Memory is defined in a number of ways by different psychologists. One of the widely accepted definitions of memory is that it is the ability of the mind to encode, store, and retrieve information, facts, and learning.

These three terms (encoding, storage, and retrieval of information) are important because they constitute three stages of memory. Therefore, these three stages will be explained in detail in this article to understand the complete process of memory, but let’s first discuss its importance briefly.

Memory is an important quality of human beings. We remember our locations, friends and even our own Identify with the help of memory. We can speak our language as well as some foreign languages due to our memory. Without memory, there would be no learning. We would not remember the happiest moments of our life and would not be able to regret our mistakes. Everything would be strange and new to us. The importance of memory can be realized more clearly by those who unfortunately experience memory problems such as patients with Alzheimer and dementia.

As noted earlier, there are three stages (or levels) of memory: 1) encoding, 2) storage, and 3) retrieval of memories. These three stages unveil the process of forming memories, as explained below.

Encoding means to covert information into codes. The information, that we receive, is converted into codes (or a specific form) so that it can be stored by the brain. Take the example of computer’s hard disk that stores information. Any information that is input into the computer is converted into specific codes and gets stored in the form of these specific codes on the hard disk. For instance, a person with good knowledge of a computer can understand that the video file on the hard disk is basically stored in the form of numerical codes. This example may confuse you a bit because when we click on a video file, it opens as a video rather than codes because this is when the codes (as in stored form) are retrieved back into the form of video (retrieved form). 

When an individual receives information whether visual (through eyes), auditory (through ears) or any other form, the received information is first encoded – converted into a specific form of codes which can be stored by the brain. There are two main methods by which the information is encoded: automatic processing, and effortful processing, as explained below.

(A) Automatic processing 

Automatic processing is that process, in which, the encoding occurs automatically without requiring our conscious attention. Information is encoded with great ease and without our active effort for remembering things. For instance, while walking on a roadside, you see a car badly damaged in an accident. At night when you are at home on your bed, you may remember that you saw a car that was damaged in an accident and may think about it for a few seconds. Though you did not want to memorize this information intentionally, but this information was automatically processed within your brain when you saw the car.

In our routine, we come across many situations providing us with information which we may not intend to make part of our memory (because either the information is not important or not relevant to us) but still some information becomes part of our memory unconsciously and we are able to recall it later on, if we tend to think about it later on. This is because of the automatic processing of information into codes that occurs unconsciously and without our intention.

Automictic processing generally operates more in relation to situations and things that we are more familiar with. For instance, when an individual listens to a song sung in a native language, his mind may grasp pieces (words or phrases) of the song easily. On the other hand, while listening to a song in a foreign language (particularly the one that the individual cannot speak or understand), the mind, as an automatic process, may grasp relatively less pieces (words or phrases) of the song.

(B) Effortful processing

Effortful processing of encoding occurs when we want to store information with our conscious effort. In such a case, we need to store information intentionally and thus, we pay proper attention to it in an effort to make it part of our memory. Some information may not be easy to be memorized which also require rehearsal or revision in order to be memorized. 

A common example is that when we need to memorize the phone number of someone. Generally, it is not easy to memorize a phone number simply by looking at it once or hearing it once. Therefore, we may repeat it several times to memorize it. Another example is when a student wants to learn some topic in his book. The student may learn the topic easily, but he also wants to retain this learning in his mind for a long time so that he can reproduce it in the exam. Therefore, he may repeat studying the topic several times and paying proper attention to it in order to be able to retain the learning for a longer time.

There are many factors that influence effortful processing. They are as follows.

(a) Spacing effect vs cramming 

In the spacing effect, the information storing process is divided into multiple periods of time. It means that the individual repeats learning the same information after some period of time to memorize the information. For instance, a man wants to learn how to drive a car. He starts driving a car with a driving instructor for an hour a day (on separate days) until he learns it fully (in other words, until he makes learning part of his memory).

In cramming, the individual attempts to memorize information in a single period of time rather than in divided several periods of time. It may also involve repeating learning the same information but takes place in one attempt or one period of time. Cramming is relatively a speedy process of memorizing information but is a short-lived memory whereas the memory produced by spaced learning lasts longer.

