Human multitasking is often the result of voluntary interruptions in the performance of an ongoing task. These selfinterruptionsoccur in the absence of external triggers such as alerts or notifications. Compared to externally inducedinterruptions, self-interruptions have not received enough research attention. To address this gap, this paper develops adetailed classification of self-interruptions arising from positive and negative feelings regarding task progress and prospectsof goal attainment. The validation of the proposed typology in an experimental multitasking environment with pre-definedtasks shows that negative feelings trigger more self-interruptions than positive feelings and that more self-interruptionsproduce more errors and lower accuracy in all tasks. Therefore, negative triggers of self-interruptions unleash a downwardspiral that ultimately affects performance.