I. Introduction:
What Is Memory?
Memory refers to the mental processes that enable us to retain and use
information over time. Memory involves three fundamental processes:
1. Encoding is the process of transforming information into a
form that can be entered into and retained by the memory
system.
2. Storage is the process of retaining information in memory so
that it can be used at a later time.
3. Retrieval is the process of recovering the stored information
so that we are consciously aware of it.
A. The Stage Model of Memory
The stage model of memory describes memory as consisting of three
distinct stages: sensory memory, short-term memory, and long-term
memory. It is based on the idea that information is transferred from
one memory stage to another.
1. Sensory memory, the first stage of memory, registers a great
deal of information from the environment and holds it for a
very brief period of time (1⁄4 second to 3 seconds). The
information you “select,” or pay attention to, is transferred to
the next stage of memory.
2. Short-term memory is the active, working memory in
which information is stored for about 20 seconds. It temporarily
holds all the information you are currently thinking about or
consciously aware of.
3. Long-term memory, the third stage of memory, represents
the long-term storage of information.
a. The transfer of information between short-term and
long-term memory is a two-way street, flowing from
long-term to short term as well.
b. Even the most routine cognitive tasks involve
processing current sensory data and retrieving relevant
stored information.
B. Sensory Memory: Fleeting Impressions of the World
1. The Duration of Sensory Memory
a. In 1960, George Sperling conducted experiments
from which he was able to identify the duration of visual
sensory memory.
b. Sperling’s classic experiment demonstrated that our
visual sensory memory holds a great deal of information
very briefly (for about half a second).
2. Types of Sensory Memory: Pick a Sense, Any Sense!
a. Memory researchers believe that a separate sensory
memory exists for each sense (vision, hearing, touch,
smell, and taste).
b. Visual sensory memory, sometimes referred to as
iconic memory, typically holds an image, or icon, for
about one-quarter to one half second.
c. Auditory sensory memory, sometimes referred to as
echoic memory, holds sound information up to three or
four seconds.
3. An important function of sensory memory is to briefly store
sensory impressions so they overlap slightly with one another
such that we perceive the world around us as continuous, rather
than as a series of disconnected visual images or disjointed
sounds.
C. Short-Term, Working Memory: The Workshop of Consciousness
1. Short-term, or working, memory provides temporary storage
for information transferred from sensory and long-term
memory.
2. The Duration of Short-Term Memory
a. You can hold most types of information in short-term
memory up to about 20 seconds before it is forgotten.
b. Maintenance rehearsal is the mental or verbal
repetition of information in order to maintain it beyond
the usual 30-second duration of short-term memory.
c. Information that is not actively rehearsed quickly
fades, or decays.
d. Another potential cause of forgetting is interference
from new or competing information.
3. The Capacity of Short-Term Memory
a. Short-term memory has a relatively limited capacity of
between five and nine—the magical number seven, plus
or minus two—items, or bits of information.
b. When the capacity is reached, new information will
displace, or bump out, currently held information.
c. Chunking increases the amount of information that
can be held in short-term memory by grouping related
items together into a single unit. To do so, chunking also
often involves the retrieval of meaningful information
from long-term memory.
4. From Short-Term Memory to Working Memory
a. Short-term memory is sometimes called working
memory because of its involvement in many mental
activities, including reading, reasoning, mental imagery,
and problem solving.
b. Working memory is defined as a short-term memory
system involved in the temporary storage and active
manipulation of information.
c. Alan Baddeley’s model of working memory includes
three main components, each of which can function
independently.
(1) The phonological loop is specialized for verbal
material.
(2) The visuospatial sketchpad is specialized for
spatial or visual material.
(3) The central executive controls attention,
integrates information, and manages the activities
of the other two components. It also initiates
retrieval and decision processes.
d. The term working memory is generally used when the
focus is on active, conscious, mental “work,” such as
language comprehension ,problem solving, or reasoning.
The term short-term memory is more likely used when
the focus is on simpler memory
processes, such as the rehearsal of lists of syllables,
words, or numbers.
D. Long-Term Memory
1. Long-term memory, the storage of information over
extended periods of time, has a limitless capacity. Retrieving
information from long-term memory usually happens quickly
and with little effort.
