Memory Processes PDF

CHAPTER 3: MEMORY DEFINITION OF THE TERM MEMORY Memory is the process by which people encode, store and retrieve information. THE BASIC PROCESSES OF MEMORY Memory is built on the basis of three basic processes namely 1. ENCODING: - It refers to the process by which information is initially recor...

CHAPTER 3: MEMORY DEFINITION OF THE TERM MEMORY Memory is the process by which people encode, store and retrieve information. THE BASIC PROCESSES OF MEMORY Memory is built on the basis of three basic processes namely 1. ENCODING: - It refers to the process by which information is initially recorded in a form usable to memory. 2. STORAGE: - it is the process of the maintenance of the material saved in the memory system. 3. RETRIEVAL: - it refers to the process of the recovery of stored information. The material in memory storage is located, brought into awareness and utilized. THE SYSTEMS OF MEMORY- Memory storehouse- ATKINSON & SHIFFRIN According to one of the most influential theories given by Atkinson and Shiffrin (1986) three kinds of memory storage systems exist. These storage houses vary in terms of their function and the length of time information is retained. These three systems of memory are:- 1. Sensory Memory 2. Short- term Memory 3. Long-term Memory In this three-stage model of memory, information initially recorded by the persons sensory systems, enters sensory system memory, which momentarily holds the information. It then moves to short term memory, which stores the information for fifteen to twenty five seconds, finally the information can move into long-term memory, which is relatively permanent. Whether the information moves from short-term memory to long term memory depends on the kind and the amount of rehearsal of the material that is carried out. (Atkinson and Shiffrin, 1986) SENSORY MEMORY It refers to the initial momentary storage of information, lasting only an instant. It is recorded by the person’s sensory memory as a raw, non-meaningful stimulus. Memory begins with a sensory input of information from the environment. This input of information is held for a brief time in the sensory channels themselves. This storage function of the sensory channels is called sensory register. Most of the information held in the sensory register is lost, meaning that the information decays from the register. Information that we attend to passes on to the short-term store for further processing. Thus, the transfer of information from sensory register to the short-term store depends on attention. Some experiments have shown that the visual sensory register holds information for about 1 second while the auditory sensory register can hold 11 to 16 items of information. The term sensory memory encompasses several types of sensory memories, each related to a different source of sensory information. Two such memories are:- 1. Iconic memory 2. Echoic memory 1. ICONIC MEMORY:- The memory that reflects information from our visual system. 2. ECHOIC MEMORY:- The memory that stores information coming from the ears. However despite the brief duration of sensory memory, its precision is high and it is able to store an almost exact replica of each stimulus exposed to. Psychologist GEORGE SPERLING conducted a series of experiments in1960 which helped in understanding sensory memory. Sperling briefly exposed people to a series of twelve letters arranged in the following pattern. F T Y C K D N L Y W B M When exposed to the array for t just 1/20 th of a second, most people could accurately recall only four or five letters. Thought they knew they had seen more, the memory for the rest of the letters had faded by the time they reported the first few letters. It was possible, that the information had initially been accurately stored in sensory memory but during the time it took to verbalise the first four or five letters, the memory of the other letters had faded. To test this possibility Sperling conducted an experiment in which high, medium and low tones sounded just after a person had been exposed to the full pattern of letters. People were told to report the letters in the highest line if a high tone was sounded, the middle line if the medium tone occurred and the lowest line if it sounded in a low tone. As the tone occurred after the exposure, people had to rely on their memory to report the correct row. The results of the study clearly showed that people had been storing the complete pattern in memory. They were accurate in their recollection of letters in the line that had been indicated by the tone, regardless of whether it was the top, middle or bottom line obviously, all the lines they had seen had been stored in sensory memory. Also, the ability to recall a particular row of the pattern when a tone was sounded declined progressively as the period between the visual exposure and tone increased. This decline continued until the period reached about one second , at which point the row could not be recalled accurately. Sperling now concluded that the entire visual image was stored in sensory memory for less than a second. CONCLUSION:- The sensory memory operates as a kind of snapshot that stores information for a brief moment in time. Unless the information in the snapshot is transferred to some other type of memory, it is lost. EVIDENCES FOR THE PRESENCE OF STM & LTM 1. SERIAL POSITIONING CURVE:- If someone read out a list of unrelated words and asked you to recall as many as possible, research indicates that you would be more likely to remember words at the beginning and at the end of the list, than at the middle. This effect is called the serial positioning curve. Psychologists have explained the existence of this due to the existence of two memory systems. You tend to remember the last few words in the list