memory

psychologypsychologyfourth editionfourth edition

Chapter 6Chapter 6MemoryMemory

Memory and Its ProcessesMemory and Its Processes• Memory: an active system that receives information

from the senses, organizes and alters that information as it stores it away, and then retrieves the information from storage

Models of MemoryModels of Memory• Parallel distributed processing (PDP) model:

memory processes are proposed to take place at the same time over a large network of neural connections

Models of MemoryModels of Memory

Levels-of-processing model: assumes that information that is more“deeply processed” or processed according to its meaning, rather than just the sound or physical characteristics of the word or words—will be remembered more efficiently and for a longer period of time

Models of MemoryModels of MemoryInformation-processing model: assumes that the processing of information for memory storage is similar to the way a computer processes memory - in a series of three stagesPrecursor: Multi-store model: Atkinson and Shiffrin's (1968) original model of memory, consisting of the sensory register, short-term store, and long-term store.

Memory and Its ProcessesMemory and Its Processes

• Processes of memory1. encoding: the set of mental operations that

people perform on sensory information to convert that information into a form that is usable in the brain’s storage systems

2. storage: holding onto information for some period of time

3. retrieval: getting information that is in storage into a form that can be used

Three-Stage Process of MemoryInformation enters through the sensory system, briefly registering in sensory memory. Selective attention filters the information into short-term memory, where it is held while attention (rehearsal) continues. If the information receives enough rehearsal (maintenance or elaborative), it will enter and be stored in long-term memory.

encode

Information-processing model

Sensory MemorySensory Memory• Sensory memory: the very first stage of memory

– the point at which information enters the nervous system through the sensory systems

– The nervous system has a specific sensory system or organ, dedicated to each sense. Humans have a multitude of senses. Sight, hearing, taste, smell, and touch are the five traditionally recognized senses.

Sensory MemorySensory Memory• Iconic memory: visual sensory memory,

lasting only a fraction of a second– capacity: everything that can be seen at one time– duration: information that has just entered iconic

memory will be pushed out very quickly by new information (within a second or so), a process called masking

• Eidetic imagery: the (rare) ability to access a visual memory for thirty seconds or more

Sensory MemorySensory Memory

• Echoic memory: the brief memory of something a person has just heard– capacity: limited to what can be heard at any

one moment; smaller than the capacity of iconic memory

– duration: lasts longer than iconic; about two to four seconds

fyi: The sensory memory for touch stimuli is sometimes known as the haptic memory. Smell and taste memories are not named.

Short-Term MemoryShort-Term Memory• Short-term memory Short-term memory (STM; working

memory): the memory system in which information is held for brief periods of time while being used– selective attentionselective attention: the ability to focus on only

one stimulus from among all sensory input

Short-Term (working) MemoryShort-Term (working) Memory

• Digit-span test: a series of numbers is read to subjects who are then asked to recall the numbers in order– conclusion: capacity of STM is about seven

items or pieces of information, plus or minus two items—or from five to nine bits of information.

– “magical number” = 7 Traditional theory! – Note: New research indicates as few as one item at a time

Short-Term (working)MemoryShort-Term (working)Memory

• Chunking: bits of information are combined into meaningful units, or chunks, so that more information can be held in STM

• Maintenance rehearsal: saying bits of information to be remembered over and over in one’s head in order to maintain it in short-term memory (STMs tend to be encoded in auditory form)

Short-Term (working)MemoryShort-Term (working)Memory• STM lasts from about twelve to thirty

seconds without rehearsal• STM is susceptible to interference

– e.g., if counting is interrupted, one will have to start over

Long-Term MemoryLong-Term MemoryLong-term memory (LTM): the memory system into which all the information is placed to be kept more or less permanently

Long-Term MemoryLong-Term Memory• Elaborative rehearsal: a method of transferring

information from STM into LTM by making that information meaningful in some way, as opposed to simply repeating the word to yourself over and over.

Types of LTMTypes of LTM

• Nondeclarative (implicit) memory: type of long-term memory including memory for skills, procedures, habits, and conditioned responses– Procedural memories are not conscious, but their

existence is implied because they affect conscious behavior

– also include emotional associations, habits, and simple conditioned reflexes that may or may not be in conscious awareness

Nondeclarative (Implicit) LTMNondeclarative (Implicit) LTMProcedural memory (often called implicit memory): memory that is not easily brought into conscious awareness

Nondeclarative (Implicit) LTMNondeclarative (Implicit) LTM

• Anterograde amnesia: loss of memory from the point of injury or trauma forward, or the inability to form new long-term memories– usually does NOT affect procedural LTM

Types of LTMTypes of LTMDeclarative (explicit) memory: type of long-term memory containing information that is conscious and known.

a memory for facts

Semantic: Of or relating to meaning or the study of meaning

Declarative (Explicit) LTMDeclarative (Explicit) LTM

• All the things that people know• Semantic memory: declarative memory

containing general knowledge– knowledge of language, information learned in

formal education• Episodic memory: declarative memory

containing personal information not readily available to others– daily activities and events

Declarative (Explicit) LTMDeclarative (Explicit) LTM• Semantic and episodic memories are forms of

explicit memory - memory that is consciously known.

