Lecture 7 Human Memory PDF

Preview

Summary

Bruce Tsuji...

Description

CHAPTER 7 - HUMAN MEMORY (A-G) A = OVERVIEW Basic Questions: Memory is much more than taking in information and putting it in some mental compartment… we have to get it back out, too. 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? - How is information maintained in memory? - How is information pulled back out of memory? Overview of Memory 1. Sensory Memory 2. Working Memory - Sensory memory encoded into WM 3. Long-Term Memory - WM stored into long-term - Long-term retrieves from WM B = MEMORY PROCESSES 3 Memory Processes 3 storage systems - what happens between them? (1) Encode: info into memory o transform info into a form that can be retained o requires attention, focus, awareness o selective attention = selection of input, filtering (early or late?) o When does selective attention operate?

-

The first for info  memory = pay attention to it. Attention involves focusing awareness on a narrowed range of stimuli or events. Selective attention is a term used by many psychologists to describe this payingattention-to-something process; however, the word selective is really redundant… attention IS 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. 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. o Levels of Processing (Craik and Lockhart 1972)  Info is encoded to different levels - deeper processing = longer lasting  (1) structural = shallow  (2) phonemic = intermediate  (3) semantic = deep  whether or not we will be able to remember something depends on how deeply we processed the info  semantic = better retention

(2) Storage: maintain in memory - storage in computers is similar to storage in human memory - 3 storage systems: o sensory memory o working memory o long-term 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, with technological advances, the analogies have become much more sophisticated... Atkinson and Shiffrin, 1968, proposed an analogy between information storage by computers and information storage in human memory – the information processing approach. Basically, this approach divides memory into 3 different stores: sensory, short-term memory, and long-term memory.

(3) Retrieval: retrieve info from memory - tip of the tongue phenomenon: o failure in retrieval o jogged with retrieval cues - recalling an event o context cues, encoding specificity - reconstructing memories o misinformation effect o source monitoring, reality monitoring The tip-of-the-tongue phenomenon shows that recall is often guided by partial information about a word….retrieval cues. 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. Memories are reconstructions of the past, which may not be entirely accurate. Research shows that reconstructions can be influenced by new information…the misinformation effect. Elizabeth Loftus has shown that eyewitness testimony can be influenced by information presented to witnesses. 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 whether there was any broken glass in the video…the “smashed into” group said yes, the “hit” group said no. The misinformation effect is explained in part by the unreliability of 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 (did I read that somewhere or think of it on my own?…cryptomnesia is inadvertent plagiarism that occurs when you think you came up with it but were really exposed to it earlier). Reality monitoring is a type of source monitoring involving determining whether memories are based in actual events (external sources) or your imagination (internal sources)…kidnapped by aliens? Possible error in reality monitoring. C = MEMORY STORAGE

Sensory Memory: - brief storage in original sensory form - visual = approx ¼ second - auditory = approx. 2 seconds - info we attend to goes into working memory o Sperling (1960) Classic experiment on visual 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… in the visual system, an afterimage. The visual and auditory sensory stores appear to decay after about ¼ second George Sperling (1960) performed a classic experiment on the visual sensory store, illustrating how brief the sensory store actually is…his experiment is depicted in the following figure. -

Sperling (1960)

Working Memory: • Limited capacity: Miller’s magic number 7 ± 2 • Limited duration: ~ 20 seconds • Rehearsal: repetitively verbalize or think about • Chunking: group familiar stimuli as a single unit • Divide a chapter into smaller pieces • Learn a phone number by its area code + 3 digits + 4 digits Short-term memory is defined as a 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. A chunk of information is a group of familiar stimuli stored as a single unit…for example, the following numbers 8 -6- 7- 5- 3- 0- 9 can be thought of as 7 individual numbers or they can be chunked together in groups of 2, 3, etc. STM also has a limited duration…in other words, information can only be kept there for a brief time before it is lost, unless rehearsal occurs. Rehearsal is the process of repetitively verbalizing or thinking about the information…keeping it in use. Peterson and Peterson (1959) conducted a study illustrating how quickly information is lost from STM…this •

