Transcript FORGETTING & THE RECONSTRUCTION OF MEMORIES

FORGETTING
&
MEMORY CONSTRUCTION
Why do we forget?
Sensory memory
The senses momentarily register
amazing detail
Short-term memory
A few items are both noticed
and encoded
Long-term storage
Some items are altered or lost
Retrieval from long-term memory
Depending on interference, retrieval
cues, moods, and motives, some
things get retrieved, some don’t
• Forgetting
can occur at
any
memory
stage
Forgetting as retrieval failure
• Retrieval—process of accessing stored information
• Sometimes info IS encoded into LTM, but we can’t
retrieve it
Encoding
Short-term
memory
X
Long-term
memory
Retrieval
Retrieval failure
leads to forgetting
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 (Dumb & Dumber example)
• Can’t retrieve info that you absolutely
know is stored in your LTM
Types of Retrieval
• Retrieval Cue – a clue, prompt, or hint that can
trigger the recall of a stored memory
• Recall—test of LTM that involves retrieving memories
without cues, also termed free recall
– Cued recall—test of LTM that involves remembering an
item of information in response to a retrieval cue
• Recognition—test of LTM that involves identifying
correct information from a series of possible choices.
• Serial position effect—tendency to remember items at
the beginning and end of a list better than items in the
middle.
Recall vs. Recognition tests
• Importance of retrieval cues evident in recall vs.
recognition tests
• Recall tests - must retrieve info learned earlier.
• Two step process: 1) generate a mental list, 2)
recognize the answer from the 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?
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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?
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•
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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
• Retrieval cue - a clue, prompt or hint
that can help memory retrieval
• Forgetting the result of using
improper retrieval cues
• Retrieval cue failure – can’t 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 cues work best?
Encoding Specificity
– When conditions of retrieval are similar to
conditions of encoding, retrieval is more
likely to be successful
– You are more likely to remember things if
the conditions under which you recall them
are similar to the conditions under which
you originally learned them
Encoding Specificity
• Context effects—environmental cues to
recall
• State dependent retrieval—physical,
internal factors
• Mood Congruence—factors related to mood
or emotions
Which retrieval cues
work 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 info than if moved to a new classroom
– 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
Context dependent effects
• Time of day is also important
Learn at 3pm
Perform better at 3pm
12
9
12
3
6
Than 9pm
9
12
3
6
9
3
6
Context-dependent effects
50
• Words heard Percentage
of words
recalled
40
underwater are
best recalled
30
underwater
20
• Words heard on
10
land are best
0
recalled on land
Water/
land
Land/
water
Different contexts
for hearing
and recall
Water/
water
Land/
land
Same contexts
for hearing
and recall
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 things you learned or did when
in that state again.
State dependent effects
Drunk doing
something
Recall better
if drunk
Than if sober
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
– Mood or emotions also a factor
– 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
Flashbulb Memory
• A type of Episodic Memory
• Memory of an event so surprising
or significant to us that it is as if we
photographed it in our mind.
• Why do these happen?
– We pay more attention to special
events
– We think about them more often
(repetition)
– We connect them to other events in our
lives
• Accuracy declines over time even
though it feels extremely accurate
Where were you on
September 11, 2001?
Memory and the Brain
• Play “Remembering What Matters” (8:30)
Segment #16 from Scientific American
Frontiers: Video Collection for
Introductory Psychology (2nd edition).
• How does adrenaline affect our ability to
remember something?
• Which part of the brain seems to be active
when you form flashbulb memories?
• How do evolutionary psychologists
explain flashbulb memories?
Memory Construction
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 gaps for you
like it does for our blind spot
Reconstructing Memories:
Sources of Potential Errors –
Why the details change over time
• Two general areas that errors occur in
memory reconstruction
1. Info stored before the memory occurred may
interfere
2. Info stored after the memory occurred may
interfere
Schemas
• Schemas – organized clusters of knowledge
and info about particular topics.
• What’s your schema for a dog?
• Contribute to memory distortions when the
info learned is inconsistent with previously
learned schemas.
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.
Sources of Potential Errors
• False Memory – distorted and inaccurate memory that
feels completely real and is often accompanied by all the
emotional impact of a real memory.
• Source Confusion/Amnesia – true source of the memory
(how, when, & where it was acquired) is forgotten. (See
box 6.2 on pg. 257 for examples)
– Something you’ve heard or seen in a film or book is confused
with something that really happened to you
• Cryptomnesia – a seemingly new or original memory is
actually based on an unrecalled previous memory.
– Ex. You think you’re remembering a past life but it is actually
based on a book you read a long time ago and forgot about. pg.
257
Elizabeth Loftus
(1944- )
• Does research in memory
construction
• 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. (3 min)
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
• Do politicians do this? How?
Loftus Experiment
Accident
• 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?
• Watch this study explained
1:20-5:35 (4 min)
Leading question:
“About how fast were the cars going
when they smashed into each other?”
Memory construction
Loftus Results
Word Used
in Question
smashed
collided
bumped
hit
contacted
Average
Speed Estimate
41 m.p.h.
39 m.p.h.
38 m.p.h.
34 m.p.h.
32 m.p.h.
Eyewitness Testimony
• Recall 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
• “Doctor’s Visit” study – children
misremembered 50% of the time when
later questioned.
• See examples from Frontline Documentary
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 as Storage
Failure
Motivated Forgetting
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
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 Theories
• Encoding failure
• Interference
theories
• Motivated
forgetting
• Decay
Forgetting as
Encoding Failure
Encoding Failures
• 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
Short-term
memory
X
Encoding
Encoding failure
leads to forgetting
Long-term
memory
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”
• This is ALWAYS BAD for recall
• Forgetting NOT caused by mere passage
of time
• Caused by one memory competing with
or replacing another memory
• Two types of interference
Two Types of Interference
Types of Interference
Retroactive
Interference
Proactive
Interference
Retroactive Interference
• When a NEW memory interferes with
remembering OLD information
• Example: When new phone number
interferes with ability to remember
old phone number
Retroactive Interference
• Example: Learning a new language
interferes with ability to remember
old language
Study French
Study Spanish
papier
livre
papel
plume
école
libro
pluma
escuela
retroactive interference
French 101
Mid-term
exam
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
Proactive Interference
• Example: Previously learned language interferes
with ability to remember newly learned language
Review of Interference Theory
• Retroactive Interference
– First Learn A, Then Learn B
Recall A, B interferes
• Proactive Interference
– First Learn A, Then Learn B
Recall B, A interferes
• Retro & Pro refer to what you want to remember.
• Interference reflects competition between responses.
• How does interference affect us as we age? NBC Report
(2 min)
Decay Theories
• Memories fade
100
100%
Average 90
away or decay percentage
of 80
information 70
gradually if
retained 60
unused
50
40
• Time plays
30
20
critical role
10
• Ability to retrieve
0
info declines with
time after original
encoding
20
1
8
24
2
6
31
mins hr hrs hrs days days days
Interval between original learning of
nonsense syllables and memory test
Decay Theory
• Biology-based theory
• When new memory formed, it creates a
memory trace
– a change in brain structure or chemistry
• If unused, normal brain metabolic
processes erode memory trace
• Theory not widely favored today
• Ability of people to retrieve memories
from long ago with retrieval cues would
show this is not true.