Sunday 5 March 2017

The Modal Model of Memory: Sensory, Short-term, and Long-term Memory

It is the most widely used model of information processing. It is essential a model of human memory. This model is first proposed by Richard Atkinson and Richard Shiffrin in the year 1968. The model is also known as modal model of memory” or multi-store model.

The modal model of memory makes an important distinction between two types of information storage (i.e. memory). These are: short-term memory (also called working memory), and long-term memoryIn some versions of the model, a third memory component is included and that is short-term sensory storage (which is also called sensory memory). Altogether, there are three separate components of human memory asserted by this model. 

Modal model of memory

Distinctions among the three types of storage are concerned mainly with the nature and extent of the processing that information undergoes.

Processing refers to activities such as paying attention, organizing, analyzing, synthesizing, and rehearsing.

Also, the three types of storage differ in their capacity and in the extent to which their contents are accessible.

This basic information processing model of cognitive psychology does two related things: First, it provides us with an overall model of human memory. Second, it addresses various learning-related questions that are critically important for teachers—questions concerning how information is organized and sorted, which teaching and learning methods can facilitate information processing, and how memory can be improved.

Sensory Memory:

Our sensory systems (vision, hearing, taste, touch, smell) are sensitive to an overwhelmingly wide range of stimulation. However, they respond only to a fraction of all available stimulation at any given time; the bulk of the information available in this stimulation is never actually processed—that is, it never actually becomes part of our cognitive structure.

Sensory memory is the label used to describe the immediate unconscious effects of stimulation. Sensory memory is highly limited, both in terms of the length of time during which stimulus information is available for processing and in the absolute amount of information available. In other words, sensory memory is no more than the immediate sensory effect of a stimulus.

Much of the stimulation to which we are not actually paying attention is nevertheless available for processing for perhaps a fraction of a second.

For example, if you are engaged in a conversation with someone in a crowded room, you might be totally unaware of what is being said in any other conversation. But if the topic in one of these other conversations turns to something that passionately interests you, you suddenly become aware of what you would not otherwise have heart. This occurrence is labeled the cocktail party phenomenon.

Short-Term Memory:

Sensory memory precedes attention; it is simply the effect of a stimulus before you pay attention to it. When you attend to a stimulus (in other words, you become conscious of it), it passes into short-term memory.

Short-term memory consists of what is in our immediate consciousness at any given time. It is a sort of scratch pad for thinking; for this reason, short-term memory is often called working memory.

One of the important characteristics of short-term memory is that it is highly limited in capacity. Its average capacity is about seven separate items (plus or minus two); that is, our immediate conscious awareness is limited to this capacity, and as additional items of information come in, they push out some that are already there.

Short-term memory lasts a matter of seconds (not minutes, hours, or days). It appears to be highly dependent or rehearsal. That is, for items to be maintained in short-term storage, they must be repeated. In the absence of repetition, they quickly fade, usually before 20 seconds have elapsed.

The apparent limitations of short-term memory are not nearly as serious as they might seem at first. Though, we cannot easily attend to more than seven discrete items at one time, a process called chunking dramatically increases the capacity of short-term memory.

In effect, a chunk is simply a group of related items of information. Thus, a single letter can be one of the seven items held in short-term memory, or it might be chunked with other letters to form a single word—which can, in turn, be one of the seven items in short-term memory.

In summary, short-term memory is the ongoing availability of a small number of items, or chunks, of information in conscious awareness. Without continued rehearsal, these items are generally lost from memory within 20 seconds.

Long-Term Memory:

Long-term memory includes all of our relatively stable information about the world—what we know but is not in our immediate consciousness.

In fact, one important distinction between short-term and long-term memory is that short-term memory is an active, ongoing, conscious process; whereas long-term memory is a more passive, unconscious process.

Short-term memory is easily disrupted by external events—as we demonstrate every time we lose our thought because of a distraction. In contrast, long-term memory cannot easily be disrupted. If you know the capital of Russia today, you are likely to know it tomorrow, next month, and even next year.

We transfer information from sensory storage to short-term storage through the process of attending, and we maintain information in short-term memory largely through rehearsal.

But the transference of material (or information) from short-term to long-term memory involves more than simple rehearsal. It involves “encoding”. Encoding is a process whereby meaning is derived from experience. To encode information is to transform or abstract it—to represent it in another form.

Encoding involves information processing, an event that can occur at different levels. The memory reflects the level to which information is processed. Information that is not processed leaves only a momentary sensory impression (sensory memory), information that is merely attended to and rehearsed is available for seconds (short-term memory), and information that is processed to a greater degree is stored in long-term memory.

But not all material (or information) in long-term memory is processed to the same level. For example, if students are asked to learn and remember a word, they can process it at a highly superficial level, paying attention only to its physical appearance. At a somewhat deeper level, they might pay attention to the word’s pronunciation. And at the deepest level, they would take into account the word’s meaning—a process called semantic encoding. 

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