Recurring forgetting would have an important evolutionary advantage

Researchers argue that recurrent forgetting represents an important evolutionary advantage, contributing to the survival of generations. In fact, these omissions would make it possible to optimize the functioning of our brain by favoring the retention of important information. Rather than being permanently lost, the forgotten information would be temporarily inaccessible and would allow us to update our memories.

One of the earliest theories of forgetting holds that it occurs because memories fade over time. Known as the “forgetting curve” theory, this theory posits that most individuals forget the details of an event quickly (between a few hours and a few days). Information is gradually lost if the brain does not try to preserve it or does not pay it the necessary attention.

Although frequent forgetfulness is generally perceived as a symptom of cognitive impairment, it has been suggested that it may also have functional benefits. Faced with a constant flow of new information, our brains would struggle to remember the essentials if they had to remember every detail. By focusing our attention on certain aspects, we could sort and forget those that are superfluous.

« Although signs of forgetfulness increase with age and memory disorders, such as Alzheimer’s disease, are associated with attention problems, being able to forget trivial details is important in forming memories. “, explain Sven Vanneste and Elva Arulchelvan, from the Department of Neuroscience and Psychology at Trinity College Dublin, in an article published on The Conversation.

Forgetfulness making it easier to update memories

Vanneste and Arulchelvan argue that forgetting helps the brain process new information and update memories. Memorizing information sometimes requires updating previous information. For example, if you take the same route to work every day, memorization of the route is strengthened through repetition. On the other hand, a temporary change of route requires a certain adaptability of the memory to update the information. Thus, the brain must set aside certain data to integrate new ones.

From an evolutionary perspective, the ability to forget old memories to integrate new information is a major asset. The researchers cite the example of hunter-gatherers who may encounter a new threat while going to their usual watering hole. Their brain must then update the information to associate the location with potential danger during future visits, thus ensuring the survival of the group.

Conversely, the inability to update memories can have negative psychological repercussions, particularly in cases of post-traumatic stress. This syndrome illustrates an individual’s inability to forget a negative memory and update information, which can lead to an overlap between old and new data. “ The inability to update or forget a traumatic memory exposes the individual to constant reminders in their environment », Explain the researchers.

Information temporarily inaccessible?

The duo of experts also argue that forgetting does not necessarily mean the loss of information, but that it is simply temporarily inaccessible. Experiments in mouse models have revealed that forgotten memories can be recovered by strengthening the synaptic connections associated with them. Rodents have been conditioned to associate a noise with an unpleasant memory. Artificial activation of the corresponding neuronal connections (by optogenetic stimulation) allowed the animals to recover the memory even in the absence of stimuli.

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In humans, the retrieval of temporarily inaccessible memories results in the “word on the tip of the tongue” phenomenon. This happens, for example, when you meet an acquaintance without immediately remembering their first name. By concentrating more, memories gradually flow in, starting with the initial letter or syllable of the first name, and finally finding the full first name.

Psychologists have demonstrated that the ability of individuals to retrieve memories through this means is greater than chance, indicating that the information is not permanently lost. Temporary forgetting would thus make it possible to optimize the functioning of the brain to recover non-essential memories only when necessary. “ The tip-of-the-tongue phenomenon could be their brain’s way of signaling that the desired information is not forgotten and that persistence can lead to successful memorization », underline Vanneste and Arulchelvan.

Furthermore, studies have suggested that the recurrence of this phenomenon indicates a weakening of neural connections linked to memorization. This could explain why it occurs more frequently with age, as the brain has to sort through more information to retrieve certain memories. Experts point out that these hypotheses are not intended to minimize the negative consequences of diseases affecting memory, such as Alzheimer’s. Nevertheless, “these forms of forgetting help our brains function more efficiently and have likely contributed to our survival over generations,” they conclude.