Chapter 7 Human Memory Human Memory Basic Questions

Chapter 7: Human Memory

Human Memory: Basic Questions • Many psychologists study factors that help or hinder memory storage and retrieval…thus attempting to answer 3 basic questions… • How does information get into memory? (ENCODING) • How is information maintained in memory? (STORAGE) • How is information pulled back out of memory? (RETRIEVAL)

Figure 7. 2 Three key processes in memory

Encoding: Getting Information Into Memory • Next-in-line effect: – When getting ready to speak, subject rarely remember what the person directly before them said… – Why?

Encoding: Getting Information Into Memory • The first step in getting information into memory is to pay attention to it – Attention involves focusing awareness on a narrowed range of stimuli or events • Selective attention = selection of input – Usually, attention is likened to a filter in an information-processing model of memory…the filter screens out most stimuli, while allowing a select few to get by

Encoding: Getting Information Into Memory – Filtering: Much research has been done to determine whether this filtering process occurs early in the information processing sequence or later. – It appears that both may be at play…sometimes you are paying attention to someone talking with you at a party, and you suddenly hear your name from across the room. Late selection based on meaning… – Research suggest both are at work (you can pick up inputs later, but have a hard time trying to monitor inputs and carry a conversation at the same time

Figure 7. 3 Models of selective attention

Levels of Processing: Craik and Lockhart (1972) • Incoming information processed at different levels • Deeper processing = longer lasting memory codes • Encoding levels: – Structural = physical structure of stimuli; shallow – Phonemic = what a word sounds like, saying or naming a word; intermediate – Semantic = the actual meaning of the stimuli; deep

Figure 7. 4 Levels-of-processing theory

Levels of Processing: Craik and Lockhart (1972) • Levels of processing theory: – The deeper the level of processing, the longer lasting the memory • Given a list of 60 words…

Figure 7. 5 Retention at three levels of processing

Enriching Encoding: Improving Memory • Elaboration = linking a stimulus to other information at the time of encoding – for example, you are studying phobias for your psychology test, and you apply this information to your own fear of spiders • Visual Imagery = creation of visual images to represent words to be remembered – Easier for concrete objects, hard for abstract principles: • Dual-coding theory (Paivio): memory is enhanced by forming semantic and visual clues • He put words into four groups…

Enriching Encoding: Improving Memory • Self-Referent Encoding – Making information personally meaningful, do the stimuli apply to you personally?

Storage: Maintaining Information in Memory • Plato and Aristotle compared memory to a block of wax that differed in size and hardness for various individuals… remembering was like stamping an impression into the wax • Today’s Analogy: information storage in computers ~ information storage in human memory

Storage: Maintaining Information in Memory • Information-processing theories: Atkinson and Shiffrin, 1968, proposed an analogy between information storage by computers and information storage in human memory – Subdivide memory into 3 different stores • Sensory, Short-term, Long-term

Figure 7. 7 The Atkinson and Schiffrin model of memory storage

Sensory Memory • Sensory Memory is basically information preserved in its original sensory form for a brief time. • This type of memory allows the sensation to linger briefly after the sensory stimulation is over Auditory/Visual – approximately ¼ second – George Sperling (1960) • Classic experiment on visual sensory store, illustrating how brief the sensory store actually is

Figure 7. 8 Sperling’s (1960) study of sensory memory

Short Term Memory (STM) • Limited capacity – limited-capacity store that can maintain unrehearsed information for up to about 20 seconds • George Miller (1956) wrote a famous paper called “The Magical Number Seven, Plus or Minus Two: – Some Limits on Our Capacity for Processing Information, " where he illustrated that the average person can hold between 5 and 9 chunks of information in STM – Chunking – grouping familiar stimuli for storage as a single unit

Short Term Memory (STM) • Limited duration – about 20 seconds without rehearsal – Rehearsal – the process of repetitively verbalizing or thinking about the information (phonemic encoding)

Figure 7. 9 Peterson and Peterson’s (1959) study of short-term memory

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Short-Term Memory as “Working Memory” • 30 years of research eventually uncovered a number of problems with the original model of STM, it is not limited to phonemic encoding • Loss of information not only due to decay, interference from incoming stimuli also play a part

