The Psychological Cost of Rigidity: Exploring the Mediation of Psychological Inflexibility Between Personality and Prefrontal Functioning

Young individuals often experience executive functioning challenges, such as attentional lapses, impulsivity, and poor self-regulation, which may indicate underlying prefrontal dysfunction and contribute to stress and emotional dysregulation. Research suggests that specific personality traits, particularly harm avoidance and self-directedness, are closely related to these executive difficulties. Harm avoidance refers to a temperament trait characterized by excessive worry, fear, and avoidance of uncertainty, whereas self-directedness reflects a character trait involving goal orientation, self-control, and responsibility. However, the mechanisms linking these traits to executive functioning remain insufficiently understood. Psychological inflexibility, defined as a rigid and avoidance-based response to internal distress, has been proposed as a transdiagnostic process that may explain this link. This study investigates the mediating role of psychological inflexibility in the link between harm avoidance and self-directedness with prefrontal dysfunction in 501 young adults (56.69% male, M = 21.00 years, SD = 2.62). Participants completed self-report measures on personality traits, psychological inflexibility and prefrontal symptomatology. Mediation analyses using PROCESS Macro (model 4) showed that harm avoidance positively predicted psychological inflexibility (path a₁: <i>β</i> = 0.50, <i>p</i> < .001), which in turn predicted greater prefrontal symptomatology (path b₁: <i>β</i> = 0.45, <i>p</i> < .001). Conversely, self-directedness negatively predicted psychological inflexibility (path a₂: <i>β</i> = -0.54, <i>p</i> < .001), which was associated with lower prefrontal symptomatology (path b₂: β = 0.40, <i>p</i> < .001). Indirect effects were significant for both harm avoidance (<i>β</i> = 0.23, 95% CI [0.17, 0.29]) and self-directedness (<i>β</i> = -0.21, 95% CI [-0.27, -0.16]), indicating partial mediation. Overall, these findings highlight that psychological inflexibility serves as a key mechanism linking personality dispositions to executive and emotional self-regulation in young adults. Interventions aimed at increasing psychological flexibility may enhance adaptive functioning and resilience during this developmental period.