Every Rome tour book will tell you about the statue of St. Peter in the Vatican, and how tourists since the dawn of time have undertaken to make a connection with the place by stroking its foot.
From (admittedly brief) observation, I'd venture you can learn some interesting stuff about people from the way they do it. I'd infer that most simply stroke the foot once, cross themselves, and rturn quickly away. I saw one who did not cross himself: he was a buff young guy wearing a tee-shirt that said ITALIAN GIGOLO. He may have had more pressing concerns.
But what particularly interested me were the nuns: they didn't merely stroke it; they would cupthe foot and hold it, as if they were trying to give it comfort.
A tall order, IMOH. And BTW, a couple of nun footnotes: I'm impressed at just how many you still see in Rome these days, and what a variety of cool habits (I don't suppose I can recognize the ones in civvies, though it is tempting to try). I'd guess that about half that I saw were Asian. I noticed a couple of them in a market trying to pick out a nice bottle of wine, like housewives getting ready for a celebratory family dinner.