1. Memory and Cognition PSY 324 Topic 5: Short-Term & Working Memory
Dr. Ellen Campana
Arizona State University

2. Modal Model of Memory

3. Modal Model of Memory Atkinson & Shiffrin (1968)
Rehearsal
Input
Sensory
Memory
Short-
term
Memory
Long-
term
Memory
Output
Three stages of memory
Input, Output, Rehearsal (a control process)

4. Modal Model Structural Features of the Model
Sensory memory: initial stage, holds info for seconds/fractions of seconds. Large capacity.
Short-term Memory (STM): holds 5-7 items for seconds. Control processes can extend this.
Long-term Memory (LTM): holds a large amount of information for years, even decades
Control processes: active memory strategies controlled by individual (example: rehearsal)

5. Control Processes Some control processes maintain info in STS
Rehearsal (repeat the items over and over)
Chunking (make connections between items)
Visualization
Some control processes affect transfer between STS and LTS (storage and retrieval)
Memorization
Recall
You can only process information in STS

6. Sensory Memory

7. Sensory Memory Sensory memory is very short
Allows you to see the “trail” of a sparkler
Allows you to see movies (flipbook, tachistoscope)
Auditory Sensory Memory is also called
Echo
Visual Sensory Memory is also called
Persistence of vision
Iconic Memory / Visual Icon

8. Sperling (1960): Iconic Memory
Whole report condition
X M L T
A F N B
C D Z P X
F D
Z C

9. Sperling (1960): Iconic Memory
Partial report condition
X M L T
A F N B
C D Z P
X M
L T

10. Sperling (1960): Iconic Memory
What’s the point?
Sperling was studying visual sensory memory
Before his study, people thought that visual sensory memory could only hold 4-5 items (full report cond)
The other conditions in his study showed that
It’s true that people can only report 4-5 items before memory decays (or fades away)
BUT sensory memory actually encodes the whole scene
Conclusion: Sensory Memory has a large capacity, but fast decay

11. Sperling (1960): Iconic Memory
Partial report delayed
condition
X M L T
A F N B
C D Z P M

12. Sperling (1960): Iconic Memory
Summary of conditions
Whole report condition
All 12 letters flash on/off -> 1s. delay -> report any
Partial report condition
All 12 letters flash on/off -> auditory cue to row -> report just that row
Partial report delayed condition
All 12 letters flash on/off -> 1s. Delay -> auditory cue to row -> report just that row

13. Sperling (1960): Timing of Decay
What’s the point?
Sperling wanted to get a clearer picture of just how fast sensory information decays
Stronger support of his hypothesis that sensory memory has large capacity and fast decay
Conclusion: Within just 1 second, most of sensory memory decays, leaving only what was moved to STS via attention.

14. Moray, Bates & Barnett (1965)
Sternberg looked at visual memory, Moray, Bates & Barnett were interested in echoic memory (auditory sensory memory)
Same task for audio domain
“four-eared listening”
Similar effects (advantage for partial reporting)
Work after that showed
Echoic memory has larger capacity and slower decay than visual iconic memory

15. Modalities of Sensory Memory
Modality: the “channel” (Broadbent) that different inputs come in through
Auditory, visual, tactile, etc.
Sensory memory is modality specific
Saying “ba, ba, ba” while receiving auditory input messes up echoic, but not iconic memory
A visual mask messes up visual memory, but not auditory memory
Mask: for control in experiments (as in demo)

16. Change Blindness

17. Change Blindness

18. Change Blindness

19. Sensory Memory Now
In Sternberg’s day, this evidence supported the Modal Model (which has since been replaced)
Sensory memory is still important and seems to be separate from other forms of memory
Still thought to have large capacity and fast decay
Thought to be important for
Collecting input
Holding input during initial processing
Filling in “blanks” (movies, static, etc.)

20. Short-Term Memory (STM)

21. Modal Model of Memory Atkinson & Shiffrin (1968)
Rehearsal
Input
Sensory
Memory
Short-
term
Memory
Long-
term
Memory
Output
Three stages of memory
Input, Output, Rehearsal (a control process)

22. Short-Term Memory Short-term memory allows you to:
Understand sentences
Do arithmetic
Dial a phone number
Navigate from one place to another
Know where we are and what we’re doing right now
Memory for current tasks, last few minutes
Momento: main character had STM, not LTM
Clive Wearing: Real-world case in book

23. Issues with STM Just as with Sensory Memory, two important issues are
Duration (how long things stay in memory)
Capacity (how many things fit in memory at a time)
Studying Short-Term-Memory is complicated because people use control processes a lot
Rehearsal seems to extend duration
Chunking seems to extend capacity

