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.