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
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
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
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 Long- Term 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
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-the- blank and matching questions are examples of cued- recall tests.
c. Recognition involves identifying the correct information from several possible choices. Multiple-
choice tests involve recognition as a measure of long- term 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. Absent- minded 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
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
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
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
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.