Overview of Memory Research

Modal Memory Model

Basic Distinctions

• STM– short term memory

• limited capacity• limited duration• holding available recent and relevant information in

a temporary store

• LTM– long term memory

• unlimited storage• relatively permanent• store for episodic and semantic memory

Modal Model of Memory(Atkinson & Shiffrin, 1968)

Short-term memory is a limited capacity store for information -- place to rehearse new information from sensory buffers Items need to be rehearsed in short-term memory before entering long-term memory

Probability of encoding in LTM directly related to time in STM

a memory test...

TABLECANDLEMAPLESUBWAYPENCILCOFFEETOWELSOFTBALLCURTAINPLAYERKITTENDOORKNOBFOLDERCONCRETERAILROADDOCTORSUNSHINELETTERTURKEYHAMMER

Serial Position Effects

• In free recall, more items are recalled from start of list (primacy effect) and end of the list (recency effect)

• Distractor task (e.g. counting) after last item removes recency effect

distractor task

nodistractor

task

Serial Position Effects

• Explanation from Modal Memory Model:

– Early items can be rehearsed more often more likely to be transferred to long-term memory

– Last items of list are still in short-term memory (with no distractor task) they can be read out easily from short-term memory

Encoding & Retrieval Effects

Levels of Processing(Craik & Lockhart, 1972)

Modal Memory Model time in rehearsal buffer determines memory strength

Levels of processing effect:The way information is processed affects recall. Deeper levels of processing (e.g., emphasizing meaning) leads to better recall encoding effect

Encoding Specificity Principle

• Recollection performance depends upon the interaction between the properties of the encoded event and the properties of the retrieval information

• Example: – context dependent effects: information learned in a

particular context is better recalled if recall takes place in the same context

Godden & Baddeley (1975)

Memory experiment with deep-sea divers– Deep-sea divers learned words either on land or underwater– They then recalled the words either on land or underwater

Mood Congruence

• Easier to remember happy memories in a happy state and sad memories in a sad state.

• Teasdale & Russell (1983): subjects study positive or negative words in normal state. Test in positive or negative induced states.

mood primes certain memory contents

State-dependent recall

• Does physical state matter?• Eich et al. (1975): study while smoking normal or

marijuana cigarette. Test words under same or different physical condition

Spacing effects

• Memory is better for repeated information if repetitions occur spaced over time than if they occur massed, one after another.

• Experiment: study 48 words, 24 of which are repeated. Spacing interval varied from 1,2,4,8,20 to 40 presentations.

• Results: better memory for items with greater spacing.

• Explanation based on encoding specificity principle: spaced items can be encoded in multiple ways more likely to be retrieved

Melton & Schulman, 1970

Working Memory

Views on Short-Term memory

• Miller’s memory span (7 ± 2 discrete slots)

• Short-term memory = activated long-term memory

• Baddeley’s theory of working memory – Set of slave systems rehearsing and “working” on

information

• Working memory capacity– Measures focus of attention with distracting tasks

Baddeley’s working memory theory• Concept of working memory: brief, immediate memory of

material we are currently processing• Working memory is not a passive store-house such as

short-term memory – it is more like a work bench where material is constantly handled, combined and transformed

Phonological Loop

Visuo-spatial sketchpad

Central Executive

Long-term memory

Phonological Loop(a.k.a. articulatory loop)

• Stores a limited number of sounds – number of words is limited by pronunciation time, not number of items

• Experiment:– List 1: “Burma, Greece, Tibet, Iceland, Malta, Laos”– List 2: “Switzerland, Nicaragua, Afghanistan,

Venezuela, Philippines, Madagascar”– Typical results:

list 1 4.2 wordslist 2 2.8 words

Phonological Similarity

• Note: most working memory tasks involve serial recall

• Short-term memory worse for phonologically similar items interference in phonological loop

(Baddeley, 1966)

man madcapcanmap

penrigdaybarcup

bighugebroadlongtall

oldlatethinwethot

Reading rate determines serial recall

• Baddeley (1986) tested recall for five words varying from 1 to 5 syllables.

