@dale.schumacher is correct. The term is in the ancient access control literature, which is where I picked up on it. Norm instead used the term “synergy”, which I’m ok with. But to understand why I like “rights amplification” better, see Bringing Object-orientation to Security Programming (Mark S. Miller, Google) - YouTube starting at 28:17 . Though it makes more sense in context, so I’d really recommend watching that talk from the beginning 
The loose electric circuit analogy fits both “amplification” and “attenuation” together so well, it’s like they were both coined together based on this analogy.
All that said, Norm’s “synergy” seems a fine alternative.