OPRM1 and psychiatric disorder: Although we were not able to detect a similar reduction of premature responses in the present study, as the baseline was too low, the two studies together concur to suggest that MOR activity normally favors both impulsivity15 and compulsive-like behavior (this study), a notion that is particularly critical for psychiatric disorders including substance use disorders33–36, behavioral addictions37,38, eating disorders with binging features39,40 or ADHD41,42.