Chapter 7
Retention & Retrieval
Remembering & Forgetting
Levels of Processing Model
• Retention depends upon how deeply information is
processed
• The shallowest levels of processing occur when the
person is merely aware of the incoming sensory
information.
• Deeper processing takes place only when the person
does something with the information
– Makes associations
– Attaches meaning
– Actively elaborates
Memory Retrieval Varies in Difficulty
Recall
Serial recall
Free recall
Retrieval cue
Recognition – hippocampus
Relearning - savings
Context Effects Improve Retrieval
• Many elements of the physical setting in which we
learn information are simultaneously encoded into
long-term memory.
• Those stimuli or similar stimuli will allow us to
more easily recall information from long-term
memory
• These stimuli appear to serve as retrieval cues.
Context Effects
– memory works better in the context of
original learning
– Good reason for coming to class
– Holidays
Context Effects
Percentage of
words recalled
40
30
20
10
0
Water/
land
Land/
water
Different contexts for
hearing and recall
Water/
water
Land/
land
Same contexts for
hearing and recall
Psychological Retrieval Cues
• Our internal psychological environment can also
be encoded and become part of our memory
strands.
• State-dependent memory:
– The tendency for retrieval from memory being
better when our state of mind during retrieval
matches our state during encoding.
– Mood-dependent memory
Encoding Specificity Principle
– Encoding specificity principle: a retrieval
rule stating that retrieving information
from long-term memory is most likely
when the conditions at retrieval closely
match the conditions present during the
original learning
Reconstruction of Memory
• Elizabeth Loftus
– What a person usually recalls is not a replica,
but a reconstruction of the event
– A reconstruction is an account which is pieced
together from a few highlights, using
information which may or may not be
accurate.
Memories Are Reconstructions of the Past
• The scientific belief in the reconstructive nature of
memory was first proposed in the 1930s by Sir
Frederic Bartlett.
– By testing people’s memories of stories they had read,
Bartlett found that accurate recollections were rare.
– Errors increased over time.
Memories Are Often Sketchy
Reconstructions of the Past
• Bartlett concluded that –
The parts that participants were most confident of remembering were
often those that they had created.
People systematically distort details (facts and circumstances).
People are largely unaware they have reconstructed the past, and
Information already stored in memory strongly influences how new
information will be remembered.
Memories are Affected by
Schemas
• Schemas are integrated frameworks of
knowledge and assumptions a person has
about people, objects and events.
• They influence what people notice and
how they encode and recall information.
• In other words, we distort new information
to fit our existing schemas.
Memories Are Affected by the
Introduction of Inaccurate Information
• Misinformation effects: distortions and alterations
in people’s memories due to them receiving
misleading information during questioning
Misinformation Effect
Depiction of actual accident
Eyewitnesses
reconstruct
memories
when
questioned
Leading question:
“About how fast were the cars
going when they smashed into
each other?”
Memory
construction
Source Confusions Can Create
Memory Illusions
• Sometimes we forget the true source of an
episodic memory and may experience a
memory illusion.
• Memory illusions appear to be shaped by
implicit remembering.
Source Confusions Can Create
Memory Illusions
– Common types of memory illusion include:
• Déjà vu: a memory illusion in which people feel a
sense of familiarity in a situation that they know they
have never encountered before
• Cryptomnesia: (hidden or forgotten memory) a
memory illusion in which people believe that some
work they have done is a novel creation, when, in fact,
it is not original
Forgetting
Most Forgetting Occurs Soon after Learning
• Much of what a person learns is quickly forgotten.
– Herman Ebbinghaus’s research (1800s)
• Most forgetting occurred within 9 hours after learning.
• Everything about it may not be forgotten.
• Implication: most forgetting is not complete.
– One reason for forgetting (encoding failure):
• Not being sufficiently attentive when information is
presented
Ebbinghaus’s Forgetting Curve
Theory of Forgetting: Encoding Failure
• Which penny is the real thing?
Theory of Forgetting: Encoding Failure
• Forgetting as encoding failure
Attention
External
events
Sensory
memory
Short- Encoding
term
memory
Encoding
failure leads
to forgetting
Longterm
memory
Theories of Forgetting: Storage Decay
• Decay Theory
– Unless memories are periodically rehearsed, the
passage of time causes them to fade and eventually
decay.
Forgetting as Storage
Decay
Percentage of
list retained
when
relearning
60
50
40
Retention,
drops
then levels off
30
20
10
0
12345
10
15
20
25
Time in days since learning list
30
Theory of Forgetting: Retrieval Failure
• Forgetting can result from failure to retrieve
information from long-term memory
Attention
External
events
Sensory
memory
Encoding
Short-term
Long-term
memory
Retrieval memory
Retrieval failure
leads to forgetting
Theory of Forgetting: Interference
• Inteference Theory
– Retroactive interference: forgetting due to interference
from newly learned information
– Proactive interference: forgetting due to interference
from previously learned information
Interference in Memory
Theory of Forgetting: Motivation
• Motivated forgetting: forgetting due to a
desire to eliminate awareness of some
unpleasant or disturbing memory
Two Types or Theories of Motivated
Forgetting
Suppression occurs when a person
consciously tries to forget something.
