Forgetting is part of our daily life. You might walk into a room and forget why you walked in there – or maybe someone says hello to you on the street and you can’t remember their name.

But why do we forget things? Is this simply a sign of memory problemsor are there any benefits?

One of the first discoveries in this field highlighted that forgetting can occur simply because the average person’s memories fade. It comes from a 19th century German psychologist Hermann Ebbinghausincluding the “forgetting curve” shows how most people forget the details of new information fairly quickly, but this lessens over time. More recently, this has been reproduced by neuroscientists.

But forgetting can also serve functional purposes. Our brains are constantly bombarded with information. If we had to remember every detail, it would become increasingly difficult to retain important information.

One of the ways The reason we avoid this is by not paying enough attention to it in the first place. Nobel Prize winner Eric Kandel and a wealth of subsequent research suggests that memories are formed when the connections (synapses) between brain cells (neurons) are strengthened.

Paying attention to something can strengthen these connections and maintain this memory. This same mechanism allows us to forget all the irrelevant details we encounter every day. So even though people show increased signs being distracted as they age and memory-related disorders such as Alzheimer’s disease are associated with attention disorders, we all need to be able to forget all the unimportant details in order to create memories.

Manage new information

Recall a memory can sometimes also lead to modifying it to cope with new information. Let’s say your daily commute involves traveling the same route every day. You probably have a strong memory of this route, with the underlying brain connections strengthened with each trip.

But let’s say on a Monday one of your regular routes is closed and a new route is open for the next three weeks. Your memory of the trip must be flexible enough to integrate this new information. The brain achieves this in particular by weakening certain memory connections while strengthening new additional connections to memorize the new route.

Clearly, the inability to update our memories would have significant negative consequences. Consider PTSD (post-traumatic stress disorder), where the inability to update or forget a traumatic memory means that an individual is perpetually triggered by reminders in their environment.

From an evolutionary perspective, forgetting old memories in response to new information is undoubtedly beneficial. Our hunter-gatherer ancestors may have visited a safe watering hole several times, only to one day discover a rival colony or a bear with its newborns. Their brains must have been able to update the memory to label this place as no longer safe. Failure to do so would have posed a threat to their survival.

Reactivate memories

Sometimes forgetting is not due to memory loss but to changes in our ability to access memories. Rodent research demonstrated how forgotten memories can be remembered (or reactivated) by supporting the synaptic connections mentioned above.

Rodents have learned to associate something neutral (like a ringing bell) with something unpleasant (like a gentle foot shock). After several repetitions, the rodents formed a “fear memory” where hearing the bell made them react as if they were expecting a shock. The researchers were able to isolate the neural connections, activated by the combination of the bell and the shock, in the part of the brain known as the amygdala.

They then wondered whether artificially activating these neurons would cause the rodents to act as if they expected their foot to be electrocuted, even though there was no bell or shock. To do this, they used a technique called optogenetic stimulation, which involves the use of light and genetic engineering, and showed that it was indeed possible to activate (and then deactivate) such memories.

This could particularly be relevant to humans via a type of transient forgetting that might not be due to memory loss. Go back to the previous example where you see someone on the street and don’t remember their name. Maybe you think you know the first letter and you’ll get the name in a moment. This is called the tip of the tongue phenomenon.

When this was initially studied by American psychologists Roger Brown and David McNeill in the 1960s reported that people’s ability to identify aspects of the missing word was better than chance. This suggests that the information was not completely forgotten.

A theory is that the phenomenon occurs following a weakening of the links in memory between words and their meaning, reflecting a difficulty in memorizing the desired information.

However, another possibility is that the phenomenon could be used as a signal to the individual that the information is not forgotten, but only currently inaccessible.

This could explain why occurs more frequently As people get older and become more knowledgeable, their brains have to sort through more information to remember something. The tip-of-the-tongue phenomenon could be their brain’s way of letting them know that the desired information is not forgotten and that persistence can lead to successful memorization.

In summary, we can forget information for a variety of reasons. Because we weren’t paying attention or because the information deteriorates over time. We can forget in order to update our memories. And sometimes, forgotten information is not permanently lost, but rather inaccessible. All of these forms of forgetting help our brains function efficiently and have supported our survival over many generations.

It is certainly not a question of minimizing negative results caused by people becoming very forgetful (for example, because of Alzheimer’s disease). Nevertheless, forgetting has its evolutionary advantages. We only hope that you found this article interesting enough that you will not forget its contents anytime soon.