Long-term Memory

Explicit Memory

Implicit Memory

SemanticMemory

EpisodicMemory

Perceptuallearning

ClassicalConditioning

Motor Skills

Possible architecture of:

Other types

Affected by Amnesia

?

• Explicit Memory (consciously available)– Semantic memory: World knoweldge. (The sky is blue. Dogs

are pets. Ferraris are expensive.) – Episodic Memory: Specific personal experience from a

particular time and place. • Implicit Memory (not consciously accessible)

– Classical conditioning: e.g., salivating when I say “cheesecake!” Or fear when you smell rubbing alcohol.

– Perceptual learning: e.g., a new friend’s accent– Skills: e.g., driving, mirror-tracing

EXPLICIT MEMORY

Semantic Memory• Capacity is huge (unlimited?)• Structure of encoding is associative/conceptual

– Evidence: Semantic Priming in a Lexical-Decision Task• Priming: prior exposure to some stimulus modifies subsequent processing of

a target• Lexical Decision Task: Subject is shown a target word or pronounceable

non-word (eg. gap or fap) and must respond “word” or “non-word.” We care about the words.

• Prime is either related or unrelated to target word• Faster “word” response when preceded by semantically related prime

Prime then Target Response“space” “gap” fast“truck” “gap” slow

•So when a concept is activated, it partially activates other concepts it’s related to.•This speeds up access to the second concept and makes responding faster.

•This shows that representation of information in semantic memory is associative. (Stuff is stored “near” stuff it’s meaningfully related to, not randomly, and not near stuff that it’s only shalowly related to.)

Episodic Memory

• Memory for an episode or event in your own life

• Has temporal context (entails a sense of duration and date)

• examples:– my trip to New Orleans– your memory of having heard of the downed

airliner last week

Recalling Episodic Memory

• Recall is highly sensitive to context - Similarities in context can trigger vivid recollections. (We’ll talk about this more next time.)

Stages of Explicit Long-Term Memory

Encoding Storage Retrieval

Establish a ‘permanent record’

Reactivate the permanent record

Acquire information via perceptual system

EpisodicMemoryEncoding(new memory)

temporal lobe is the hub that relates all object’s properties into an integrated memory

In Context: ‘today’ ‘at home’

Storage(Consolidation)

temporal lobe is not needed anymore

Old memory(10 years later)

Storage of Memories (consolidation)

EpisodicMemoryEncoding(new memory)

temporal lobe is the hub that relates all object’s properties into an integrated memory

In Context: ‘today’ ‘at home’

Storage(Consolidation)

temporal lobe is not needed anymore

Old memory(10 years later)

RECENT MEMORIES ARE LOST

OLDMEMORIES

ARE SPARED

1990’s1980’s1960’s 1970’s

Brain Damage(1975)

Retrograde Amnesia(Pre-Damage)

Recent memory(lost)

Old memory(spared)

Anterograde Amnesia(Post-Damage)

New memories(not encoded)

Imagine a 1975 accident that severely damages the temporal lobe...

Evidence for double dissociation betweenimplicit and explicit memory

Middle temporal lobe lesion (e.g., patient HM)• Impaired explicit memory• Spared perceptual priming

Visual cortex lesion (e.g., patient MS):• Spared explicit memory• Impaired perceptual priming

This demonstrates that there are (at least) two separate systems, each responsible for a different type of memory.

Implicit and explicit memory can be dissociated in the lab.

• Explicit memory tested with direct tasks (e.g., recall, recog). – You’re asked directly about targets.

