MEMORY....
Human beings are learning all the time, storing information and then recalling it when it is required.
Massive volumes of information are being received continually. But only some of this information is selected and stored, and so becomes available for recalling later when required. Selection seems to be necessary as otherwise it may take far too long to recall any specific memory or possibly because we may not have sufficient capacity for storing everything in our brain.
But on the other hand we may not be able to recall a specific memory when we want to remember it, some stored information may have been forgotten.
TYPES OF MEMORY
Memory and memories have been defined or classified in different ways. Established is that there are two main types of memory, namely 'procedural memory' with information about how to proceed when doing something, and 'declarative memory' which contains what we know.
Both procedural and declarative memories are long-term memories and we also have a working (short-term) memory which enables the brain to evaluate the mass of incoming information and select what is to be retained and memorised and what is to be rejected.
Distinctions have been drawn also between different kinds of memory and memories, such as semantic (verbal), episodic (events as part of a sequence), eidetic (detailed mental images) and visual (images as seen). In addition to what we see, we also remember other sensory information such as sounds, smells, tastes and what we touch.
Procedural Memory
This memory stores information about how to proceed when doing something, stores information such as how to drive a car, play football or play an instrument.
This type of memory is long-lasting. The memories are actions, habits or skills which are learned by repetition and which can be changed by many repetitions, by training.
Declarative Memory
This is long-term memory and it contains all you have experienced or learned, all the information gained by you from childhood onwards.
No one really knows where this enormous database is located but it seems that each type of component memory is located in a kind of memory location of its own.
Associating Memories and their Components
Suppose we remember a person saying something. The component parts of this memory, components such as shape of face, sound of voice, colour of hair, are stored in different locations. They are associated with each other, cross-indexed if you like, so that a memory can be recalled from remembering just one of its components. Component memories are continually being associated with other old or new component memories, enormously increasing the range and flexibility of what can be recalled.
And so we may be able to recall a person's name by remembering the colour of his hair, or the shape of his face.
Working Memory
The working memory enables the brain to evaluate the mass of incoming information and select what is to be retained and memorised and what is to be rejected.
External Memory
In addition we have the vast mass of externally prepared and stored information which is accumulating. It has accumulated ever since people told stories to their young who in turn retold them to later generations and ever since writing was invented and the printed word accumulated, followed by pictures, photographs, films and videos, television and computerised manipulation of text and images. All of which spread and proliferated together with corresponding search (recall, retrieval, associating and selecting) procedures.
STORED INFORMATION (PERCEIVED CONTENT)
Much of what we are storing includes semantic information, that is information which consists of words and is about words, information relating to what words mean and imply.
And images, that is scenes, including events and sequences of events, and their components.
Including what happened, when it happened and the sequence in which it happened.
People with an eidetic (image-retaining) memory remember images, often clearly and in detail <1>. "Many, if not all, young children apparently do normally see and remember eidetically, but this capacity is lost to most as they grow up. What is in young children an apparently general capacity has become a remarkable rarity in adults."
The information one receives may be fact or fiction, right or wrong, intended to inform or to mislead, understood or misunderstood. Even so, what is stored is the perceived content of the received information.
LEARNING (MEMORISING) AND UNDERSTANDING
Rose defines an animal's learning by "learning is a response by an animal to a novel situation such that, when confronted subsequently with a comparable situation, the animal's behaviour is reliably modified in such a way as to make its response more appropriate"
Pointing out that human memory is very different from that of a non-human animal, Rose says that "procedural memory dominates the lives of non-human animals, ... but declarative memory profoundly shapes our every act and thought." Our memory includes a verbal memory which "means the possibility of learning and remembering without manifest behaviour."
But our memory consists of much more than just verbal memories.
Continually associating new information with older information, and older information with other older information, is much more than random cross-referencing.
It is because of the meaningful way in which we associate over such large volumes of stored information, that the process of associating amounts also to the seeking of meaningful associations.