Stores info from Sensory Memory & info retrieved from Long Term Memory

• •

Info loss from decay; but maintained thru rehearsal, chunking. Baddeley (1986) – Working Memory – Phonological rehearsal loop - active when one uses recitation to temporarily hold on to information – Visuospatial sketchpad - temporary holding/manipulation of visual images – Executive control system - handles the limited amount of information juggled at one time as people engage in reasoning and decision making – Episodic buffer - 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 (LTM) • Unlimited capacity. • Permanent, accurate storage? – Penfield’s ESB http://www.youtube.com/watch?v=52bYneF6JEk – Flashbulb memories (yours? mine?) While most researchers agree that LTM has an unlimited capacity; that is, our memory store never gets FULL, much debate remains over whether storage is permanent. Flashbulb memory and hypnosis based memory 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). Research shows, however, that flashbulb and hypnosis based memories are not always accurate. Is the information still there, or does it decay over time, and we make up for this by building up decayed memories so that they make sense? And are STM and LTM really different stores? 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. We also 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. 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, although the multiple stores view is still dominant.

LTM Subsystems: • Implicit (procedural): motor skills, habits, classically conditioned responses. – Eating with knife & fork, chopsticks. – Riding a bicycle. – Sniffling. – Playing piano. • Explicit (Declarative): verbal or image info. – Episodic: events of your life. (personal) – Semantic: general knowledge, objective facts & information. (encyclopaedic) How is Knowledge Organized in Memory? • Analogical & Conceptual representations • Clustering and Conceptual Hierarchies • Semantic Networks • Schemas and Scripts Clustering is the tendency to remember similar or related items in groups. Conceptual hierarchies are multilevel classification systems based on common properties among items. Schemas are organized clusters of knowledge about a particular object or event abstracted from previous experience. A script is a particular type of schema, organizing what a person knows about common activities…for example going to a restaurant. Research shows that people are more likely to remember things that are consistent with their schemas than things that are not…the reverse is also true – people sometimes exhibit better recall if information really clashes with a schema. Semantic networks consist of nodes representing concepts, joined together by pathways that link related concepts….explains why thinking of butter makes bread easier to remember… depicted on following slide. Connectionist, or parallel distributed processing models, assume that cognitive processes depend on patterns of activation in highly interconnected computational networks that resemble neural networks….that is, 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.

Sir Frederic Bartlett (1920s) • Cambridge U subjects tried to memorize an aboriginal legend • Memory very poor over time – Simplified, sometimes detail added – Remembered “isolated but striking details” – Memory organized within framework of own experience—schemas D = WHEN MEMORY FAILS Measuring Memory Recall: info without retrieval cues (eg essay questions). Recognition: info with retrieval cues (eg MC questions). Relearning: measuring time it takes to relearn Recognition (MC) is almost always better than recall (essay) Ebbinghaus’ Forgetting Curves

Serial Position Test - Memorize 50 words and see how well you remember them - Primacy effect – info at beginning of sequence recalled because placed in long-term memory.

already

-

Recency effect – info at end of a sequence recalled because still in working memory.

Why do we forget? • Poor Encoding • Decay theory: forgetting occurs because memory traces fade with time • Interference - negative impact of competing info on retention - people forget info because of competition from other material – Proactive: occurs when previously learned information interferes with the retention of new info Study Sociology

Study Psychology

Psychology Exam

– Retroactive: occurs when new information impairs the retention for previously learned info Study Psychology

• • •

Study Sociology

Psychology Exam

Sometimes adaptive Pseudo forgetting - due to lack of attention  encoding does not occur Ineffective encoding - encode on a more superficial level than you need to

Retrieval Failure • Encoding Specificity (retrieval cue match to stored code) • 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 • Transfer-Appropriate Processing (encoding match to retrieval) • when the initial processing of information is similar to the type of processing required by the subsequent measure of retention, retrieval is easier • Repression: motivated forgetting of painful or unpleasant memories • Recent years = reports of repression towards memories of child sexual abuse

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 • 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 Roediger and McDermott (2000) 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 non-presented target word over 50% of the time…on a recognition test, they remember it about 80% of the time…a memory illusion. •

