Systems that attempt to understand natural human input make mistakes, even humans. However, humans avoid misunderstandings by confirming doubtful input. Multimodal systems--those that combine simultaneous input from more than one modality, for example speech and gesture--have historically been designed so that they either request confwmation of speech, their primary modality, or not at all. Instead, we experimented with delaying confirmation until after the speech and gesture were combined into a complete multimodal command. .
