When is ostensive communication used for joint action?

Abstract Joint actions typically require that information relevant for performing a task together is available to the interaction partners. In some situations, such perceptually retrievable and salient enough co-actors simply use it. other needs be actively shared among co-actors, e.g., by making it more or indicating means of conventional signal. Here we consider third case, where not cannot communicated means. How do joint action partners coordinate in situations? We propose resort ostensive communication, is, they draw attention fact intend communicate specific information. Two experiments tested proposed role communication action. non-verbal building task, category membership different objects was known only one person dyad, who needed inform partner which object type use. line with our hypothesis, most participants highlighted particular an gesture (characterized containing submovements than natural placing movement) resolve perceptual ambiguity. conclude especially useful situations task-relevant all conventionally communicated.