2. Encoding Long-Term Memories
An important function that occurs in short-term memory is
encoding, or the transformation of new information into a form
that can be retrieved later.
a. Elaborative rehearsal is an effective technique for
encoding and transferring information into long-term
memory. You relate the new information to other
information you already know; that is, you elaborate on
the new information in some meaningful way.
b. Two factors that enhance encoding are
(1) the self-reference effect—applying information
to yourself
(2) visual imagery—using vivid images
3. Types of information in long-term memory
a. Procedural memory refers to the long-term memory
of how to perform different skills, operations, and
actions.
b. Episodic memory refers to your long-term memory of
specific events or episodes in your life, including the
time and place that they occurred. Autobiographical
memory refers to the events of your life—your personal
life history.
c. Semantic memory refers to general knowledge that
includes facts, names, definitions, concepts, and ideas
stored in long-term memory.
4. Implicit and Explicit Memory: Two Dimensions of LongTerm Memory. Studies of patients with amnesia indicate that
long-term memory is composed of two separate but interacting
subsystems and abilities:
a. Explicit memory is memory with awareness—
information or knowledge that can be consciously
recollected, including episodic and semantic memory.
Also called declarative memory.
b. Implicit memory is memory without awareness—
memories that cannot be consciously recollected, but that
still affect behavior, knowledge, or performance of some
task. Also called nondeclarative memory.
5. Culture and Human Behavior: Culture’s Effect on Early
Memories Cultural differences in the sense of self influence the
content of our earliest memories. In one experiment,
Americans’ memories were more discrete, one-point-in-time
events, whereas Asian students had more general, routine
memories. Shared reminiscing also differs in Western and
Asian cultures.
6. The Organization of Information in Long-Term Memory
Information in long-term memory is organized, although
exactly how it is organized is not completely understood by
memory researchers. They do know, however, that it is
clustered and associated.
a. Clustering means organizing items into related
groups, or clusters, during recall.
b. Different pieces of information are also logically
linked, or associated.
c. The semantic network model is a model that
describes units of information in long-term memory as
being organized in a complex network of associations.
When one concept is activated in the semantic network, it
can spread in any number of directions,
activating other associations in the network.
II. Retrieval: Getting Information from Long-Term Memory
A. The Importance of Retrieval Cues
1. Retrieval refers to the process of accessing, or retrieving,
stored information in long-term memory.
2. A retrieval cue is a clue, prompt, or hint that helps trigger
recall of a stored memory.
3. Retrieval cue failure is the inability to recall long-term
memories because of inadequate or missing retrieval cues.
4. Common Retrieval Cue Failures: The Tip-of-the-Tongue
Experience
a. The tip-of-the-tongue (TOT) experience, a common
example of retrieval failure, refers to the inability to get
at a bit of information that you are certain is stored in
your memory.
b. Tip-of-the-tongue experiences illustrate several aspects
of the retrieval process:
(1) Retrieving information is not an all-or-nothing
process.
(2) Information stored in memory is organized and
connected in relatively logical ways.
5. Testing Retrieval: Recall, Cued Recall, and Recognition
a. Recall, also called free recall, involves producing
information using no retrieval cues. This memory
measure is used on essay tests.
b. Cued recall involves remembering an item of
information in response to a retrieval cue. Fill-in-theblank and matching questions are examples of cuedrecall tests.
c. Recognition involves identifying the correct
information from several possible choices. Multiple-
choice tests involve recognition as a measure of longterm memory.
6. The Serial Position Effect: The serial position effect refers
to the tendency to retrieve information more easily from the
beginning and the end of a list rather than from the middle.
There are two parts to the serial position effect:
a. The tendency to recall the first items in a list is called
the primacy effect. This is especially prominent when you
have to engage in serial recall.
b. The tendency to recall the final items in a list is called
the recency effect.
B. The Encoding Specificity Principle: The encoding specificity
principle is the principle that when the conditions of information
retrieval are similar to the conditions of information encoding,
retrieval is more likely to be successful.
1. The Context Effect: The context effect is the tendency to
remember information more easily when the retrieval occurs in
the same setting as the original learning of the information.
