Abstract
Hesitation phenomena are intricately connected with prospective and retrospective speech-production tasks and mark critical points in processing. They are also causally related to types of quality control which can be expressed as conversational postulates governing wellformedness criteria. Corresponding to the concepts of forestalled versus committed errors (error-free or error-full output), two major hesitation categories suffice: stalls and repair. Supported by a corpus of English and German, the new taxonomy captures previously uncategorized information: the grammatical locus of repair operations and the structural changes they cause.