Who has never forgotten where their keys were or the name of a person? We all experience memory lapses from time to time. But what is memory? Can it be improved and how is it affected by ageing?
Memory is our ability to recall past events. Memory is essential to our learning, as it is how the brain stores the information we learn. There is not one, but many memories. In fact, it seems that the different types of memory in humans involve different parts of the brain.
THREE TYPES OF MEMORY
A major criterion, that of the duration of the memory, makes it possible to distinguish three types of memory.
Sensory memory or register: this is extremely brief (from a few milliseconds to one or two seconds). It is simply the time it takes for our senses to perceive information. For example, when we eat a food, our register gives meaning to the sensory information transmitted by the taste. This allows the recognition of the food by recalling previous experiences with the same or similar food. Although it is very short-lived, sensory memory is essential for storing information in short-term memory.
Short-term memory (STM): also called “working memory”. It is the temporary memory of events in our lives, such as a telephone number that we remember while dialling it. It can be a face we meet in the street that stays with us for a short time or the subject matter of a course that we retain just long enough to take the exam. TCM is an immediate memory with a storage capacity limited to about seven items and lasts only a few tens of seconds.
Long-term memory: its storage capacity is unlimited and can last a lifetime. It contains our memories, learning and all the information we have made a conscious effort to remember. The names of our friends, the day of our wedding, the date of our spouse’s birthday or the way we tie our shoes are all examples of information stored in long-term memory.
Another criterion for understanding memory is whether or not we can verbalise a memory. This involves two main memory systems: declarative (explicit) memory and non-declarative (implicit) memory.
Explicit memory: this is a conscious memory. It contains semantic memory and episodic memory. Semantic memory is our general knowledge of the world, the meaning of words. It allows us, for example, to remember what a bird is, to use language and to define different colours.
Episodic memory deals with the facts and events of our lives. It is also called ‘autobiographical memory’. It is the memory of our old address, the number of visits to the doctor last year, our grade in an exam, etc.
Implicit memory: this is usually unconscious and includes procedural memory, which is know-how. This is used to carry out complex, often motorised, operations such as driving a car, making a coffee, brushing our teeth or dancing the salsa.
There are three main stages in storing information in memory.
1. Encoding of information: for encoding to be possible, it is essential to pay attention to what you want to remember. Attention is crucial at this stage because it allows us to filter the information and select what we want to retain (for example, a sentence underlined in a book, a piece of information in a conversation, a name in a list). Encoding sometimes requires an effort of concentration.
2. Consolidation of information: this process allows information to be stored in a durable way. This can be done, for example, by mental rehearsal.
3. Ability to recall information: the better the information is encoded, the better the recall. That is, if we pay attention to the name of a person we have just met, make an effort to remember it and repeat it to ourselves several times mentally, the chances are high that we will be able to remember his or her name the next time we meet that person.
MEMORY AND LIFESTYLE
There is no magic pill to improve memory. However, Dr Gary Small, from the University of California at Los Angeles, has shown that there are ways to improve it. And how? By improving your lifestyle. According to Dr Small, the recipe is simple: train and exercise your memory regularly, eat well, exercise and reduce stress.
As for the idea that you can learn by sleeping, it has never been confirmed. It is known, however, that we retain the things we learn during the day better after a good night’s complete sleep. The REM phase of sleep is thought to play a role in memory.
EVERYDAY TIPS TO IMPROVE MEMORY
Most of the time, those who seem to have an elephantine memory are simply people who use better memorization strategies than others. Here are some of them.
- Reduce interference: avoid multitasking and focus on what you are hearing or doing.
- Repeat: an effective technique for retaining information is to repeat it. Short-term memory is based on self-repetition.
- Visualise the information: associate ideas, make word games and visualise the information. These little tricks make sense of the information, which makes it easier to remember.
- Group: if you have a lot of things to remember, learn to group them together to make it easier to remember.
- Memorise out loud: feel free to repeat information out loud. Encoding information in different forms helps recall.
- No more than seven: remember that the storage capacity of short-term memory is no more than seven items (plus or minus two depending on the person). So there is no point in trying to memorise endless lists… unless you group things together.
- Use memory aids: according to neuropsychologist Sophie Brière, it is not true that when we use external memory aids (a diary, for example), we do not work our memory sufficiently, and its capacities will diminish.
The information we want to remember must be well structured, organised and encoded if we want to find it quickly later.
FORGETTING AS WE AGE, NORMAL OR NOT?
Ageing can affect memory by changing the way we store information. It can also affect memory by making it more difficult to recall information that the brain has stored. Neuropsychologist Sophie Brière explains that the ability to encode information remains with age, but that older people no longer spontaneously encode information. This is normal ageing. In pathology, the problem comes from consolidation. A memory disorder is considered serious when it affects a person’s daily life.
Here are some examples of memory problems that are not part of normal ageing:
- forgetting how to do things you have done many times in the past;
- repeating sentences or facts in the same conversation;
- not remembering what you do every day;
- losing your manners;
- having memory lapses more often than before.
Sophie Brière, neuropsychologist, puts a damper on this. Forgetting is a normal phenomenon and it happens at any age. Often, as people age, they become more worried about their memory and the slightest forgetfulness can cause stress. Stress causes a rise in cortisol in the system, which in turn short-circuits the neural circuits. When you forget someone’s name or where the car is parked, the best thing to do is to calm down. The memory will come back more quickly. If we are too anxious about our memory, it is best to consult a doctor.