And what it turned out was going on was that Facebook was looking at which links I clicked on, and it was noticing that, actually, I was clicking more on my liberal friends' links than on my conservative friends' links.
E quello che ho scoperto è che Facebook prendeva nota dei siti che visitavo determinando che, effettivamente, visitavo maggiormente i siti dei miei amici liberali rispetto a quelli degli amici conservatori.