It turns out that the brain has different centers for "wanting" and "liking".
We all know from experience that you can want something, but not like - as in enjoy - it, perhaps a new gadget, or a cheap bar of chocolate. You can also like something, perhaps getting very very drunk, but not really want to do it.
What's new is that this sort of ambivalence isn't you maturing, or failing to mature, or human weakness, or hypocrisy; it's actually just a normal interaction between two chunks of your brain, meaning it's not going to resolve itself very easily.
To me, this has stunning implications for masochism (in its broadest sense, covering all submissive proclivities).
First of all, it validates the idea of an authentic BDSM experience without adding layers of role play. I can genuinely want to be a mistreated slave, but genuinely not enjoy it. If you beat me, you are being genuinely cruel. If you are a sadist, then you can enjoy that experience with no self-deception. (I think it's more complicated than that, but that will require a different post.)
It also explains how this exquisite ambivalence can be so very stable; how we can fear the lash, and crave it, time and time again without learning one of the two logically possible lessons, either: "Shit! That's painful, I won't do that again!" or, "Actually, I rather like doing this."
This study suggests to me that erotic masochism is a lot simpler than it seemed: a masochist really does seek out unpleasant experiences, and the experiences really are unpleasant.
Update: Very illuminating thread here.