quite well- a recency effect- because they are still in your short-term memory when you were asked to recall them. And you remember the words at the start of the list because they have been entered into your long- term memory called the primacy effect. Words in the middle, in contrast have vanished from the short-term memory, and are not yet fully present in the long-term memory. An experiment was conducted to show the evidence of STM and its features. The subjects were shown a list of 15 nouns; each noun was presented for 1 second, with a 2- second interval between the presentations. After the presentation, subjects were asked to recall in any order (free recall). It was found that when recalled immediately after presentation the name presented early in the list were recalled relatively well, recall for nouns in the middle of the list was rather poor. So recall depends on where an item is in a series of items and generally called the serial-position effect. The better recall at the beginning of the list which contributes to the serial-position effect is known as the primacy effect- items encountered first are remembered relatively well. The better recall at the end of the list is known as recency effect- items encountered most recently are remembered well. But when the recall is delayed like after 10 seconds or 30 seconds during which subjects were engaged in counting it was found that there is a decrease or eliminates the recency effect but primacy effect will be there. The reason given for the disappearance of the recency effect with delay is that the last items in a list are still in short-term memory when list presentation stops. They have not yet been transferred to long- term memory, and such transfer is prevented by the mental activity occurring during the delay interval. The primacy effect remains during delayed recall because the first items in the list have had time, during the presentation of the list, to be put into long-term memory. Several different studies have proved consistent results and thus show evidence of two distinct memory systems- short term and long term.  2. BRAIN DAMAGE:- People with certain kinds of brain damage have no lasting recall of new information following the damage. Although, people and events stored in memory prior to the injury remain intact, thus proving that there are 2 distinct types of memory. SHORT-TERM MEMORY It refers to a kind of memory which holds information for fifteen to twenty five seconds. Here, the information is stored in terms of its meaning. Short-term memory is the memory store in which material which has meaning is stored although the maximum length of retention is relatively short. It holds information received from the sensory register for up to bout 30 seconds. It has a very limited storage capacity about 7 ± 2 items. Unlike sensory memory which holds a relatively full and detailed representation, the STM has incomplete representational capabilities. The storage capacity of STM can be enhanced by using the following methods: a. Chunking b. Rehearsal c. Mnemonics CHUNKING:- Chunking is a meaningful grouping of stimuli that can be stored as a unit in STM. Eg:- C N Q M W N T Each letter here qualifies as a separate chunk, and since there are seven, they can easily be stored in STM. Eg:- T W A C I A A B C C B S M T V U S A N B C TWA CIA ABC CBS MTV USA NBC In this case, even though there are 21 letters, it is possible to store all of them since they represent seven chunks. Most of the psychologists believe that information in the STM is lost after 15-20 seconds, unless it is transferred to LTM through rehearsal. REHEARSAL: - It is the repetition of information that has entered short-term memory. It is very important because:  As long as information is repeated, it is kept alive in the short-term memory.  It allows us to transfer the material into long-term memory. There are two types of rehearsal namely i. Elaborative rehearsal ii. Maintenance or repetitive rehearsal i. ELABORATIVE:- It occurs when material is considered and organized in some fashion. It is an active process of organization which might include expanding the  information to make it fit into a logical framework, linking it into another memory or transferring it in some way to LTM. ii. MAINTENANCE OR REPETITIVE:- It refers to the repetition of information over and over again which will be forgotten the moment it is stopped. It helps to retain information in STM. MNEMONICS:- Formal techniques for organizing material in a way that makes it more likely to be remembered. COMPONENTS OF SHORT TERM MEMORY (WORKING MEMORY):- Although STM has been considered as a single system, more recent evidence suggests that it may actually consist of several components. According to the psychologist Alan Baddley STM can be considered as a 3 part working memory. In this view, one part is the central executive which coordinates material required for the processes of thinking, reasoning and decision-making. This is made up of 2 sub-components- the visuospatial sketch pad – which concentrates on visual and spatial information (e.g. Mental map, design of an area or a face) and the phonological loop which is responsible for holding and maintaining material relating to speech words and numbers. Some psychologists suspect that a breakdown of the central executive may result in memory loss characteristic of degenerative diseases that produce loss of memory and confusion. (E.g. Alzheimer’s disease) LONG TERM MEMORY – THE FINAL STOREHOUSE It refers to the storage of information on a relatively permanent basis, although retrieval might be difficult. The information which is important enough to survive, will be transferred from the STM to the LTM through some physiological mechanism, which is yet to be understood. The items are stored