ISTM that someone who would one-box on Newcomb for the reasons given by Gary Drescher (act for the sake of what would be the case, even in the absence of causality) would press the button here; if you're the kind of person who wouldn't press the button, then prior to copying you would anticipate more pain than if you're the other kind.

Getting the button is like getting the empty large box in the transparent boxes version of Newcomb's problem.