24. Duration of Short-term Memory
Brown (1958) / Peterson & Peterson (1959)
Same studies at the same time, same results
Step 1: three letters + one number given
Step 2: count backward from number
Step 3: 3-18 s. delay (while counting backward)
Step 4: recall three letters

25. Duration of Short-term Memory
Brown (1958) / Peterson & Peterson (1959)
Same studies at the same time, same results
Percent
Recalled
FIRST TRIAL
ONLY 3 18
Delay

26. Duration of Short-term Memory
Brown (1958) / Peterson & Peterson (1959)
Same studies at the same time, same results
THIRD TRIAL
ONLY
Percent
Recalled 3 18
Delay

27. Duration of Short-term Memory
Brown (1958) / Peterson & Peterson (1959)
Same studies at the same time, same results
MANY
TRIALS
LATER
Percent
Recalled 3 18
Delay

28. Duration of Short-term Memory
Brown (1958) / Peterson & Peterson (1959)
Same studies at the same time, same results
AVERAGE
OVER ALL
TRIALS
Percent
Recalled 3 18
Delay

29. Duration of Short-term Memory
The studies by Brown and Peterson & Peterson show that the percentage of letters recalled decreases with longer delays, BUT this pattern interacts with where in the series of trials the individual trail occurs
Recall of letters after long delays decreases as the series of trials gets longer

30. Duration of Short-term Memory
What’s the point?
Peterson & Peterson / Brown were interested in decay of short term memory
It turns out, their studies demonstrate that another type of forgetting that happens in STM: proactive interference
What is already in STM affects ability to add new things
Larger point is that forgetting in STM occurs through both decay and interference (proactive and other types too) – effective duration is 15-20s.

31. Capacity of Short-term Memory
Capacities can vary from person-to-person, measured by digit span
Get out some paper and something to write with, we’re going to calculate your digit span

32. Capacity of Short-term Memory
Directions: Make sure you are running the next slides in presentation mode. You will see a list of single-digit numbers. Remember them. When you see “go” (but not before), write them down from memory, in order. When you are done writing, click to get the next set of digits.

33. Capacity of Short-term Memory
GO!
GO!
GO!
GO!
GO!
GO!
GO!

34. Capacity of Short-term Memory
How many digits were in the longest row that you got completely right?
That’s your digit span.

35. Capacity of Short-term Memory
“My problem is that I have been persecuted by an integer. For seven years this number has followed me around, has intruded in my most private data, and has assaulted me from the pages of our most public journals. This number assumes a variety of disguises, being sometimes a little larger and sometimes a little smaller than usual, but never changing so much as to be unrecognizable…..

36. Capacity of Short-term Memory
…. The persistence with which this number plagues me is far more than a random accident. There is, to quote a famous senator, a design behind it, some pattern governing its appearances. Either there really is something unusual about this number or else I am suffering from delusions of persecution.”
George Miller (1956)
The Magical Number 7 (plus or minus 2)

37. Capacity of Short-term Memory
Miller (1956): People can remember 7±2 ….
Digits
Words
Numbers (with multiple digits)
Phrases
We can remember more if it’s organized
Chunking is combining smaller units into larger meaningful units, to improve capacity

38. Chunking
Chunking involves using Long-term memories to organize information in Short-term memory
Ericcson and coworkers (1980)
College student had digit-span of 79 after training
Chunked digits into meaningful times for running, a sport he was familiar with
Chase and Simon (1973)
Chess players chunk information based on meaningful points within a game of chess

39. Chunking Chase & Simon (1973) Meaningful Arrangements Random
Correct
Piece
Placements
Master
Beginner
Master
Beginner

40. Chunking & Information Coding
What’s the point of all these chunking studies?
Capacity is related to how information is represented
Recall our last discussion of how information is represented, during “Cognition and the Brain”
Specificity coding vs. Distributed coding
Dealt with how information is represented by neurons’ firing rates
This is called a physiological approach to coding
We can also take a mental approach to coding

41. Information Coding Mental approach to coding Three Types of Coding
More abstract than physiological approach
Deals with how things are represented in the mind / thoughts
Three Types of Coding
Auditory Coding – represented as a sound
Visual Coding – represented as an image
Semantic Coding –represented through meaning

42. Auditory Coding Conrad (1964)
Participants saw target letters (quickly flashed)
Then they wrote them down
Mistakes were made
Not likely to replace with something that looked like the target (E for F)
Likely to replace with something that SOUNDED like the target (E for B)
Suggests that letters are represented by sound information (auditory coding)

