Abstract
Personality traits have consequences and are malleable throughout the lifespan. However, it is unclear if and how personality traits can be changed in desired directions. A 3-mo digital personality change intervention was deployed, and a large-scale randomized controlled trial (n = 1,523) was conducted to examine the effects of intended personality change in a nonclinical sample. The intervention group showed greater changes than the control group, and changes aligned with intended goals for change. Observers also perceived personality changes, but reported changes were less pronounced. Moreover, self- and observer-reported changes persisted until 3 mo after the end of the intervention. These findings provide the strongest evidence to date that normal personality traits can be changed through intervention in nonclinical samples. Personality traits predict important life outcomes, such as success in love and work life, well-being, health, and longevity. Given these positive relations to important outcomes, economists, policy makers, and scientists have proposed intervening to change personality traits to promote positive life outcomes. However, nonclinical interventions to change personality traits are lacking so far in large-scale naturalistic populations. This study (n = 1,523) examined the effects of a 3-mo digital personality change intervention using a randomized controlled trial and the smartphone application PEACH (PErsonality coACH). Participants who received the intervention showed greater self-reported changes compared to participants in the waitlist control group who had to wait 1 mo before receiving the intervention. Self-reported changes aligned with intended goals for change and were significant for those desiring to increase on a trait (d = 0.52) and for those desiring to decrease on a trait (d = −0.58). Observers such as friends, family members, or intimate partners also detected significant personality changes in the desired direction for those desiring to increase on a trait (d = 0.35). Observer-reported changes for those desiring to decrease on a trait were not significant (d = −0.22). Moreover, self- and observer-reported changes persisted until 3 mo after the end of the intervention. This work provides the strongest evidence to date that normal personality traits can be changed through intervention in nonclinical samples.