From the moment we're born, we're learning. Learning, however, would be useless if we didn't have a way to store all the information we're learning and then access it later. Fortunately, memory takes care of that - memory allows us to process information, store information, and then access it later when we need it.
This may sound very simple, but it's actually quite complex. But have no fear, we'll break it down for you so it's not too tough.
You can think of human memory like a library. The purpose of a library is to store books, magazines, music, and other material. A library has a system of filing and categorizing the materials so they can be retrieved later. If books wear out from excessive use or get lost, they need to be replaced. Libraries obtain new books and materials every year that also need to be filed and categorized. If certain books are rarely used or never retrieved, they are removed to make room for new ones.
We don't know exactly how this process works or where memory is stored, however, researchers believe the parts of the brain that are used in this process are the hippocampus, thalamus, and amygdala. People who have damage to one or all of these areas are not able to store or retrieve information efficiently or even at all.
The hippocampus is in the temporal lobe of the brain, which is located just above the ears. One of its functions involves spatial memory, i.e. a person's ability to move about in the environment and know where he or she is located. It allows us to travel around in familiar cities or places we live and remember where things are. The hippocampus is also believed to be vital for long term memory. When there is damage done to the hippocampus, the ability to store new information is lost, however, the person can still remember things from before the damage took place.
The thalamus is located above the brain stem which is near the center of the brain. It is like a relay station that receives signals from our senses and then passes the signals to its corresponding area in the cerebral cortex. The thalamus receives signals from all our senses except smell. The thalamus also is responsible for motor control and states of consciousness such as alertness and sleep. The thalamus is important for the retrieval of memory, like the "librarian" of the brain. Not only does it send signals to the right areas of the brain, it is also the relay station to retrieve information later.
The amygdala is also located in the temporal lobe. It is responsible for our emotional perceptions of events. This is important to memory because it associates cues with consequences. When we remember how we felt when something in the past happened, the amygdala is at work. It is also used for the consolidation of long term memory. Researchers have found that the level of emotional arousal a person has when learning something affects its strength in long term memory. The more emotional arousal a person has, the stronger the memory will be.
Short Term Memory
Short term memory allows a person to recall something after a short period of time without practicing or rehearsing. George Miller wrote a paper on short term memory called "The magical number 7 +/- 2." He concluded from his experiments that we could retain 5 to 9 items with our short term memory without rehearsal. The amount can be increased if items are "chunked" together. Most people remember phone numbers in three chunked sets, the area code, the first three numbers, and the last four numbers. After a short period of time, this information degrades and becomes lost unless it is repeated or rehearsed.
Long Term Memory
Long term memory refers to retention of information over the long term from days to years. There are 2 types of long term memory, declarative and procedural. Declarative memory concerns historical events and knowledge of the external world. Procedural memory concerns remembering how to use objects and moving our body. For example, riding a bike would be considered a procedural memory. Remembering something that happened as a child would be declarative memory. Another difference between these two types of long term memory is procedural memory does not require conscious recall, while declarative memory does.
Long term memory is stored in many different places in the brain. Some theorists even believe some memories are stored elsewhere in the body such as the heart. When memory is stored, it tends to cluster together like the librarian in our example categorizes books. Information is connected together to related subjects that are meaningful and relevant to each other. The ways information becomes connected is unique to each person and the experiences they have had. For instance, coconuts remind me of my family. These two subjects may seem unrelated so let's track my thoughts to see how they are connected. If I think about coconuts, I see what the coconut looks like on the outside and inside, I know where it is grown, and I remember what it tastes like. As I remember this information, I think of coconut crème pie. Coconut crème pie is my favorite. Then I remember eating it on my birthday with my family because I don't like cake. This memory in turn brings up other information about my family, and so on.
There is no limit to how much information a person can store in long term memory although various brain disorders and damage can prevent or slow the process. Many techniques can aid and increase the likelihood that information will be retained long term. The next section will illustrate different ways to memorize and strengthen retention of information as well as describe some reasons why we may forget things.