• Implicit memory tested with indirect tests. – Task seems unrelated. E.g., – Word fragments

– Perception of degraded stimuli

– Anagrams

– Free Association

– Prediction

– Mood

– Preference

– Performance

EGNOPS *AN*Y *OL*H**PACKAGE P*S*E* LICORICE*E*RA SE*T*O* C**OU*LA*E*I*TA*E PORTAL KNAPSACKCOFFEE*U*IL AEILNP*AN*LE *A*T*Y ACEPRT*A*E* C*L** *RE*S**EAALLM EILOOR *C*ID

Rajaram & Roediger, 1993

PHASE 1: Read words (e.g., unicorn) and rate pleasantness. PHASE 2: RecallPHASE 3: Word fragment completion

_ n i _ o r _

Rajaram & Roediger, 1993

PHASE 1: Read words (e.g., unicorn) and rate pleasantness. PHASE 2: RecallPHASE 3: Word fragment completion

Word stem completionuni_ _ _ _

Rajaram & Roediger, 1993

PHASE 1: Read words (e.g., unicorn) and rate pleasantness. PHASE 2: RecallPHASE 3: Word fragment completion

Word stem completion Word identification (flashed)

Rajaram & Roediger, 1993

PHASE 1: Read words (e.g., unicorn) and rate pleasantness.PHASE 2: Recall PHASE 3: Word fragment completion

Word stem completion Word identification

Anagram: corunni

More "unicorn“s in Phase 3 than if hadn't had Phase 1.I.e., “unicorn” was primed, even without explicit memory (recall). Even when recall had failed.This dissociation shows unconscious processing differs from conscious processing.

Implicit Memory in Korsakoff Patients

Damage to hippocampusAmnesia

Cued recall terrible, but stem completion as high as for normals.

Subliminal Perception

Auditory: Direct task: What do you hear?Indirect: "ESP" task -- was the tone

you didn't hear high or low?

Even if items not consciously heard, performance on indirect task better than chance.

Subliminal Perception

Visual: Direct task: See a flash?Indirect: "ESP" -- red or green?

Again, indirect performance better than direct. So: unconscious processing.

Subliminal Perception

Social: Subliminally flash words on screen.0%, 20%, or 80% hostile (e.g., "kill")

Direct task: What word was flashed?Indirect: Rate likeability of neutral person

The more hostile words flashed, the worse the judgment of the person.

How do you walk?Conduct memory search? Use chopsticks?Put in contacts?How do you know when your car is in the

wrong gear?Expertise (e.g., medical diagnosis)

Why fire a sea dart at a plane?

Persian Gulf, February 1991: Lt. Michael Riley, Radar Operator on the

HMS Gloucester (British Destroyer)decides to fire two sea darts….

How do objects fall?

Rules of Your LanguageIsraeli

FinlanderFrenchman

GreekJapanesePeruvian

Does This Sound Right As An English Sentence?

Does This Fit The Rules For A Well-Formed English Word?

GRAMMAR RULES

You learn a bunch of instancesYou learn a bunch of instances VJVJ VTVJJVTVJJ XXXXVJTXVXJJJJXXXXVJTXVXJJJJ XVXJXVXJ XVJTVXVJTV VJTXXVXVJTXXVXThen two different tests...Then two different tests...

GRAMMAR RULES

Direct Test: Tell me the rules.Indirect Test: Does this seem right to you?

VTJXV

People typically can't express the rules, but can tell legal from illegal. So do know the grammar rules, but implicitly.

More Rule/Skill Learning

• Tower of Hanoi task– Amnesics cannot remember playing, but they

get faster at solving the game.

Start Position Goal 2 (2 moves) Goal 10 (5 moves)

Covariation Learning in Visual Search

Ray & Reingold:

Eye movements monitored during search task in flicker paradigm, Task: Which letter has changed?

Two conditions: Background luminance varied with the target, or not.

Ss better at search when covariation existed.

Didn't need to consciously know the rule.

Preference

We tend to like things we've been exposed to.

Direct Test: Which of these have you seen?Indirect: Which of these do you like more?

ConclusionsMuch of cognition is unconscious.We can perceive, learn, & perform skills that we aren't fully aware of.

Examples: automatic skillslow-level perceptionmemorygrammar rulespreference

Entirely different brain systems may underlie explicit & implicit processing.