Types of Long-Term MemoriesLong-term memory can be divided into declarative memories, which are factual and typically conscious (explicit) memories, and Nondeclarative memories, which are skills, habits, and conditioned responses that are typically unconscious (implicit). Declarative memories are further divided into episodic memories (personal experiences) and semantic memories (general knowledge).

Organization of MemoryOrganization of Memory• LTM is organized in terms of related meanings and

concepts• Semantic network model: assumes that information

is stored in the brain in a connected fashion– concepts that are related stored physically closer to each

other than to unrelated concepts

A semantic network, or frame network, is a network that represents semantic relations between concepts. This is often used as a form of knowledge representation. It is a directed or undirected graph consisting of vertices, which represent concepts, and edges, which represent semantic relations between concepts.

An Example of a Semantic NetworkIn the semantic network model of memory, concepts that are related in meaning are thought to be stored physically near each other in the brain. In this example, canary and ostrich are stored near the concept node for “bird,” whereas shark and salmon are stored near “fish.” But the fact that a canary is yellow is stored directly with that concept.

Declarative (Explicit) LTMDeclarative (Explicit) LTM• Semantic and episodic memories are forms of

explicit memory - memory that is consciously known.

Cues to Help You RememberCues to Help You Remember

• Retrieval cue: stimulus for remembering• Priming can occur where experience with

information or concepts can improve later performance

• Priming is a nonconscious (implicit) form of human memory concerned with perceptual identification of words and objects. It refers to activating particular representations or associations in memory just before carrying out an action or task. For example, a person who sees the word "yellow" will be slightly faster to recognize the word "banana." This happens because yellow and banana are closely associated in memory

Cues to Help You RememberCues to Help You RememberEncoding specificity: tendency for memory of information to be improved if related information (e.g., surroundings or physiological state) available when the memory was first formed is also available when the memory is being retrievedEncoding Specificity is state-dependent learning: memories formed during a particular physiological or psychological (affective /emotional ) state will be easier to recall while in a similar state.

RecallRecall

• Recall: memory retrieval in which the information to be retrieved must be “pulled” from memory with very few external cues

• Retrieval failure: recall has failed (at least temporarily)– tip of the tongue (TOT) phenomenon

RecallRecall

• Serial position effect: information at the beginning and the end of a body of information more accurately remembered than the information in the middle– primacy effect: tendency to remember

information at the beginning of a body of information better than what follows

– recency effect: tendency to remember information at the end of a body of information better than the information ahead of it

Serial Position EffectIn the serial position effect, information at the beginning of a list will be recalled at a higher rate than information in the middle of the list (primacy effect), because the beginning information receives more rehearsal and may enter LTM. Information at the end of a list is also retrieved at a higher rate (recency effect), because the end of the list is still in STM, with no information coming after it to interfere with retrieval.

RecognitionRecognition

• Recognition: ability to match a piece of information or a stimulus to a stored image or fact

• False positive: error of recognition in which people think that they recognize a stimulus that is not actually in memory

Eyewitness TestimonyEyewitness Testimony• What people see and hear about an event after the

fact can easily affect the accuracy of their memories of that event– eyewitness testimony is notnot always reliable! – research into this area has found that eyewitness

testimony can be affected by many psychological factors:– Anxiety / Stress– Reconstructive Memory– Weapon Focus– Leading Questions (Loftus and Palmer, 1974)

Automatic Encoding and Flashbulb MemoriesAutomatic Encoding and Flashbulb Memories

• Automatic encoding: tendency of certain kinds of information to enter long-term memory with little or no effortful encoding

• Flashbulb memories: automatic encoding that occurs because an unexpected event has strong emotional associations for the person remembering it

How LTMs Are FormedHow LTMs Are Formed

• Constructive processing: memory retrieval process in which memories are “built,” or reconstructed, from information stored during encoding– with each retrieval, memories may be altered,

revised, or influenced by newer information

How LTMs Are FormedHow LTMs Are Formed

• Hindsight bias: the tendency to falsely believe, through revision of older memories to include newer information, that one could have correctly predicted the outcome of an event– “Monday morning quarterbacking”

Memory Retrieval ProblemsMemory Retrieval ProblemsMisinformation effect: tendency of misleading information presented after an event to alter the memories of the event itself

Reliability of Memory RetrievalReliability of Memory Retrieval

• False memory syndrome: creation of inaccurate or false memories through the suggestion of others, often while the person is under hypnosis

• Evidence suggests that false memories cannot be created for just any kind of memory– memories must at least be plausible.

