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Memory. How does memory work?. The Modal Model. Basic info-processing model of memory Atkinson-Shiffrin 1968 The modal model. Sensory Registry. Short-Term Memory. Long-Term Memory. Attention. Rehearsal. Sensory Memory. Recall Sperling

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How does memory work?

the modal model
The Modal Model
  • Basic info-processing model of memory
    • Atkinson-Shiffrin 1968
    • The modal model

Sensory Registry







sensory memory
Sensory Memory
  • Recall Sperling
  • Participants view a briefly presented array of letters.
  • Tone cued participants to recall items.
    • Change the duration between presentation of array and the recall tone
  • Partial report suggested sensory memory is rather large but has a short duration
short term memory
Short-term memory
  • The theory of STM was brought about during the cognitive revolution and is a product of the information processing perspective
  • It proposed that attended information went into an intermediate short-term memory where it had to be rehearsed (processed) before it could go into a relatively permanent long-term memory.
  • STM is biased toward keeping recent information available and has a limited capacity to do so.
    • Memory span - the number of elements one can immediately repeat back
short term memory5
Short-term memory
  • In a study of memory span, participants might rehearse digits by saying them over and over again to themselves
  • With each rehearsal of an item, it was assumed there was a probability that the information would be transferred to a relatively permanent long-term memory
  • If the item left short-term memory before a permanent long-term memory representation was developed, however, it would be lost forever
  • One could not keep information in short-term memory indefinitely because new information would always be coming in and pushing out old information from the limited short-term memory
short term memory6
Short-term memory
  • One of the questions with STM regarded its duration
  • What determines the duration of STM?
    • Decay?
      • Gradual loss of memory “strength” over time.
    • Interference?
      • Access to information is blocked by the retrieval of other information
    • Overwriting?
      • Original memory trace is altered
  • Brown-Peterson Paradigm
    • “You will not be shocked during this experiment”
    • Study unrelated information
      • ‘T’ ‘K’ ‘B’
      • “wood” “dog” “candy”
    • Count backward by 3’s
      • Prevent rehearsal
    • Vary duration of counting
    • Recall studied items
brown peterson


  • Decay
    • (on average) memory information is accessible up to 18 seconds.

Proportion of correct recalls




Interval of counting (sec.)

  • Reconcilable with sensory memory
    • Use it or lose it.
  • Once memory is established, decay is constant
  • What constitutes “established”?
    • Is it always ~18sec.?
very rapid forgetting
Very Rapid Forgetting
  • Sebrechts, Marsh, & Seamon (1989) based on Muter (1980)
  • Used a modified Brown-Peterson paradigm with false trials.
    • B-P task
      • Acoustic (shallow)
        • Long E sound?
      • Semantic
        • Is it animate?
      • Reading
        • say the stimuli aloud
    • Exp 1 regular B-P experiment
    • Exp 2 “Surprise” memory test
sebrechts marsh seamon
Ss presented words sequentially and made a yes/no decision for each word presented or just read aloud depending on condition

Countdown followed

Sebrechts, Marsh, Seamon

Brown-Peterson trial




sebrechts marsh seamon12

Proportion of words recalled*













Sebrechts, Marsh, & Seamon
  • Forgetting within 6 seconds
  • Expectation of retrieval is necessary to maintain information in memory, but also elaboration can have an effect
  • So again the idea of decay doesn’t provide for the whole story



Proportion Recalled

Surprise Trials




Interval of counting (sec.)

*They looked also at the strict scoring i.e. remembering the whole trigram,

the pattern was the same but with poorer performance overall

  • Memory is more active
  • Newly encountered information (if used) limits the access to previous information.
  • Interference is often confounded with “decay”
  • Waugh & Norman (1965)
  • Present a set of 16 digits at a fixed interval.
    • 1 digit per second
    • 4 digits per second
  • Last digit in the set served as a probe, and had previously been presented once
  • Report the digit that appeared after the probe digit had appeared in the list the first time (target)
  • Manipulate the number of digits that appear between target and the probe
    • Retention interval
  • If forgetting is a function of decay (time) then there should be less recall for slower rate (16 secs) vs. faster rate (4 secs)
  • If interference then should be little to no difference between the two
waugh norman
Waugh & Norman


