From Joint Attention to Common Knowledge

What is the relation between joint attention and common knowledge? On the one hand, the relation seems tight: the easiest and most reliable way of knowing something in common with another is for you and that other to be attentively aware of what you are together experiencing. On the other hand, they couldn’t seem further apart: joint attention is a mere perceptual phenomena that infants are capable of engaging in from nine months of age, whereas common knowledge is a cognitive phenomenon involving (so it seems) complex, overlapping metarepresentational states that require the kind of sophisticated mindreading skills that developmental psychology has shown to be beyond the capabilities of young children. In 'The Shared World: Perceptual Common Knowledge, Demonstrative Communication, and Shared Social Space', Axel Seemann attempts, inter alia, to makensense of this conundrum.