Making this measure of interaction work would require clients to automatically rebroadcast notes on view.  Not just scrolling by in a feed, but if I click on a post, my client should rebroadcast it to my relays, even if I don't like or comment or zap.  Then other clients can measure the "viralness" of a post by counting how many relays have that post. 

 Yeah, I think that measures "wants more information".