The most important factor determining the transfer from short to long term memory is rehearsal. Consider the phrase, "Practice makes perfect." This phrase basically means that our ability is enhanced based on the amount of rehearsal we put in. People use this statement as though practice always results in a positive improvement. However, if we rehearse something incorrectly, we will get better.... at doing it incorrectly! Therefore, taking things slow and learning things correctly the first time is an important technique. It is harder to change inaccurate information and or behaviors once they have been stored in long term memory, e.g. habits.
Another important factor to consider when looking at practice is the time frame in which the practice occurs. Smaller increments of practice over time are stronger than "cramming" in one night. Anyone who has tried this method for test taking has learned that the hard way.
As stated before, emotions connected with memories also strengthen retention. Memories of trauma are very strong because of the emotions attached to them. This does not mean these memories are always completely accurate representations of what happened, however, because perceptions and other factors influence our memory and they can slowly change over time. Have you ever heard of someone catching a fish and the fish somehow gets bigger every time the story is told?
Other techniques for enhancing memory consist of using more than one of our senses to rehearse information. For example, reading a vocabulary list out loud will strengthen retention more than reading the list on the paper. Putting information together in meaningful ways such as poems, clusters, music or even rhythms also improve retention as well as retrieval of the information later. This explains why memorizing a list of nonsensical words is more difficult than remembering words that have meanings.
Memory is also strengthened by making connections and associations between new information and previously learned information. The more associations are made, the easier the information is to remember and access. Going back to our library analogy, books are easier to find when they are connected to more than one category. Therefore, if we learn a concept and then connect it will similar things we already know and distinguish it from opposites, we will be able to remember it better.
Don't forget about forgetting
When we forget things, it is often a problem of encoding. Perhaps we were distracted while trying to learn information or while we were doing something. For instance, how many times you have lost your keys or misplaced the remote control? Perhaps you were thinking about something else when you put your keys down. Distraction reduces encoding efficiency while memory requires conscious attention. Thus, distraction explains why you put your keys in the refrigerator and threw the remote control in the garbage can.
Perhaps you weren't distracted but also didn't make enough associations to strengthen the memory of where you put your keys. This leads to an inability to retrieve the memory of where you left them. You may be able to imagine several possible places they could be but can't quite remember which. A common solution to this is to "retrace your steps." In essence, "retracing your steps" goes through all the associated locations in your mind until you find the correct one that is connected to the keys' location.
Disorders that affect memory
Alzheimer's: Alzheimer's is a disease of the elderly (usually seen in patients aged 65 or older) in which the brain slowly degenerates. The symptoms are confusion, memory loss, problems with verbal expression, emotional liability (means they switch moods frequently), and a progressive loss of bodily control that leads to death. In the advanced stages of Alzheimer's, patients are unable to recognize significant others, they may wander off aimlessly, and they are not able to care for themselves.
Dementia: Dementia is defined as the loss of previous cognitive ability and function. It is a name of a symptom rather than an actual disorder. For instance, Alzheimer's is a disease that includes dementia as a symptom. People with dementia may have damage to long term memory, short term memory, or both.
Huntington's Disease: Huntington's is a degenerative disease that affects muscle coordination as well as cognitive impairment. It is usually diagnosed in between 35 and 44 years of age. The symptoms are jerky movements or abnormal posturing, personality changes, dementia, general physical instability, sleeping problems, and seizures.
Parkinson's Disease: Parkinson's Disease is a degenerative disease of the central nervous system (the system responsible for coordination of movement). The symptoms are stiffness, tremor, and slowing of movement. Patients may or may not experience loss of cognitive abilities such as memory. Many people experience a slowing of cognitive function and others progress into dementia.
