Zeigarnik Effect

The Zeigarnik Effect is a psychological phenomenon where people tend to remember incomplete or interrupted tasks better than completed ones. In UX, this principle is used to design systems that keep users engaged by providing progress indicators or reminders of unfinished tasks, which can encourage users to complete actions or tasks.

The Zeigarnik Effect is the psychological mechanism behind progress bars on profile completion, multi-day onboarding sequences, and checkout carts that persist between sessions. Once users have started something, their brain keeps it as an 'open loop' that creates mild tension until completion — a tension that designers can leverage through visual progress indicators. For SaaS onboarding, starting users on a partially completed setup flow (rather than an empty one) increases completion rates significantly.

LinkedIn's profile completion bar ('Your profile is 70% complete') exploits the Zeigarnik Effect — users who've already invested effort in completing 70% feel compelled to close the open loop by finishing the remaining 30%, even if they hadn't planned to spend more time on their profile.