Repression occurs when a person
unconsciously pushes unpleasant
memories out of conscious awareness.
These memories continue to unconsciously
influence the person’s thoughts, feelings, and
behavior.
Can people repress & later recover memories?
• Many memory researchers believe:
– It is naive to assume that people can accurately recover
memories that were previously unconsciously
repressed
– People can unknowingly manufacture false memories.
– False memories can be implanted into the minds of
both children and adults.
Can people repress & later recover memories?
Many psychologists believe that memories
“recovered” in therapy are actually false or
pseudo memories.
Many research participants who are instructed to
imagine that a fictitious event happened later
develop a false memory of the fictitious event.
False childhood memories can be experimentally
induced.
Can people repress & later recover memories?
Garry & Loftus implanted a false memory of
being lost in a shopping mall at age 5 in 25% of
their research participants (aged 18-53) after
verification of the experience by a relative.
“Memories” from the first years of life are very
suspect. Psychologists believe that the brain in
insufficiently developed to create or sustain a
long-term (until older childhood or adulthood)
memory in a child under age three.
Repressed & Recovered Memories?
• Simply repeating imaginary events to people
causes them to become more confident that they
actually experienced these events.
• Certain techniques used in therapy to recover
childhood memories of abuse (hypnosis and
dream interpretation) can distort patients’
recollections of past events and create false
memories of abuse.
Repressed Memories Controversy
• Current evidence supports the possibility
of repressed memories and also the
construction of false memories in
response to suggestions of others.
• American Psychological Association,
American Psychiatric Association,
• American Medical Association
The Brain Physiology of Memory
Long-Term Potentiation May Be
the Neural Basis for Memory
• There is no scientific consensus on what an
engram (or memory trace) is or where it is located
in the brain.
• However, it appears that memories begin as
electrical impulses traveling between neurons,
and that the establishment of long-term memories
involves changes in these neurons.
How Does Storage Work? The
Search for Memory
• Karl Lashley (1950)
– trained rats to solve maze, then cut out
pieces of their cortex and retested their
memory of maze
– partial memory retained
– concluded memory is distributed
Parallel (simultaneous) Processing
– Parallel processing of information is possible because
millions of neurons are active at once, and each
neuron is communicating with thousands of other
neurons.
– Parallel distributed processing models: models of
memory in which a large network of interconnected
neurons, or processing units, distributed throughout
the brain simultaneously work on different memory
tasks
Parallel Processing
• Parallel distributed processing models:
– Contend that information in memory is not
located in a specific place in the brain, but
instead, resides in connections between the
involved processing units in the neural
network.
– Better represents the actual operation of
the brain.
How Does Storage Work?
The Search for Memory
• Long-Term Potentiation
– A long-lasting increase in the efficiency of
neural transmission at the synapses
(junctions or connection points between
nerve cells) .
– Donald O. Hebb argued that learning and
memory must involve the enhancement of
transmission at the synapses
How Does Storage Work?
The Search for Memory
• Long-Term Potentiation
– increase in synapse’s firing potential after
brief, rapid stimulation
– Kandel & Schwartz (1982) – classically
conditioned aplysia
– Neural connections released more
neurotransmitter, became more
sensitive/efficient
– Increased number of receptor sites
Classical Conditioning: Sea snail associates
splash with a tail shock
Event 1
Long-term Potentiation
Double receptor sites
Event 2
Long-Term Potentiation May Be
the Neural Basis for Memory
• Long-term potentiation: the long-lasting strengthening of
synaptic transmission along a specific neural circuit, which
is believed to be the neural basis for long-term memory
– When a new memory is formed, changes occur in specific
neurons, creating a kind of memory circuit.
– Each time the new memory is recalled, the neurons in this
new circuit are activated, which strengthens their neural
connections.
– As the communication links between the neurons increase in
strength, the memory becomes established as a long-term
memory.
Biological Factors Affecting Memory
Processing
• Strong emotions make for stronger memories –
stress hormones boost learning & retention; anxiety
affects memory (cortisol)
• Drugs like alcohol that block neurotransmitters may
prevent memory storage (retrograde amnesia)
• Blows to the head and electric current may also
block information storage.
Brain Regions Involved
in Memory Formation & Storage
– The hippocampus appears to be most
important in the encoding of new explicit
memories and the transfer of them from shortterm to long-term memory.
Brain Regions Involved
in Memory Formation & Storage
– Implicit memory:
• The neocortex, striatum, and amygdala play
important roles in the type of long-term memory
previously identified as implicit memory.
– Explicit memory:
• Several brain regions are involved, including the
hippocampus and nearby portions of the cortex
and the thalamus.
•
Brain Regions Involved
in Memory Formation & Storage
• The inability to form new memories due to the brain
experiencing physical injury is called anterograde
amnesia.
• This appears to be caused by damage to the
hippocampus.
• Explicit memories cannot be formed, but implicit
memories can.