Memory is subdivided into three processes of encoding, storage and retrieval. For memory to function properly, we take information (encoding), store it or represent it in a certain way (storage) and then later recall it (retrieval).
Encoding is a way through, which the information is processed for storage in the memory. Some of the information gets processed automatically, whereas for some we have put conscious effort. Eg- when you are listening to the lecture in class, you encode whatever the professor is saying, most of the times. For encoding, it is necessary that we attend to the information (Posner & Rothbart, 2007). Not just attention, but also the level of processing affects our memory.
Storage encompasses how the information is retained over the period of time and how it is represented in the memory. According to Atkinson-Shiffrin’s theory, memory storage involves three systems-(a) Sensory memory: Through our different senses, we perceive the information. It is rich and detailed but the information in it is not retained for long. (b) Short-term memory/ Working memory: From sensory memory, the important information goes to short-term memory. It is a limited-capacity memory system, in which information is retained for around 30 seconds unless it is rehearsed. The concept of working memory is a workbench where information is manipulated. It helps us to understand how the damage to the brain affects our cognitive skills. (c) Long-term memory: It is a permanent type of memory, which stores huge amount of information.
Retrieval is when the stored memory is recalled. The memory is taken out of the storage. It usually takes few seconds to search for the memory and retrieve it. It is a complex and sometimes an imperfect process (Dodd, Castel & Roberts, 2006).
Terminology
- Implicit and Explicit memory. Implicit memory in which that is expressed through physiological or behavioral changes when the individual has no or limited consciousness of the information being stored. Whereas explicit memory is when the memory is consciously accessed and it covers most standard memory tasks.
- Semantic and Episodic memory. Semantic memory is where the concepts or facts are culturally or educationally acquired, eg- general knowledge. Episodic memory is information encoded, stored and utilized, through the personally experienced events.
- Recent and Remote memory. Recent memories are those, which are stored within last few hours, days or weeks. Remote memories date from childhood till present.
- Anterograde and Retrograde memory loss. After a neurological illness/ injury, it is difficult for an individual to acquire new knowledge and remember the recent events. In retrograde, the memory for events before the onset of illness/injury is affected.
- Prospective memory. It requires interaction between episodic and executive functions, to enable an individual to remember something, at a particular time in future.
- Material specificity. Memory for verbal and non-verbal material is affected differently, in individuals, as different hemispheres encode different information. Encoding/ retrieval differences may be hemisphere specific as other memory processes (Kennepohl et al. 2007).
- Recall and Recognition. Recall is the uncued retrieval of the information and involves active search process. Whereas, recognition is when the individual feels familiarity with the recall component, from many other stimuli.
In my next blog, I would be writing about memory disorders and their rehabilitation.