A Smartphone-Based Implicit Theories Intervention for Health Behavior Change: A Randomized Trial (Preprint)
Authors: Schreiber Mike , Dohle Simone 
Published: May 2022

BACKGROUND

Implicit theories of health describe individuals' beliefs about the malleability of health. Individuals with an incremental theory of health believe that health, in general, is malleable, whereas individuals with an entity theory of health endorse the idea that health is largely fixed and predetermined. Previous research has shown that an incremental theory of health is associated with beneficial health outcomes and behaviors. A mobile health (mHealth) implicit theories intervention could be a an effective way to increase health-promoting behaviors in the general population.

OBJECTIVE

The aim of this study was to estimate the effect of a smartphone-based intervention designed to promote an incremental theory of health on the frequency of health-promoting behaviors in everyday life. The study used ecological momentary assessment to measure health behavior change.

METHODS

This two-arm, single-blind, delayed intervention design included 149 German participants (meanage=30.58, SD 9.71; 79 female). Participants were asked to report their engagement in 10 health-promoting behaviors throughout the day for three weeks. Participants were randomly assigned to either an early intervention group (n=72) or a delayed intervention group (n=77). The intervention materials designed to promote an incremental theory of health were provided to participants after one week (early intervention group) or two weeks (delayed intervention group) of baseline behavior measurement. Data for this study was collected between September and October 2019.

RESULTS

A paired-samples t-test revealed that participants reported a stronger incremental theory after responding to the intervention materials (mean 5.58, SE 0.07), compared to incremental theories measured in an entry questionnaire (mean 5.29, SE 0.08; t148=4.07, SE 0.07, P<.001, 95% CI 0.15-0.43, d=0.33). Multilevel analyses showed that participants reported engaging in health-promoting behaviors more often after being presented with the intervention materials compared to baseline across conditions (b=0.14, t146.65=2.06, SE 0.07, P=.04, 95% CI 0.01-0.28). However, when the analysis was conducted separately for the early and delayed intervention groups, the intervention effect was only significant for the delayed intervention group (b=0.27, t1492.37=3.50, SE 0.08, P<.001, 95% CI 0.12-0.42). There was no significant increase in health-promoting behaviors for the early intervention group (b=0.02, t69.23=0.14, SE 0.11, P=.89, 95% CI -0.2 to 0.23).

CONCLUSIONS

This study suggests that a smartphone-based intervention designed to promote an incremental theory of health is a cost- and time-effective approach to increase the frequency of engaging in health-promoting behaviors. However, research is needed to understand the reasons for the difference in intervention effects between the early and delayed intervention group. The results of this study can guide the development of future digital health interventions that focus on implicit theories to promote health behavior change.

CLINICALTRIAL

DRKS – German Clinical Trials Register DRKS00017379; https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00017379