So to me it seems that all the information we take in and retain results in a more comprehensive view and deeper understanding of the world in which we live, of our social organisation and physical environment. Thus, in the end, at some time and in some way, the information we have taken in affects and changes what we do, changes our behaviour.
DEVELOPMENT OF BRAIN FUNCTIONS IN HUMANS
Development of Brain Functioning in Foetus and Newborn
Rose describes how the human brain develops before and after birth, saying "Early brain development in the foetus and newborn is itself associated first with a massive proliferation of cells, and then by a steady drop in numbers, but the space once occupied by the lost cells is taken up by an increase in the branching and synaptic connections made by those that remain."
Role of REM Sleep in Infants
Lavie pointed out that in animals which are born fairly mature, such as sheep, REM sleep is low and near adult level. In species which are born immature, "such as rats, cats, and humans, initial amounts of paradoxical (REM) sleep are very large. In kittens, during the first ten days of life paradoxical (REM) sleep occupies 90 percent of their time."
We already saw that Jouvet hypothesised that one of the roles of REM sleep in animals was to train the neural networks which are related to instinctive behaviour.
We also saw that during the first few days after birth the actual amount of REM sleep in babies is very great and Lavie concluded that "it plays a vital role in the maturing stage of the nervous system" and that "it is possible that REM sleep is particularly important for procedural types of learning in which humans acquire motor and perceptual skills. Since during the first few months of life infants are busy acquiring new motor and perceptual skills, these findings may also explain the abundance of REM sleep at that particular time in our life".
Stevens says "REM sleep is thought to play an important role in developing the infant brain and in activating those neural programmes responsible for basic and characteristic patterns of behaviour, such as maternal bonding, environmental exploration and play."
He added that common childhood fears "of the dark, of strangers, of rapidly approaching objects, are all ... early warning devices put there by evolution because of the constant dangers in the ancestral environment".
Children do not distinguish between dreams and waking life until they are three or four years old, but can usually understand the difference when between five and eight years old.
Changes in Sleep-wakefulness Rhythm during First Year of Infant's Life
A baby wakes and sleeps roughly every four hours in its first month. This changes gradually until at about six months "the baby begins sleeping almost through the night and the sleep-wakefulness rhythm stabilises at twenty-four hours". And so during the first year "a single and continuous sleep period and a period of continuous wakefulness begin to emerge, and at the same time a pattern of coordination between the sleep-wakefulness rhythm and the demands of the external environment slowly begins to develop".
Lavie notes that it is during the first months of life that the longest duration of REM sleep occurs and that this coincides with the time when sleep becomes consolidated into a single and continuous sleep period.
Learning by Playing and by Experience
Playing is a way of learning how to behave, of learning about social co-operation and conflict, about family relations and about bringing up a family.
Social responsibility, the caring, giving and sharing with others, the taking on of responsibility for others, including conflict management, can be and is being taught.
From infant through child and adolescent to being an adult, we go through a long period in which we learn through playing and by experience, and also absorb information from external memory, from the mass of information now available to us from sources external to ourselves.
And learning by experience and by gaining knowledge continues while we are alive. Each new experience adds to our knowledge and plays a part in shaping our view of the community and society in which we live, of the world at large, and helps to determine what we do and how we do it, helps to determine our behaviour.
Change from Eidetic to Linear Memory
We already saw that many, if not all, young children apparently do normally see and remember eidetically, but that this capacity is lost to most as they grow up.
Rose considers that at birth all types of input are likely to be seen as about equally relevant, that all input is registered and ordered "so as to enable each individual to build up his or her own criteria of significance". Eidetic memory gives equal importance to all inputs so that all inputs are analysed, are processed and stored.
It seems that children remember everything. But at some time before puberty most of us cease to remember eidetically, 'there is for most of us a transition in how we perceive and remember the world ... as we consciously or unconsciously learn to select salient information that we need to commit to memory from the environment around us."
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