Different types of memory: An analysis of memory stores

How many different types of memory are there? Illustrate your answer with examples of the kinds of information that each system stores.

Memory allows us to recognize our surroundings as well as people who are related to us. Moreover, it also allows us to record our past so that we can refer to our past experiences in our today and future. “In large part, we are what we remember.” (cited in Myers, 2013, p 298). Since memory is a mandatory cognitive perception, psychologists have dedicated lots of time and effort to understand the various types of memory that exist and also to find ways as to how to improve and enhance memory (Wayne Weiten, 2007, p 260). “If you lose the ability to recall your old memories, then you have no life. You might as well be a rutabaga or a cabbage.” (Myers, 2010, p 349). The theory that memory consists of three different stores has been put forward by Atkinson and Shiffrin (1968). These memory stores are named as long-term memory, sensory memory and short-term memory. Long-term memory is furthermore divided into explicit and implicit memory and this essay elaborates on the three types of memory aforementioned.

The sensory memory is involved in receiving huge amount of environmental information and thereafter transmitting the details from our senses to our brain in a short span of time. Sensory memory acts like a storage for stimulations experienced via our five human senses which are hearing, sight, taste, smell and touch. (Istvan Winkler and Nelson Cowan, 2004, p 2). An example of this type of memory is the point at which an individual sees an item prior to its disappearance. As soon as the item disappears, it continues to stay for a brief moment in the memory. (Sperling G., 1960). Sensory memory is furthermore divided into two types, namely, iconic memory which relates to the visual and echoic memory which relates to sound. An example of visual sensory memory is when a spotlight moves rapidly around inside a dull room, people will see a ring of light instead of the individual focuses through which the electric lamp moved. This experiment was done by Segner (1740, p10) where he attached a glowing ember to a rotating wheel. Thus, sensory memory holds the progressive pictures of the moving spotlight long enough for the brain to see a round. According to George Sperling’s test (1960), it was found that when a set of letters was shown quickly for 50 milliseconds, participants could remember half of the letters only. Sperling next modified the experimentation which is termed as the partial report method and in this experiment, noises of different audibility was made following the flashing of the letters. It was observed by Sperling that when the sound was heard within 250 milliseconds (a quarter second) after the flash, people recalled 3 out of 4 letters from any row since a memory of the entire image was preserved over 250 milliseconds. This implies that iconic memory is a momentary photographic memory. (Karl R. Gegenfurtner and George Sperling, 1993, p 845). Similarly, the ear clings onto sensory information. Auditory sensory memory is called echoic memory and this form of memory enables us to recall what we have heard over a period of one fifteenth minute. In an experiment by Darwin et al. (1972), nine letters were presented to subjects wearing headphones. Three letters were sounded to one ear followed by three letters to the other ear and finally, three letters were sounded to both ears. The subjects were then shown on a screen which letters they had to recall and the results showed that echoic memory lasts a bit longer than iconic memory, about two to four seconds.

Short-term memory, also called working memory can hold a small amount of information, on average seven items, in the mind in an active mode for a brief period. This has been demonstrated through George Miller’s experiment known as “The Magical Number Seven”. Atkinson and Shiffrin (1971) observed that the duration of short-term memory is between fifteen and thirty seconds as whatever it stores fades away rapidly over a period of time. Many theories associated to short-term memory support the assumption of decay and this is even reflected in the working memory model by Baddeley (1974). For example, to be able to understand this sentence, one needs to retain the beginning of the sentence in mind while reading the rest of the sentence and it is the short-term memory which handles this activity. In this case, the working memory is the component that probably does most of the processing within the human memory system. (Ormrod, 1998). Another illustration is when someone is required to retain a telephone number in his mind, then in order not to forget the number, the person repeats the number over and over again in his mind. This practice ensures that the information is retained in the short-term memory for a longer period. According to Craik & Lockhart (1972), there are two types of rehearsal, maintenance and elaborative, that keep information active more than 20 seconds in the working memory. George Miller’s (1956) Magic number 7 has proved that as far as the storage of short-term memory is concerned, most grown-ups can keep from five to nine pieces of data. However, the amount of each piece of information can be expanded by chunking. Consolidating bits of information into a bigger chunk helps to expand the limit of transient memory in short-term memory. Chunking is the process of combining separate items into large, meaningful units (Miller, 1956). For example, the ten digits, 2, 3, 0, 8, 2, 3, 5, 4, 7, 6 may be too much to retain in the correct order in one’s short-term memory but if the same numbers are clubbed together as in the format of a phone number, that is, 230-823-5476, then it is easier to retain this information in the short-term memory for a longer duration. If the data stored in the short-term memory is not retrieved for transfer to the long-term memory, then the data stored will be lost when the short-term memory lapses.

