Development of an individualized procedure to induce reward-related impulsivity and evaluating its impact on drinking...

High impulsivity predisposes young adults to engage in hazardous alcohol use. Experimental research has shown that reward-related impulsivity is causally-related to heavier drinking. Correlational studies suggest that positive alcohol outcome expectancies mediate this effect, but causation has yet to be established. This study sought to clarify this relationship by: 1) developing a new, individualized procedure for inducing reward-related impulsivity with high generalizability; 2) experimentally manipulating positive alcohol expectancies to determine its mechanistic role in reward-related impulsivity risk for drinking. Eighty-seven young adults (67% female; M_age = 19.19, SD = 2.01) received either a covert manipulation to reduce positive alcohol expectancies (n = 43) or control (n = 44) after being administered the Individualized Reward-Seeking Induction Schedule (IRIS). The primary outcome was self-reported confidence in the ability to refuse alcohol in cued situations (drinking refusal self-efficacy). Results showed that IRIS increased reward-related impulsivity (p < .001, d_rm = 0.48) and reduced drinking refusal self-efficacy (p = .029, η²_P = .055, ω_p² = .043). Experimentally diminishing positive alcohol expectancies had a marginal effect on the reward-seeking induction when controlling for covariates (p = .057, η²_P = .044). Findings provide preliminary validation of IRIS as a new methodology for investigating the causal role of reward-related impulsivity in alcohol-related cognition and youth drinking.