The tendency to remember things better if they were left incomplete. Bluma Zeigarnik, a young Lithuanian psychologist, first discovered this effect in the 1920's while in a viennese coffee shop. She noticed that a waiter was able to recall endless numbers of orders unless he had completed them. She formulated the hypothesis that needs cause tensions which persist until the needs are satisfied. She explored this theory and in 1927 published a paper presenting her findings - that unfinished tasks were remembered approximately twice as well as completed tasks.