43. Semantic Coding Wickens and Coworkers (1976)
Participants divided into groups
Groups heard lists with different meanings (fruits, professions, meats, etc.)
Proactive Iterferecen for same list-TYPE repeated
Category switch caused release from proactive interference
Effect was larger for categories that were less similar
Evidence for semantic (meaning) coding

44. Short-term Memory Today
The Modal Model had a nice clean vision of Short-term Memory
All-purpose store with 15-20s duration and capacity of 7±2
Simply holds information
How information is coded affects how much information fits in STM, but not much else
This view of STM turned out to be too simple, so it has been replaced with working memory

45. Working Memory

46. Modal Model of Memory Atkinson & Shiffrin (1968)
Rehearsal
Input
Sensory
Memory
Short-
term
Memory
Long-
term
Memory
Output

47. Working Memory Baddeley & Hitch (1974)
Input
Sensory
Memory
Central
Executive
Long-
term
Knowledge
Phonologal Loop
Visuospatial Sketchpad

48. Comparing Memory Models
Short-term Memory (Attkinson & Shiffrin)
Single component for all types of info
Mainly used for holding information for a short time
Working Memory (Baddeley & Hitch)
Three components:
Central Executive
Visuospatial Sketchpad
Phonological Loop
Used for manipulation of information during complex cognition

49. Components of Working Memory
Phonological Loop
Holds verbal and auditory information
Coding or source can determine whether it’s verbal/auditory information or not
Visuospatial Sketch Pad
Holds visual and spatial information
Central Executive
Pulls info from long-term memory, coordinates other components, directs and maintains attention…

50. A component of working memory
Phonological Loop
A component of working memory

51. Phonological Loop
The phonological loop holds verbal and auditory information (for longer than the echo)
Sources of experimental support for a component specialized for Language
Phonological similarity effect
Word-length effect
Articulatory suppression

52. Phonological Similarity Effect
The basic effect: words that sound similar are confused by people
We saw that earlier today when we discussed Auditory Coding: Condrad’s study with letters
Another example is the Coglab “Phonological Similarity” (which you can get extra credit for doing)

53. Phonological Similarity Effect
Experiment design
Half of the time the letters were similar and half of the time they weren’t
Half of the time you had to speak (recite numbers 1-4 in order) and half of the time you were to be quiet
Speaking in this experiment is called articulatory suppression (which we’ll come back to)
The two factors were independent

54. Phonological Similarity Effect
The U-shape doesn’t matter for now
How do similar and dissimilar compare to each other for the quiet trials?
How does this support the phonological similarity effect?

55. Phonological Similarity Effect
What was the point of the Phonological Similarity Effect experiment?
Demonstrated the phonological similarity effect (people confuse letters that sound similar)
Key point: even though information was presented visually, people converted it to auditory
As we’ll see later, it also showed that the phonological loop is necessary for the conversion (not just holding info)

56. Phonological Loop
The phonological loop holds verbal and auditory information (for longer than the echo)
Sources of experimental support for a component specialized for Language
Phonological similarity effect
Word-length effect
Articulatory suppression

57. Word-Length Effect
The basic effect: When memorizing words, you can remember fewer words if the words are long
Here’s another demo…. Just do what you did earlier for the digit span test. When you see the words try to remember them. Then, when you see “go” (but not before) write down the words you can remember. It can be any order this time. Then click to go on.

58. Word-Length Effect GO! GO!
alcohol, property, amplifier, officer, gallery, mosquito, orchestra, bricklayer
beast, bronze, wife, golf, inn, limp, dirt, star
GO!
GO!

59. Word-Length Effect
The basic effect: When memorizing words, you can remember fewer words if the words are long
That was a demo of a real experiment …. People remembered more of the short words than long words (Baddeley & Coworkers, 1984)
American children have a longer digit span than Welsh children (Ellis & Hennelly, 1980)
Because welsh numbers take longer to pronounce!
Number of words you can say in seconds is likely to be your digit span

60. Phonological Loop
The phonological loop holds verbal and auditory information (for longer than the echo)
Sources of experimental support for a component specialized for Language
Phonological similarity effect
Word-length effect
Articulatory suppression

61. Articulatory Suppression
The basic finding: if you speak while memorizing (which keeps the phonological loop busy) you get worse at remembering, AND the other two effects disappear
Coglab “Phonological Similarity Effect” illustrates both
Remember: You can get extra credit for doing it

62. Articulatory Suppression
Which is less accurate on average, quiet or suppression (circles or squares) ?
Is the phonological similarity effect (difference btwn black & white) stronger for quiet or suppression (circles or squares)?

