Unfinished business

Alex Eben Meyer

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A lot of people live by to-do lists, whether tapped into a phone calendar or scrawled on a scrap of fast-food napkin. What’s more satisfying than clicking check or crossing off a task? ​​It turns out, unfinished business is hard to forget. 

In a new study, published in the Journal of Experimental Psychology: General, professor of psychology Brian Scholl, director of the Yale Perception and Cognition Laboratory, along with Joan Ongchoco ’17YNUS, ’22PhD, and Kimberly Wong ’25PhD, explored why unfinished tasks stick in our mind. “This may be an evolutionary example of an automatic to-do list,” he says. In past eons, tasks like hunting a mammoth or gathering medicinal herbs were important to finish—even life-changing. Today crossing off every item on a grocery list isn’t necessarily going to mean life or death. “The general idea is that the things we start are usually important,” Scholl says, “and you need to either abandon them or finish them in order to get them off of that to-do list.” 

But if you abandon them, they haunt you. 

For the experiment, his team created mazes adorned with little colorful squares. Participants followed a line through the maze—in the process noticing where the colorful bits were. That information had nothing to do with the outcome of the maze; what was important was if the line got to the end of the puzzle. When the maze was not completed, testers were more likely to remember the location of the colorful shapes. “There’s no reason to care about that,” Scholl says. “It’s not even relevant to your task, whether the path finishes or not. And yet, when the path didn’t finish, that information is just stuck in your mind.” 

Blame the Zeigarnik effect, postulated by Bluma Zeigarnik, a psychologist in the Soviet Union, in 1927. “It really is this boost in memory for unfinished things,” Scholl says. “It doesn’t have anything to do necessarily with how you think about these tasks or the obligation you feel. It’s just a basic fact of how your mind encodes information that if you see something that appears not to have been finished, you keep a little file open in your mind, and that information sticks around better if that circuit is never completed. 

“If I start a puzzle, it’s urgent in my mind until I finish it,” Scholl adds. “And I have to assume that our ancestors felt the same thing 1,000 years ago or 10,000 years ago. It’s not a part of how you are thinking about things. It’s a much more basic effect of how the mind encodes information in the first place.”