– 1 syllable:wit, sum, harm, bay, top

– 5 syllables:university, opportunity, aluminum,

constitutional, auditorium

• Reading rate seems to determine recall performance

• Phonological loop stores 1.5 - 2 seconds worth of words

Working memory and Language Differences

• Different languages have different #syllables per digit

• Therefore, recall for numbers should be different across languages

• E.g. memory for English number sequences is better than than Spanish or Arabic sequences

(Naveh-Benjamin & Ayres, 1986)

Problems with Baddeley’s theory

• Pronunciation time does not always predict recall very well

Problems with Baddeley’s theory

• Even with long delays, memory span does not decrease much

• Underspecified processes and representation– Serial recall requires memory for the order of items

how is order information stored?– How does central executive work?– How does interference in phonological loop work?

Long-Term Memory Systems

Are there multiple LTM memory systems?

• How do you learn a new skill?• How do you learn a new fact?• How about learning about an event?

• Is there one long-term memory (LTM) system for these types of knowledge or are there multiple LTM systems?

Squire’s Taxonomy of memory

MEMORY

EXPLICIT IMPLICIT

SEMANTIC(facts)

EPISODIC(events)

PROCEDURAL(skills)

PRIMING(perceptual,semantic)

Implicit and explicit memory• Implicit memory:

past experiences influence perceptions, thoughts & actions without awareness that any info from past is accessed

• Explicit memory:conscious access to info from the past (“I remember that..” )

-> involves conscious recollection -> term often used synonymously with episodic memory

Explicit & Implicit MEMORY TESTS

Look at the following words. I will test your memory for these words in various ways.

SPONGE CANDY DOLPHIN

PACKAGE POSTER LICORICE

ZEBRA SECTION CAMOFLAGE

MISTAKE PORTAL KNAPSACK

COFFEEQUAIL ALPINE

HANDLE PANTRYCARPET

EAGER CELLO PRESSURE

LLAMA ORIOLE ACRID

EXPLICIT TEST OF MEMORY: RECALL

WRITE DOWN THE WORDS YOU REMEMBER FROM THE LIST IN THE EARLIER SLIDE

IMPLICIT TEST OF MEMORY: WORD FRAGMENTS

ON THE NEXT SLIDE, YOU WILL SEE SOME WORDS MISSING LETTERS, SOME “WORD FRAGMENTS” AND SOME ANAGRAMS. GUESS WHAT EACH WORD MIGHT BE.

EGNOPS *AN*Y *OL*H**

PACKAGE P*S*E* LICORICE

*E*RA SE*T*O* C**O*LA*E

*I*TA*E PORTAL KNAPSACK

COFFEE*U*IL AEILNP

*AN*LE *A*T*Y ACEPRT

*A*E* C*L** *RE*S**E

AALLM EILOOR *C*ID

Implicit Memory Tasks• Word-fragment completion is an implicit memory task.

Fragments are (often) completed with words previously studied in the absence of an explicit instruction to remember the word

• Amnesiacs often showed spaired implicit memory dissociation suggest different systems for implicit and explicit memory systems

HM: Amnesic• Severe epilepsy, treated with surgery to

bilaterally remove medial temporal lobes, including hippocampus

• Operation 9/1953, 27 years old

HIPPOCAMPUS MEDIAL TEMPORAL LOBES

HM: Amnesic

Operation 9/1953, 27 years old• Tested 4/1955, age 29

– Reported date as 3/1953, age of 27– No memories since operation– IQ better than pre-op (112)– Fewer seizures

HM: Amnesic

• Profound failure to create new memories– Can’t find new home (after 10 mos.)– Can’t remember new people, names, tasks – Events/People since operation– Language essentially frozen in 50’s– Exceptions: Ayatollah, rock ‘n roll

HM: Amnesic• Mirror tracing task, Milner, 1965

Mirror tracing task, Milner, 1965• improvement in H.M.• no conscious recollection of previous training

episodes

HM: Amnesic

HM: Stem-completionGraf et al. (1984):Study: word list (table, garden,umbrella)Test:- free recall- cued recall: complete word stem with word

from study list umb____ ??

