How and why we forget 🧠

In today’s world, the ability to retain information is highly sought after. This goes beyond studying for an exam and includes daily activities: Make your breakfast (don’t forget your vitamins), pack the car (don’t forget your charger), drive to work (don’t forget to make that dinner reservation). If we forget, we are deemed incompetent.

However, research tells us that our brains are actively seeking to forget, and even require it to avoid overloading. Imagine if you went through each day trying to retain every sound we hear, sensation we feel and word we speak or read. By the end of a single day, we would be exhausted!

Research shows that the human brain forgets a lot more than we think. Within one hour, people will forget an average of 50 percent of the information they are presented. Within 24 hours, they forget an average of 70 percent, and within a week, forgetting claims an average of 90 percent. 


How we remember

As we go through life, our brain's hippocampus sorts new sensations and compares them with previous memories to decide what to store. 

The traditional thought of ‘memory’ can be broken down into three stages:

  • Acquisition - when a new experience reaches the hippocampus
  • Consolidation - when the experience is stored to become a memory
  • Recall - the ability to access the memory from storage.
In order to improve retention of long-term memories, we can improve memory consolidation by speaking it out loud, writing it down or re-enacting the experience multiple times so that our brains can re-synthesis the memory with new experiences. 

New research also reports that sleep acts to optimize the consolidation phase of your memories by reactivating the newly encoded memories to form stronger connections. 

Process of how we forget 

To fully grasp our memories we need to understand the process of how we forget. Famous psychologist, Elisabeth Loftus, has identified four main reasons as to how and why we forget.

  1. Retrieval failure - The information is stored somewhere in your memory, yet you can’t quite retrieve it. It’s that feeling when it’s on the tip of your tongue. This is known as trace decay theory, which suggests that your short-term memory can only hold information for 15-30seconds before it needs to rehearse the memory otherwise the chemical traces of that memory fade away and it can no longer be recalled. 
  2. Interference - Sometimes you forget because a new memory is very similar to a previous memory. For example; if you meet someone new and they remind you of someone you used to know, you may forget their name and only remember who they look like to you. 
  3. Failure to store - In order to remember something beyond 15-30seconds (the capacity period for short-term memory), your brain needs to transfer this memory into a long-term memory. One study describes this issue as an ‘encoding failure’ by asking subjects to draw a penny from memory. Most subjects were able to draw the correct size, shape, and image but forgot minor details like the words or details of the image. This is because your brain has chosen to encode the important details of the memory and forgot the ones less crucial for identifying a penny. 
  4. Motivated forgetting - less relevant to overload but equally important to life. Sometimes a memory is too difficult emotionally to remember so either consciously or unconsciously our brains act to protect our mental state and actively forget an experience. This memory is still stored yet you are currently unable to access it. Research emphasizes the importance of eventually dealing with these ‘suppressed memories’ in order to release the associated stress and prevent chronic illnesses caused by holding stress. 

What can I do

To prevent and manage overload, you first need to accept that you are not a robot; humans are designed to forget. After all, Black Mirror shows us what could happen if we were able to remember everything!

That said, you can implement tools into your lifestyle to remember more of the things that are important to you without the stress. David Allen’s book ‘Getting things done’ highlights the importance of offloading your memory system by storing important things to remember, outside of your head. It seems simple, but carry a to-do list with you everywhere you go. The easiest way to do this is with a task management app on your phone, like Evernote and Trello, or simply use your phone’s notes function. When a thought pops in your head, jot it down and file those thoughts at the end of every day / week.