MemoryMemory

Three Stages of Memory:Three Stages of Memory:An Information-Processing ViewAn Information-Processing View

Information processing theories

◦Brain and computer operations are similar

Information-processing model

◦Operations: input, storage, and retrieval

◦Variety of control mechanisms at each point

Memory

Information-Processing TheorySensory

information

economics

history

religionculture science

literatureInformation is taken into brain

Information gets processed, analyzed, and stored until use

RETRIEVALInformation is used as basis of behaviors and interactions

INPUT

math

STORAGE

MemoryMemoryInformation-processing model

◦Information enters through sensory receptors

◦Attention selects information to be entered

◦Information encoded for next memory stage

◦Some memory is saved, other information is lost or discarded

Stage theory of memory◦Assumes humans have 3-stage memory

Memory

Long-TermMemory

(increasingor

decreasingavailability)

Working

Memory

(Short-term

Memory)

SensoryRegister

Response(output

orreaction

behavior)

Stimuli(input)

DiscardedDiscarded

Control Processes(selective attention, emotional regulation, strategic thinking)

lasts lessthan a

second,interpretsstimulus

Stages of MemoryStages of Memory

Sensory register◦Holds image or experience until processing

◦Can last up to 4 seconds; usually lasts less

Short-term memory (STM)◦Usually attention transfers information from

sensory register to STM

◦Usually information lasts less than one minute unless control processes like rehearsal and chunking are used

Memory

Demonstration

Attend to the words in the green box as they flash on the screen. When the last word disappears, write down as many words as you can recall.

CATBREADDOORHATTABLEFOOTDOGSONSNOWBUSEND

Stages of MemoryStages of Memory

◦Rehearsal – mental repetition of information Humans have preference for transforming

information into acoustic codes or sounds

◦Chunking – grouping information into bits Capacity limited to 7 items plus or minus 2 Rare to hold between 5 and 9 items in STM

STM functions◦Temporary storage of information◦Serves as working memory: space used for

retrieved memories from long-term memory

Memory

Per

cent

of

accu

racy

of

reca

ll

3 6 18

20

9 15120

40

60

80

100

0

Interval before recall in seconds

Accuracy of recall for a single group of three consonants declines rapidly when subjects are prevented from rehearsing by being asked to count backwards

Stages of MemoryStages of Memory

Volume: vast amount◦Indexed and

retrieved selectively by cues

Processing location◦STM – frontal lobes of

cortex

◦LTM – hippocampus then transferred to other brain areas

Memory

Differences between LTM and STM

• Type of information

– In terms of meaning or semantic codes

• Durability – Appears to be

permanent, forgetting occurs

Types of Long-Term MemoryTypes of Long-Term Memory

Procedural ◦Memory for skills and procedures

(how to)

Episodic◦Information about time and

places (when, where)

Semantic◦Memory for meaning

(importance)

Memory

Long-Term MemoryLong-Term MemoryLong-term memory

◦Storehouse for almost unlimited information over long periods of time

◦Easy to store procedural and semantic memories, but stores episodic information less well

◦Semantic and episodic memories grouped together as declarative memory

Memory

Types of Long Term Memory

Semantic memory Episodic memory

Procedural memoryDeclarative memory

“I remember buying my first guitar.”

“I know what a guitar is.”

“I remember how to play a guitar.”

Organization in Long-Term Organization in Long-Term MemoryMemory

Organization eases retrieval process

◦Grouped into categories

◦Associative network: memories linked together through experience

◦Spreading activation model: representations of concepts and their characteristics are activated (ie: canary and bird)

Closeness of association affects retrieval time – distant associations take longer

Memory

Example of Associative Links

Skin

Breathes

Red

Green

Orange

Animal

Pat

Cat Dog

Canary

Tiger

Ostrich

Robin

Sparrow

Feathers

Sings Yellow

Bird

Retrieval of Long-Term MemoriesRetrieval of Long-Term Memories

Frustration of unable to retrieve information

Three ways to test retrieval◦Recall method: cues or hints used for

recall

◦Recognition method: select correct from alternative information (ie: multiple choice)

◦Relearning method: relearn previous learned information

Memory

Serial LearningSerial LearningOrder of memorizing is as important as

items on the list

Serial position effect – better recall of items at beginning and end of lists

◦Affected by timing or delay of recall◦Involves simultaneous use of STM and LTM

Tip-of-the-tongue phenomenon◦Most recall occurs within a few minutes

Memory

162 3 5 6

Pro

port

ion

corr

ect

10 11 13 151 4 7 9 12 14

30

8

Position in original list0

40

50

60

70

80

20

Test delayed 20 secondsTested immediately

Effects of Recall Timing on Short-Term Memory

Levels of Processing:Levels of Processing:An Alternative to the Stage An Alternative to the Stage ModelModel

Two levels of memory processing

Distinction between STM and LTM

◦Matter of degree, not separate stages

◦Differing levels of processing during encoding process

Memory

Levels of Processing:Levels of Processing:An Alternative to the Stage An Alternative to the Stage ModelModel

Processing continuum

◦Shallow level – processed briefly

◦Deeper level – processed much deeper involves greater elaboration (creating more associations between new and existing memories)

An excellent way to improve memory

Memory

Forgetting and Why It OccursForgetting and Why It OccursDecay theory

◦Unused memories fade gradually over time

◦Causes of forgetting fading memory traces over time Interference with retrieval

Memory

Forgetting and Why It OccursForgetting and Why It Occurs

Interference theory◦Other memories interfere with retrieval

◦ Interference mostly from similar memories

Types of interference◦Proactive – interference from prior learning

◦Reactive – interference from later learning

Memory

Forgetting and Why It OccursForgetting and Why It Occurs

Interfering with STM

◦Overloading STM capacity or weakening/ blocking an item out of storage

Interference with LTM

◦Interference plays lesser role in disrupting semantic memories than in episodic memories