2. Mood Congruence: Mood congruence refers to the idea that
a given mood tends to evoke memories that are consistent with
that mood.
C. Flashbulb Memories: Vivid Events, Accurate Memories?
1. A flashbulb memory is the recall of very specific images or
details surrounding a vivid, rare, or significant personal event.
2. Flashbulb memories are said to be characterized by a high
degree of distinctiveness; that is, the encoded information
represents a unique, different, or unusual memory.
3. The accuracy of flashbulb memories—like that of normal
memories—declines over time. What distinguishes flashbulb
memories from ordinary memories is the high degree of
confidence people have in their accuracy.
III. Forgetting: When Retrieval Fails: Forgetting is the inability to recall
information that was previously available.
A. Hermann Ebbinghaus: The Forgetting Curve
1. German psychologist Hermann Ebbinghaus used himself as
a research subject to study how much information was forgotten
after different lengths of time.
2. Ebbinghaus tested his recall of nonsense syllables
(combinations of two consonants and one vowel) and plotted
his results in the forgetting curve, which reveals two distinct
patterns in the relationship between forgetting and the passage
of time.
a. Much of what we forget is lost relatively soon after we
originally learn it.
b. The amount of forgetting eventually levels off.
B. Why Do We Forget?
1. Encoding Failure: It Never Got to Long-Term Memory
One cause of forgetting, encoding failure, is the inability to
recall specific information because of insufficient encoding of
the information for storage in long-term memory.
a. Absent-mindedness is a form of encoding failure that
occurs because you don’t pay enough attention to a bit of
information when you should be encoding it. Absentminded memory failures often occur because your
attention is divided.
b. Absent-mindedness is also implicated in prospective
memory, remembering to do something in the future.
Prospective memory failures are due to retrieval cue
failure—the inability to recall a memory because of
missing or inadequate retrieval cues.
2. Decay Theory: Fading with the Passage of Time
Decay theory is the view that forgetting is due to normal
metabolic processes that occur in the brain over time. New
memories create memory traces, which, if not used, fade with
time. Researchers have found no compelling evidence to
support this theory; however, many believe that decay does
somehow contribute to forgetting.
3. Interference Theory: Memories Interfering with Memories
Interference theory is the theory that forgetting is caused by
one memory competing with or replacing another.
a. Retroactive interference is forgetting in which a new
memory interferes with remembering an old memory.
b. Proactive interference is forgetting in which an old
memory interferes with remembering a new memory.
4. Motivated Forgetting: Forgetting Unpleasant Memories
Motivated forgetting refers to the idea that we forget because
we are motivated to forget, usually because a memory is
unpleasant or disturbing.
a. Suppression is motivated forgetting that occurs
consciously; that is, a person makes a deliberate,
conscious effort to forget information.
b. Repression is motivated forgetting that occurs
unconsciously: that is, all memory of an event or
experience is blocked from conscious awareness. Among
psychologists, repression is a controversial topic.
5. In Focus: Déjà Vu: An Illusion of Memory
The term déjà vu, French for “already seen,” refers to a brief
but intense feeling of having experienced something before.
These are experienced by about two-thirds of individuals. Déjà
vu experiences may be disruptions in source memory, or
source monitoring, our ability to remember the original details
of a memory. Encoding failure may also be implicated.
IV. Imperfect Memories: Errors, Distortions, and False Memories
Every new memory you form is not simply recorded, but actively
constructed. To form a new memory, you actively organize and encode
information. When you later attempt to retrieve those details from memory,
you actively reconstruct, or rebuild, the memory.
1. The Misinformation Effect: The Influence of Postevent
Information on Misremembering
a. In a now-classic study, psychologist Elizabeth Loftus
had subjects watch a film of an automobile accident.
After the film, she asked the critical question: “About
how fast were the cars going when they
contacted/hit/bumped/collided/or smashed each
other?” A week after subjects saw the film, they were
asked whether they had seen any broken glass. Because
many subjects whose question used the word smashed
reported inaccurate information, this study demonstrated
how new information can distort the reconstruction of
memories.
b. The misinformation effect is a memory-distortion
phenomenon in which people’s existing memories can be
altered by exposing them to misleading information.
2. Source Confusion: Misremembering the Source of a Memory
Source confusion is a memory distortion that occurs when the
true source of the memory is forgotten.
