Transcript Forgetting & Memory Construction

FORGETTING
&
MEMORY CONSTRUCTION
Types of Amnesia
• ANTEROgrade Amnesia – Can’t form NEW
Memories
• RETROgrade Amnesia – Can’t recall OLD
memories
Memory Consolidation
• Physical process of a
memory going from
short-term memory to
long-term memory
• If disrupted, the LTM
does NOT form
• This happens in
Retrograde Amnesia
• Sleep can aid in memory
consolidation.
Memory Consolidation is like Jello:
• At first it is fluid and easily
changed or lost
• Given time, it will harden and be
laid down by the brain (longterm potentiation)
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 Theories
• Encoding failure
• Interference
theories
• Motivated
forgetting
• Decay
Forgetting as encoding failure
• Info never encoded into LTM
Short-term
memory
X
Encoding
Encoding failure
leads to forgetting
Long-term
memory
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
– Not paying attention to information
Demonstrating Encoding Failure
• A standard phone has 10 numbers with letters of the alphabet on
them but not all 26 letters of the alphabet. Which don’t appear?
–Q& Z
• What is the color of the top stripe of the American flag?
• Most wooden pencils are not round. How many sides do they
typically have?
6
• In what hand does the Statue of Liberty hold her torch?
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 Storage
Failure
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
• Ability of people to retrieve memories
from long ago with retrieval cues would
show this is not always true.
Hermann Ebbinghaus
The Forgetting Curve
• Studied forgetting using
nonsense syllables
• Nonsense syllables are
three letter combinations
that look like words but
are meaningless (ROH,
KUF)
• Forgetting is at first rapid
and then levels off over
time.
Combatting The Forgetting Curve
• OVERLEARNING/
Spacing Effect
• 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.
• Mastery Learning 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 (Dumb & Dumber example)
• Can’t retrieve info that you absolutely
know is stored in your LTM
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 in its new spot today
Proactive Interference
• Example: Previously learned language interferes
with ability to remember newly learned language
Review of Interference Theory
• Retroactive Interference (Backward Acting)
– First Learn A, Then Learn B
Recall A, B interferes
• Proactive Interference (Forward Acting)
– 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 to Combat Interference
• Study an hour before sleep and then
minimize your exposure to new info.
• Studying as you fall asleep though is NOT
helpful.
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
Memory Construction
“To Some Degree All Memory is False”
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
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.
MISINFORMATION
• As Memory fades with time following an event,
the injection of misinformation becomes easier.
– Misinformation Effect: Incorporating misleading
information into one’s memory of an event
• Imagination Inflation occurs because visualizing
something and actually perceiving it activates
similar brain areas.
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.
• When unsure of a detail, you’ll rely on your
schemas to fill in the gaps.
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.
– Something you’ve heard or seen in a film or book is confused with
something that really happened to you
• Déjà vu – “already seen” something seems familiar but
you’re unsure where you’ve encountered it before.
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 55% 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