Rational Emotive Behavior Therapy (REBT) is a psychotherapeutic approach based on the premise that when faced with adversity irrational beliefs determine unhealthy negative emotions and maladaptive behaviors, whereas rational beliefs lead to healthy and adaptive alternatives. The detrimental effects of irrational beliefs on psychological health are established, however less is known about the deleterious effects on human behavior and performance. In the present study we examined the effects of irrational and rational self-statements on motor-skill performance (Experiment 1), performance effectiveness, and efficiency during a modified hazard perception task, and task persistence during a breath-holding task (Experiment 2). Using a repeated m...