The Normative Underpinnings of Population-Level Alcohol Use: An Individual-Level Simulation Model

Abstract

Background. By defining what is "normal," appropriate, expected, and unacceptable, social norms shape human behavior. However, the individual-level mechanisms through which social norms impact population-level trends in health-relevant behaviors are not well understood. Aims. To test the ability of social norms mechanisms to predict changes in population-level drinking patterns. Method. An individual-level model was developed to simulate dynamic normative mechanisms and behavioral rules underlying drinking behavior over time. The model encompassed descriptive and injunctive drinking norms and their impact on frequency and quantity of alcohol use. A microsynthesis initialized in 1979 was used as a demographically representative synthetic U.S. population. Three experiments were performed in order to test the modelled normative mechanisms. Results. Overall, the experiments showed limited influence of normative interventions on population-level alcohol use. An increase in the desire to drink led to the most meaningful changes in the population's drinking behavior. The findings of the experiments underline the importance of autonomy, that is, the degree to which an individual is susceptible to normative influence. Conclusion. The model was able to predict theoretically plausible changes in drinking patterns at the population level through the impact of social mechanisms. Future applications of the model could be used to plan norms interventions pertaining to alcohol use as well as other health behaviors.

Keywords: alcohol use; individual-level simulation modeling; social norms.

Figure 1

Conceptual social norms model of health risk behavior on the example of alcohol use.

Figure 2

Flow-chart of simulation model processes, individual-level decision making, and process scheduling.

Figure 3

Calibrated simulation model outputs (baseline model) compared to target data with 95% confidence intervals: prevalence of current drinking in the past 12 months (left); average grams of pure alcohol consumed per day among current drinkers in the past 30 days (middle) and average number of drinking days in the past 30 days among current drinkers (right) by gender. The solid line shows modelled estimates using the baseline parameter set, the dotted line shows target data used for calibration. The shaded range indicates the confidence interval (based on stochastic variation across 10 simulation runs for model outputs).

Figure 4

Perceived descriptive norms on quantity (top row) and the number of heavy episodic drinking days (HED; bottom row) in the past 30 days in two exemplary individuals (young males, heavy drinkers). Individual A (autonomy=0.9) is shown on the left, individual B (autonomy=0.5) is shown on the right. Moving averages were used to smooth outcomes over 90 days. Norms and drinking behavior under the baseline setting and under experiment 1 (starting five years into the simulation) are shown. The latter entailed an intervention directed at heavy drinkers, aiming to decrease the perception bias regarding the level of alcohol use per occasion in relevant others, starting five years into the simulation.

Figure 5

Prevalence of current drinking in the past 12 months under the baseline setting compared to experiment 3. The latter entailed a public campaign targeting injunctive norms in order to discourage alcohol use, starting five years into the simulation.