What is the Zeigarnik effect?

Discover the Zeigarnik effect, which explains why unfinished tasks linger in our memory longer than completed ones.

The Zeigarnik effect is a phenomenon which hypothesizes that one has a higher tendency to remember things, actions, or events that were left unfinished than those that were completed. It is something that one probably experiences on a daily basis. The effect can be experienced when you have an unreturned phone call, unfinished chore, or even a partially eaten breakfast that only filled a portion of your tummy. If it is unfinished or was interrupted, there is a high chance that you will remember it. The Zeigarnik effect was first studied and introduced by Lithuanian-Soviet psychologist Bluma Zeigarnik, after whom it was named. She first looked into it following an observation made by her academic advisor and psychologist Kurt Lewin, wherein he had noticed that a waiter could easily memorise orders that were still unpaid for. But after the customers had paid for their meals, the waiter failed to recall any details of the same order. Following this incident, Bluma Zeigarnik began conducting experiments that would further explain this phenomenon. Her research was published in the journal Psychological Research: An International Journal of Perception, Attention, Memory, and Action.  

Now here’s a question. Why do unfinished tasks tend to linger in our memory with far more stubbornness than those that are finished? Zeigarnik had stated that the brain can distinguish between tasks that were completed and those that were unfinished. Whenever we start a task, there is a type of tension that builds up in the mind. Information is sent to the sensory memory (information taken in through the five traditional senses), where it is momentarily stored before being transferred to short-term memory. The information here is soon forgotten. However, when a task is left incomplete, it becomes an open loop and is constantly replayed in the short-term memory region of the brain, so the information is not lost. This brings out a cognitive tension (mental discomfort when an individual is faced with conflicting situations).

Yes, those two opposing words definitely fit this phenomenon. Similar to how scissors in the wrong hands can lead to injuries, but can create marvellous paper crafts in the right ones, it is important to understand some cases in which the Zeigarnik effect can be utilised for benefits. Like during study sessions, where strategic interruptions, or short breaks, are taken in between to relax the mind with the last-read information stored safely within. Then there are times when the effect needs to be prevented since it can cause the mind to be cluttered with a large list of unfinished tasks. In this case, prevention can be achieved by ‘not procrastinating’. If you have a short task (making your bed, returning a phone call, etc), do not stop until it is complete. 

While experiments have been performed in the making of the study of this phenomenon, it has been met with its fair share of controversies. Since there are many external factors to take into account: the mindset of the person performing the task, the nature of the interruption, etc. In a systematic review conducted in 2025 on both the Zeigarnik and the Ovsiankina effect (the urge to finish incomplete tasks), the validity of the latter was chosen over the former.