Context-Dependent Memory: • Info easier to recall when in same environmental context as when learned. – Underwater – Same classroom – Odours – Clothes State-Dependent Memory: • Info easier to recall (but not recognize) when same emotional or physical state when learned. – Anxiety. – Alcohol, – Marijuana & other drugs. Atkinson & Schiffrin Model:

E = MEMORY & CRIMINAL JUSTICE Cause of Forgetting: • Consolidation failure (trauma, loss of consciousness, no REM)

•

Motivated forgetting

Motivated Forgetting-Repression - unconscious, inadvertent forgetting

Reported Abuse %

Estimates of Childhood Abuse (Macmillan et al, 1997) 35 30 25 20 15 10 5 0

Males Females Physical

Sexual

Type of Abuse

10 000 Ontario adults reports about childhood abuse Williams (1994) • Apr 1973 to Jun 1975, 206 sexual abuse victims (1 to 12 yrs) in hospital. • In 1991 re-contacted, interviewed 129. • 38% did not report sexual abuse. • Did they forget? Choose not to? Eyewitness Testimony • Often erroneous. • Children good eyewitnesses only when special precautions taken. • Hypnosis does not improve, only confidence. • Research supports existence of repressed memories & false memories can be reconstructed in response to suggestions of abuse. • http://www.youtube.com/watch?v=gCswq5JDTaw (17:36) • http://www.youtube.com/watch?v=buhMdC7MO0U (20:50) Children Remembering Sexual Abuse? • Real or imagined? • Poor memory of birth to 3 yrs because hippocampus incompletely developed & language poor. • Repressed memory from trauma? Happens 3.9% to13.6% of cases (Connie Kristiansen, Carleton). F = BIOLOGY OF MEMORY Biology of Memory: • Biochemistry

•

•

– Alteration in synaptic transmission – Changes in synaptic transmission may be the building blocks of memories – Hormones modulate neurotransmitter systems – Protein synthesis has been shown to be a necessity for memory formation Neural circuitry – Localized neural circuits in the brain • Reusable pathways in the brain that may be specific for specific memories – Long-term potentiation occurs with learning • 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 Anatomy – Several brain regions important for memory – Amnesia: deficit in memory caused by brain damage, trauma, etc • Anterograde Amnesia - loss of abilities to create new memories • Retrograde Amnesia - can create new memories, cannot recall old ones – Hippocampus, PFC, amygdala ***

Retrograde Amnesia: • John O’Donnell: 45-year old white male • Ran grocery store with wife, 2 children • Store burned down without insurance • Depressed, started drinking, stopped, mother died, started drinking again. Wife & children left him • Found in woods near home, disoriented, malnourished • Korsakoff’s Syndrome, retrograde amnesia. Anterograde Amnesia: • Remember the example of HM? • Module 03:B • Hippocampus removed at 27 yrs.

•

Complete anterograde amnesia & inability to learn new things

The Nature of Memory • Memory as permanent record: video recorder analogy? No. • Memory as reconstruction: partly fact & partly fiction. – Piece together highlights with info that may or may not be accurate consistent with our Schemas. • Specific brain location of memory? No, but we understand how specific structures contribute. • When we remember (retrieve) something, do we change our memory of it? G = IMPROVING MEMORY Better Encoding: • Elaboration: link to other info – Examples related to a concept • Visual Imagery: create images – Dual-coding theory (textbook Concept Charts) • Self-Referent Encoding: Make info personally meaningful • Deep Processing: do meaningful things with info—don’t just repeat or highlight it Elaboration is a process by which a stimulus is linked 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. Elaboration often consists of thinking of examples…self-generated examples seem to work best. Visual imagery involves the creation of visual images to represent the words to be remembered…concrete words are much easier to create images of (example, juggler vs. truth). Dual-coding theory holds that memory is enhanced by forming semantic or visual codes, since either can lead to recall. Self-referent encoding involves deciding how or whether information is personally relevant, that is, information that is personally meaningful is more memorable. Improving our Memory • Effective encoding & rehearsal. • Distribute practice, minimize interference. • Organize information. Personalize it. • Use verbal, visual mnemonics. • Use SQ3R. • Allow time for memory consolidation....