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 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
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
• 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?
•
•
•
•
•
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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?
•
•
•
•
•
•
•
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 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 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
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?
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
• 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
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”
• 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
Retroactive
Interference
Proactive
Interference
Retroactive Interference
• When a NEW memory interferes with
remembering OLD information
• Example: Learning a new language interferes
with ability to remember
old language
Study French
Study Spanish
papier
papel
livre
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
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
100
100%
or decay gradually if
Average 90
unused
percentage of 80
information 70
• Time plays critical
retained 60
role
50
40
• Ability to retrieve
30
info declines with
20
time after original
10
encoding
0
• If unused, normal
brain metabolic
processes erode
memory trace
20
1
8
24
2
6
31
mins hr hrs hrs days days days
Interval between original learning of
nonsense syllables and memory test
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)