cannabis than those without such history, who in turn value cannabis less than alternative reinforcers—a pattern consistent with behavioural economic accounts of addiction.