What Works Best for Whom?

Abstract: Positive psychology interventions (PPIs) mostly address changes in trait-like measures of subjective well-being. Addressing psychobiological state change, the present study employed experience sampling and smartwatch sensing to evaluate the effects of self-selected PPIs on real-world psychological and biological indicators and the moderating role of the Big Five personality traits. In linear mixed effect models, we analyzed data of N = 27 participants in a four-week study, yielding N ESM = 2317 measurement points of psychological stress and well-being, and N Bio = 433 measurement points for biological stress values as registered by a smartwatch. The results indicate PPI effects on mostly psychological, but not biological indicators with agreeableness and neuroticism as moderators. Across participants, the psychobiological correspondence was weak, yet stronger for more conscientious and more neurotic persons. The present study highlights the contrast between psychological and biological states and the need for personalized interventions that are evaluated on different effectiveness indicators.