Chapter 7: Human Memory
Human Memory: Basic Questions
• Many psychologists study factors that help or
hinder memory storage and retrieval…thus
attempting to answer 3 basic questions…
• How does information get into memory?
(ENCODING)
• How is information maintained in memory?
(STORAGE)
• How is information pulled back out of
memory? (RETRIEVAL)
Figure 7.2 Three key processes in memory
Encoding: Getting Information Into Memory
• Next-in-line effect:
– When getting ready to speak, subject
rarely remember what the person directly
before them said…
– Why?
Encoding: Getting Information Into Memory
• The first step in getting information into
memory is to pay attention to it
– Attention involves focusing awareness on a
narrowed range of stimuli or events
• Selective attention = selection of input
– Usually, attention is likened to a filter in an
information-processing model of
memory…the filter screens out most
stimuli, while allowing a select few to get
by
Encoding: Getting Information Into Memory
– Filtering: Much research has been done to
determine whether this filtering process occurs
early in the information processing sequence or
later.
– It appears that both may be at play…sometimes
you are paying attention to someone talking with
you at a party, and you suddenly hear your name
from across the room. Late selection based on
meaning…
– Research suggest both are at work (you can pick
up inputs later, but have a hard time trying to
monitor inputs and carry a conversation at the
same time
Figure 7.3 Models of selective attention
Levels of Processing:
Craik and Lockhart (1972)
• Incoming information processed at different
levels
• Deeper processing = longer lasting memory
codes
• Encoding levels:
– Structural = physical structure of stimuli;
shallow
– Phonemic = what a word sounds like,
saying or naming a word; intermediate
– Semantic = the actual meaning of the
stimuli; deep
Figure 7.4 Levels-of-processing theory
Levels of Processing:
Craik and Lockhart (1972)
• Levels of processing theory:
– The deeper the level of processing, the
longer lasting the memory
• Given a list of 60 words…
Figure 7.5 Retention at three levels of processing
Enriching Encoding: Improving Memory
• Elaboration = linking a stimulus to other information
at the time of encoding
– for example, you are studying phobias for your
psychology test, and you apply this information to
your own fear of spiders
• Visual Imagery = creation of visual images to
represent words to be remembered
– Easier for concrete objects, hard for abstract
principles:
• Dual-coding theory (Paivio): memory is
enhanced by forming semantic and visual clues
• He put words into four groups…
Enriching Encoding: Improving Memory
• Self-Referent Encoding
– Making information personally meaningful,
do the stimuli apply to you personally?
Storage: Maintaining Information in Memory
• Plato and Aristotle compared memory to a
block of wax that differed in size and
hardness for various individuals…
remembering was like stamping an
impression into the wax
• Today’s Analogy: information storage in
computers ~ information storage in human
memory
Storage: Maintaining Information in Memory
• Information-processing theories: Atkinson
and Shiffrin, 1968, proposed an analogy
between information storage by computers
and information storage in human memory
– Subdivide memory into 3 different stores
• Sensory, Short-term, Long-term
Figure 7.7 The Atkinson and Schiffrin model of memory storage
Sensory Memory
• Sensory Memory is basically information
preserved in its original sensory form for a
brief time.
• This type of memory allows the sensation to
linger briefly after the sensory stimulation is
over Auditory/Visual – approximately ¼
second
– George Sperling (1960)
• Classic experiment on visual sensory
store, illustrating how brief the sensory
store actually is
Figure 7.8 Sperling’s (1960) study of sensory memory
Short Term Memory (STM)
• Limited capacity – limited-capacity store that
can maintain unrehearsed information for up
to about 20 seconds
• George Miller (1956) wrote a famous paper
called “The Magical Number Seven, Plus or
Minus Two:
– Some Limits on Our Capacity for
Processing Information," where he
illustrated that the average person can hold
between 5 and 9 chunks of information in
STM
– Chunking – grouping familiar stimuli for
storage as a single unit
Short Term Memory (STM)
• Limited duration – about 20 seconds
without rehearsal
– Rehearsal – the process of repetitively
verbalizing or thinking about the
information (phonemic encoding)
Figure 7.9 Peterson and Peterson’s (1959) study of short-term memory
FYO 239
Short-Term Memory as “Working Memory”
• 30 years of research eventually uncovered a
number of problems with the original model of
STM, it is not limited to phonemic encoding
• Loss of information not only due to decay,
interference from incoming stimuli also play a
part
Capacity of STM
• Nelson Cowan (2001):
– 4 items plus or minus 1
Short-Term Memory as “Working Memory”
• Alan Baddeley (1986-1992) – 4 components
of working memory
– Phonological rehearsal loop:
represented ALL of STM in the original
model
– Visuospatial sketchpad: allows
temporary holding and manipulation of
visual images
Short-Term Memory as “Working Memory”
– Executive control system: handles the
limited amount of information juggled at
one time as people engage in reasoning
and decision making
– The episodic buffer: a temporary, limited
capacity store that allows the various
components of working memory to
integrate information, and that serves as
an interface between working and LTM.