Schizophrenia: Schizophrenia is a disease most known for symptoms of visual and auditory hallucinations, however, it also involves many other cognitive deficits. Some of these symptoms are delusions, inability to experience pleasure, problems with memory, language, and problem solving to name a few. People suffering from schizophrenia believe in their delusions and or hallucinations so strongly because they are unable to distinguish true memories and reality from their symptoms of unreality. If you have ever had someone try to tell you something you remembered didn't really happen, you are a little closer to understanding how schizophrenia feels.
Read this Comprehensive Essay on Memory: Meaning, Nature and Types of Memory !
Meaning and Nature:
Memory is one of the important cognitive processes. Memory involves remembering and forgetting.
These are like two faces of a coin. Though these two are opposed to each other by nature, they play an important role in the life of an individual.
Remembering the pleasant experiences makes living happy, and on the other hand remembering unpleasant experiences makes living unhappy and miserable. So here forgetting helps individual to forget unwanted and unpleasant experiences and memories and keeps him happy.
In this way, remembering the pleasant and forgetting the- unpleasant both are essential for normal living. In the case of learners, remembering is very important, because without memory there would be no learning.
If learning has to progress, remembering of what is already learnt is indispensable, otherwise every time the learner has to start from the beginning.
The memory is defined as ‘the power to store experiences and to bring them into the field of consciousness sometime after the experience has occurred’. Our mind has the power of conserving experiences and mentally receiving them whenever such an activity helps the onward progress of the life cycle.
The conserved experience has a unity, an organisation of its own and it colours our present experience.
However, as stated above we have a notion that memory is a single process, but an analysis of it reveals involvement of three different activities- learning, retention and remembering.
This is the first stage of memory. Learning may be by any of the methods like imitation, verbal, motor, conceptual, trial and error, insight, etc. Hence, whatever may be the type of learning; we must pay our attention to retain what is learnt. A good learning is necessary for better retention.
Retention is the process of retaining in mind what is learnt or experienced in the past. The learnt material must be retained in order to make progress in our learning. Psychologists are of the opinion that the learnt material will be retained in the brain in the form of neural traces called ‘memory traces’, or ‘engrams’, or ‘neurograms’.
When good learning takes place –clear engrams are formed, so that they remain for long time and can be remembered by activation of these traces whenever necessary.
It is the process of bringing back the stored or retained information to the conscious level. This may be understood by activities such as recalling, recognising, relearning and reconstruction.
Recalling is the process of reproducing the past experiences that are not present. For example, recalling answers in the examination hall.
It is to recognise a person seen earlier, or the original items seen earlier, from among the items of the same class or category which they are mixed-up.
Relearning is also known as saving method. Because we measure retention in terms of saving in the number of repetition or the time required to relearn the assignment. The difference between the amount of time or trials required for original learning and the one required for relearning indicates the amount of retention.
Reconstruction is otherwise called rearrangement. Here the material to learn will be presented in a particular order and then the items will be jumbled up or shuffled thoroughly and presented to the individual to rearrange them in the original order in which it was presented.
Types of Memory:
There are five kinds of memory. These are classified on the basis of rates of decay of the information.
a. Sensory memory:
In this kind of memory, the information received by the sense organs will remain there for a very short period like few seconds. For example, the image on the screen of a TV may appear to be in our eyes for a fraction of time even when it is switched off, or the voice of a person will be tingling in our ears even after the voice is ceased.
b. Short-term memory (STM):
According to many studies, in STM the memory remains in our conscious and pre-conscious level for less than 30 seconds. Later on this will be transferred to long-term memory.
c. Long-term memory (LTM):
LTM has the unlimited capacity to store information which may remain for days, months, years or lifetime.
d. Eidetic memory:
It is otherwise called photographic memory in which the individual can remember a scene or an event in a photographic detail.
e. Episodic memory:
This is otherwise called semantic memory which is connected with episodes of events. The events are stored in the form of episodes and recalled fully in the manner of a sequence.