If the pain ray just affects the skin, as the military has said for years, why do the “Human Surrogate” systems need simulated organs?

The spokesperson mentioned in the piece below said that the surrogate will be, “A common test target that can be used across the spectrum of non-lethal stimuli.”

That’s fine, nothing to see here, obviously. But don’t be surprised if the pain ray has some other modes that .mil hasn’t mentioned yet.