The Function of Conditioned Fear in Reward Propensity: Evidence for Interrelated Approach-Avoid Systems
Walker, Rosemary Sara Webb
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Processes related to approach and avoidance behavior have largely been investigated independently. Thus, the understanding of how reward and fear systems work together is underdeveloped. This is problematic because threat and reward are often juxtaposed in real-life. Effective navigation of one’s environment requires balance between approach and avoidance. To better characterize the interplay between systems, we examined the effect of conditioned fear on reward propensity. We hypothesized that those in a fear-relevant condition will show attenuated reward propensity compared to those in a fear-irrelevant condition and that higher anhedonia and lower salivary estradiol will predict lower reward propensity, with those in a fear-relevant condition with higher anhedonia and lower salivary estradiol showing lower reward propensity than those in a fear-irrelevant condition. Ninety-nine female participants underwent a fear conditioning paradigm and were subsequently randomized to fear-relevant or fear-irrelevant conditions of an adapted probabilistic reward task involving a differential reinforcement schedule. The key dependent variable was reward bias, operationalized as systematic preference for the response paired with the more frequent reward. A moderation effect of anhedonia, depression, anxiety, and salivary estradiol was examined. There was a significant Group x Time interaction, F(2, 192) = 3.42, p = .03, such that those in the fear-relevant condition showed significantly higher response bias scores (M = .24, SD = .24) as compared to those in the fear-irrelevant condition (M = .12, SD = .17); d = 0.39. In other words, conditioned distress increased the development of a bias towards identifying the ambiguous stimulus as the stimulus more frequently associated with reward. Anhedonia moderated this effect, such that higher anhedonia predicted higher response bias in the fear-relevant group but not in the fear-irrelevant group during middle learning (β = .26, t(95) = 2.52, p = .01) and late learning (β = .23, t(95) = 2.10, p = .04). This study helps characterize integral mechanisms related to avoidance and approach, suggesting that conditioned fear influences reward functioning. Increased reward propensity in the presence of cues signaling low to moderate threat may promote goal-motivated behavior in order to increase the likelihood of successfully avoiding an aversive outcome. Further, there may be stronger effects of conditioned fear on reward responding in individuals with higher anhedonia, either because they develop higher levels of distress via fear conditioning or because they are more vulnerable to dysregulation to approach-avoid balance. More precise understanding of the functional relationship between fear and reward will yield avenues for effectively incorporating reward-related treatment components and targets into interventions for pathological avoidance.
- Psychology