forgetting & memory construction. why do we forget? forgetting can occur at any memory stage...

FORGETTING &

MEMORY CONSTRUCTION

Why do we forget?

• Forgetting can occur at any memory stage

Retrieval from long-term memoryDepending on interference, retrieval

cues, moods, and motives, some things get retrieved, some don’t

Long-term storageSome items are altered or lost

Short-term memoryA few items are both noticed

and encoded

Sensory memoryThe senses momentarily register

amazing detail

Forgetting as Storage Failure

Hermann Ebbinghaus (1850-1909)

• German philosopher who did early memory studies with nonsense syllables

• Developed the forgetting curve, also called the “retention curve” or “Ebbinghaus curve”

The Forgetting Curve

Hermann Ebbinghaus first began to study forgetting using nonsense syllables

Nonsense syllables are three letter combinations that look like words but are meaningless (ROH, KUF)

Ebbinghaus’ Forgetting Curve• Ebbinghaus found that

the more times he practiced a list of nonsense syllables on day 1, the fewer repetitions he required to relearn it on day 2.

• Said simply, the more time we spend learning new information, the more we retain.

How to combat the Forgetting Curve: Overlearning

• Continuing to rehearse after the point the information has been learned

• Rehearsing past the point of mastery

• Helps ensure information will be available even under stress

Forgetting as retrieval failure

• Retrieval—process of accessing stored information• Sometimes info IS encoded into LTM, but we can’t

retrieve it

Retrieval failureleads to forgetting

RetrievalX

Encoding

Short-termmemory

Long-termmemory

Tip of the tongue phenomenon

• TOT—involves the sensation of knowing that specific information is stored in long-term memory but being unable to retrieve it

• Can’t retrieve info that you absolutely know is stored in your LTM

Recall vs. Recognition tests• Recall tests - must retrieve info learned earlier.

• Two step process: 1) generate a mental list, 2) recognize the answer from your list.– Examples: Fill-in-the-blank test; essay exams

• Recognition tests - only need to identify the correct answer.

• 1 step process: 1) recognize answer from the list. List was already generated for you.– Example: Multiple choice tests

What is the capital of Vermont?

• Raise your hand if you know the answer

What is the capital of Vermont?

• A. Brattleboro

• B. Montpelier

• C. Rutland

• D. Cabot

• Raise your hand if you know the answer

• Which was easier: recall or recognition?

• For your psychology exam, would you rather have a fill-in-the-blank or a multiple choice test?

What is the capital of Vermont?

• A. Brattleboro

• B. Montpelier

• C. Rutland

• D. Cabot

• Raise your hand if you know the answer

• Which was easier: recall or recognition?

• For your psychology exam, would you rather have a fill-in-the-blank or a multiple choice test?

Retrieval Cue Theories

• Forgetting the result of using improper retrieval cues

• Retrieval cue failure – inability to recall LT memories because of inadequate or missing cues.

• Memories only appear to be forgotten. You are only lacking the right retrieval cue.

Which retrieval cueswork best?

• Context-dependent memory - improved ability to remember if tested in the same environment as the original learning environment– Better recall if tested in classroom where you initially

learned information– If learning room smells of chocolate or mothballs,

people will recall more info if tested in room with the same smell

• compared to different smell or no smell at all

State-dependent effects

• Recall improved if internal physiological or emotional state is the same during testing and initial encoding

• If you are in an altered state of consciousness you will be more likely to remember SOME/MORE things you learned or did when in that state than if asked to recall in another state.

Mood Congruence

• Mood Congruence – Mood tends to evoke memories of when you were in that same mood.

• Positive mood will likely cause you to remember other times you were positive.

Mood Congruence effects

Example:

Bipolar depressives• Info learned in manic state, recall more if

testing done during manic state

• Info learned in depressed state, recall more if testing done during depressed state

Memory Construction

Reconstructing Memories: Sources of Potential Errors –

Why the details change over time

• Interference of new or old information can alter memories

Sources of Potential Errors• Source Confusion – true source of the memory

(how, when, & where it was acquired) is forgotten.

• False Memory – distorted and inaccurate memory that feels completely real and is often accompanied by all the emotional impact of a real memory.

Memory Jigsaw Analogy

• Memories, rather than being like a video tape, are formed as bits and pieces.