Proportion Correct

1 Cond.

4 Cond.




Number of items between target & probe

More about the number of items that interfered rather than decay

over time

  • So the Waugh and Norman results suggest interference from additional information can disrupt memory for particular items
  • Two types of interference
    • Retroactive Interference
      • New information interferes with previously learned information
    • Proactive Interference
      • Previously learned information interferes with the acquisition of new information
  • A possible explanation for interference is that when given cue, information associated with cue interferes with other info also associated with cue
    • More items a cue is stored with the less effective it will be in retrieving any one particular item
    • Recall fan effect
  • But along with interference as another possible explanation of forgetting, the Sebrechts et al., shows other factors will have a say in how forgetting occurs
    • Expectancy
    • ‘Depth’ of encoding
the decline of stm
The decline of STM
  • The idea of a short-term passive ‘store’ fit in with the current information processing models
    • Rapid forgetting
      • Transient nature suggests different type of store
    • Amount of rehearsal controlled the amount transferred to LTM
      • More rehearsal more remembering
      • Info had to ‘do time’ before getting to LTM
the decline of stm19
The decline of STM
  • Problems
  • Loss similar for better learned material (initial rapid loss followed by slower loss later)
  • Rehearsal by itself won’t determine what makes it to LTM:
    • Chunking
      • 7 + 2
      • What may be chunked and how chunking occurs can depend on a variety of factors and varies across individuals
    • Depth of processing (Craik & Lockhart, 1972)
      • The Sebrechts article was an example of how DoP had a role even if there was decay
    • Some experiences gain immediate access to LTM
      • E.g. traumatic events
  • Such findings suggested there was more to short-term memory functioning than as a passive storage device
working memory
Working Memory
  • Function: short-term retention and manipulation of information.
  • Active memory
  • Issues regarding working memory
    • How long?
    • How much?
    • What type?
  • Capacity
    • Forgetting curve (Brown-Peterson)
    • Miller’s 7 +/- 2
  • Model of WM
    • Based on perceptual codes
      • Acoustic
      • Visual and Spatial
    • Information can be retained separate from its use for a short time
    • Coordinating process guides the use of retained information
    • Central Executive
    • “Slave” systems
      • “Rehearse” information for a short time
      • Perceptually based
baddeley s model of wm

Central Executive





Baddeley’s Model of WM

Coordinates the Slave Systems

Response Selection

Guides Attention

Maintains visual and

spatial information

Maintains acoustic


phonological loop
Phonological Loop
  • Two components
    • Phonological store
    • Articulatory control process
      • Subvocal articulatory rehearsal
    • Traces within the store decay over a period of about two seconds unless refreshed by rehearsal, a process akin to subvocalization and one that is dependent on the second component, the articulatory system
  • Important for long-term phonological learning
    • e.g., language learning
some evidence for the loop
Some evidence for the loop
  • Phonological similarity effect
    • Similar phono code leads to confusion
  • Irrelevant speech effect
    • Colle & Welsh (1976): even a foreign language can interfere with immediate recall of items
    • Because of the nature of the code, the language gains access to the phono store
  • Articulatory suppression
    • Operation of the loop is disturbed if overt or cover articulation takes place
    • Vocalization utilizes same system as subvocal rehearsal, and hence can lead to difficulty learning verbal information
  • Word length effect
    • Span decreases as the length of a word increases
    • Less can be rehearsed within the ~2 sec time frame
visuo spatial sketchpad
Visuo-spatial Sketchpad
  • Temporarily maintains and manipulates visuospatial information
  • Plays an important role in spatial orientation and in the solution of visuospatial problems
    • Both visual (imagery) and spatial component
    • Possibly two different systems
some evidence for the sketchpad
Baddeley & Lieberman (1980)