here in terms of mental categories with some descriptions. Once an item is put into the LTM, it is available mostly permanently, if unknown how to retrieve it. The storage capacity is unlimited. All information coming through every sense organ and transferred from STM to LTM is more permanent- memories are encoded in the form of engrams and preserved by categorization. Results from laboratory experiments are also consistent with the notion of separate short and long term memories. The information in the long memory is mostly about the meanings of words, sentences, ideas, concepts and the life experienced we have had. Long term memories in contrast with the short term memories last for months, years or a lifetime. Evidence of the existence of LTM as distinct from STM comes from a number of sources. THE MODULES OF LONG-TERM MEMORY/ COMPONENTS OF LTM Although long term memory initially was viewed as a unitary unit, most research now suggests that it is composed if several different components, or memory modules. Each of these memory modules is related to a separate memory system in the brain. The different types of LTM are: 1. Declarative Memory- is subdivided into i. Episodic ii. Semantic 2. Procedural Memory 1. Declarative Memory This is the memory for factual information, names, faces, dates and the like. Information about things is stored in this memory. E.g. George Washington was the first U.S president. The facts in the declarative memory can be further sub-divided into: i. Semantic Memory This is the memory that stores general knowledge and facts about the world, as well as memory for the rules of logic for deducing other facts. It is similar to a kind of mental almanac of facts. Here we develop relationships between pieces of information. E.g Mathematical and Historical facts ii. Episodic Memory This is the memory for information relating the biography details of our individual lives. Our memories of what we have done and the kinds of experiences we have had constitute episodic memory. Episodic memory can be surprisingly detailed. It can provide information from events that happened long in the past. E.g Recalling our first date, the time we fell off the bicycle, etc. 2. Procedural Memory This is the memory for skills and habits. Information regarding how to do things is stored in procedural memory. E.g. riding a bicycle, hitting a basket, etc. ASSOCIATIVE MODELS OF LTM It is a technique of recalling actual information by thinking about related information. Using associative models, many psychologists argue that semantic memory consists of associations between mental representations of many pieces of information. Since semantic memory is so impressive, further elaboration is required. The basic notion behind associative models is that when we think about a particular concept, our semantic memory activates the recall of related concepts, bringing those more readily to mind. As a test if we are trying to remember some specific bit of information, thinking about associated material may help us recollect it. PRIMING A technique of recalling information by having been exposed to related information at an earlier time. Prior presentation of information subsequently makes it easier to recall related items, even when we have no conscious memory of the original information. The discovery that people have memories about which they are unaware has been an important one. It has led to speculation that two forms of memory may exist side by side namely: 1. Explicit Memory It refers to intentional or conscious recollection of information E.g. trying to remember a name or a date 2. Implicit Memory It refers to memories of which people are not consciously aware of but which can affect subsequent behavior and performance. e.g. an event that we are unable to recall consciously affecting behavior RECALLING LONG-TERM MEMORY 1. RETRIEVAL CUES A retrieval cue is a stimulus that allows us to recall information that is located in the long-term memory more easily. It may be a word, an emotion, a sound, whatever the specific cue, memory will suddenly come to mind when retrieval cue is presented. They are particularly important when we are making an effort to recall information as opposed to our being asked to recognize material stored in the memory. Recalling is when memories are retrieved with few or no external cues. E.g. such as answering in an exam. Recognition on the other hand involves looking at or learning information and matching it to what is already in our memory. The importance of retrieval cues is seen in context and state dependent memory. 2. CONTEXT AND STATE DEPENDENT MEMORIES Context dependent memory refers to that memory which depends on the contextual cues we store in. Material learned in one environment easier to remember in a similar environment that context in a different environment. In an experiment conducted by Golder and Baddley, participants who were deep-sea divers were asked to learn a list of words either on the beach or beneath fifteen feet of water. Then they were asked to recall the words either in the same environment in which they had learned them or in another setting. Results showed a clear impact of context dependent memory- words learned in the sea were better recalled in the same location than on land and vice versa. So if you study for an exam in your room, and then take the exam in a very different setting, it may be helpful to imagine yourself back in your room when you try to remember specific information which may provide you with additional cues. State dependent memory refers to that memory which depends on the physiological and psychological state of an individual and helps n recalling information. For example, during your preparations for an exam if you had a cup of coffee, it may help to remember