Combining PPI Domains and Targeting Cognitive Mechanisms: A Failed Proof-of-Concept for PPI Research

Positive psychological interventions (PPIs) are activities that target positive variables (e.g., gratitude or kindness) to elicit a positive response in a population, such as improving adaptive functioning, promoting well-being, reducing depression, or enhancing quality of life. Despite several decades of evidence, a meta-analysis by White et al. (2019) concluded that the effect sizes of PPIs may be smaller than previously recorded and that their effects on depression may be generally nonsignificant. In the current study, we created a new PPI, called the Best-Self PPI (BS-PPI), to provide a proof-of-concept of two relatively unexplored properties of PPIs that may enhance effect sizes, which are: (1) combining PPI domains (i.e., multiple targeted positive variables) into a single intervention and (2) designing PPIs to target cognitive mechanisms of change. Using a double-masked procedure, we randomly assigned undergraduate students (n = 133) between the ages of 18 and 32 (Mage = 19.97, SD = 1.66; women; n = 85, 63.9%; White: n = 87, 65.41%) to complete either the BS-PPI – containing elements of meaning, character strengths, and optimism – or a control condition before completing measures of depression, psychological well-being, and affect. One day later, the participants completed a measure of affect and the Self-Referential Encoding Task, a behavioral measure of self-referential processing bias, which is the strength and the valance of the words one uses to describe oneself, to test the potential of targeting a cognitive mechanism of change. One week later, participants completed measures of depression, psychological well-being, and affect. The results suggest the BS-PPI did not affect depression, well-being, or affect compared to the control group despite the consistency of this study with many other PPI studies (e.g., sample size, design, and population), which aligns with the White et al. (2019) meta-analysis. We discuss the implications of this failed proof-of-concept for PPI research and recommendations for moving forward with these relatively unexplored properties.