Long-Term Memory: Unlimited Capacity
• While most researchers agree that LTM has an
unlimited capacity; much debate remains over
whether storage is permanent
• Permanent storage?
– Flashbulb memories: vivid recall of momentous
events
– Recall through hypnosis
• suggest that LTM is indeed permanent, that the
only reason we forget is that we aren’t able to
access information that is still in LTM
(interference theory). Pinfield
• flashbulb and hypnosis based memories are
not always accurate
Long-Term Memory: Unlimited Capacity
• Debate: are STM and LTM really different?
– Phonemic vs. Semantic encoding
• We used to think that phonemic encoding
occurred in STM and semantic (or meaning
based) encoding in LTM. Now we know that
both occur for both
– Decay vs. Interference based forgetting
• used to think that decay occurred in STM and
interference in LTM, with regard to forgetting.
Now, it is unclear what exactly occurs in LTM, it
may be both
How is Knowledge Represented
and Organized in Memory?
• Some researchers argue that STM and LTM are the
same thing, that STM is just a little part of LTM that is
in a state of heightened activation
• Clustering: the tendency to remember similar or
related items in groups
• Conceptual Hierarchies: multilevel classification
systems based on common properties among items
• Schemas and Scripts: script is a particular type of
schema, organizing what a person knows about
common activities
How is Knowledge Represented
and Organized in Memory?
• Semantic Networks: Semantic networks consist of
nodes representing concepts, joined together by
pathways that link related concepts
• Connectionist Networks and PDP Models: assume
that cognitive processes depend on patterns of
activation in highly interconnected computational
networks that resemble neural networks
– this model of memory uses as inspiration the way
neurons appear to handle information through
connections…according to this model, specific
memories correspond to specific patterns of
activation in these networks
Retrieval: Getting Information
Out of Memory
• The tip-of-the-tongue phenomenon – a failure
in retrieval
• shows that recall is often guided by partial
information about a word…retrieval cues
• Recalling an event
– Memories can also be reinstated by
context cues…easier to recall longforgotten events if you return after a
number of years to a place where you used
to live
Retrieval: Getting Information
Out of Memory
• Reconstructing memories
– Misinformation effect: recall of an event is altered
due to misleading info post-event
• Research shows that reconstructions can be
influenced by new information
– Example…showed a video of two cars in an
accident…asked some people how fast the cars
were going when they HIT each other, asked
others how fast the cars were going when the
SMASHED INTO each other…a week later asked
whether there was any broken glass in the
video…the “smashed into” group said yes, the “hit”
group said no./ KFC chicken
Retrieval: Getting Information
Out of Memory
• Source monitoring: the process of making attributions
about the origins of memories
– people make decisions at the time of retrieval
about where their memory is coming from
– cryptomnesia is inadvertent plagiarism that occurs
when you think you came up with it but were really
exposed to it earlier
• Reality monitoring: type of source monitoring
involving determining whether memories are based in
actual events (external sources) or your imagination
(internal sources)…
Forgetting: When Memory Lapses
• Hermann Ebbinghaus studied forgetting using
retention in the late 1800s, by using himself
as a subject.
– He found that retention and forgetting
occur over time and plotted his data…
– Current research suggests that this curve
is unusually steep, probably due to the fact
that Ebbinghaus was using nonsense
syllables that are difficult to encode
semantically.
Figure 7.16 Ebbinghaus’ forgetting curve for nonsense syllables
Forgetting: When Memory Lapses
• Retention – the proportion of material
retained
– Recall: involves requiring subjects to
reproduce information on their own without
any cues (essay, fill-in-the-blank)
– Recognition: requiring subjects to select
previously learned material from an array
of options (mult. choice, matching)
– Relearning: requiring subjects to relearn
previously learned information to see how
much LESS time or effort it takes them
Figure 7.17 Recognition versus recall in the measurement of retention
Why Do We Forget?
