How Memory Works and Why We Forget Certain Things and Not Others
A friend of mine from gather.com asked me to write about human memory; a topic he is very interested in.
Memory is behind everything we do from remembering information needed to passing an exam, to remembering a phone number or somebody’s name, to remembering how to talk or even how to walk. Memory is the underlying factor behind everything we do.
Memory is a very complicated process and there are all sorts of ways human memory works well or not so well. To start with, I will say that we have several different ways of using memory and two different centers in the brain for storing memory. Basically there are long-term memory center in the brain and short-term memory center.
The topic of memory is at the heart of the branch of psychology called cognitive psychology. Cognitive psychology deals with our mental processes, how we think, how we feel, how rationalize things, and of course how we remember things. Then after we do all these things cognitive psychologists examines how these processes affect our behavior. To illustrate using an example from memory, if you meet and old dear friend in the mall that you haven’t seen in years, think of what your reaction would be. Now think of bumping into that same person and yet he is a stranger to you, or perhaps you get a feeling you may know him but you just can’t figure out how. You probably would react differently in each situation, in the first situation you may run up to him, hug him, shake his hand, and engage in a conversation, in the second situation you may give him a dirty look mumble under your breathe and move on. In the third situation you may go up to him and explain how you feel you may know him, or you may be too shy or embarrassed and just move on. Sometimes you will tell your family and think about it for days wondering why do you feel you know this person. Every situation about this memory or lack of memory will change your behavior.
There are three steps involved in the memory process.
First, the brain encodes all the information it encounters. This means it must transform sensations, images, sounds, visual information, tastes, touch, and so on into meaningful information. Many psychologists refer to the brain as a human computer and in this sense it is. Computers encode data into a binary code of 1 and 0’s, which it will then transfer into data that makes sense to us.
A physiological change in the body must occur for memory to be stored. Memory is stored in a short-term memory center or a long-term memory center in the brain. This too would be similar to a computer that stores information in a hard drive.
Retrieval means taken the information out of the brain storage centers and reversing the encoding so that the brain can translate this information into meaningful information that we call a memory.
There are three different kinds of memory: sensory memory, short-term or working memory and long-term memory.
Sensory memory refers to everything from the outside world and even the inside that we see, fee, hear, taste, and recognize. It is memory derived through our senses. This memory only lasts for a few seconds and goes directly to the brain. There is a reason it only lasts for a second. We are bombarded with millions of things each minute of the day, from important things we need to remember to the sound of a pencil dropping on the floor. Could you imagine what it would be like to remember every time somebody coughed, or sneezed or dropped a pencil, or to remember every rainstorm in detail? It is way too much information and our brain would go into information overload, so that is why this type of information is not remembered.
Short-term memory centers can be found in the prefrontal lobes of the brain. Language memory would be in found in the left hemisphere of the brain in what is called the Broca area, and the Wernicke area. What is known as the phonological loop, will involve language memory and spatial and visual memory in the right hemisphere of the brain. The short-term memory here seems to be in the occipital cortex.
Because it would be a daunting feat to remember everything that happens around us for as long as well live, we are programmed to remember certain things. These are the things that grab our attention or things we want to remember. This kind of memory is called working memory. It is the memory that we use every day for routine things and it too has a limited memory span. There is also a reason for that as well. Just like we don’t want to remember every single time everyone coughs; there are things that are important to remember for a short period of time but not forever. For example, if you at a movie and you meet someone you know and you begin to talk and the person says tell your mother I said hi. You may want to remember that long enough to get the information back to your mother, but it may not be important enough to remember it the rest of your life, especially if you see this person quite often. On the other hand, it may have significant importance if you find out later that you will never see this person again due to a terminal illness or other factors. When that situation occurs the memory may be transferred into long-term memory. Another example of working memory would be to remember a phone number long enough to get to a piece of paper and pen to jot it down.
Studies have shown that when a person is speaking to us, we can only remember as many exact words as we ourselves can speak in two seconds. Individuals who speak fast have a longer working memory than people who speak slowly.
You might say, “but I remember whole conversations,” you do, but you have already began to paraphrase, you are no longer using the same words the speaker did or in exactly the same order. Even then you may tend to leave out parts of that conversation, either because you really weren’t able to remember everything or your brain never found that piece of information important enough to remember. For example, you are having dinner with a friend who is telling you about a great summer vacation. You will remember the essence of what he is saying. You would never remember exactly word for word how he said it and you may not remember he said the waiter was busy, because it is not important to you. You may not remember that he coughed at one point while telling his tale, but you may remember he said the waiter tripped and fell into his lap, because that is something very unusual.
Long-term memories are the memories that are stored in the brain for life. Long- term memory is stored in the hippocampus, entrohinal cortex, and perirhinal cortex; there is also activity in the amygdala. Declarative memory, which is the long-term memory you have for remembering facts, is stored in the diencephalons and the hippocampus. Procedural memory is the memory you have for certain procedures, such as how to walk, talk, ride a bike, paint a house, and so on. This memory is stored in the amygdala and the cerebellum.
No doubt if you are getting older you have wondered how is that you can remember your first dog’s name and you were only three years old at the time, yet now that you are over 50 you can’t remember something that happened a few month ago. That is because again, when that situation happened a few months ago, it depends upon how important was it to you at the time if it was not that important it may never get transferred over to the long-term memory centers. The storehouses in the brain for short-term and long-term memory are in different locations. Some memories are transferred to long-term memory such as what we learned in school, and some are just not deemed important enough and so never gets transferred over. Back to the example of the waiter falling into your friend’s lap, for a short-term memory it may have had significance, but for a memory that you want to retrieve 30 years later, maybe it is not so important at all.
Also it is important to note that forgetting something in long-term memory does not necessarily mean it is permanently lost. It can mean that it is not accessible at the time you need it, but it is still there in the brain’s memory stores. For example, how many times have you had a conversation with someone and you want to mention the name of a celebrity and it just won’t come to you. You will explain everything you know about this celebrity. For example, you might talk about the movies or songs he or she recorded, you may even see his or her face vividly in your mind, but you just can’t think of the person’s same. If the person you are talking to does not have a clue of whom you are talking about, it can get pretty frustrating. Then a few days later you are at the sink washing dishes and out of nowhere it comes to you, and you may even yell out, “James Garner, that is the actor I was talking about!” This is because that long-term memory was never lost. It was just not close enough to consciousness at the time you wanted it.
Disease or accidents can damage the brain’s memory capacity. For example, Alzheimer's disease begins by affecting the short-term memory. You will often find that an early stage Alzheimer’s patient will not be able to remember what you said to him or her five minutes later, but still can tell you all about his or her childhood that took place 40 or 50 years before.
There are also false memories to consider. This happens when new information is added to older memories and we mistakenly think it is still part of the same original memory. For example, let’s say you used to go strawberry picking with your grandmother every year from the time you were 5-years-old to the time you were 16. This is the original memory, and at this time it was only two of you who went together. But let’s say when you were 8 years old, your big brother decided to come along. This is new information and new memory. However, now that you are 40 years old, you are explaining this memory to your own children as you take them strawberry picking. You might tell them that you, your grandmother, and your big brother always went strawberry picking each year from the time you were 5 years old. Your memory has been altered, but you do not realize that it has. You might continue remembering the altered memory, or it might be corrected if big brother is on the strawberry picking experience with you and your family and reminds you that he was never with you when you were 5 years old as he only started strawberry picking when he was 12 years old, which made you 8 at the time.