The temporal trajectories of habit decay in daily life: An intensive longitudinal study on four health-risk behaviors

Habits are cue‐behavior associations learned through repetition that are assumed to be relatively stable. Thereby, unhealthy habits can pose a health risk due to facilitating relapse. In the absence of research on habit decay in daily life, we aimed to investigate how habit decreases over time when trying to degrade a habit and whether this differs by four health‐risk behaviors (sedentary behavior, unhealthy snacking, alcohol consumption, and smoking). This 91‐day intensive longitudinal study included four parallel non‐randomized groups (one per behavior; N = 194). Habit strength was measured daily with the Self‐Report Behavioral Automaticity Index (11,805 observations) and modelled over time with constant, linear, quadratic, cubic, asymptotic, and logistic models. Person‐specific modelling revealed asymptotic and logistic models as the most common best‐fitting models (54% of the sample). The time for habit decay to stabilize ranged from 1 to 65 days. Multilevel modelling indicated substantial between‐person heterogeneity and suggested initial habit strength but not the decay process to vary by behavioral group. Findings suggest that habit decay when trying to degrade a habit typically follows a decelerating negative trend but that it is a highly idiosyncratic process. Recommendations include emphasizing the role of person‐specific modelling and data visualization in habit research.