• Research indicates that forgetting may be
related to encoding, storage, or retrieval
processes
• Much forgetting may only look like
forgetting…it may have never been inserted
into memory in the first place…
pseudoforgetting…usually due to lack of
attention so that encoding does not occur
Why Do We Forget?
• Ineffective Encoding: occurs when you encode on a
more superficial level than you need to…
– for example, you are distracted when studying and
encode what you are reading on a phonemic
rather than a semantic level
• Decay theory: proposes that forgetting occurs
because memory traces fade with time
• Interference theory: negative impact of competing
information on retention
– Proactive: previously learned information
interferes with the retention of new information
– Retroactive: new information impairs the retention
for previously learned information
Figure 7.19 Retroactive and proactive interference
Retrieval Failure
• Encoding Specificity: holds that the
effectiveness of a retrieval cue depends on
how well it corresponds to the memory code
that represents the stored item…
– the closer a retrieval cue is to the way we
encode the info, the better we are able to
remember.
Retrieval Failure
• Transfer-Appropriate Processing: holds
that when the initial processing of information
is similar to the type of processing required
by the subsequent measure of retention,
retrieval is easier
• In other words, you must learn the
words/concepts the way you want to
remember them…
Retrieval Failure
• Repression: involves the motivated
forgetting of painful or unpleasant memories
– Authenticity of repressed memories:
challenged by empirical studies that show
that it is not at all hard to create false
memories and that many recovered
memories are actually the product of
suggestion
Retrieval Failure: Repression (cont.)
– Roediger and McDermott (2000) have
shown that when participants are asked to
learn a list of words, and another target
word that is not on the list but is strongly
associated with the learned words is
presented, the subjects remember the nonpresented target word over 50% of the
time…on a recognition test, they remember
it about 80% of the time…a memory
illusion
Figure 7.22 The prevalence of false memories observed by Roediger and McDermott (1995)
Retrieval Failure
– Controversy: While research clearly shows that
memories can be created by suggestion, in cases
of child sexual abuse memories, for example, this
issue becomes quite emotionally charged.
• Some cases of recovered memories are
authentic, and we don’t yet have adequate data
to estimate what proportion of recovered
memories of abuse are authentic and what
proportion are not.
• Still, this controversy has helped inspire a great
deal of research that has increased our
understanding of the fallibility and malleability
of human memory.
Figure 7.20 Estimates of the prevalence of childhood physical and sexual abuse
The Physiology of Memory
• Biochemistry
– memory appears to be related to
alterations in synaptic transmission at
specific sites
• Durable changes in synaptic
transmission may be the building blocks
of memories
• learning causes hormonal changes
which may modulate activity in a variety
of neurotransmitter systems
• Protein synthesis has also been shown
to be necessary for memory formation
The Physiology of Memory
• Neural circuitry
– memories appear to depend on localized
neural circuits in the brain
• Reusable pathways in the brain: may be
specific for specific memories
• Long-term potentiation (occurs with
learning): a long-lasting increase in
neural excitability at synapses along a
specific neural pathway
• This supports the idea that memory traces
consist of specific neural circuits.
The Physiology of Memory
• Anatomy
– Anterograde Amnesia: subsequent events
– Retrograde Amnesia: for prior events
• Cerebral cortex: aide in phonological
loop
• Prefrontal cortex: working memory
• Hippocampus: bind together memories
(amnesia guy)
• Dentate gyrus: part of the Hippo. region
• Amygdala: formation of memories for
learned fears
• Cerebellum
Figure 7.23 The anatomy of memory
Figure 7.25 Retrograde versus anterograde amnesia
Are There Multiple Memory Systems?
• Procedural memory is memory for actions, skills,
operations and conditioned responses,
• Declarative memory is memory for factual
information.
• declarative memory can be subdivided
– episodic memory: memory for personal facts
– semantic memory: for general facts
• Retrospective memory is memory for past events
• Prospective memory is remembering to do things in
the future.
Figure 7.26 Theories of independent memory systems
Improving Everyday Memory
• Engage in adequate rehearsal
• Distribute practice and minimize interference
• Emphasize deep processing and transferappropriate processing
• Organize information
• Use verbal mnemonics
• Use visual mnemonics