You're correct in that it is focused on making the user's brain feel good. I think a more accurate comparison, however, would be casino gambling. The slot machi

You're correct in that it is focused on making the user's brain feel good. I think a more accurate comparison, however, would be casino gambling. The slot machines ding at you and flash lights and make your brain release the dopamine. Facebook has the users on a similar bent via notification graphics and sounds, feeds, and various other things. It's the same idea though, and it is legitimately addictive (I've seen many family members get taken in by it to the point where they get anxiety if they can't constantly check their notifications or whatever).