If you're too chicken to touch it, you can buy a fence tester for about $10. One way to touch-test is to wear rubber boots and hold the wire firmly, rather than just touch it. It's not the pain that gets you (or the horse) it is the shock/surprise factor.
My friend introduced a few horses to electric due to their history. What she did was put them in the enclosure, called the horse to the fence line, let the horse relax and then she moved the wire with a long stick. The horses see the fence move, not realizing it's from her. She usually makes a point of ensuring the fence touches them. One time is enough.
I had a stud once who thought he was stronger than the electric fence. He reared/twisted near the fence and somehow or other managed to get his important parts on the fence. I'm still not sure how he did it without going over the fence, but he NEVER went any NEAR the fence again! :)
I also had a horse that jumped the fence once. I put it up higher and she never tried again.