Sudden Gains and Losses in Personality Change Interventions: Predictors, Outcomes and Implications for Individualized Personality Change

Recent research suggests that volitional personality change is possible through structured interventions, yet little is known about the temporal dynamics of such change. In psychotherapy, sudden gains—abrupt, substantial improvements between sessions—are robust predictors of treatment success. Based on 448 participants who completed a 12-week personality intervention, we examined whether similar sudden shifts occur in the context of volitional personality change and whether they explain differences in trait, life satisfaction, and self-esteem changes from the pre-test to the follow-up 3 months later. We compared four different measures for detecting shifts: daily and weekly personality states, generic change factors (e.g., gaining insight), and subjective progress. Sudden gains were relatively common and—with the exception of daily states—consistently associated with improvements in the targeted traits, life satisfaction, and self-esteem. Sudden gains in weekly states co-occurred with increased intervention engagement and key change processes such as gaining insight and practicing new behaviors—paralleling mechanisms found in psychotherapy. In contrast, sudden losses were less frequent and showed no meaningful negative effects for trait changes or life satisfaction. However, high dropout rates may have masked more consequential losses. These findings challenge the assumption that personality change is exclusively gradual and underscore the value of capturing dynamic, within-person fluctuations. Monitoring and leveraging such shifts may help to personalize interventions and optimize their impact. Future research should explore how sudden gains can be intentionally triggered and how interventions can be designed to support lasting change through both gradual and sudden pathways.