Trial-by-trial responses of individuals with mild depression in tasks with varying reward probabilities

Numerous studies have traditionally employed monetary incentives to investigate reward and loss processing in individuals exhibiting depressive symptoms, despite the fact that depression often arises and persists due to maladaptive responses to social rewards and losses.In this study, we explored the responses of individuals with mild depression under different reward tasks and reward probabilities and further clarified the psychological mechanism of individuals with mild depression under reward and loss. 57 participants with mild depression and 57 healthy controls (HC) completed the monetary incentive delay (MID) and social incentive delay (SID) tasks. The results revealed that there was no interaction between reward task and group reaction time(RT). Responses of the two groups in MID and SID were similar. Under conditions of high reward probability, the reaction time of the HC was distinctively shorter than that of the group with mild depression, while there was no difference between the two groups under low reward probability conditions. In conclusion, individuals with mild depression demonstrate a more pronounced impairment in their reward function under conditions of high reward probability. They exhibit normal responses to monetary loss and and social negation under conditions of low reward probability.