Using Demand Curves to Quantify the Reinforcing Value of Social and Solitary Drinking

Abstract

Background: Young adults typically drink in social settings and report high levels of episodic heavy drinking despite a range of adverse consequences. Behavioral economics posits that this may reflect a reinforcer pathology in which alcohol is overvalued relative to other reinforcers. Theoretically, the value of alcohol is related to both the direct pharmacological effects of alcohol (euphoria, sedation) and the associated social reinforcement, but to date no studies have differentiated the value of social vs. solitary drinking. The current study examines two modified hypothetical alcohol purchase tasks (APTs), one explicitly social and one explicitly solitary, in order to quantify the reward value of social vs. solitary drinking and to determine whether there are unique clinical correlates of solitary alcohol demand.

Methods: Participants were young adults (N = 274, M_age = 25.15, SD = 4.10) recruited from Mturk and from a university subject pool. Participants completed a solitary and social APT, in addition to measures of alcohol consumption and problems.

Results: Participants reported significantly greater demand in the social APT compared to the solitary APT across all demand indices. Elevated solitary and social demand were associated with elevated levels of alcohol use and problems. Using a residualized change approach, solitary demand amplitude (maximum consumption and expenditure) and persistence (price sensitivity) contributed additional variance above and beyond their social APT composite counterparts in predicting typical drinks per week and the self-care, academic/occupational, and physical dependence subscales of the YAACQ.

Conclusions: The presence of peers increases alcohol demand compared to a solitary scenario, and greater relative solitary drinking demand may be a risk factor for greater alcohol consumption and problems.

Keywords: Alcohol; Alcohol Demand; Social Drinking; Solitary Drinking; Young Adults.

Figure 1.

Demand curves for average consumption (Panel A) and expenditure (Panel B) for the Social and Solitary APT conditions. The x-axis is log-transformed. Each data point represents average hypothetical consumption across participants on a particular price of the APT, with error bars reflecting standard error for each price. Consumption and expenditure values were lower in the solitary condition compared to the social condition.

Figure 2.

Percent change in alcohol demand from the social to the solitary hypothetical purchase task, split by participants with low (n = 168; M = 2.27, SD = 2.55) and moderate/high (n = 103, M = 24.10, SD 9.14) alcohol problems. Results were only provided for prices retaining at least 2/3 of the sample for each group (from $0 to $5.00 price point). Between-subject alcohol problems groups were determined using empirical cutoffs resulting from a relative operating curve analysis (Read et al., 2015). Males/females scoring below 8/10 on the YAACQ, respectively, were categorized into the low group; all others were combined into a single moderate/high category. Independent sample t-tests suggested a significant difference at zero price (p = .04); trend-level effects were evident for prices up to $1.00 and for $5.00. All other prices were not significant.