better if you have a cup of coffee during your examination because your internal chemical state is similar or the same. 3. TIP-OF-THE-TONGUE PHENOMENA The inability to recall information that one realizes one knows which a is a result of the difficult of retrieving information from long term memory is called the tip-of-the-tongue phenomena this is especially frustrating in situations where a person cannot recall the name of someone he or she has just met. 4. FLASHBULB MEMORY They refer to the memories of a specific event that is so clear that they seem like snapshots of the events. They are memories centered on specific important or surprising events. They do not contain every detail of an original scene. These memories still seem extra ordinary because of the details they do include. They illustrate a more general phenomenon about memory. Flashbulb memory enables us to recall vivid details about important personal or historical events. LEVELS OF PROCESSING- CRAIK AND LOCKHART So far, we have relied on a model of memory that suggest that the processing of information in memory proceeds in three sequential stages, starting with sensory memory, advancing to short term memory, and potentially ending in long term memory. The levels of processing theory emphasize the degree to which new material is mentally analyzed. In contrast to the view that there are sensory, short term and long term memories. Levels of processing theory suggest that the amount of information processing that occurs when material is initially encountered is central in determining how much of the information is ultimately remembered. According to this approach, the depth of processing during exposure to material – meaning the degree to which it is analyzed and considered is critical; the greater the intensity of its initial processing, the more likely we are to remember. The theory goes on to suggest that there are considerable differences in the way information is processed merely in terms of its physical and sensory aspects. For example, we may pay attention only to the shapes that make up the letters in the word “dog”. At an intermediate level of processing, the shapes are translated into meaningful units- in this case, letters of the alphabet. These letters are considered in the context of words and a specific sound of the word may be attached to the letters. At the deepest level of processing, information is analyzed in terms of its meaning. It may be seen in a wider context, and associations between the meaning of the information and broader networks of knowledge may be drawn. For instance, we may think of dogs not merely as animals with four legs and a tail, but in terms of their relationship to cats and other mammals. We may form an image of our own dog, thereby relating the concept to our own lives. According to the levels of processing approach, the deeper the initial levels of processing of specific information, the longer the information will be retained. 1. Shallow – Where there is an emphasis on sensory memory and physical structural level structure. 2. Intermediate – Sound of the word and naming it is analyzed phonetic/encoding level 3. Deepest- semantic Meaning of the word and it relationship to other contexts level FORGETTING The term forgetting is defined as the apparent loss of information already encoded and stored in the long-term memory. The first attempt to study forgetting was made by German psychologists Hermann Ebbinghaus about a hundred years ago. Using himself as his only subject, he memorized a list of three-letters nonsense syllables. He found out that forgetting occurred systematically and that the most rapid forgetting occurs in the first nine hours and particularly in the first hour. After nine hours, the rate of forgetting slows down and even after the passage of many days. Despite his primitive research methods, Ebbinghaus’s research had an important influence on subsequent research with his basic conclusions being updated. CAUSES OF FORGETTING There are many theories or factors which try to explain as to why one forgets. Some of them are: 1. A failure of encoding: One reason that we might forget is because we might not have paid proper attention to the material being learnt and consequently no encoding takes place. Studies show that though we have been exposed to thousands of currency notes and coins, yet despite this we do not have a clear picture of them, and cannot recognize them when we are shown slightly altered images. This is because we have not encoded the information into the LTM and since it is not been placed there initially, there is no way that the information can be recalled. E.g. rupee coin, stairs. 2. Decay theory: The process of decay can be defined as the loss of information through its nonuse. This explanation assumes that when a new material is learnt, a memory trace or engram is formed. In the decay process, the memory trace just fades away because of the mere passage of time. But this is not always true because most often there is no relationship of how long ago an individual was exposed to information and how well that information could be recalled. Also one may recall long learnt material- such as nursery rhymes though one has not used or recalled them often. 