Visual tracking interferes with imagery mneumonic

Irrelevant picture effect

Same result even from just looking at visual stimuli

Some evidence for the sketchpad
central executive
Central Executive
  • Most complex and least understood component of WM
  • Model suggests CE coordinates the activity of the two slave systems
  • Other potential roles
    • Coordinating retrieval strategies
    • Selective attention
    • Suppression of habitual responses
    • Task switching
    • Temporary activation of long term memory
    • Binding of sensory and conceptual information
assumptions and predictions
Assumptions and Predictions
  • Slave systems are independent of each other
    • It is possible to do a both a verbal task and a spatial task at the same time
    • Extremely difficult to do two verbal (or two spatial) tasks at the same time.
    • Dual-Task Paradigm
      • Participant must perform more than one task at a time
  • Slave systems have limited capacity
    • Span
  • Slave systems can function autonomously from the Central Executive
    • Can do “Central Executive tasks” and slave system tasks at the same time
  • Central Executive coordinates information based on current goals
    • Implies intentional (conscious) control of WM
    • Coordination involves many processes.
the episodic buffer
The Episodic Buffer
  • “A limited capacity temporary storage system that is capable of integrating information from a variety of sources”
  • Controlled by the CE
  • Feeds information into and retrieves information from LTM
  • Uses a common “multidimensional” code
  • The Episodic Buffer makes the link between Working Memory and LTM more explicit
long term memory
Long-term memory
  • Basically includes anything retained that did not occur few moments earlier
  • Source of information that does not come from the environment
  • Storage of information in memory as a consequence of experience
  • Process of acquiring new associations among stimuli, responses and outcomes.
  • What is Learned?
  • How is it Learned?
  • Associative theories
    • Learning
  • Cognitive theories
    • Encoding and Retrieval
classical conditioning
Classical Conditioning
  • Characterized by the generalization of a fixed or previously learned behavior
  • Responses are elicited from stimuli
  • Unconditioned stimulus (US)
    • Elicits a response without training
    • Shock
  • Unconditioned Response (UR)
    • Elicited without training by a (US)
    • Smacking whoever gave you the shock
  • Conditioned Stimulus (CS)
    • That which through training elicits a particular response
    • Pretty flowers
  • Conditioned Response (CR)*
    • Response to the conditioned stimulus
    • Smacking whoever gives you pretty flowers
operant instrumental conditioning
Operant / Instrumental Conditioning
  • Based on the principle of reinforcement
    • What is reinforced?
    • What is reinforcing?
  • Development of associations between particular responses and consequences of the response (outcomes).
basic mechanisms of operant conditioning
Basic Mechanisms of Operant Conditioning
  • Behaviors have consequences
  • Consequences are contingent on behaviors
  • Organisms adapt behavior to match contingencies
  • Consequences usually satisfy a “drive”
    • Biological need
    • Motivational need
    • Well-being of individual
consequences of behavior
Consequences of Behavior
  • Reinforcement or Punishment
    • Reinforcement
      • Consequences of behavior increase the probability of response (behavior)
    • Punishment
      • Consequences of behavior decreases the probability of response
  • Both Reinforcement and Punishment can be positive or negative
    • Positive: presentation of stimuli
    • Negative: removal of stimuli
  • The result is a table of contingencies…
reinforcement and punishment
Reinforcement and Punishment


Increase (rein.)

Decrease (pun.)

Positive Reinforcement


Positive Punishment


Apply a stimulus (+)


Negative Reinforcement

Negative Punishment


Remove a stimulus(-)

associative learning
Associative Learning
  • Accounts for certain types of memory phenomena
    • Memory Structure
    • Highly practiced information
    • Habitual responses
    • Stimulus generalization
  • Assumes memory mechanism is the same as associative mechanism (single system)
associative memory
Associative Memory
  • Associative memory theory alone cannot account so well for other phenomena
    • Free Recall
      • No cue
    • Subjective organization
      • Von Restorff Effect
        • Effect of stronger memory for a salient item in a series
    • Sensory Memory
      • “Direct” memory of sensory information
      • Short-term representations
      • No Practice
    • Complexity of language acquisition/production
    • Systematic memory distortions
beyond association
Beyond association
  • Although simple associative mechanisms described by classical and operant conditioning may account for some aspects of learning, more was needed
  • Subtle shift from learning theories to theories of memory, which emphasized knowledge representation in an information processing system
  • Focused on encoding and retrieval processes to help explain memory performance in a variety of settings
  • Levels of Processing
  • Encoding specificity
  • Transfer appropriate processing
basic mechanisms of memory
Basic Mechanisms of Memory
  • Encoding
    • Acquisition of Information
    • “Learning” ?
  • Maintenance
    • Retaining information
  • Retrieval
    • Using information
  • How do the processes of Encoding and Retrieval influence what is remembered?
levels of processing
Levels of Processing
  • Craik & Lockhart (1972)
    • Formalized the notion of “depth” of processing and demonstrated how it affects memory.
  • There are “depths” to which information can be processed
    • Shallow: encoding information in terms of its physical or sensory characteristics
    • Deep: encoding information in terms of meaning
  • Levels (for words)
    • Structural
      • Is it all caps?
      • Shallow
    • Phonetic
      • Does it rhyme with _?
    • Semantic
      • Is it an animal?
      • Deep
levels of processing43
Levels of Processing


