Research report: The successor representation in high-risk drinking and alcohol-related contexts

A study of 520 adults found no evidence that people with high-risk drinking behavior rely more heavily than low-risk drinkers on a particular form of successor representation, or SR. The computational analysis instead suggested that both groups used less of a reduced, random-policy SR-like strategy and more model-free control in alcohol-related contexts. The findings came from an online, multistage decision-making task that participants completed in either a virtual bar or a virtual apartment. The task assessed how well participants adapted their choices to different types of distal changes in the environment, allowing the investigators to distinguish SR-like behavior from model-based and model-free learning strategies.

Successor representation has been proposed as a reinforcement-learning strategy that may support nuanced forms of habitual behavior, making it a candidate mechanism for mental health conditions involving habitual control, including addiction. However, the study notes that existing paradigms used to assess habits in humans cannot detect the use of SR. Many such paradigms are also conducted in contexts unrelated to the disorder under investigation, which may help explain inconsistent evidence for a proposed shift from goal-directed to habitual behavior in addiction. Behavioral results supported the involvement of a reduced, random-policy SR-like strategy in both risk groups, but high-risk drinkers did not differ from low-risk drinkers in their overall use of that strategy.

The reported group-related finding concerned performance in the alcohol-related context: both groups appeared to rely less on the reduced SR-like strategy and more on model-free control. The results therefore do not support the interpretation that high-risk drinkers categorically favor a more rigid strategy across every component of the task. The authors interpret the pattern as evidence that an adaptive, resource-efficient decision-making strategy may be selectively downregulated in substance-related settings.

The study highlights the possible importance of contextual modulation and of distinguishing nuanced decision strategies when examining habitual and goal-directed behavior in addiction. As a comparison between high- and low-risk drinking groups, however, the analysis does not show that individual participants shifted from goal-directed to habitual behavior over time. It also does not establish that model-free control causes high-risk drinking, and the supplied findings report neither clinical outcomes nor treatment effects.

Subject of Research: Computational decision strategies associated with high-risk drinking in alcohol-related contexts

Article Title: The successor representation in high-risk drinking and alcohol-related contexts

Article References: Musial, M. P. M., Hall-McMaster, S., Shimomura, K., Kato, A., Bode, E. L., Grundmann, C. C., Ebrahimi, C., Morita, K., Gershman, S. J., Endrass, T., & Schlagenhauf, F. (2026). The successor representation in high-risk drinking and alcohol-related contexts. PLOS Computational Biology, 22(10), e1014873. https://doi.org/10.1371/journal.pcbi.1014873

Image Credits: AI Generated

DOI: 10.1371/journal.pcbi.1014873

Keywords: successor representation, high-risk drinking, alcohol-related contexts, model-free control, reinforcement learning, habitual behavior, goal-directed behavior, decision-making, context dependence, addiction, successor, representation