Memory

Reconstruction (Schema) TheoryReconstruction (Schema) TheorySchemas – associative networks of

beliefs, knowledge, and expectations

◦During retrieval process, LTM information recalled in distorted and incorrect manner that is consistent with our schemas

May occur because brain stores meaning better than episodic details

May result in false memory – recalling something that never happened

Memory

Motivated ForgettingMotivated ForgettingFreud: some threatening information is

repressed – pushed into unconsciousness

Emotional arousal improves memory in some ways or has little effect on memory

◦Mild levels of positive and negative arousal appear to enhance memory

◦Emotion-laden violence on TV programs decreases recall of program advertisements

Memory

Human Diversity: Cultural Human Diversity: Cultural Circumstances and Memory Circumstances and Memory SkillsSkills

Kearins – environmental demands and culture may influence type of memory used◦Aboriginals have better visual memory

skills

Memory

Biological Basis of MemoryBiological Basis of MemorySynaptic theories of memory

◦Physical change must occur in nervous system

◦Engram: something remaining after learning

◦Synaptic facilitation (Hebb) is biological basis of learning and memory

Individual experiences produce unique patterns of neural activity causing structural changes in synapses

Memory

Biological Basis of MemoryBiological Basis of MemorySynaptic theories of memory

◦Classical conditioning of snails (Kandel)

Amount of neurotransmitter in synapse increased – synapse holds memory

Drugs that interfere with protein synthesis block memory formation

Consolidation – fragile memories grow more permanent over a few minutes

Memory

Stages of Memory and the BrainStages of Memory and the BrainSTM and LTM differences in brain

◦In role of synaptic changes: synapse changes involved in LTM but not STM

◦In brain structures involved

Three stages of memory involve various structures of brain as information is stored and retrieved

◦Allows memory recall with visual images or auditory sensations

Memory

Amnesia: Disorders of MemoryAmnesia: Disorders of MemoryRetrograde amnesia

◦No memory of what happened immediately before an accident or highly stressful event

Little or no disruption in STM

New long-term memories can be formed

Usually memory loss does not last lifetime

Stress of event disrupts consolidation and retroactive interference blocks retrieval

Memory

Amnesia: Disorders of MemoryAmnesia: Disorders of MemoryAnterograde amnesia

◦Inability to store and retrieve new information

◦Case of H.M. – epilepsy and neurosurgery

Does not affect procedural memory abilities but disrupts episodic memory formation

Hippocampus involved in episodic memory

◦Damage prevents formation of new long-term declarative memories

Memory

Amnesia: Disorders of MemoryAmnesia: Disorders of Memory

Korsakoff’s syndrome

◦Brain disorder from prolonged loss of vitamin thiamine as in diet of chronic alcoholics

◦Extreme degree of memory loss

◦Often engage in confabulation – cannot remember ending to a statement so make it up; an exaggerated version of normal reconstruction distortion

Memory

Inaccurate Recall Due to Biased Inaccurate Recall Due to Biased Questioning Questioning Research on eyewitness information

◦Can be potent source of distortion

Interviewer questions can contain cues that influence retrieval

Reconstruction theory of forgetting – people remember something that did not occur because it seemed consistent with the event

Perceived expertise of interviewer may bias informational response

Memory

Inaccurate Eyewitness Recall Inaccurate Eyewitness Recall Eyewitness testimony frequently

inaccurate◦Children, adolescents are particularly

suggestible when interviewed by adults

Sometimes describe what never happened Neutral questions get best results

Eyewitnesses who look but do not see◦Some things processed in shallow ways due

to inattentiveness or lack of importance attached

Memory

Stereotypes and Eyewitness Stereotypes and Eyewitness TestimonyTestimonyAllport: memories distorted by prejudices

◦Research in US – common African American names more stereotyped with criminality when memories fit personal schemas of prejudice

Inaccurate recall due to characteristics of the eyewitness

◦Being tired, upset, intoxicated may effect recall

◦Drunk eyewitness: visual recall may be accurate in some circumstances

Memory

Recall of Recall of Repressed MemoriesRepressed Memories of of Sexual and Physical AbuseSexual and Physical AbuseMost compelling testimony is from

victims

◦Many cases of repressed memories when adult was abused as child now in media

Dilemma - hard to know what is accurate

Many traumatic childhood memories discovered in psychotherapy may be false memories

Memory

Hypnosis and Eyewitness Hypnosis and Eyewitness TestimonyTestimonyHypnotizing witnesses to crimes is

controversial

◦Hypnotic age regression: hypnotized person goes back in time to earlier age – relives event and recalls forgotten experiences

May be heightened imagination more than accurate relived memories

◦Hypnotized witnesses to recent crimes may have more accurate recall

Memory

Improving the Accuracy of Improving the Accuracy of Eyewitnesses’ TestimonyEyewitnesses’ Testimony

Thousands of experiments in research have raised concerns but little has been done

◦DNA saved innocent persons on death row convicted on eyewitness testimony

◦U.S. Dept. of Justice made recommendations in 1999 about use of eyewitness testimony

Memory

Eyewitness TestimonyEyewitness TestimonyRecommendations

◦Establish good rapport

◦Ask open-ended questions

◦Use fillers in lineup fitting witness description

◦Place only one suspect in identification lineup

◦Unbiased instructions to eyewitnesses before viewing photos and lineups

◦Avoid giving feedback to eyewitnesses after identification of photo or person in lineup

Memory

The EndThe End

Memory