People are unaware of the psychological processes that attenuate negative feelings, thus resulting in affective forecasting errors. Since people are unaware that these processes work more efficiently during intense negative feelings, they may expect intense negative feelings to last longer than mild ones. This study aimed to elucidate these affective forecasting errors and demonstrate that they occur in the absence of an external need for affect regulation. Additionally, people's predictions of the emotional states of others in the same situation were investigated. Those who only imagined receiving feedback (forecasters) predicted their affective states would be more negative five minutes after very negative feedback than after mildly negative feedback. However, the affective states of those who actually received very negative and mildly negative feedback (experiencers) differed less than those of forecasters and were less negative than the forecasters' predictions. Furthermore, predictions of an average student's feelings indicated that experiencers predicted that an average student's negative affective state would last longer than their own.