Memory: An Overview of Processes and Theories

However you use it, memory is necessary, but what is it, and how can we be sure we understand it?

Anastasija Petrovic
5 min readMar 25, 2021

Whether it be walking over a sand-covered beach, with your feet gliding against the soft yet warm sand or biting into your first slice of sugary madness, memory enthralls one’s life and the human experience.

But the unknown question remains, what exactly is that sometimes lovable other times unforgivable entity, and how do we know we understand it?

What is memory?

Memory is usually defined as the processes used to acquire, store, retain and later retrieve information from the brain. Memory is a crucial part of human cognition. It allows one to check items off at the grocery store and overall remember past experiences to frame their current understanding and behaviour. Three major processes characterize how memory works: encoding, storing and retrieving (recall).


All the information our brain receives through our senses will first have to be transformed into a form our (let’s collectively refer to this wide process as “memory”) memory will store. This process occurs first with the perception we receive through our senses.

How exactly this information will be encoded or, if this process were a programming project, which language you would use, it is variable to what kind of information you are trying to store and how it was received.

Information received can usually be encoded in one (or more) of these methods:

  1. 👀 Visual encoding (how something looks).
  2. 👂 Acoustic encoding (how something sounds).
  3. 🧠 Semantic encoding (what something means).
  4. ✋ Tactile encoding (how something feels).


The idea most people think of first when referring to memory as a whole. Storing these perceptions refers to how, where, how much, and how long encoded information is retained within a memory system. The modal model of memory (storage) highlights the existence of two types of memory: short-term and long-term memory. The encoded information is first stored in short-term memory, and then if need be, is stored in long-term memory.

The Atkinson-Shiffrin memory model argues that information encoded through the acoustic method is primarily stored in short-term memory (STM). It is only kept there through constant repetition (practice does make perfect!).

Time and inattention may cause information stored in STM to be disregarded. STM only lasts 15–30 seconds and can store anywhere between 5–9 items of information. In this context, let’s refer to the term “items” as any piece of information.

On the other hand, long-term memory (LTM) has an immense storage capacity that stores the information indefinitely. To get that wonderful guarantee, you do have to understand the information semantically.


Now, onto the key thing if you are trying to maximize the 1.5 kg mass of mystery in your head. Retrieval is the process through which individuals retrieve the information that was once stored. Of course, information in STM and LTM is stored differently. STM is retrieved in list-like order of when they were stored, while LTM is retrieved through an association between entities.


Human memory involves both the ability to preserve and recover information we have learned, experienced or tried cramming before your Calculus final. However, as we all know, that is not a perfect process. Sometimes (or for most of the time), we misremember or forget things. Sometimes things are not properly encoded in memory in the first place.

The Dual-Process Theory


This is where our paths diverge and get a little complicated. The Dual Process Theory is the idea that our memory functions with two systems or processes: System 1 and System 2. Think of these two metaphors as two wheels on a 1930s bike. Each wheel a little different from the other but together serving a unified purpose to make the bike move. These two processes work together to enable researchers to understand the patient’s individual memory. What are the differences between the two?

System 1 is intuitive, efficient and pattern recognition based. If you were to want to visualize reasoning in System 1, it would occur so quickly we wouldn’t even be able to recognize it as if it is a distinct cognitive process. Some core characteristics behind System 1 are that it is fast, unconscious, and automatic. Evidently, creating an everyday decision system that is error-prone.

In contrast, System 2 is an analytical cognitive process that is time-intensive and deliberate. It involves the conscious, explicit application of an analytical approach to arrive at a certain understanding. Some core characteristics behind System 2 are that it is slow, conscious and effortful. Evidently, this process can be used for complex decisions and is reliable.

Improving Recall

To not go too deep into the very elaborate ideas about improving general recall, the main idea lies in the forgetting curve. Hermann Ebbinghaus led an experiment in which he tested how well individuals remembered a list of nonsense syllables over increasingly longer periods of time. Using his experiment results, he created what is now known as the “Ebbinghaus Forgetting Curve.”

Ebbinghaus Forgetting Curve

After his research, Ebbinghaus concluded that the rate at which your memory decays is variable to the time that has elapsed and how strong your memory is. For example, how many syllables you remembered.

One technique that was derived from this curve to expand memory (non-invasively) was spacing. According to the spacing effect, when students repeatedly learn and recall information over a prolonged time span, they are more likely to retain that information. Shucks, no more cramming one day before an exam!

Implications of the Future

We all need memory to get through the day, to remember what makes one idea so amazing or one experience so unforgettable. Going beyond just the processes in question, with acknowledging the technology available, it is now time to ask ourselves a question: Do we want to expand the human memory?

As you will see with my next piece on Connectomics I’m testing our memory capacity limit and am therefore asking myself if through connectomic analysis and target-based answers we can not just try and implement it but live with it.

Acting as architects of the brain can be dangerous or beneficial, but the first step towards any of these exciting forks in the road is understanding the connections previously existing and the ones that one should target.

Ciao, I’m Anastasija, a 15 y/o innovator at TKS interested in the intersection between bioinformatics and biotechnology! Check out my website, connect with me on LinkedIn and follow me on Twitter!



Anastasija Petrovic

I’m Anastasija, a 17-year-old interested in the intersection between biotechnology and bioinformatics. I also write about mindsets and emerging technologies!