Therefore, research has also thrown considerable light on the complexity of spoken interaction in either a first or second language. For example, Luoma (2004) cites some of the following features of spoken discourse: Composed of idea units (conjoined short phrases and clauses) May be planned (e.g., a lecture) or unplanned (e.g., a conversation) Employs more vague or generic words than written language Employs fixed phrases, fillers, and hesitation markers Contains slips and errors reflecting online processing Involves reciprocity (i.e., interactions are jointly constructed) Shows variation (e.g., between formal and casual speech), reflecting speaker roles, speaking purpose, and the context