A common strategy for providing a physicalist account of intentionality is the attempt to derive intentional content from causal connections. If something has the causal connections of something with a particular intentional content, then, according to this view, it indeed has that intentional content. This Vallicella entry includes a quote by Putnam on the ability of causal connections to fix reference.
One cannot simply say that the word "cat" refers to cats because
the word is causally connected to cats, for the word "cat," or
rather my way of using the word "cat," is causally connected to
many things. It is true that I wouldn't be using "cat" as I do if
many other things were different. My present use of the word "cat"
has a great many causes, not just one. The use of the word "cat" is
causally connected to cats, but it is also causally connected to
the behavior of Anglo-Saxon tribes, for example. Just mentioning
"causal connection" does not explain how one thing can be a
representation of another thing, as Kant was already aware.