Capacity of STM • Nelson Cowan (2001): – 4 items plus or minus 1

Short-Term Memory as “Working Memory” • Alan Baddeley (1986 -1992) – 4 components of working memory – Phonological rehearsal loop: represented ALL of STM in the original model – Visuospatial sketchpad: allows temporary holding and manipulation of visual images

Short-Term Memory as “Working Memory” – Executive control system: handles the limited amount of information juggled at one time as people engage in reasoning and decision making – The episodic buffer: a temporary, limited capacity store that allows the various components of working memory to integrate information, and that serves as an interface between working and LTM.

Long-Term Memory: Unlimited Capacity • While most researchers agree that LTM has an unlimited capacity; much debate remains over whether storage is permanent • Permanent storage? – Flashbulb memories: vivid recall of momentous events – Recall through hypnosis • suggest that LTM is indeed permanent, that the only reason we forget is that we aren’t able to access information that is still in LTM (interference theory). Pinfield • flashbulb and hypnosis based memories are not always accurate

Long-Term Memory: Unlimited Capacity • Debate: are STM and LTM really different? – Phonemic vs. Semantic encoding • We used to think that phonemic encoding occurred in STM and semantic (or meaning based) encoding in LTM. Now we know that both occur for both – Decay vs. Interference based forgetting • used to think that decay occurred in STM and interference in LTM, with regard to forgetting. Now, it is unclear what exactly occurs in LTM, it may be both

How is Knowledge Represented and Organized in Memory? • Some researchers argue that STM and LTM are the same thing, that STM is just a little part of LTM that is in a state of heightened activation • Clustering: the tendency to remember similar or related items in groups • Conceptual Hierarchies: multilevel classification systems based on common properties among items • Schemas and Scripts: script is a particular type of schema, organizing what a person knows about common activities

How is Knowledge Represented and Organized in Memory? • Semantic Networks: Semantic networks consist of nodes representing concepts, joined together by pathways that link related concepts • Connectionist Networks and PDP Models: assume that cognitive processes depend on patterns of activation in highly interconnected computational networks that resemble neural networks – this model of memory uses as inspiration the way neurons appear to handle information through connections…according to this model, specific memories correspond to specific patterns of activation in these networks

Retrieval: Getting Information Out of Memory • The tip-of-the-tongue phenomenon – a failure in retrieval • shows that recall is often guided by partial information about a word…retrieval cues • Recalling an event – Memories can also be reinstated by context cues…easier to recall long-forgotten events if you return after a number of years to a place where you used to live

Retrieval: Getting Information Out of Memory • Reconstructing memories – Misinformation effect: recall of an event is altered due to misleading info post-event • Research shows that reconstructions can be influenced by new information – Example…showed a video of two cars in an accident…asked some people how fast the cars were going when they HIT each other, asked others how fast the cars were going when the SMASHED INTO each other…a week later asked whethere was any broken glass in the video…the “smashed into” group said yes, the “hit” group said no. / KFC chicken

Retrieval: Getting Information Out of Memory • Source monitoring: the process of making attributions about the origins of memories – people make decisions at the time of retrieval about where their memory is coming from – cryptomnesia is inadvertent plagiarism that occurs when you think you came up with it but were really exposed to it earlier • Reality monitoring: type of source monitoring involving determining whether memories are based in actual events (external sources) or your imagination (internal sources)…

Forgetting: When Memory Lapses • Hermann Ebbinghaus studied forgetting using retention in the late 1800 s, by using himself as a subject. – He found that retention and forgetting occur over time and plotted his data… – Current research suggests that this curve is unusually steep, probably due to the fact that Ebbinghaus was using nonsense syllables that are difficult to encode semantically.

