Pain and Expectation

Does anticipation of pain worsen the actual experience of it? I've noticed, for example, that many patients jump when I put a lidocaine wheal in the back as local numbing for an epidural. I warn the patient it is coming, and this anticipation is worsened by the fact that the patient can't see what I'm doing. Does all of that make the subjective experience of pain worse? Since I use a tiny 30 gauge needle, I don't expect most people to jump. Perhaps the rigmarole around placing the lidocaine heightens the sensitivity of needle-phobic patients, making their overall experience worse. I imagine this is important in children scared of shots. They have fallen, scraped their knees, banged their elbows, stubbed their toes, and yet a tiny shot scares them far beyond playing outside. Knowing this, then, I wonder if we should be catching patients off guard rather than warning them. Maybe I should inject on "2" when counting "1-2-3." Is that ethical? Is that appropriate?