Forgetting: EbbinghausForgetting: Ebbinghaus

• Curve of forgetting: a graph showing a distinct pattern in which forgetting is very fast within the first hour after learning a list and then tapers off gradually– distributed practice: spacing one’s study

sessions produces better retrieval

– massed practice: studying a complete body of information all at once

Curve of Forgetting

Ebbinghaus found that his recall of words from his memorized word lists was greatest immediately after learning the list but rapidly decreased within the first hour. After the first hour, forgetting leveled off.

Forgetting: Encoding FailureForgetting: Encoding Failure

• Encoding failure: failure to process information into memory

Stop!Many people look at stop signs multiple times a day. Which of these stop signs is closest to an actual stop sign?

(The answer can be found in the notes section of this slide.)

Forgetting: Memory Trace TheoryForgetting: Memory Trace Theory

• Memory trace: physical change in the brain that occurs when a memory is formed – decay: loss of memory due to the passage of

time, during which the memory trace is not used– disuse: another name for decay, assuming that

memories that are not used will eventually decay and disappear

– memories recalled after many years are not explained by memory trace theory

Forgetting: Interference TheoryForgetting: Interference Theory

• Proactive interference: memory retrieval problem that occurs when older information prevents or interferes with the retrieval of newer information

• Retroactive interference: memory retrieval problem that occurs when newer information prevents or interferes with the retrieval of older information

Proactive and Retroactive InterferenceIf a student were to study for a French exam and then a Spanish exam, interference could occur in two directions. When taking the Spanish exam, the French information studied first may proactively interfere with the learning of the new Spanish information. But when taking the French exam, the more recently studied Spanish information may retroactively interfere with the retrieval of the French information.

Formation of LTMsFormation of LTMs

• Consolidation: changes that take place in the structure and functioning of neurons when a memory is formed – long-term potentiation: changes in number

and sensitivity of receptor sites/synapses through repeated stimulation

• Hippocampus: area of brain responsible for the formation of LTMs

AmnesiaAmnesia

• Retrograde amnesia: loss of memory from the point of some injury or trauma backwards, or loss of memory for the past

• Anterograde amnesia: loss of memory from the point of injury or trauma forward, or the inability to form new long-term memories– “senile dementia” (Senile dementia' is a outdated term that used to

be used when it was thought that memory loss and confusion was a normal part of ageing, rather than being caused by specific diseases like Alzheimer's. These days, it is more common to refer to dementia, or early-onset dementia if the person is under 65.)

AlzheimerAlzheimer’’s Diseases Disease• Alzheimer's disease (AD) is the most common form

of dementia among older people. Dementia is a brain disorder that seriously affects a person's ability to carry out daily activities.

• AD begins slowly. It first involves the parts of the brain that control thought, memory and language. People with AD may have trouble remembering things that happened recently or names of people they know.

• In AD, over time, symptoms get worse. People may not recognize family members. They may have trouble speaking, reading or writing. They may forget how to brush their teeth or comb their hair. Later on, they may become anxious or aggressive, or wander away from home. Eventually, they need total care. This can cause great stress for family members who must care for them.

• AD usually begins after age 60. The risk goes up as you get older. Your risk is also higher if a family member has had the disease.

AlzheimerAlzheimer’’s Diseases Disease

• 5.3 million cases in U.S.• Primary memory difficulty in Alzheimer’s is

anterograde amnesia– retrograde amnesia can also occur as the

disease progresses• There are various drugs in use or in

development for use in slowing or stopping the progression of Alzheimer’s disease, but no cure.

AlzheimerAlzheimer’’s Diseases Disease

• Risk factors include– high cholesterol– high blood pressure– smoking– obesity – Type II diabetes– lack of exercise

AmnesiaAmnesia

Infantile amnesia: the inability to retrieve memories from much before age three

AmnesiaAmnesiaAutobiographical memory: the memory for events and facts related to one’s personal life story (usually after age three)

Health and MemoryHealth and Memory

• Sleep is important in forming memories– memories rehearsed during sleep as well as during

waking are more likely to be consolidated– one can’t learn something new while sleeping, but new

information can be better consolidated while sleeping– sleep deprivation severely interferes with hippocampal

function and memory• Even brief exercise can be good for your memory• Fish is brain food?

– omega-3 fatty acid called DHA (docosahexaenoic acid) appears to help memory cells communicate

psychologypsychologyfourth editionfourth edition

Chapter 6 Chapter 6 MemoryMemoryThe EndThe End