Proportion correctly recognized





levels of processing44
Levels of Processing
  • Such results suggests that deeper levels of processing produce more permanent retention than shallow levels of processing.
  • Distinctiveness and elaboration may be responsible for the effectiveness of deep levels of processing
  • Other results
    • Intention to learn does not change LOP pattern of results (Hyde & Jenkins, 1973)
    • Generation effect (Slamecka and Graf, 1978)
    • Self-reference task encourages especially deep levels of processing (Rogers, Kuiper, & Kirker 1977
  • Problem: What is “deep” and what is “shallow?”
    • Circular logic
    • If processing is deep then retention will be better.
    • If retention was better, then processing must have been deeper.
    • There is no precise way to measure ‘depth’
encoding specificity principle
Encoding-Specificity Principle
  • Information is available to the extent to which retrieval cue matches encoding
    • Tulving and Thomson, (1973)
morris bransford franks 1977
Morris, Bransford, & Franks (1977)
  • Had people make one of two judgments at presentation
    • Shallow: Rhyming (Does it rhyme with hat?)
    • Deep: Semantic (Does it have a tail?)
  • Two test conditions
    • Recognition
    • Rhyming
      • “Hat”
      • “Did you see a word that rhymes with X?”
  • Test Condition either matched or mismatched original encoding
morris bransford franks











Morris, Bransford, & Franks
morris bransford franks48
Morris, Bransford, & Franks
  • LOP effect for standard test.
  • But opposite for rhyming test
  • Deep processing does not always enhance memory
transfer appropriate processing
Transfer Appropriate Processing
  • Memory performance depends on the extent to which processes used at the time of learning are the same as those used when memory is tested
  • LOP approach assumed that semantic processing was always superior to non-semantic processing
  • The transfer appropriate processing approach demonstrates that a form of encoding which is “shallow” for one purpose might be “deep” for another.
  • Conclusion
    • Memory not just a function of depth of processing
    • Depends also on the match between encoding processes and type of test
interaction of encoding and retrieval
Interaction of Encoding and Retrieval
  • Context Congruency
  • Godden & Baddeley
    • Divers memorized a list of words
    • Half learned the words on dry land
    • Half learned words underwater
    • Tested either on dry land or underwater


  • emphasizes operations at encoding
  • semantic/elaborative processing better for LTM


  • emphasizes that information about retrieval cue must be encoded at study for cue to be effective


  • memory best when processes at test match processes used at study

*For another view, see Nairne, 2002

different methods of retrieval
Different Methods of Retrieval
  • What is your name?
    • Automatic
  • What is the Capital of Australia?
    • Generate & recognize
  • What are you doing next Tuesday at 1200?
    • Schema + Search
  • What is the layout of your house?
    • Spatial
  • Is “FLORB” a word?
    • Direct access
  • What was Beethoven’s telephone number?
    • General knowledge search
basic mechanisms
Basic Mechanisms
  • General Principles of Memory
  • Strength
    • Background
    • Contextual
  • Congruity
    • Between encoding and retrieval
  • Organization
  • Distinctiveness
    • Segregate item in memory
  • Spacing
    • Massed vs. Distributed
  • Recency and Primacy
  • Old rule: Spacing learning enhances recall
  • Bahrick family and foreign language learning 
  • Why does it work?
  • Varying encodings may lead to more associations
  • Reminds of earlier presentation, so may reinforce earlier learning (perhaps increasing baseline activation)
recency and primacy


Proportion Recalled





Position in List

Recency and Primacy
  • Demonstrated in the serial-position curve
  • Learn a list of items in order…
  • ..and reproduce the list in order
recency and primacy57
Recency and Primacy
  • Primacy
    • Memory advantage for items initially encountered.
    • Rehearsal?
    • Distinctiveness?
  • Recency
    • Memory advantage for items recently encountered.
    • Working memory?

What and how information is retrieved.

Memory trace



Emphasis on information available at retrieval


Contextual information

Something guides retrieval

Memory as a Decision

Many different theories about how retrieval takes place.

Information Processing Theories

Modal Model, LOP, TAP

Associative Theories


Search Models


Trace Theories

Perturbation Model

Connectionist Models


Biological-Based Theories