AIMS: To estimate the aggregated effect sizes of reward-related decision-making deficits in internet gaming disorder (IGD) and to explore potential moderators on the variability of effect sizes across studies.

FINDINGS: The overall ES for decision-making deficits in IGD was small (g = -0.45, P < 0.01). The effects were comparable across risky, ambiguous and inter-temporal decision-making. Larger aggregate ESs were identified for pure-gain and mixed compared with pure-loss decision-making. Studies based on clinical and community samples showed similar effects. No significant difference between behavioral studies and those with extra measurements was observed. Decision-making alterations were not closely associated with IGD severity or self-reported impulsivity differences at the study level.

CONCLUSIONS: Internet gaming disorder appears to be consistently associated with reward-related decision-making deficits.