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• The study of learning emphasises acquisition process while the study of memory emphasise on retention process. • Memory is studied in terms of mental processes involved in storing & retrieving information. Memory • Human Memory is a system for storing and retrieving information which is acquired through our senses. • It consists not of one but of many systems which range in a) Storage duration from fractions of a second up to a lifetime and in b) Storage capacity from tiny buffer stores to the long-term memory system. Memory Memory • Memory is our cognitive systems for storing and retrieving information. • We can form memories of information, events, emotions, & sensations. • It is not a perfect system. Theories Theory of General Memory Functions • Three distinct processes 1. Encoding Process: Transformation of a physical stimulus into a form that human memory accepts. 2. Storage: Retention of information that is encoded. 3. Retrieval: Recovering information from storage. Information-Processing Theory (Richard C. Atkinson & Richard M. Shiffrin, 1968) Sensory Input Sensory Memory 0.25 sec.-2 sec. Some materials are rehearsed & kept in STM. Short Term Memory 20-30 sec. Retrieval Some information is not transferred to STM. It is forgotten. Some materials are not transferred to LTM. They are forgotten. Rehearsal Long Term Memory Factors like decay & interference may lead to Forgetting from LTM. Information Processing Model • Right kind of information processing is more important than intentional goal of learning. • “Who am I?” - autobiographical memory: Record of the experiences of a lifetime that go together to create myself as a person. • “What do I know?” - semantic memory: • “How do I learn?” • General information about the world • Best method of efficient retrieval depends on how material is stored. Level of Processing Theory (Craik & Lockhart, 1972) (Craik & Tulving, 1975) Incoming Information Depth of processing Level 1: Perception Level 2: Structural Level Level 3: Semantic Level Amount of elaboration Neural Network Perspective • Parallel distributed processing • Collections of modules process information in different ways simultaneously • Activation & spreading • Memory is making or strengthening interconnections between these modules A Model of Memory Environmental Input Sensory Register Visual Auditory Haptic Short-Term Memory Working Memory Control Processes: Rehearsal Coding Decision Retrieval Strategies Long-Term Memory Response Output Sensory Memory • Visual, hearing, smell, taste, touch • The storage of sensory information provides a microcosm of the memory system as a whole. Sensory Memory • It begins with the systems of iconic and echoic memory that store visual and auditory information over a matter of milliseconds, as part of the processes involved in perception. • Both of these appear to have characteristics that allow the initial stimulus to be prolonged, probably so as to ensure that adequate later processing is possible. Sensory Memory • VISUAL MEMORY – – – – Iconic memory Short-term visual memory Flashbulb memory Long-term visual memory • AUDITORY MEMORY – Echoic memory – Short-term auditory memory – Long-term auditory memory Sensory Memory Sensory Memory: Visual Iconic Memory Echoic Memory • Holds information • Holds information for up to 1-2 for up to about 4-5 seconds. seconds. • 11-16 items can be hold. Sensory Memory: Auditory ECHOIC MEMORY • Persistence of audition • Capable of storing sequences of at least ~250 milliseconds and possibly more • Masking sound Short Term Memory • Information hold for 20-30 seconds after which it is displaced by incoming information. • Information encoded in STM is acoustic in nature (Speech, Sounds, Visual Images & Words). • It is semantic in nature. Meaningful words may be stored easily as compared to nonsense syllables. Short Term Memory • Serial-Position Effect: • Primacy Effect: Better recall of items at the beginning of the list. • Recency Effect: Items encountered most recently are remembered well. • STM can hold 5-9 chunks of information. • Several items of information can be combined into one chunk. • About 7 chunks can be retained. • About 40 items can be combined into 7 chunks & can be held in STM. Reason behind Primacy Effect • Primacy effect remains during delayed recall because the first items get time to be put into LTM during the presentation of the list. Visual Memory ICONIC MEMORY • • • • • FLASHBULB MEMORY Holds information for • Phenomenon of vivid up to 1-2 seconds. memories of important events Visual persistence • Not necessarily accurate: ~ 100 milliseconds what we typically recall in Short-time visual trace such situations is not what ‘icon’ we experience but what we Features such as color, abstract from that shape and direction can experience (i.e. Eyewitness be stored testimony, Recognition of faces). Brightness-masking • • Pattern-masking Auditory Memory SHORT-TERM AUDITORY MEMORY • There is evidence for two short-term auditory storesa) one operating over a timescale of 150-350 milliseconds, and b) the other one lasting somewhere between 2 and 20 seconds. • Modality effect: Advantage to spoken terms • Recency effect: Enhanced recall of the most recently presented items Auditory Memory LONG-TERM AUDITORY MEMORY • Memory for language: Stored in terms of meaning than sound. • Memory for music: Both contour and pitch interval information are retained. • Memory for voices: Voice recognition of a familiar person is reasonably good, but is poor for a stranger. Rehearsal in STM (The process of keeping items of information in the center of attention) Maintenance Rehearsal Elaborative Rehearsal • Repetition of • Giving the material