Types of memory: how does the human brain store memories?

Episodic, short-term, long-term, semantic? What types of memory are there?

What we commonly know as memory (remembering something) is usually a general concept, because we usually speak of memory long-term.

But there are other types of memory, such as short-term memory and sensory memorywhich are involved in the formation of this more durable memory. In fact, through several decades of scientific research, it is known that these different varieties of memory follow different logics and are based on different parts of the brain. Let's see what their characteristics are.

One memory or many kinds of memory?

If we start to reflect on the capacities of the human being, it is very likely that we will come to the conclusion that our species is characterized by a good memory.. Every day we learn and memorize things about the environment in which we live: who is the new president of a distant country, where we can find a national park whose photos have surprised us, what is the meaning of a word we didn't know, etc.

Compared to ours, the memory of other animals seems to be dwarfed. After all, they do not have a language from which to memorize complex concepts that refer to elements they have not seen directly. But... is memory really just that?

After all, many migratory birds memorize the places they have to pass through to travel thousands of kilometers each year on their journey from North to South and vice versa. In the same way, salmon memorize the point in a river where they have to spawn and arrive there, after much effort and having spent a long time at sea. Are these examples not proof that there are different types of memory?

The types of memory, summarized

The different types of memory have their own particular way of functioning, but they all cooperate in the process of memorization. Memory helps us adapt to our environment and marks us in defining who we are; our identity. Without it we would be unable to learn, nor would we be able to make sense of our surroundings or ourselves.

On the other hand, the information that memory "archives" does not remain stored without being altered; it is constantly being modified, even if we are not aware of it. However, the contents we memorize are altered through somewhat different mental processes, just as they are assimilated and internalized by the brain in different ways.

But what are the types of memory? But what types of memory are there? What are the stages of memory? Below we will answer these questions and explain how human memory works and how it allows us to recall events, data, experiences and emotions that we have experienced in the past.

Early research on memory

The first research on memory has its origin in the studies of Hermann Ebbinghausa German psychologist who, at the end of the 19th century, tried to decipher the fundamental laws of memory. attempted to decipher the fundamental laws of memory by studying nonsense syllables (bat, sit, het). (BAT, SIT, HET).

Ebbinghaus' theory of memory

One of his most outstanding achievements was the demonstration that higher mental functions could be studied in the laboratory in a scientific manner. He also concluded that there was a "forgetting curve", which shows the deterioration of memory over time from the time of learning. In addition, he formulated a theoretical model in which he formulated a theoretical model in which he argued that the mechanism of memory requires repetitionin order for the data we remember to be associated with each other.

Barlett takes the study of memory out of the laboratory.

Ebbinghaus succeeded in having his approach used for many decades, what became known as "the verbal learning tradition," but in 1932, Sir Frederick Barlett began his studies of memory functioning in natural environments (Ebbinghaus conducted his memory studies in the laboratory), giving rise to a new paradigm. Barlett, instead of using nonsense syllables, used stories, and introduced the schema theory to his research to explain its influence on memories..

In addition, he proposed that human beings remember through a general impression by means of a general impression with some detailsHe also proposed that human beings remember by means of a general impression with some details, and that from such components they construct a version considered as close to the original; memory works with schemas, not with faithful replicas. Although he was criticized for his lack of methodological and statistical rigor, he stands out for his adherence to the constructivist theory of memory and for his contributions on the cultural formation of memory.

Miller and the current paradigm on how we store memories

Two decades later, in 1956, George Miller demonstrated that people can retain 5 to 7 items at a time in short-term memory. These items can be a single letter, a number, a word or an idea. Currently, there is a certain consensus in cognitive psychology that a person interprets information based on his or her previous knowledge, and thus constructs his or her memories. It is therefore important to emphasize that not all the events experienced are stored, because there is a selection of relevant facts, and what is not interesting is eliminated.and what is of no interest is eliminated. In addition, the events experienced undergo a process of structuring and interpretation and, therefore, what is remembered is a perceived reality.

