Depressive symptoms are associated with negative expectations and reduced belief updating by positive information. Cognitive immunization, the devaluation of positive information, has been argued to be central in this relationship and predictive processing models suggest that more positive information is associated with greater cognitive immunization. In an online experiment, N=347 healthy participants took part in a performance task with standardized feedback that was either mildly, moderately, or extremely positive. Effects of the feedback positivity on cognitive immunization were investigated. Further, depressive symptoms, interpretation bias, as well as participant’s self-evaluation were examined as potential moderators of belief updating. Participants in the mildly positive condition showed the greatest amount of cognitive immunization, with no difference between the moderately and the extremely positive condition. Irrespective of the feedback condition, participants’ positive expectations increased after feedback, yet depressive symptoms were associated with a weaker increase. Interpretation biases were unrelated to these associations, but exploratory analyses suggested that self-evaluation may be a potentially central factor. The results suggest that healthy participants engaged in cognitive immunization when feedback was less positive than expected. Depressive symptoms were associated with reduced belief updating, with self-evaluation being a promising factor for future research.