Digital Psychology

Need to Complete

We, as humans, don’t like to leave things incomplete. We are motivated to finish a set of tasks, even with no further reward other than the satisfaction of completing them.


During the 2016 Christmas season, Harvard researchers Barasz, John, Keenan and Norton (2017) conducted a study with the Canadian Red Cross. Potential donors were directed to one of three landing pages. The first group received a request for cash donations. The second group was asked to select gifts from a selection of six items, like blankets, baby diapers, or hot meals, among others. A location marker on a globe indicated where the selected items would be donated. The third landing page offered the same gifts, but in a pseudo-set called a “Global Survival Kit.” Each time an item was selected, instead of location markers, a line grew further around the globe. A closed circle meant that all six items were funded, but potential donors could choose as many gifts as they wanted. 21% of the people in the third group decided to donate all six gifts, compared with only 5% on the second page, and 3% in the cash condition.

We like to tick things off that we gotten done. In the days before paper and pen, our memories had to perform the whole job. To keep track, our mind fixates on unfinished tasks – the so-called Zeigarnik effect. The psychologist Bluma Zeigarnik had noted that waiters could remember open orders more efficiently than those that had been delivered. Further experiments have proven that we can recall incomplete or interrupted things better than things we’ve finished (Zeigarnik, 1927).



No, I don’t mean those bearded guys with hats. We’re talking about the step-by-step process that takes the user through a sequence of input requests. It’s a popular design pattern to split up complex forms into smaller, more digestible, tasks. Display either a progress bar or the number of steps that are left to indicate to users how long the whole process will take. An indicator will also act as a reminder of how much time they’ve already invested – time that would be lost should they not complete the process.

Need to Complete Example: Wizards

Progress bars

People want progress indicators. They give feedback about the current status, but also stimulate the desire to continue the process. Each time the progress bar moves through our actions, we feel the positive effects of dopamine, which motivates us to repeat the previous task. This phenomenon is also referred to as self-directed learning, which is likely evolutionarily developed to maximize learning opportunities and, therefore, to reproduce human intelligence (Herd, Mingus & O’Reilly, 2010).

Need to Complete Example: Progress bars

Starting with a high percentage

Make your progress indicator prominent, and show after the first completed task a relatively high completion rate. But, don’t overdo it. Keep it plausible. We are more motivated to reach a goal the closer we get to it (Kivetz, Urminsky & Zheng, 2006).

Need to Complete Example: Starting with a high percentage

Counters and notifications

You might have heard about the Inbox Zero approach: a technique developed by Merlin Mann to keep your email inbox empty almost all the time. For many people, counters, especially those that indicate incomplete tasks, trigger discomfort, which we try to avoid. According to a study from 2002, employees reacted to 70% of their unread emails within 6 seconds. These interruptions can be instant gratification. They give us little dopamine rushes every time we complete something, which in turn, reinforces us to lurk for more distractions.

Need to Complete Example: Counters and notifications

To-do lists

Dropbox has an excellent “Get Started” checklist. The user is asked to refer friends to them, to connect social media accounts, and to follow Dropbox on Twitter, which resulted in more free space. This growth hack is undoubtedly one reason why Dropbox became a multi-billion-dollar company. Providing small, achievable quests can produce small wins when completed. But, not all users will be seduced solely by the need to complete. In this case, give them extrinsic rewards, as Dropbox does.

Need to Complete Example: To-do lists

Digital Psychology – a free library of psychological principles and examples for inspiration to enhance the customer experience and connect with your users. Written by Daniel Stefanovic.