Experts in the study of memory agree that not only the cerebral cortex is involved in the memory process but also the cerebral cortexbut that other brain areas also participate in this process, for example the limbic system. limbic system. It has also been shown that the left hemisphere processes verbal information, and the right hemisphere processes visual information. The ability to retain words is less than the ability to remember images.

Phases of memory: encoding, storage and retrieval

As Brenda Milner demonstrated after her research with patients with memory disorders, memory is not located in one particular place in the brain, but rather consists of several systems that enable what are known as the three phases of memory: encoding, storage and retrieval.The encodingencoding storage and retrieval.

• The encryption is the process in which information is prepared so that it can be stored and retrieved.. In this first phase of memory, the individual's concentration, attention and motivation are very important.
• The storage consists of retaining data in memory for later use..
• The retrieval allows us to be able to information when we need it, i.e., to remember..

Classification and types of memory

There are different types of memory, and William James (1890) was a pioneer in formulating the distinction between the two, as he he concluded that there were primary and secondary memories..

Later, Richard Atkinson and Richard Shiffrin's so-called multistore theory appeared, which understands that information passes through different memory stores as it is processed. According to this theory we have three different types of memory: the sensory memorysensory memory, short-term memory (STM), short-term short-term memory (STM) and long-term memory (LTM). James' primary and secondary memories would refer to the STM and LTM respectively.

Sensory memory

The sensory memorywhich comes to us through the senses, is a very brief memory (lasting between 200 and 300 milliseconds) and immediately disappears or is transmitted to short-term memory.

Mnesic information remains the necessary time for it to be selectively attended and identified in order to be processed later. Thus, its usefulness has to do with the here and now, everything that happens in the present moment and to which one has to react in real time. The information can be visual (iconic), auditory (echoic), olfactory, etc.

Short-term memory

When information has been selected and attended to in the sensory memory, it passes to short-term memory, also called working memory or working memory.. Its capacity is limited (7+-2 elements), and it performs two functions. On the one hand, it keeps information in the mind when it is not present. On the other hand, it can manipulate this information allowing it to intervene in other higher cognitive processes, and therefore, it is not a mere "memory box".

Baddeley and Hitch, in 1974, instead of calling it "short-term memory", they called it working memory because of its functional importance in cognitive processing, since it enables the performance of cognitive tasks such as reasoning, comprehension and problem solving. Through this concept, the idea that long-term memory depends on short-term memory is abandoned, and this type of memory is fragmented into four subcomponents:

• Phonological loopThe phonological loop is a specialized system that operates with verbal information, and allows to maintain the internal speech that is involved in short-term memory, which is involved in reading or learning a telephone number.
• Visuo-spatial agendaThe phonological loop operates similarly to the phonological loop, but its function is the active maintenance of information, but in this case in an image format, visuospatial. The visuospatial agenda would intervene, for example, or in the learning of an itinerary.
• Episodic storeThis system integrates information from a variety of sources, so that a multimodal (visual, spatial and verbal) and temporal representation of the current situation is created.
• Executive systemIts function is the control and regulation of the entire working memory system.

Long-term memory

The long-term memory allows to store information in a lasting way, and we can classify it into implicit and explicit memory.

Implicit memory

The implicit memory (also called procedural) is stored unconsciously. It is involved in the learning of various skills and is activated automatically. Riding a bicycle or driving a car would not be possible without this type of memory.

Explicit memory

The explicit or declarative memoryis associated with consciousness, or at least with conscious perception. It includes objective knowledge of people, places and things and what they mean. Therefore, two types are distinguished: semantic and episodic memory.

• Semantic memorySemantic memory: This refers to the mnesic information we have accumulated throughout our lives. It is the knowledge about the outside world (historical, geographical or scientific), the names of people and things, and their meaning, that we have learned throughout our lives. This type of memory is necessary for the use of language. Knowing that Madrid is the capital of Spain is an example of this type of memory.
• Episodic memoryThis is the autobiographical memory that allows us to remember specific events or personal experiences, such as the first day of school, the birthday at age 18 or the first day of university.