3. Interference theory: Interference is defined as the phenomena by which recall is hindered because of other information in memory which displaces or blocks it out. Since decay theory does not account for all forgetting, psychologists have proposed the interference theory. A vast amount of experimental evidence indicates new things interferes with our memory of what we learnt earlier and prior learning interferes with our memory of things learnt later. Retroactive: It refers to difficulty in recall of information because of later exposure to different material (present interferes with the past). Exposure to new material hinders the recall of material already learnt. E.g. 1) Study French  Study Spanish  Take French Test The French test performance is affected by Spanish 2) Learn A  Learn B  Recall A Proactive: It refers to the difficulty in recall of information due to the events that come the to-be-remembered information learned earlier interferes with the recall of newer material (past interferes with the present). Information learnt earlier interferes with the recall of newer material. E.g. 1) Study French  Study Spanish  Take Spanish Test The Spanish test performance is affected by French 2) Learn A  Learn B  Recall B 4. The Biological Bases of Memory: Work done on long-term potentiation shows that neutral pathways become easily excited when a new response is being learnt. Long term potentiation refers to the increased sensitivity of neurons to stimulation after it has been repeatedly stimulated Also changes occur in the number of synapse between neurons as the dendrites branch out receive messages. These changes reflect a process called consolidation in which memories become fixed and stable in the LTM, which is a process that can continue for a long time. Further research has shown that the location of memory traces (the physical record of memory in the brain) depends on the nature of the material being learnt and the specific neural systems that process the information being learned. Information storage appears to be linked to the sites in which the processing occurs, and is therefore located in the particular areas that initially process the information in terms of its visual, auditory and other sensory stimuli. Since several brain processing systems are involved in any learning situation, memory traces are distributed throughout the brain. Investigations using PET scans, which measure bio-chemical activity of the brain have found that neuronal memory traces are highly specialized (a particular part of the brain may be involved in learning new words, as opposed to words that are routinely used). Certain areas and structures of the brain also seem to specialize in different types of memory- related activities. E.g. working memory related to spatial task appears to reside in the frontal cortex while hippocampus (part of limbic system) plays an important role in the consolidation of memories. It also seems to aid the initial encoding and passing of information to the cerebral cortex. Research has also indicated that emotional memories may reside in the amygdala, a part of the limbic system MEMORY DYSFUNCTIONS:- 1. Alzheimer’s disease: one of the memory dysfunctions that begin later in life. In its initial stages, Alzheimer’s symptoms appear as simple forgetfulness of things like forgetting appointments and birthdays. As the diseases progresses memory loss becomes more profound, and even the simplest tasks- such as how to dial a telephone are forgotten. Ultimately, the victims can forget their own names or family members’ faces. In addition physical deterioration sets in, and language abilities may be lost completely. Although the causes of Alzheimer’s diseases are not fully understood recent evidence suggests that it may be linked to a specific inherited defect. The flaw leads to difficulties in production of the protein beta amyloid, necessary for the maintenance of nerve cell connections. When the manufacture of beta amyloid goes awry, it leads to deterioration of nerve cells in the brain producing the symptoms of Alzheimer’s. 2. Amnesia: Loss of memory. In retrograde amnesia, memory is lost for events prior to a certain event. There is usually a gradual reappearance of lost memory, although it may take as long as several years for a full restoration to occur. In certain cases, some memories are lost forever. A second type of amnesia is exemplified by people who remembered nothing of their current activities. In anterograde amnesia, loss of memory occurs for events following an injury. Information cannot be transferred from STM to LTM storage after the accident. The study of amnesia has added greatly to our understanding of the biological bases of memory. 3. Korsakoff’s syndrome: Amnesia is also displayed by people who suffer from this syndrome. This is disease that afflicts long term alcoholics who has also had an impaired diet, resulting in thiamine deficiency. Although many of their intellectual abilities may remain intact, they display a strange array of symptoms, including having hallucinations, repeating questions, even after being told the answer and repeating the same story again and again. 4. Motivated forgetting or Repression: Repression refers to the tendency of people to have difficulty retrieving anxiety provoking or threatening information from long term memory. This probably explains why people generally remember pleasant events, than unpleasant memories have been repressed. Many lapses in daily life illustrate motivated forgetting. E.g. I may forget my dentist’s appointment because I do not like to go there or forget to buy vegetables because I don’t like vegetables etc. Retrieval of the forgotten material can eventually occur according to psychoanalysis only under special circumstances. 1) Free association/ Projective technique- having an individual to say whatever comes to their mind when presented with emotionally arousing stimuli, 2) Hypnosis, 3) Truth serums can also used with occasional success to retrieve repressed information not available to consciousness in the normal waking state. Studying motivated forgetting in the laboratory has proved difficult, since we cannot produce powerful anxieties to demonstrate motivated forgetting. The best evidence for motivated forgetting is from case studies of Freud and other psychoanalysts..