Done and ticked off - why it's good to forget things

"Memorising things is easy to learn, there are various techniques, but forgetting is not so easy". Prof Dr Erb, a social psychologist at Helmut Schmidt University in Hamburg, explained it to me in a similar way during our conversation.

Because what I want to know from him has to do with our memory. More precisely: the so-called Zeigarnik effect. And this has to do with forgetting things as soon as they are done.

The Zeigarnik effect relieves the brain

According to history, the Russian psychologist Bljuma Zeigarnik discovered the effect in 1927 - with a waiter in a Berlin coffee house. He was very good at remembering things as long as they were still unfinished. As soon as the order was delivered, his brain seemed to erase the exact food and drinks to be served at each table from his memory as if by magic.

The student of the then already famous psychologist Kurt Lewin, co-founder of field theory, repeated her observations with further experiments and established a rule: if a task has not yet been completed, we remember it better than if it has already been done.

Practical, because this way we stay on the ball as long as it is in the air. Media companies, for example, also take advantage of this phenomenon. The Zeigarnik effect is better known here as the cliffhanger effect: TV series keep our curiosity going by continuing and concluding plots in new episodes. To be continued! But how long can we be patient and how long does the effect last?

Memory: limited receptivity is normal

First of all: in simple terms, human memory can be divided into two systems: short-term and long-term memory. "Short-term memory has a retention period of a few seconds to a few minutes - possibly even longer for chess players," says Professor Erb.

In science, the amount of information that the short-term memory can generally hold is understood in so-called chunks - i.e. information units. The rule of thumb, which goes back to the US psychologist George A. Miller, is that people cannot process more than 7 +/- 2 chunks of information at the same time and retain them in their short-term memory.

In contrast, the long-term memory. This is where information is stored for a long time and can be retrieved even years later. The basic process is always as follows: A task that has been started activates the brain and creates tension between the neurons. If this tension is not released immediately - for example, because the task has been completed - the long-term memory takes over and memorises the project that is still open.

People with dementia can no longer make this transfer: they forget what they have just done - no more information is transferred from short-term memory to long-term memory. There is therefore no further processing of the experience, which is why it disappears.

The path from short-term memory to long-term memory

Back to the Zeigarnik effect: this takes place in long-term memory - but only for a short time. Expert Erb explains: "The waiter from the example above not only remembers the order, but also links it to the people and the table at which it was placed. As a result, the information moves from short-term memory to long-term memory in the short term - and can be recalled from there.

"If we stay with the waiter, it turns out that the information, for example table 7, two beers and a bockwurst, ends up in long-term memory for a short time, so to speak, and when he has delivered, it is overwritten. The brain no longer needs this information and deletes it," says Prof Erb.

Learning from forgetting and remembering

But what does "erasing" actually mean when it comes to memory? It is indeed questionable - and there is still disagreement in scientific circles - whether humans are even capable of forgetting something completely. The social psychologist says that hypnosis can also be used to retrieve old, i.e. distant, memories: "There are various tricks that can be used to recall memories. Perhaps establishing the context - in other words, if I am in the exact situation again and feel the same way, it is quite possible that I will be able to retrieve memory content."

Memo techniques, such as rhymes and mnemonics, mind maps or stories, which you can come up with as a mnemonic aid to help you retrieve content from your memory, are well-known.

Let us help you: Consciously use the Zeigarnik effect

The exciting thing about the Zeigarnik effect is that if you are aware of its effect, you can actively use it. On the one hand, the effect can naturally lead to you taking unfinished tasks and projects from work, training or university home with you, where they continue to occupy you and possibly rob you of sleep and nerves.

On the other hand, you can consciously use the Zeigarnik effect to your advantage:

If you have not been able to solve a project or are not yet satisfied with it, deliberately leave it until later. This is where the so-called incubation effect comes into play, says Erb:

"I consciously use the effect and say to myself: Yes, I'll put that away now, I can't think of anything - but it doesn't matter. Let's see what it looks like tomorrow or the day after." The idea behind it: Solutions are allowed to come to us spontaneously when there is time. You give your brain a break, so to speak, and, true to the Zeigarnik effect, rely on not forgetting the tasks because they have not yet been completed. And this sometimes works very well: with the paper you still haven't finished writing for university as well as with the ideas for the next Christmas present.