Abstract
Human decision-making favors approach behavior to gain reward and avoidance behavior to prevent punishment. While adaptive in some cases, this Pavlovian bias can also interfere with instrumental motivation, leading to suboptimal decisions. As maladaptive avoidance is a known maintenance factor in anxiety and depression, this could be especially relevant to individuals with these disorders. To assess whether Pavlovian bias is altered in this population, we examined 106 healthy comparisons (HCs), 88 individuals with depression (Dep), and 184 with comorbid anxiety and depression (AnxDep) using an Orthogonalized Go/No-Go Task. Participants' choices and reaction times were modeled using a reinforcement learning and drift diffusion model (RL-DDM). As expected, results showed that accuracy was highest when Pavlovian and instrumental biases aligned and lowest when they conflicted. Linear models revealed no group differences in accuracy, reaction times, or any of the computational parameters. However, Pavlovian bias was positively associated with depression severity across individuals with both anxious and non-anxious depression. Anxiety sensitivity was also positively associated with Pavlovian bias in the AnxDep group specifically. Consistent with this, both depression severity and anxiety sensitivity in this group were also negatively associated with accuracy on the task when approach actions were required to avoid punishment. These results suggest that Pavlovian bias may contribute to symptom severity in both unique and overlapping ways within anxious vs. non-anxious depression. This may also specifically reflect suppression of approach behaviors when they would have adaptive value - potentially amplifying the avoidance behaviors known to maintain these disorders.