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

The successor representation (SR) has been suggested to underlie nuanced forms of habitual behavior and a reduced SR variant (redSR) produces addiction-like behavior in simulations. Neither of these strategies can be detected in paradigms assessing habits in humans, which are usually conducted in disorder-irrelevant contexts, and this may explain inconsistent evidence for a goal-directed-to-habitual behavior shift in addiction. We tested whether individuals with high-risk drinking behavior rely more on (red)SR, particularly in alcohol-related contexts. Findings suggest that a (reduced) random-policy SR-like strategy contributes to human behavior, but that high-risk drinkers do not differ from low-risk drinkers in their use of this strategy. Instead, both groups rely less on (reduced) random-policy SR and more on model-free control in alcohol-related contexts. Results suggest that (reduced) random-policy SR supports adaptive, resource-efficient behavior and is selectively downregulated in substance-related contexts, highlighting the importance of contextual modulation in understanding decision strategies in mental health.