Previous studies have shown that confirmatory questions enhance the understandability of an explanation. Examples include asking a degree of understanding of the listener and current state of the description target in verbal explanation. In the current study, we examined the effect of two types of confirmatory question by tbe speaker on tbe degree of understanding of the listener. The experimenter verbally explained to participants how to draw a geometric figore. We manipulated tbe types of explanation: (a) tbe speaker aaks a degree of understanding of the listener dwing explanation, (b) the speaker asks a current state of the description target during explanation, and (c) the speaker simply repeats the explanation. As a result, tbe highest understandability score was attained when tbe explanation was repeated. Accuracy scores of the drawing were high in all three situations; we therefore conclude that conimnatory questions are not effective in every situation of verbal explanation. Repetition of the explanation is sufficient to increase the listener's understanding if the content of the description is simple