(b) Serial position effect

The serial position effect is a psychological effect that an individual who tends to remember the first and last items occurring in a series better than the middle items in the same series. For instance, if an individual is given a list of items (such as grocery items: milk, eggs, bread, sugar, tomatoes, apples), he is likely to remember the first and last items easily but may find it a bit hard to remember the middle ones.

The term serial position effect was first introduced by Hermann Ebbinghaus who explained how things occurring in series may affect memory. The ease to remember the first and last items is attributed to the primary effect and recent effect. The first item is remembered due to the primary effect because the first item provides the very first impression (or primary impression) to an individual which is readily accepted and processed by his mind. The last item is remembered because the last item provides the most recent impression (or last impression) which is still fresh in the memory.  

The process of encoding visual information such as images is called visual encoding. The visual information is first encoded as a mental image in the iconic memory and is then transferred to the long-term memory. The part of the brain, called the amygdala, plays an important role in visual memories.

(b) Acoustic encoding 

The process of encoding auditory information such as sounds and words is called acoustic encoding. The received auditory information is modified into codes and stored in the brain for long-term memory. This is why we can recognize the voice of our father, mother, brother and sister, even if they sometimes call us from a different phone number. We can distinguish between the voices of different people because these voices have been modified into different forms (or codes) before getting stored in the brain. Another aspect of acoustic encoding is that the more frequently we hear someone’s voice, the more it strengthens as part of our memory.

(c) Semantic encoding 

The process of encoding sensory input, that has a specific meaning or context, is called semantic encoding. The characteristic of having a specific meaning means that there is an association between the sensory input and the meaning. This association can be straight or opposite, but an association does exist which calls for semantic encoding.

For instance, we generally remember a specific date because something important had happened on that very date. Since there is an association between the date and the important event that took place on that date, this association helps us remember the date for a fairly long time (sometimes for years). Another example is memorizing a definition of the concept because we have to memorize a definition in association with the name of the concept (which is being defined).

Semantic encoding involves chunking where two or more things are organized into a meaningful whole in order to be stored in the memory.

As noted earlier, sensory input can also have an opposite (or non-straight) association with the meaning. For instance, some words may be used with different connotations rather than their original meanings. Their connotations may be different from their real meaning, but since they are used in association with these specific words, memorizing such information also involves semantic encoding.

Storage is the second stage of memory formation. After the information is encoded into a storable form (in the first stage), it is stored in the brain (in the second stage). Information can be stored in short-term memory or long-term memory. The information that is stored in short-term memory lasts for up to 30 seconds, whereas if is stored in the long-term memory, it lasts for a relatively longer time – sometimes for up to years.

There are many factors, based on which, the information may be stored either in the short-term memory or in the long-term memory. One of the main factors is attention. For instance, while walking on a roadside, you may see many people and things, but you may not remember all of them. However, if something on the roadside catches your attention, it goes into your long-term memory and is retained in the memory for a longer time. Another important factor is the frequency of coming across something. If we see or hear something more frequently, it is retained in our memory for a long time. 

An important point to add here is that information is stored in different regions within the brain, if any of these regions get damaged or destroyed, the memory in that specific region will be lost.

The term retrieval means the process of getting something back from somewhere.

Memory retrieval means to get back the information that is stored in the brain. The information, that was previously encoded and stored in the brain, is now recalled back. This recall process is called retrieval. There are two methods of recalling information, as explained below.

1. Recognition

Recognition means that we recognize something when we come across it because its information is already stored in our memory. The object is physically present, and information about it (stored in our mind) helps us recognize it. For instance, if we see a friend at a store, we recognize him because his information (e.g., face image, voice, height, body structure etc.) is already stored in our memory due to our previous interactions with him.

2. Recall 

In the process of recall, the object is not present, but the brain retrieves stored information to help us remind it. For instance, a student has to write an answer in the exam which he had studied a day (or more days) before the exam. The student has to retrieve the information (obtained through studying a book) that is stored in his memory in order to write the answer. Another example is to remind oneself of a past event (e.g., a party, get-together friends, wedding ceremony) that he had enjoyed a lot.