Long-term memory is the third type of memory and it comprises of information that can be stored in the brain for days, months, years or a lifetime (Ormrod, 1998). Although we tend to think that we forget a lot of things, an unlimited quantity of data that can be retrieved after a day or even after a lifetime is actually being stored in our long-term memory. Reference memory is the name given to long-term memory since a person must refer to the contents stored in this type of memory whenever an action is being performed. (Mazur, 2006, p 1). Explicit memory is one main type of long-term memory while the other main type of memory is referred to as implicit memory. Conscious thought, for example, such as recalling who we have appointment with or the names of capital by country is required by explicit memory. Explicit memories, also known as declarative memories, are treated by the hippocampus before they are delivered to the brain where the memories are stored (Larry R. Squire, 1992, p 195). Memories about our life events as well as information about our environment are registered in declarative memory. These memories are those that we deliberately recall, for example, an event in our life or the birthday of our best friend. According to John Growdon, MD, Neurology, amnesia can be caused when the hippocampus or its nerve connections are damaged. People suffering from amnesia tend to forget information soon after they hear or see it because of their inability to develop new long-term memories. Declarative memories are further divided into two categories which are semantic memory and episodic memory (Larry R. Squire & Stuart M. Zola, 1998, p 205). Semantic memory is part of declarative memory that helps store general information such as a name or general knowledge, for example, Paris is the capital city of France (Saul Mc Leod, 2010). The storage of data related to the events in our life, for example, my first day at Middlesex University, is being handled by episodic memory. Implicit memory forms part of the long-term memory which does not involve conscious thoughts. Implicit memories are responsible for knowing how to do things and they are developed through repetition and practice and no deliberate reference is made to past involvements (Schacter D. L., 1987, p 501). Implicit memories are memories of skills acquired and how to do things, for example, driving a car or tying a shoelace. These memories of learned skills are so deeply ingrained that the activities are carried out without consciously thinking about them. The effect of implicit memory has been tested using priming procedures (Schacter D. L., 1987, p 506).

Flashbulb memories can be classified as another type of memory and these memories are uniquely clear, highly detailed, precise and long-lasting (Roger Brown & James Kulik, 1977, p 73). Flashbulb memories relate to the moment as well as the circumstances in which a revelation of shocking incident was conveyed to that person, for example, the death of a close relative. Two studies were carried out regarding the assassination attempt on President Reagan, the first one after one month while the second one, six months later. Most participants reported flashbulb memories and stronger emotional reactions to the event were found to be associated with greater consistency of narrative and visual memories (David B. Pillemer, 1984, p 63). Repressed memories are memories unconsciously blocked, due to the memory being linked to a high level of stress or a traumatic event, for example, child abuse. These memories, though stored in some inaccessible corner of the unconscious, can be remembered many years later and these recovered memories can be triggered by natural events or therapeutic techniques such as hypnotism or dream therapy (Elizabeth F. Loftus, 1993).

To conclude, there are three main types of memory as shown by the multi store model of Atkinson and Shiffrin (Myers, 2010). Sensory memory stores information detected by the sense organs and this information is captured into short-term memory if attended to. If the contents of short-term memory are rehearsed, encoded or retrieved, then they may be pushed and reside on a permanent basis into the long-term memory. In the absence of rehearsal or retrieval, information in short-term memory is lost or forgotten through the process of displacement or decay. Throughout our life, we are constantly in a process of learning and registering things, be it consciously or unconsciously. “The process by which information is kept and updated over a period of time is known as memory.” (Matlin, 2005). Not being able to hold back past memories will neither allow us to function in our present life nor to contemplate our future because if we cannot recall what we did yesterday, then each day will start with a blank sheet and even if we plan for tomorrow, the next day will again start will a blank sheet. “Memory is the means by which we draw on our past experiences in order to use this information in the present.” (Sternberg, 1999).

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