The Science of Memory
Like consciousness memory is both a psychological phenomenon and a physiological process. There are several different types of memory, many areas of the brain responsible for establishing them and an infinite number of things that will trigger them. And then there is the question of how our memory changes as we get older, and ultimately why we need to forget. It is this complexity that makes memory the second most complicated problem (after consciousness itself) neuroscientists face.
Like consciousness memory is both a psychological phenomenon and a physiological process. There are several different types of memory, many areas of the brain responsible for establishing them and an infinite number of things that will trigger them. And then there is the question of how our memory changes as we get older, and ultimately why we need to forget. It is this complexity that makes memory the second most complicated problem (after consciousness itself) neuroscientists face.
So what are the different types of memory?
Where in my brain are memories kept?
How does my memory change as I get older?
So what are memories?
On a psychological level memories are highly subjective and so difficult to quantify in any objective way. In terms of what is actually happening in your brain a memory is essentially when a cluster of neurons are activated at the same time. Scientists call the patterns created by these interconnecting neurons engrams and like tracks in a forest the more these patterns are activated the more engrained they become.
So what are the different types of memory?
Explicit, implicit, declarative, procedural, semantic, short term long term
Where in my brain are memories kept?
Memories are not kept in any one area of your brain, but are spread out depending on the type of memory (e.g. the cerebellum is where procedural memories tend to be kept) and whether it is short term or long term. In some cases memories even overlap and so trigger one another, hence why memories sometimes get stuck ‘on the tip of our tongues’.
Most relevant to learning, it is the limbic system where memories are transferred from short term to long term. The limbic system is also in charge of strong emotions so the emotional impact of an event, either positive or negative has a big influence on whether an event is stored in memory or not.
What triggers my memories?
Memories are triggered by a repeat of the sensory stimuli present when the memory was originally established. We all have sensory preferences so nothing is cast in stone but some sense do seem to provide a stronger trigger to our memories than others.
Sight
It has been shown that in the short term, we retain almost 100% of visual information. This drops to approximately 50% within 3 months
Smell
Research has indicated smell to be the strongest memory-provoker. This might be because the receptors for these sensors go directly into the brain through the olfactory bulbs to the hippocampus (part of the limbic system ), and require less processing than do the other senses.
Taste
Closely related to smell, taste is another strong sense. Tasting a meal again will elicit many related memories.
Sound
Sound stimuli can provide needed cues in memory retrieval. If, for example, you listen to a certain type of music every time you studied history, for example, you would have a better chance of remembering the facts you learned if you were hearing the same music as when you learned them.
Words are often stored in our memory by how they sound as well as by their what they mean. When you are learning a new language saying the words aloud as you read them will therefore give you more chance of remembering them.
Touch
How does my memory change as I get older?
Research indicates that memory may start to develop even before you are born. As a child your capacity for memory becomes increasingly sophisticated and then as you progress in old age your memory may deteriorate.
So let’s start at the beginning. Within a few days of birth most infants are able to recognize their mother's voice and face, and within a few weeks, their father's voice. The next big jump in memory ability occurs around nine months, when the child develops the ability to store and then recall memory, what scientists call ‘object permanence’. What this means in plain English is that if you put a blanket over the teddy bear, the infant will not be fooled, but remember the teddy bear is underneath. The plus side to object permanence is that it allows the baby to compare and connect new experiences to old ones. The down side, however, especially for parents, is that this ability also means the child remembers their parents when they are not in the room and starts to miss them.
A child’s memory is still not fully developed at this stage. Another key development is learning to speak. Without language children’s memories remain entirely non-verbal, something which may explain why we cannot remember our earliest childhood experiences. As language develops 24 so too does a child’s short term and long term memory.
Even when our memory is fully matured, we all know that it is not 100 % accurate. Even when we remember something clearly, it may not be as accurate as we think. This is because our memory has a habit of deleting, generalizing and distorting - it will fill in the gaps of half memories with what was probably true, it will take parts of separate memories and merge them into one new one and it will adapt memories to show us in the best light to name but a few.
Most scientists believe that, as we get older, our brain cells start to die off (perhaps a reduction of 5-10% if we were to live to 100 years of age. This used to provide the basis for theories about why our memory declines as we get older - from age 25 to 65, a normal person can have a decline in memory performance by as much as 40% (Hainsworth, 2000, p.21) with at least 65 % of people over 75 years old having some form of memory loss.
However, recent experiments show that new brain cells do grow in some parts of the brain to replace the dying ones. Even better news is that research has shown regular exercise and the conscious use of memory techniques such as the ones you can find in m e mory masters c an prevent this memory decline.
Why do we forget?
The answer to this question lies with another. Would you like to remember absolutely everything that happens to you? Imagine remembering every single second of every single day of your life. It would be very difficult to keep all the information organized and to focus on one thing at a time. Would you want to keep all of your most painful memories, the ones that show you in a bad light, let alone the thousands of advertising messages you are subject to on a day to day basis? Forgetting is actually both necessary and useful. There is just too much information to be remembered. Automatically we forget most of the sensory information we take in without even realizing it.
Firstly, most believe that ‘forgetting’ does not mean the memory has gone out of our brains altogether, but that we can no longer retrieve the information. Perhaps then, remembering is simply choosing not to forget.