Simulated die-rolling behaviours express illusions of control in regular gamblers

Illusions of control (IOC) – beliefs that actions or rituals can influence ostensibly probabilistic game outcomes – are typically studied using questionnaires, think-aloud methods, or inferred from shifts in betting patterns following manipulations of IOC. However, naturalistic studies of dice-based games (e.g., 'Craps') suggest that IOC can be manifest in players' motor actions: e.g., rolling dice hard to hit higher value outcomes. Here, in three experiments, we investigated the action-based expression of IOC while rolling a single computer-simulated die for monetary prizes in samples of community-recruited gamblers. We report (i) that action-based expressions of IOC are dependent on the congruence of game features (i.e., larger winning numbers linked to larger value prizes); (ii) that action-based expressions of IOC can reflect the joint betting of gambling co-actors (as a form of 'illusion of control by proxy') and (iii) that prior induction of motor-caution can weaken the links between the action-based expression of IOC and gamblers' self-report beliefs that game outcomes can be controlled. These data indicate that gambling-related IOC can be expressed in the action repertoires afforded by gambling games; can reflect their structural features and social contexts; and can be disrupted by the modulation of inhibitory control over motor behaviour.