People remember information generated by themselves much better than things learned from other sources

Research:

The Economist’s ad campaign utilized the generation effect by using a series of clever, abstract ads that made viewers need to think in order to understand them. An example of one simply read, “All work and no play makes Jack an intern”, a funny reference to the classic horror film “The Shining” without giving much information.

This ad campaign gained the Economist 9500 new subscribers with a predicted lifetime increase in revenue of nearly 12 million dollars, based on the average 7-year subscription per user.