- word stem completion: complete word stem with first word that comes to mind

gar___??

HM: No memory for studying of list

HM: Stem-Completion

Free Cued CompletionRecall Recall

Learning to Miror-Reverse Read

Amnesics can learn to mirror-reverse read and are sensitive to repetitions

Spared implicit memory in anterograde amnesia

• Claparede study (1911). – Patient never remembered having met Claparede

(doctor) before– Claparade offers handshake with pin hidden in his

hand – Next time, patient has no explicit memory of painful

event (or doctor)– Still, patient refuses to shake hands and offers

explanation: “sometimes pins are hidden in people’s hands”

Implicit/ Explicit Memory with Normals

• Jacoby (1983)

• Study conditions:– generate: give antonym to hot - ...– context: study word in context hot -

COLD– no context: ... -

COLD

• At test:– Explicit memory test: recognition memory– Implicit Memory test: Speed up on perceptual

identification test: how much faster can you identify a word flashed 40ms on screen when you have studied word before?

Results

Knowledge & Memory

How well do people recall events?

• Memory is not just reproductive– We do not recall the original event exactly

• Memory for events is often reconstructive– We construct a memory by combining elements

from the event with our existing knowledge.

What does a penny look like?

Memory for Details vs. Gist

• Memory is better for meaningful, significant features than for details of language or perception, suggesting that we have knowledge representations based on our interpretations of meaning.

• Representation for meaning– Propositional representations– Semantic Networks– Schemas– Scripts– Latent Semantic Analysis (LSA)

Evidence for Schema’s

A simple demonstration experiment

I am going to show you a picture of a graduate student’s office. Just take a look at it for a while

Now write down all the things you can remember

Potential responses:

ChairsDeskTableBoxes

Bottle of winePicnic basket

BooksSkull

Brewer & Treyens (1981): 30% of subjects (falsely) recalled that books were present

Story Retelling involves Schemas

• Bartlett (1932) told a native American story “war of the ghosts” to one subject

• This subject tells story to the next subject, and so on (method of serial reproduction)

• What happens during retelling of story from memory?

War of the Ghosts

[excerpt] One night two young men from Egulac went down to the river to hunt seals and while they were there it became foggy and calm. Then they heard war-cries, and they thought: "Maybe this is a war-party". They escaped to the shore, and hid behind a log. Now canoes came up, and they heard the noise of paddles, and saw one canoe coming up to them. There were five men in the canoe, and they said: ....

Typical Results

• Gist remains intact -- the main plot and sequence of events

• Omission Errors– Quite a bit of material is omitted (e.g. the name

Egulac) and minor events• Normalization Errors

– Additional info was added to make the story more coherent

– As Ss recalled/retold the story more and more, it tended to warp over time.

Memory for Event Sequences

1. John was hungry2. He went into a restaurant and ordered a sandwich3. He paid his bill and left

Question: Did John eat his sandwich? From whom did he order a sandwich? What was the bill for?

None of the answers is stated in the sentences but are based on inferences

Scripts• Inferences are based on representations for stereotyped

sequences of actions scripts• A restaurant script:

Evidence for Scripts

• Bower et al. (1979)

• Ss. study a sequence of events

• when an event is out of order, Ss might correct the order to the stereotypical order

E.g., restaurant story where bill is paid first is remembered in correct order (bill is paid last)

• Some events are (incorrectly) filled in based on inference

• Suggests: Events encoded with respect to general script

Schemas & Scripts: Implications

• Information from specific events is combined with general knowledge– Experience shapes scripts– Scripts guide recall

• Advantages & Disadvantages