A Smartphone-Based Implicit Theories Intervention for Health Behavior Change: A Randomized Trial (Preprint)

Abstract

BACKGROUND Implicit theories of health are beliefs about whether health is perceived as malleable (incremental theory) or fixed (entity theory). Research has shown that an incremental theory of health is connected to many health-promoting outcomes. However, research on its influence on actual health-promoting behaviors is scarce. OBJECTIVE The objective of our study was to investigate whether a smartphone-based ecological momentary intervention designed to promote an incremental theory of health increases the frequency of performing health-promoting behaviors in daily life. METHODS In this two-arm, single-blind, delayed intervention, 149 German participants (mean[age]=30.58, SD 9.71; 79 female) were asked daily over a period of three weeks to indicate whether they had performed 10 health-promoting behaviors throughout the day. Either after one week (early intervention; n=72) or two weeks (delayed intervention; n=77) of baseline behavior measurement, participants were presented with intervention materials designed to strengthen an incremental theory of health. Data collection for this study ran between September and October 2019. RESULTS Multilevel analyses revealed that across conditions, participants reported to engage in health-promoting behaviors more often after being confronted to the intervention materials compared to baseline (b=0.14, t[146.65]=2.06, SE 0.07, P=.04, 95% CI 0.01-0.28). When analyzed separately, this intervention effect was only present for the delayed intervention group (b=0.27, t[492.37]=3.50, SE 0.08, P<.001, 95% CI 0.12-0.42) while no significant increase in health-behaviors occurred for the early intervention group (b=0.02, t[69.23]=0.14, SE 0.11, P=.89, 95% CI -0.2 to 0.23). CONCLUSIONS This intervention shows that a smartphone-based intervention promoting an incremental theory of health can serve as a time- and cost-efficient approach to increase the frequency of performing health-promoting behaviors. We discuss why the intervention's effectiveness differs between intervention groups. In addition, implications are derived that may guide future digital health interventions that focus on implicit theories to achieve health behavior change. CLINICALTRIAL DRKS – German Clinical Trials Register DRKS00017379; https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00017379

A Smartphone-Based Implicit Theories Intervention for Health Behavior Change: Randomized Trial

“…The study was approved by the faculty's ethics commission (ID MSHF0047). It was registered as a randomized trial in the German Clinical Trials Register (trial number DRKS00017379) and was preregistered in the Open Science Framework (OSF [41]).…”

“…More precisely, the intervention materials included (1) a (fictitious) newspaper article that described health as mainly influenced by lifestyle and engagement in health-promoting behavior [7], (2) three fictitious blog posts in which individuals reported positive health changes, (3) an essay priming in which participants were asked to describe health changes in their lives, and (4) an article that focused on the benefits of beliefs in changeability in other domains. The materials are available in the OSF repository [41]. After reading the articles and the 3 blog posts, participants answered one question regarding the content of the materials as an attention check.…”

“…Based on the preregistration [41], a mixed ANOVA was conducted to test whether the intervention increased the frequency of performing health-promoting behaviors on a weekly level. As within-subject factor, the mean number of health-promoting behaviors per day was aggregated for every week, and intervention group (early versus delayed) was entered as between-subject factor.…”