organization & meaning information over & as it is being rehearsed. over again. • Just going over & over • It uses strategies of giving meaning & again does not organizing materials so necessarily succeed that it can fit in with the transferring the existing organized information into LTM. LTM. Short Term Memory (Working Memory) • 7+2 Chunks of memory can be kept in mind at a time and combined to make a decision. • The size of the chunk varies greatly between experts and novices. • Experts can combine many memory units to a whole (e.g. master chess players retain a series of moves) Model of Working Memory Allen D. Baddeley’s Model (1986) (Little consensus at present) • Articulatory Loop (Verbal rehearsal takes place here) • Visio-spatial sketchpad (Rehearsal of visually presented information) • Central executive • Control & decision making • Reasoning & Language comprehension • Transfer to LTM • Recency effects (Short term buffer) • Articulatory processes • Recycling items for immediate recall • If imagery task is difficult executive’s resources are drained • Visual Imagery Tasks • If imagery task is difficult executive’s resources are drained fMRI: Working Memory Fig. 1 Location of Working Memory Fig. 2 Organization in Short Term Memory In STM Chunks are organized in hierarchy. • 5.6 • 4.1 • 2.0 • .25 Long Term Memory • Intended to store information over a long time. • It has unlimited capacity. • Tulving (1972, 1983) ,a Canadian Psychologist, was the first to make distinction between episodic & semantic memory. Long Term Memory Declarative Memory Semantic Memory Specific Memory Procedural Memory Episodic Memory Autobiographical Memory Long Term Memory Episodic memory • Represents our memory of events and experiences in a serial form. • Records an individual’s past experiences & episodes of one’s daily life. Long Term Memory Long Term Memory Semantic Memory • It is a structured record of facts, concepts and skills that we have acquired. • Abstract knowledge & meaning of words, symbols, etc. are retained. • It also contains ideas & rules for relating them. Autobiographical Memory • Memories about event and experiences of our own lives. • The factors that affect other forms or memory also affect organization of autobiographical memory. • Infantile Amnesia: Supposed inability to remember events from the first 2-3 year of life. Semantic Memory • This memory system stores general knowledge that is not associated with a specific place and time of acquisition. Organization of semantic memory • Semantic networks • Concepts • Prototypes • Exemplars Episodic Memory • It is the memory for factual information that we acquire at a specific time. • Episodic memory is more susceptible to forgetting as compared to semantic memory. • Organizations of information in LTM is subjective. • Images of information are concrete & abstract. • Concrete words are easier to learn than abstract words. Episodic Memory • Tip-of-the-tongue phenomenon supports the fact that information in LTM is organized. • Search in LTM is not random. Factors affecting episodic memory: memory • • • • • • • Amount and spacing of practice Type of processing Levels of processing view Retrieval cues Context-dependant memory State-dependant retrieval Encoding specificity principle New Developments in MEMORY • Items can directly go into LTM (Anderson, 1995). • Studies on patients gave two more concepts1. Implicit memory 2. Explicit memory • Two more concepts1. Declarative memory 2. Procedural memory New Developments in MEMORY • Declarative memory is memory of ‘what’, of facts & events. • Procedural memory is memory of ‘how’, or the procedure. • Procedural memory is usually implicit. • It is the knowledge of how to perform a task. • Older people show problems of Prospective Memory (Fail to remember what they were going to do). Procedural Memory • Memory systems that contain information that we cannot readily express • Procedural knowledge & skilled behaviors • Skill acquisition • Automatic & controlled processing Sensory STM Approximate duration Iconic: 1-2 sec. Echoic: 4-5 sec. Capacity Relatively large. At Relatively small. About 7 Very large. least 16 items. items or chunks. Limit unknown. Probably much more. Transference 20-30 seconds. LTM Attention & Rehearsal: Items recognition. appropriately rehearsed Items attended to & move to LTM. recognized move to STM. Days, months, years or life time. - Copy of input. Sounds, visual images, Primarily meaningful words & sentences. sentences, life events & concepts, some images, semantic & episodic memory. Decay of trace. Information loss (Reason) Displacement of old Faulty organization, information by incoming inappropriate retrieval information. strategy, interference. Type of information stored Memory: Complex Cognitive Task • There are fundamental differences between complex tasks and standard memory tasks. • Working memory does not consist of a single general capacity, rather it consists of several subsystems for various types of tasks. • Working memory in a specific skilled activity increases as one aspect of acquired skill. • With practice and acquisition of memory skills, recall performance on a specific memory task can be improved by 100 to 1000%. Memory in Children • The effects of memory distortion and construction are more pronounced in children • Children are more likely to commit errors in reality and source monitoring Reconstructive Memory Bartlett (1932) • A group of students were asked to read a story about North American Indians ‘The War of the Ghosts’. • The story was reproduced after passing through several mouths. • Almost all details related to American Indian culture were omitted & other were rationalized. • Each narrator added something to