Good observation Blair: "Looked at this way, sentences can contain two elements and a link." ... "speech reflects a doubling that enables people to hold two points of attention at the same time." This is exactly what our school has theorized. See also the last book by my colleague Giulio Benedetti "An Enigma in Language" https://www.novapublishers.com/catalog/product_info.php?products_id=12667&osCsid=b We think that also the link is the result of attentional operations; however, they are not sufficient alone, also working memory is needed (even if some model of attention include WM as an element of attention). Anyway, it must be noted that, given certain condition, not only can you split your attention between two points, but also between four or five (see the empirical work of Zenon Pylyshyn on Multiple object tracking) It is not yet fixed whether the splitting is done by discrete operations (by which attention switches rapidly between the targets) or by a continuous allocation of attention (see here the work by Rufin VanRullen)