Even as the increasingly high capacity of artificial memory is evoking wonder in all, the capacity of the human memory continues to amaze the scientists, which seems to be always ahead over the artificial memory. Thus this essay puts the cognitive process of human memory under lens, before concluding on an approbatory note.
Memory in Brief
Memory is a package of distinctive cognitive abilities of the brain to retain any past experience that is stored in it. These abilities are multi-dimensional and they have conceptual divisions in them (Lucas, 2002). However, the activity of this package can be classified by three different phases like sensory, short-term and long-term memory. Among them, the first one, sensory memory is ephemeral and lasts about few seconds at the most. It deals with the flurry of inputs humans receive through hearing, smelling or viewing, etc. The second one, short-term memory retains the experience for a longer period than the first one and provides the brain the chance it for more longer period through the repetition of that experience (such as reading, viewing or listening again and again of an input).
If short-term memory can be called RAM (virtual memory, that gets lost with shutdown of the machine) of a computer, then long-term memory deserves to be called as the hard disk of it – where the inputs are stored and can be brought up for future use (here the memory is stored even with the shutdown (Harris, 1995). According to John A. Lucas, the professor of psychology, short-term memory has a limited capacity, and can hold “only seven pieces of information on an average” at any one time, though that can be converted into longer time by repetition. A sudden dealing with an unknown telephone number could explain the situation – one can see it and instantly dial it, which is thereafter is usually forgotten. Now if the telephone happens to be placed at the other side of the room, the person keeps repeating the number while covering the distance and time to reach the telephone.
On the other hand, long-term memory has a huge storage capacity and can hold information for an indefinite period. However, all three classes of memory undertake a journey through the process like encoding, retention and retrieval, though their life-spans are different. It is because of this flexible quality of memory, even any sensory experience can end up into long-term memory – which also brings in the ‘declarative memory’ in the discussion.
Declarative memory denotes the ready pack of knowledge which one can recollect at will (Cohen, 1980). That kind of knowledge includes memory for events (episodic memory) and facts (semantic memory) (Tulving, 1983). Episodic memories are those which humans freely recall, recognize from a hint (Graf & Schacter 1985). Episodic memory is a neurocognitive system, which is uniquely different from other memory systems, like the non-declarative or procedural types of memory. The hippocampus performs great role in declarative memory and there are many views about its mechanism (Eichenbaum, 2004). According to Baddeley (2000), “our initial construction of reality within consciousness is a form of episodic buffer that contains a representation of the stream of events as they just occurred.” This fits any example of recalling one event that might be aligned with some elements of the present event; like recalling a specific conversation with a specific person under a similar circumstance. This speaks of the nature of the episodic memory – that it exists in a unique cluster of memories who share many features among them (Eichenbaum, 2004).
Non-declarative memory is a process where acquisition, retention and retrieval of knowledge happen to be the outcome of experience-induced changes in performance (Gabrieli, 1998). This means it is dependent on the more than one experience about an event. Skill learning, repetitions, priming or conditioning belong to this category. It is mostly expressed through performance or skill rather than conscious recollection.
Memory is heavily dependent on the smooth functioning of its three stages of acquisition, retention and retrieval, to come into its full cycle. However the degree of such dependency on any of its stages varies according to the nature of memory. As for example, ‘free recall’ of information depends most on retrieval process, while in the case of answering some multiple choice questions, memory depends more on retention instead of retrieval. (Lucas, 2002).
How it Forgets
There are several reasons for which memory cannot reproduce everything it experiences. It can be disrupted by events or information around the time of acquisition, which is known as “interference effect”. It holds some categories within its folds, like Retroactive Interference or Proactive interference, where a new learning can subside the earlier experience. Besides this, there can be Anterograde and Retrograde amnesia due to injury or other reasons. Anterograde memory denotes the ability to learn new information towards forming new memory, while the retrograding memory recalls or recognizes a specific experience from past.
The unique system of memory speaks of its vast potential and its significance in the human activities. It is truly that magic wand of mind that saves time and energy, besides ensuring safety and scope to develop much to the heart’s content in one life.
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Harris, D (1995). Cognitive Learning And Memory. Web Article. Retrieved on 17 December, 2007, from http://comp.uark.edu/~jdharris/cogmem.html
Lucas, J.A (2002). Memory, Overview. Encyclopedia of the Human Brain Volume 1 [ed. V.S. Ramchandran].
Tulving, E (1983). Elements of Episodic Memory. London: Oxford Univ. Press.