First and foremost, it is primarily a tool of Distraction. Anytime you see them on the brink of waking up or crying…if you pat them just right, they’ll stop and turn to you, slightly confused…They spend the next few moments trying to isolate the patting.
“Where’s that rattling coming from?…Anybody else feel a shaking? Like a thump, thump, thump, thump?…Nobody? Okay, maybe it’s just me…as I was about to say…Waaahhh…” And then they go ahead and cry anyway. But for a second there, you feel very clever. You momentarily outwitted an infant.
Quoted from Babyhood