3. A false memory is a distorted or inaccurate memory that
feels completely real and is often accompanied by all of the
emotional impact of a real memory.
4. Schemas, Scripts, and Memory Distortions: The Influence of
Existing Knowledge on What Is Remembered
a. Schemas are organized clusters of knowledge and
information about particular topics. Schemas are useful
in forming new memories, but they can also contribute to
memory distortions.
b. One kind of schema, called a script, involves the
typical sequence of actions and behaviors at a common
event.
c. Memories can easily become distorted: We remember
objects and events as we expect them to be, not as they
actually are.
A. Forming False Memories: From the Plausible to the Impossible
1. Imagination Inflation: Remembering Being Lost in the Mall
a. In the lost-in-the-mall study, Loftus and Pickrell were
able to create false memories by having participants
remember real events along with imagining
pseudoevents. This research strategy has been dubbed the
lost-in-the-mall technique.
b. Imagination inflation is a memory phenomenon in
which vividly imagining an event markedly increases
confidence that the event actually occurred.
c. Several factors are involved in creating a compelling
memory from imagining an event.
(1) Repeatedly imagining the event makes the
event seem familiar; this familiarity is
misinterpreted as an indication that
the event really happened.
(2) People experience source confusion, that is,
confusion arises over whether a retrieved memory
is based on a real or imagined event.
(3) The more vivid and detailed the imaginative
experience, the more likely people will confuse the
imagined and real events.
d. Simple manipulations, such as suggestions,
imagination exercises, vivid memory cues, and
photographs, can increase the incidence and realism of
false memories.
2. Critical Thinking: The Memory Wars: Recovered or False
Memories?
a. In the 1990s, proponents of recovery therapy (trauma
therapy, repressed memory therapy) claimed to have
identified the root cause of many psychological
problems—sexual abuse in childhood. They asserted that
many adult “survivors” had completely repressed all
memories of the abuse.
b. Critics contend that many of the supposedly
“recovered” memories are actually false memories
produced by the suggestions of
well-intentioned but misguided therapists.
V. The Search for the Biological Basis of Memory
A. The Search for the Elusive Memory Trace
1. Pavlov believed that the memory involved in learning a
classically conditioned response would be explained as a matter
of changes in the brain.
2. In the 1920s, American physiological psychologist Karl
Lashley began the search for the memory trace, or engram—
the brain changes associated with the formation of a long-term
memory.
a. He believed that memory was localized—a particular
memory is stored in a specific brain area.
b. Lashley systematically removed different sections of
the cerebral cortex in rats trained to run a maze, but he
failed to find a specific location for the memory.
c. At the end of his career, Lashley concluded that
memories are not localized in specific locations, but
instead are distributed, or stored throughout the brain.
This assumption was not entirely correct either.
3. American psychologist and neuroscientist Richard F.
Thompson confirmed Pavlov’s belief that some memories are
localized, or stored, in specific areas of the brain. He found that
in rabbits a classically conditioned eye-blink response was
formed and stored in a small area of the cerebellum.
4. Combining the findings of Lashley and Thompson suggests
that memories have the potential to be both localized and
distributed; very simple memories may be localized in a
specific area, whereas more complex memories seem to be
distributed throughout the brain.
5. Focus on Neuroscience: Assembling Memories: Echoes and
Reflections of Perception Studies have confirmed that
retrieving a sensory memory reactivates the sensory area of the
cortex that was involved in the initial perception of the event.
Memories that involve more than one sense tend to
reactivate multiple sensory areas of the brain.
B. The Role of Neurons in Long-Term Memory
1. The notion of a memory trace suggests that some change
must occur in the workings of the brain when a new long-term
memory is stored. Two possible changes could occur:
a. The functioning of the neurons could change.
b. The structure of the neurons could change.
2. In the last 30 years, memory researchers have studied
Aplysia, a sea snail with only about 20,000 good-sized neurons.
