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Chapter 7: Human Memory Human Memory: Basic Questions • How does information get into memory? • How is information maintained in memory? • How is information pulled back out of memory? Figure 7.2 Three key processes in memory Encoding: Getting Information Into Memory • Attention- focusing awareness on a narrowed range of stimuli or events. • Divided attention- can have a negative impact on the performance of quite a variety of tasks. – When participants are forced to divide their attention between memory encoding and some other task, large reductions in memory performance is seen. Encoding: Getting Information into Memory • Levels of processing – Incoming information processed at different levels – Theory proposes that deeper levels of processing result in longer-lasting memory codes – Encoding levels: • Structural = shallow-emphasizes the physical structure of the stimuli • Phonemic = intermediate-emphasizes what a word sounds like • Semantic = deep-emphasizes the meaning of verbal input Figure 7.3 Levels-of-processing theory Enriching Encoding to Improve Memory • Elaboration = linking a stimulus to other information at the time of encoding – The additional associations created usually help people remember information – Often consists of thinking of examples that illustrate an idea • Visual Imagery = creation of visual images to represent words to be remembered – Easier to form images for concrete objects than of abstract concepts • Dual-coding theory- memory is enhanced by forming both semantic and visual codes, since either can lead to recall. Storage: Maintaining Information in Memory • Information storage in computers ~ information storage in human memory • Information-processing theories- subdivide memory into 3 different stores – Sensory- preserves information in its original sensory form for a brief time, usually only a fraction of a second (afterimage) – Short-term- a limited-capacity store that can maintain unrehearsed information for up to about 20 seconds – Long-term- an unlimited capacity store that can hold information over lengthy periods of time Figure 7.6 The Atkinson and Schiffrin model of memory storage Short Term Memory (STM) • Limited duration – about 20 seconds without rehearsal – Rehearsal – the process of repetitively verbalizing or thinking about the information (keeping it in use) • Limited capacity – people can only recall about 7 items on tasks that required them to remember unfamiliar material (magical number 7 plus or minus 2) – When STM is filled to capacity, the insertion of new information often displaces some of the current information. – Chunking – grouping familiar stimuli for storage as a single unit (phone numbers) • Helps increase the capacity of your STM Short-Term Memory as “Working Memory” • STM not limited to phonemic encoding • Loss of information not only due to decay • Baddeley (1986) – 4 components of working memory – Phonological rehearsal loop- is at work when you use recitation to temporarily hold onto a phone number – Visuospatial sketchpad- allows temporary holding and manipulation of visual images – Central executive system-handles the limited amount of information juggled at one time as people in reasoning and decision making – Episodic buffer- temporary limited capacity store that allows the various components of working memory to integrate information (serves as an interface between Figure 7.7 Short-term memory as working memory Long-Term Memory • Unlimited capacity- our memory store never gets full. • Flashbulb memories- unusually vivid and detailed recollections of momentous events – the only reason we forget is that we aren’t able to access information that is still in LTM • How is knowledge represented and organized in memory? – Schemas and Scripts – Semantic Networks – Connectionist Networks and PDP Models Organization in Long-Term Memory • Schemas- an organized cluster of knowledge about a particular object or event abstracted from previous experience with the object or event – script is a particular type of schema, organizing what a person knows about common activities, for example going to a restaurant • Semantic Networks- consists of nodes representing concepts, joined together by pathways that link related concepts – explains why thinking of butter makes bread easier to remember • Connectionist Networks- assume that cognitive processes depend on patterns of activation in highly interconnected computational networks that resemble neural networks – specific memories correspond to specific patterns of Retrieval: Getting Information Out of Memory • The tip-of-the-tongue phenomenon – the temporary inability to remember something you know, accompanied by a feeling that it’s just out of reach. (failure in retrieval) – Retrieval cues- stimuli that help gain access to memories (hints, partial recollections) • Reinstating the context through context cues – Trying to recall an event by putting yourself back in the context in which it occurred. Retrieval: Getting Information Out of Memory • Reconstructing memories-sketchy reconstructions of the past that may be distorted and cause the misinformation effect – A recall of an event that was witnessed but altered due to the introduction of misleading postevent information • Source monitoring error- an error that occurs when a memory derived from one source is attributed to another source – A crucial part of memory retrieval that contributes to many of the mistakes that people make in reconstructing their experiences Forgetting: When Memory Lapses • Ebbinghaus’s Forgetting Curve- graphs retention and forgetting over time – Showed that most forgetting occurs very rapidly after learning something. • Retention- the proportion of material retained (remembered). Can assessed with measures of forgetting – Recall-requires participants to reproduce information on their own without cues – Recognition- requires participants to select previously learned information from an array of options – Relearning- requires a participant to memorize information a second time to determine how much time or effort is saved by having learned before Figure 7.10 Ebbinghaus’ forgetting curve for nonsense syllables Why We Forget • Ineffective Encoding-the information may have never been inserted in the memory in the first place – Pseudoforgetting- you can’t remember something you never learned • Decay- forgetting occurs because memory traces fade with time • Interference-people forget information because of competition from other material – Proactive- occurs when previously learned information interferes with the retention of new information – Retroactive- occurs when new information impairs the retention of previously learned information Why We Forget • Retrieval failure- may occur when a mismatch exists between retrieval cues and the encoding of the information to be recalled Figure 7.11 Effects of interference Figure 7.12 Retroactive and proactive interference Retrieval Failure • May occur when a mismatch exists between retrieval cues and the encoding of the information to be recalled • Encoding Specificity-sometimes we are unable to retrieve information because the retrieval cues do not correspond very well to memory cues. • Transfer-Appropriate Processing-occurs when the initial processing of information is similar to the kind of processing that is required by the measure of retention. Retrieval Failure • Repression-the motivated forgetting of material, especially anxiety-provoking memories. – Authenticity of repressed memories? • sharply debated because experiments show that it is relatively easy to create very real-seeming false memories. – Memory illusions-false memories that can be reliably created in normal, healthy participants in minutes. – Controversy • Evidence suggests that sometimes therapists have unwittingly produced false memories in their clients, but it is likely that at least some recovered memories are accurate. • http://www.youtube.com/watch?v=23Pum-7-pyM&feature=BFa&list=PLF9A174B24892CB44&index=6 Figure 7.14 The prevalence of false memories observed by Roediger and McDermott (1995) The Physiology of Memory • Anatomy-many brain structures have been shown to be important in memory. – Anterograde (for subsequent events)and Retrograde Amnesia (for prior events) • Hippocampus • Medial temporal lobe memory system • Neural circuitry-memories appear to depend on localized neural circuits in the brain – reusable pathways in the brain that may be specific for specific memories • Biochemistry – Hormonal changes which may modulate activity in a variety of neurotransmitter systems. – Protein synthesis-has also been shown to be necessary for memory formation. Figure 7.16 The anatomy of memory Systems and Types of Memory • Two memory systems: • Declarative- handles recall of factual information (names, dates, events, ideas) • Nondeclarative- handles recall of actions, skills, and operations (riding a bike or typing) Declarative Memory System: Type of memory Semantic vs. Episodic • Semantic memory system contains general knowledge that is not temporally dated • Episodic memory system handles temporally dated recollections of personal experiences Prospective vs. Retrospective • Prospective memory involves remembering to perform actions in the future • Retrospective memory involves remembering events from the past or previously learned information • http://www.youtube.com/watch ?v=rSzPn9rsPcY&NR=1 Figure 7.17 Theories of independent memory systems Figure 7.18 Retrospective versus prospective memory http://www.youtube.com/watch?v=TausqSK9p9k&feature=related