• People may retrieve only some of the pieces of the memory

• Brain fills in the blanks and doesn’t care if its right

Elizabeth Loftus

• Has found that subjects’ memories vary based on the wording of questions

• Demonstrated the

misinformation effect

Misinformation Effect

• Incorporating misleading information into one’s memory of an event

• Affects eyewitness testimony

•Elizabeth Loftis explains her experiments on Misinformation/attribution effect.

Memory Distortion

• Memory can be distorted as people try to fit new info into existing schemas

• Giving misleading information after an event causes subjects to unknowingly distort their memories to incorporate the new misleading information

Loftus Experiment

• Subjects shown video of an accident between two cars

• Some subjects asked: How fast were the cars going when they smashed into each other?

• Others asked: How fast were the cars going when they hit each other?

Accident

Leading question:“About how fast were the cars going

when they smashed into each other?”

Memory construction

Loftus Results

Word Usedin Question

AverageSpeed Estimate

smashedcollidedbumpedhitcontacted

41 m.p.h.39 m.p.h.38 m.p.h.34 m.p.h.32 m.p.h.

Eyewitness Testimony

• Scripts—type of schema– Mental organization of events in time

– Example of a classroom script: Come into class, sit down, talk to friends, bell rings, instructor begins to speak, take notes, bell rings again, leave class, etc.

– INFLUENCES memory

Eyewitness Testimony

• Not an exact replica of original events• What you recall is a construction built and

rebuilt from various sources

• Often fit memories into existing beliefs or schemas

• Schema—mental representation of an object, scene or event– Example: schema of a countryside may include green grass,

hills, farms, a barn, cows, etc.

Factors that Influence Memory

Memory Construction:

Children’s Recall

Children’s Testimony on Abuse

• Research has shown children’s testimony to be unreliable

• Children are very open to suggestions

• As children mature their memories improve

Accurate Interviewing Methods

• To promote accuracy with children’s testimony the interviewer should:

– Phrase questions in a way the child can understand

– Have no prior contact with the child

– Use neutral language and do not lead or suggest answers

Forgetting Theories

• Encoding failure

• Interference theories

• Motivated forgetting

• Decay

Forgetting as Encoding Failure

Encoding Failures or

You never remembered it in the first place!

• People fail to encode information because:– It is unimportant to them– It is not necessary to know the

information– A decrease in the brain’s ability to

encode

Forgetting as encoding failure

• Info never encoded into LTM

EncodingX Long-termmemory

Encoding failureleads to forgetting

Short-termmemory

Which is the real penny?

Answer

Encoding Failures

Even though you’ve seen thousands of pennies, you’ve probably never looked at one closely to encode

specific features

Forgetting as Retrieval Failure:

Interference

Interference Theories

• “Memories interfering with memories”

• Forgetting NOT caused by mere passage of time

• Caused by one memory competing with or replacing another memory

Two Types of Interference

Types of Interference

RetroactiveInterference

ProactiveInterference

French 101Mid-term

exam

Retroactive Interference• When a NEW memory interferes with remembering

OLD information• Example: Learning a new language interferes with

ability to remember old language

F-Study French

papier

livre plume

école

Study Spanish

papel

libro pluma

escuela

retroactive interference

Proactive Interference• Opposite of retroactive

interference• When an OLD memory

interferes with remembering NEW information

• Example: Memories of where you parked your car on campus the past week interferes with ability find car today

Motivated Forgetting(I meant to forget it?)

Undesired memory is held back from awareness– Suppression—conscious forgetting

– Repression—unconscious forgetting (Freudian)

Repression

• Part of Freud’s psychoanalysis• Process of moving anxiety-producing

memories to the unconscious• Supposed means of protecting oneself

from painful memories• Not well-supported by research; stressful

incidents are actually more likely to be encoded

Decay Theories

• Memories fade away or decay gradually if unused

• Time plays critical role

• Ability to retrieve info declines with time after original encoding

• If unused, normal brain metabolic processes erode memory trace

Average percentage of

information retained

20mins

1hr

8hrs

24hrs

2days

6days

31days

Interval between original learning of nonsense syllables and memory test

100%

Amnesia

• Infantile – don’t accurately remember much of your childhood (2 & under) due to your hippocampus not being fully developed.

• Anterograde – injury that prevents new memories from forming

• Retrograde – injury that prevents memory from before the trauma (severe cases effect years of memory; most cases are of moments or hours before trauma)