Pavlovian bias instigates suboptimal choices in humans

Value-based decisions are often biased by Pavlovian (e.g., reward-associated) cues present in the environment. However, it remains unclear whether this Pavlovian bias can disrupt optimal decision-making, leading to maladaptive (or suboptimal) choices in humans. To test this hypothesis directly, a modified Pavlovian-to-Instrumental Transfer (PIT) paradigm was used. Participants first learned an optimal decision-making strategy, which involved preferring the rich option (70% reward probability) over the poor option (30% reward probability) to maximize rewards. Subsequently, Pavlovian cues predicting one or the other option were introduced during the decision-making process. Results confirmed our hypothesis that Pavlovian cues can indeed interfere with optimal choices. Notably, maladaptive Pavlovian influence persisted with both unobservable and observable rewards, reducing overall reward income. In a second experiment, we reduced the cue-outcome association strength during Pavlovian learning, decreasing the Pavlovian bias with observable rewards. This highlights the pivotal role of the predictive value of cues in this effect. These findings establish a direct link between Pavlovian biases and maladaptive behaviors, with implications for understanding and potentially mitigating environmentally triggered pathologies such as addiction and impulsivity.