Memory
Article on types of memory and forgetfulness
All of us encounter with millions of events and sensations every day. They are encoded in our brain and stored, according to their value in our life, for being recalled when necessary. This ability of the brain to share previously recorded information is known as memory.
Types of Memory:
Depending on the longevity of memory in our mind, they are categorized into two classes:
• Short term memory: the sensory information acquired from visual, auditory, olfactory and tactile cues are seized by the mind for fraction of a second giving rise to an ‘immediate memory’. After the present moment has passed, the brain holds the information from a second to a few minutes; this is so we can execute work at utilising the ‘working memory’. Capacity of the brain for temporary storage of such memories is immense. We find such memory useful when we search for an object in a well thought-out manner, remembering the places we have already searched and hence avoiding them accordingly.
• Long term memory: after recording short term memory, the brain assesses its significance and permanently retains it for days, weeks or even a lifetime. Such shift from working memory to long term memory or consolidation is witnessed in a phenomenon called ‘Priming’ in which previously studied information exerts an influence on subsequent performance while remaining unavailable to conscious recall. This trait of our mind is exploited by advertisers to influence the way we think and act. Long term memory can be of several types, namely,
• Declarative or explicit memory: It is the storage and retrieval of incidents and sensations perceived consciously and expressed verbally. Such memories are quickly acquired but vulnerable to loss. Every time you recall a telephone number, sing your favourite song or feel nostalgic about some outstanding past event; you are recollecting a declarative memory. It can be further subdivided into:
• Episodic memory: our brain is capable of recording events which take place throughout our lifetime. It is due to such episodic memories that we can remember the days we enjoyed on a trip or who gave your flowers and even what you had for dinner and so on. Some incidents enjoy special importance in our life. Such momentous episodes have a strong impact on memories and enable the brain to remember them for a lifetime. We can hardly ever forget our high school days, our first romantic getaway or even our day of graduation. It is because people tend to store their most exciting memories forever. Such memories are called autobiographical memories. It is observed that shocking and surprising events leave a deep mark in our memories and that is why people are found to recollect where they were at the moment of attack of the World Trade Centre for example.
• Semantic memory: the kind of explicit memory which we can call to mind without remembering the source or time of gaining the information is called the semantic memory. This memory helps us to boost our general knowledge as a result of which we can identify our country’s president, name the capital of a country or discern characteristic smell of a particular flower. Such a memory can persist in spite of growing age and remain highly functional even in your 60’s after which they start degenerating.
• Non declarative or implicit memory: Non declarative memory, sometimes referred to as procedural memory, involve skills and associations that are adopted and retrieved at an unconscious level. Such memories are not easy to acquire but once we get hold of the skill, it is difficult to lose. We never forget how to walk, eat, brush our teeth, wear a shirt or carry out any of our daily chores but we are unable to articulate the procedure in our own words. This is why NLP Modelling is so revolutionary.
Associative reminiscence and forgetting:
If the human brain has a limited capability to remember things, then how can it store such a huge archive of memories? Capacity of the brain to store memories can be increased dramatically by the act of association.
For example in one study, a college student, who also happened to be a competitive runner, spent an hour each day practicing the task of remembering randomly presented numbers for some months. Afterwards, he was able to recall a string of up to about 80 digits primarily by making subsets of the string of numbers. He was giving meaningless items a meaningful context.
This same strategy of association is used by most professional “mnemonists,” who amaze audiences by apparently prodigious feats of memory. Thus, the capacity of working memory very much depends on what the information in question means to the individual and how readily it can be associated with information that has already been stored.
While one stores important memories deep inside their brain, similarly, the brain erases out the insignificant ones through the act of forgetting to save itself from getting overloaded with futile information. We tend to forget that with no particular importance and eventually the unused memories weaken with time.
Role of the brain in storage and retrieval of information:
Hippocampus and cerebral cortex plays the principal role in encoding and recalling memories. Sensory cues like vision, auditory and tactile are perceived by the sensory association cortex. After staying there for fraction of a second it enters a signalling loop within the neural circuits and gets transformed into short term memory. Depending on the type of information either it gets lost within short span of time while vital ones get converted into long term memory. This memory then gets fragmented into a number of parts and remains stored in various regions of hippocampus. However, non declarative memories are found in basal ganglia, prefrontal cortex and cerebellum of the brain. When one desires to recall specific memories, the stimulus is sent to the medial temporal lobe and regions of frontal cortex for recollection.
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