Probably one of the most powerful incentives that can exist, is peer pressure. As individuals, we want to belong, and to belong, we cannot stick out.
Things like making the default to an option an “opt-out” instead of having to take any action to actually opt-in, or showing individuals how they compare against their peer group are all very simple, yet powerful strategies.
One notable example is how all airlines have the Executive or First Class at the very front of the plane and most of them allow premium class members to board first, serve them refreshments and THEN have all passengers pass champagne wielding business people, on their sorry ways to the back of the plane.
“Tier envy” is a term used in program design and carefully placing the benefits and requirements in such a way that they drive partners to make the effort and come up through the ranks. Will the benefit in the next level make it worthwhile to go through all the requirements? Getting it right is not easy, and it is sort of an art.
When designing incentives I always ask, Is it possible to get a nudge for free anywhere?