Background: Public health issues arising from excessive online gaming have garnered significant research interest. Existing studies indicate that, within the framework of the dual-systems theory, the equilibrium between the goal-directed and habitual control systems is disrupted in patients with Internet gaming disorder (IGD). Nevertheless, the understanding of how this imbalance manifests within the brain is limited. This study aims to investigate real-time brain activity in individuals with IGD during the activation of both the goal-directed and habitual systems using electrophysiological techniques. Methods: Twenty-four individuals with IGD and twenty-three matched recreational game users (RGUs) underwent electroencephalography (EEG) data collection while completing an outcome devaluation task. Differences between the two groups at the Fz, Cz, and Pz electrodes were compared using repeated measures ANOVA. Results: The behavioral results revealed that the RGU group exhibited higher accuracy than the IGD group during the learning phase (t(45) 5
3.08, p < 0.001, ç2 5 0.42). During the slip-of-action test, the IGD group made more action-slip responses for devalued outcomes than the RGU group (F(1,45) 5 6.22, p 5 0.016, ç2 5 0.12). The EEG experiment results indicated that, upon stimulus presentation during the slip-of-action test, the IGD group had significantly more negative average amplitudes at the Fz and Cz electrodes compared with the RGUs (
7.26 +- 6.28 ěV;
5.18 +- 5.49 ěV; F(1,40) 5 5.54, p 5 0.024, ç2 5 0.12; F(1,40) 5 4.92, p 5 0.032, ç2 5 0.11). Concurrently, the single-group analysis based on RGU revealed that habitual control appears to be associated with greater N2 and P3 amplitudes during the stimulus-locked phase. Conclusions: The goal-directed system of individuals with IGD is impaired, manifesting in the increased cognitive resources required to activate the goal-directed system when they need to disrupt habitual responses. This suggests that the imbalance due to IGD within the dual systems may originate from an impaired goal-directed system rather than the overactivation of the habitual system.  Kulcsszavak: internet gaming disorder, goal-directed, habitual, instrumental learning, electroencephalography