the story from his own imagination. • Many details of the story was leveled, making it simpler. • Narrators sharpened some other facts in the story & exaggerated those aspects which they liked. • All these processes changed the story. Reconstructive Memory: Indian Contribution • Durganand Sinha has done work on rumors in Indian setting. • J.P.Das & R. Kanungo’s study>Two group of students (Brahmins & Kayasthas) were given 4 lists of adjectives. >List 1 had adjectives that described Brahmins in favourable terms: nice, good looking, clean, etc. >List 2 had adjectives that described Brahmins in unfavourable terms: rude, greedy, fat, etc. >List 3 had adjectives that described Kayasthas in favourable terms. >List 4 had adjectives that described Brahmins in unfavourable terms. ¾ Brahmin students remembered adjectives favourable to them, but not favourable to the Kayasthas Similar was the case with the Kayasthas. ¾ Everyone remembered more unfavourable adjectives than favourable one. ¾ It suggests that, in general, people prefer to remember bad rather than good attributes. Zeigarnik Effect (B. Zeigarnik) • This Russian psychologist compared memory for tasks that were successfully completed & those which were not. • In fact she interrupted the work & did not allow them to finish it. • Interrupted tasks were remembered more frequently than those which were completed. # This mismatches with our daily experience. Zeigarnik Effect: Indian Contribution • Dutta & Kanungo gave a new interpretation to Zeigarnik effect. • The intensity of emotion aroused by the completed or the interrupted task is the critical factor. • Any activity that gives rise to strong emotion, be it pleasant or unpleasant, is remembered better than ordinary everyday action. Memory Construction • Recall of events that did not take place. • Memory implantation • These are not necessarily deliberate • Suggestibility • Source monitoring • Illusion of out group homogeneity Memory Distortion • The change in the content of recall (memory) as a result of internal or external factors. • • • • • • • Cognitive biases Suggestive questioning Factors affecting distortion Schemas Motivation Source monitoring Reality monitoring Methods for Studying Memory • Free recall & recognition • Sentence verification • Priming • Neuroimaging Forgetting • One characteristic of human memory is that humans forget. • Forgetting is a very useful attribute of the human memory system. • Forgetting happens if learned messages haven’t been transfered to the long-term memory. • With hypnosis it is possible to retrieve things that have been forgotten. Forgetting • During the process of forgetting important features are filtered out and preserved, while irrelevant or predictable detail is either destroyed, or stored in such a way that it is not readily accessible in its original form. • One obvious benefit of forgetting is the way in which it softens emotional pain or grief ”Time heals all wounds” - but it also represents a distortion of our recollection of the past. Forgetting • Forgetting is the loss, decay, inaccessibility of information in LTM • Interference • Retroactive: Newly learnt information prevents retrieval of previously stored ones. • Proactive • Retrieval inhibition Repressed Memories • Elimination of threatening or extremely painful memories from consciousness • Very controversial • Methods of eliciting false memories Effect of Mood on Memory • Mood can serve as an internal retrieval cues • Mood-dependent memory • Mood congruence effects Towards Better Memory • Overlearning (leads to automatisation) • Mnemonics (Rhymes & jingles) • Method of loci • Number-peg technique Memory Disorders Amnesia • Retrograde: Memory loss for things learnt prior to the event initiating amnesia. • Anterograde: Disruption of memory for experiences after the onset of amnesia. Alzheimer’s disease • Gradual deterioration of memory functions • It appears that chemical and neurotransmitters may be involved Memory Location in the Brain: Hippocampus • Transfers information from memory to long term memory working • It helps the brain form memories by stimulating it to form new synapses. Neurons in the adult brain do not reproduce, they simply form new synapses. Memory Location in the Brain: Hippocampus • It appears that stimulation through the hippocampus causes new synapses to form & strengthen the synapses that already exist. This process is called long-term potentiation, LTP. • This is the primary means by which learning, & consequently memory, takes place. Memory Location in the Brain • Frontal lobes: Working memory, lobes encoding and retrieval of information from long term memory • Temporal lobes: lobes Semantic memory Memory Location in the Brain • Some memories may be localized in certain specific areas of the brain. • Learning through classical conditioning is apparently stored in the cerebellum (McCormick et al., 1982). • However, there is also evidence that in many cases memories are not stored in any single part of the brain. • A single memory can be stored in numerous parts of the brain, so that removal of any one part can diminish but not erase the whole memory (Lashley, 1950) . Memory Location in the Brain • Once these new connections have been formed & long-term potentiation has taken place, the hippocampus is no longer necessary for the particular memory- the memory & all its connections to other information have become an integral part of the brain’s structure & will persist even if hippocampus is totally destroyed. (Zola-Morgan & Squire, 1990; Squire & ZolaMorgan, 1991) Summary of Memory Function Fig. 3 References 1 www.nimh.nih.gov 2 www.nimh.nih.gov 3 Markowitsch, H.J. (1998). Cognitive Neuroscience of Memory. Neurocase, 4, 429-435.