Anhedonic Traits Do Not Impair Performance in a 3-Arm Bandit Task

Anhedonia, a core symptom of mood disorders such as depression, is marked by diminished pleasure and motivation for rewards. Traditional reinforcement learning (RL) tasks, like the 4-arm bandit (4AB), show limited sensitivity to reward-processing impairments associated with anhedonia. Here, we developed and validated a modified 3-arm bandit (3AB) task designed to reduce cognitive load while retaining sensitivity to reward and punishment learning. Following this validation, 1,000 participants were pre-screened with the Snaith-Hamilton Pleasure Scale (SHAPS), Dimensional Anhedonia Rating Scale (DARS), Generalized Anxiety Disorder Assessment (GAD), and Zung Self-Rating Depression Scale (ZUNG). Participants scoring above 2 on SHAPS and below 45 on DARS were classified as anhedonic, while those scoring 0 on SHAPS and above 55 on DARS were classified as non-anhedonic, resulting in 111 anhedonic and 95 non-anhedonic individuals who completed the 3AB task. Modelling results revealed no significant group differences in reward learning rate (p = 0.23), punishment learning rate (p = 0.37), reward sensitivity (p = 0.28), or punishment sensitivity (p = 0.46). Additional assessments of win-stay/lose-shift strategies and reaction times also showed no significant differences. Bayes Factor t-tests provided moderate -to-strong evidence for the null hypothesis, with BF01 values of 3.36, 5.14, 4.97, and 5.96 for each of the above parameters, respectively. These findings indicate either that anhedonia does not impair reward and punishment learning or that the 3AB task lacks the sensitivity to detect such differences. By simplifying the task structure while maintaining core learning mechanisms, the 3AB task provides a novel approach for studying reward processing, challenging the notion that anhedonia impairs reward sensitivity and indicating that this learning mechanism may remain intact.