Eric Kandel has studied the neuronal changes that occur when
Aplysia forms a new memory for a simple classically conditioned
response.
a. The function of the neurons is altered; there is an
increase in the amount of the neurotransmitters produced
by the neurons.
b. The structure of the snail’s neurons also changes; the
number of interconnecting branches between the neurons
increases, as do the number of synapses, or
communication points, on each branch.
c. Collectively, these changes are called long-term
potentiation, which refers to a long-lasting increase in
synaptic strength.
d. Forming a memory seems to produce distinct
functional and structural changes in specific neurons.
These changes create a memory circuit. As the changes
in the neurons strengthen the communication links in this
circuit, the memory becomes established
as a long-term memory.
C. Processing Memories in the Brain: Clues from Amnesia
Amnesia is severe memory loss.
1. Retrograde Amnesia: Disrupting Memory Consolidation
Retrograde amnesia is loss of memory, especially for episodic
information. Retrograde means “backward moving.”
a. Memory consolidation is the gradual, physical
process of converting new long-term memories to stable,
enduring memory codes.
b. If memory consolidation is disrupted before the
process is complete (e.g., by brain trauma or drugs),
memories of the events that immediately preceded the
brain trauma are completely lost.
2. Anterograde Amnesia: Disrupting Explicit Memory
Formulation Anterograde amnesia is the inability to form new
memories. Anterograde means “forward moving.” The case of
H.M., who was studied extensively by Brenda Milner and
Suzanne Corkin, provided insight into understanding how the
brain processes memory. (Note that H.M. died in December
2008 at the age of 82.)
a. Following the removal of portions of his temporal
lobe, including the hippocampus to reduce epileptic
seizures, H.M. was unable to form new memories of
events and information. This suggests that the critical
role of the hippocampus seems to be the encoding
of new memories for events and information and the
transfer of them from short-term to long-term memory.
b. Cases of anterograde amnesia have contributed to our
understanding of the distinction between implicit
memories and explicit memories.
(1) H.M. could not form new episodic or semantic
memories, which reflect the explicit memory
system; H.M. could form new procedural
memories, which reflect the implicit memory
system.
(2) Therefore, the hippocampus is less crucial to
the formation of new implicit memories, such as
procedural memories, than to the formation of new
explicit memories.
3. In Focus: H.M. and Famous People
When H.M.’s hippocampus was removed, psychologists
questioned whether other areas of the brain might support some
limited learning of new knowledge. H.M. was tested on
learning last names of people who became famous after his
surgery. He had acquired some declarative semantic
knowledge, including details about some of the famous people
4. Brain Structures Involved in Memory
a. The cerebellum is involved in the classical
conditioning of simple reflexes and in procedural and
other motor skill memories.
b. The amygdala seems to encode the emotional qualities
associated with particular memories, such as fear or
anger, as well as memories of sensory stimuli that are
associated with rewards and punishments.
c. The frontal lobes are involved in retrieving and
organizing information associated with autobiographical
and episodic memories.
d. The prefrontal cortex seems to play an important role
in memory, especially in the ability to remember the
order of information.
e. The medial temporal lobes are involved in encoding
complex memories by forming links among the
information stored in multiple brain regions.
5. Alzheimer’s Disease
a. Dementia is characterized by decline and impairment
of memory, reasoning, language, and other cognitive
functions. Alzheimer’s disease (AD) is the most
common cause of dementia.
b. The brains of AD patients develop an abundance of
two abnormal structures—beta-amyloid plaques and
neurofibrillary tangles.
6. Focus on Neuroscience: Mapping Brain Changes in
Alzheimer’s Disease
Alzheimer’s disease progressively destroys neurons in the
brain. The disease first attacks the temporal lobes, affecting
areas involved in memory. Next affected are the frontal areas,
which are involved in thinking, reasoning, self-control, and
planning. There is also significant loss in the limbic areas,
involved in regulating emotion.
VI. Application: Superpower Memory in Minutes Per Day!
Effective techniques to enhance memory include the following:
1. Focus your attention.
2. Commit the necessary time.
3. Space your study sessions.
4. Organize the information.
5. Elaborate on the material.
6. Use visual imagery.
7. Use a mnemonic device.
8. Explain it to a friend.
9. Reduce interference within a topic.
10. Counteract the serial position effect.
11. Use contextual cues to jog memories.
12. Sleep on it to help consolidate those memories.
13. Forget the ginkgo biloba.