Users remember unfinished or interrupted tasks better than completed tasks and will continue thinking about them over and over again. The Zeigarnik effect is being used in some systems to onboard users faster and effectively.
Most of us do not like not being able to see what others see or make sense of something new. We do not like it when things do not come together and fit nicely for us. That is why most popular movies have Hollywood endings. So we feel compelled to reduce it, solve it, complete it, reconcile it, make it make sense. And when we do solve these puzzles, there's relief. It feels good.
— Peter T. Coleman
«bear in mind»
The reliability of the effect has been a matter of some controversy. Several investigations, performed later in other countries, attempting to replicate Zeigarnik's experiment, failed to find any significant differences in recall between completed and interrupted tasks.