Figure 7. 16 Ebbinghaus’ forgetting curve for nonsense syllables

Forgetting: When Memory Lapses • Retention – the proportion of material retained – Recall: involves requiring subjects to reproduce information on their own without any cues (essay, fill-in-the-blank) – Recognition: requiring subjects to select previously learned material from an array of options (mult. choice, matching) – Relearning: requiring subjects to relearn previously learned information to see how much LESS time or effort it takes them

Figure 7. 17 Recognition versus recall in the measurement of retention

Why Do We Forget? • Research indicates that forgetting may be related to encoding, storage, or retrieval processes • Much forgetting may only look like forgetting…it may have never been inserted into memory in the first place… pseudoforgetting…usually due to lack of attention so that encoding does not occur

Why Do We Forget? • Ineffective Encoding: occurs when you encode on a more superficial level than you need to… – for example, you are distracted when studying and encode what you are reading on a phonemic rather than a semantic level • Decay theory: proposes that forgetting occurs because memory traces fade with time • Interference theory: negative impact of competing information on retention – Proactive: previously learned information interferes with the retention of new information – Retroactive: new information impairs the retention for previously learned information

Figure 7. 19 Retroactive and proactive interference

Retrieval Failure • Encoding Specificity: holds that the effectiveness of a retrieval cue depends on how well it corresponds to the memory code that represents the stored item… – the closer a retrieval cue is to the way we encode the info, the better we are able to remember.

Retrieval Failure • Transfer-Appropriate Processing: holds that when the initial processing of information is similar to the type of processing required by the subsequent measure of retention, retrieval is easier • In other words, you must learn the words/concepts the way you want to remember them…

Retrieval Failure • Repression: involves the motivated forgetting of painful or unpleasant memories – Authenticity of repressed memories: challenged by empirical studies that show that it is not at all hard to create false memories and that many recovered memories are actually the product of suggestion

Retrieval Failure: Repression (cont. ) – Roediger and Mc. Dermott (2000) have shown that when participants are asked to learn a list of words, and another target word that is not on the list but is strongly associated with the learned words is presented, the subjects remember the nonpresented target word over 50% of the time…on a recognition test, they remember it about 80% of the time…a memory illusion

Figure 7. 22 The prevalence of false memories observed by Roediger and Mc. Dermott (1995)

Retrieval Failure – Controversy: While research clearly shows that memories can be created by suggestion, in cases of child sexual abuse memories, for example, this issue becomes quite emotionally charged. • Some cases of recovered memories are authentic, and we don’t yet have adequate data to estimate what proportion of recovered memories of abuse are authentic and what proportion are not. • Still, this controversy has helped inspire a great deal of research that has increased our understanding of the fallibility and malleability of human memory.

Figure 7. 20 Estimates of the prevalence of childhood physical and sexual abuse

The Physiology of Memory • Biochemistry – memory appears to be related to alterations in synaptic transmission at specific sites • Durable changes in synaptic transmission may be the building blocks of memories • learning causes hormonal changes which may modulate activity in a variety of neurotransmitter systems • Protein synthesis has also been shown to be necessary for memory formation

The Physiology of Memory • Neural circuitry – memories appear to depend on localized neural circuits in the brain • Reusable pathways in the brain: may be specific for specific memories • Long-term potentiation (occurs with learning): a long-lasting increase in neural excitability at synapses along a specific neural pathway • This supports the idea that memory traces consist of specific neural circuits.

The Physiology of Memory • Anatomy – Anterograde Amnesia: subsequent events – Retrograde Amnesia: for prior events • Cerebral cortex: aide in phonological loop • Prefrontal cortex: working memory • Hippocampus: bind together memories (amnesia guy) • Dentate gyrus: part of the Hippo. region • Amygdala: formation of memories for learned fears • Cerebellum

Figure 7. 23 The anatomy of memory

Figure 7. 25 Retrograde versus anterograde amnesia

Are There Multiple Memory Systems? • Procedural memory is memory for actions, skills, operations and conditioned responses, • Declarative memory is memory for factual information. • declarative memory can be subdivided – episodic memory: memory for personal facts – semantic memory: for general facts • Retrospective memory is memory for past events • Prospective memory is remembering to do things in the future.

Figure 7. 26 Theories of independent memory systems

Improving Everyday Memory • Engage in adequate rehearsal • Distribute practice and minimize interference • Emphasize deep processing and transferappropriate processing • Organize information • Use verbal mnemonics • Use visual mnemonics