63. Articulatory Suppression
The basic finding: if you speak while memorizing (which keeps the phonological loop busy) you get worse at remembering, AND the other two effects disappear
Performance worse in suppression condition
Phonological effect weaker in suppression condition
Similar findings regarding the word length effect
What is going on in these situations? Why does this support the concept of a phonological loop?

64. Visuospatial Sketch Pad
Another component of working memory

65. Working Memory Baddeley & Hitch (1974)
Input
Sensory
Memory
Central
Executive
Long-
term
Knowledge
Phonologal Loop
Visuospatial Sketchpad

66. Visuospatial Sketch Pad
The visuospatial sketch pad holds visual and spatial information
Experiments we’ll talk about show just that visual and spatial information is separate from phonological loop

67. Visuospatial Sketch Pad
Brooks (1968) – the sentence experiment
Memorize a sentence
Indicate whether each word is / is not a noun
Condition 1: indicate by speaking
Condition 2: indicate by pointing

68. Visuospatial Sketch PadY N Y N Y N Y N Y N Y N Y N Y N Y N

69. Visuospatial Sketch Pad
Brooks (1968) – the sentence experiment
Memorize a sentence
Indicate whether each word is / is not a noun
Condition 1: indicate by speaking
Condition 2: indicate by pointing
Results: pointing was easier than speaking for the participants
Explanation: Phonological loop was busy processing the sentence, but sketch pad was free

70. Visuospatial Sketch PadF
Brooks (1968) – the “F” demo
Memorize a shape (in this case an F)
Indicate whether each corner is an “inside corner” or an “outside corner”
Condition 1: Indicate by speaking
Condition 2: Indicate by pointing

71. Visuospatial Sketch PadY N Y N Y N Y N Y N Y N Y N Y N Y N

72. Visuospatial Sketch PadF
Brooks (1968) – the “F” demo
Memorize a shape (in this case an F)
Indicate whether each corner is an “inside corner” or an “outside corner”
Condition 1: Indicate by speaking
Condition 2: Indicate by pointing
Results: Speaking is easier than pointing (the OPPOSITE of what happened before)
Explanation: Sketch Pad was busy with image, but phonological loop was free

73. Visuospatial Sketch Pad
What is the point of these studies?
Tasks are easier when the information being held in mind and the operation being performed on it involve different types of short-term memory
Verbal / Phonological
Visual / Spatial
That means that the two types of short-term memory are somewhat independent
At the least, separate capacities

74. Another component of working memory
Central Executive
Another component of working memory

75. Central Executive
The Central Executive does the “work” of working memory
Coordinating sketchpad and phonological loop
Performing calculations
Directing and maintaining attention
A lot of what we learned about in the attention topic is part of what the central executive does
Sample source of evidence: central executive’s ability to suppress is correlated with memory

76. Central Executive Gazzaley and coworkers (2005)
Compared two versions of the task
“face-relevant”: Remember faces, ignore scenes (test: faces)
“passive”: Just watch pictures (test: arrow right/left)

77. Central Executive

78. Central Executive Gazzaley and coworkers (2005)
Compared two versions of the task
“face-relevant”: Remember faces, ignore scenes (test: faces)
“passive”: Just watch pictures (test: arrow right/left)
Measures:
Accuracy at remembering faces
Brain activity in areas used for perceiving scenes
Good suppressors: less activity in scene areas (good at ignoring)
Poor suppressors: more activity in scene areas (poor at ignoring)
Results: good suppressors remembered more faces

79. Back to the big picture…

80. Working Memory Baddeley (2000)
Remember the other components!
Episodic Buffer
Input
Sensory
Memory
Central
Executive
Long-
term
Knowledge
Phonologal Loop
Visuospatial Sketchpad

81. Working Memory Now The model successfully explains a lot of data
Still a useful model that is used by many
There is a newer one (Cowan) but details are beyond this class
Still changing, though….
Baddeley was frustrated that certain things didn’t seem to “fit” (effect sizes larger or smaller, etc)
Episodic buffer has been added as a 5th component

82. Working Memory Baddeley (2000)
Episodic Buffer
Input
Sensory
Memory
Central
Executive
Long-
term
Knowledge
Phonologal Loop
Visuospatial Sketchpad

83. What’s this Episodic Buffer?
The episodic buffer is a “backup” that talks to the central executive and long-term memory
Greater duration than loop & sketch pad
Greater capacity than loop & sketch pad
Very vague, still needs to be tested
The point is that models are constantly being refined and modified to account for new results

84. Working Memory and the Brain

85. Working Memory and the Brain
Prefrontal cortex involved in working memory
Gets inputs from the sensory areas
Gets inputs from areas involved in action
Connected to areas involved in long-term memory

86. Working Memory and the Brain
Prefrontal Cortex

87. Working Memory and the Brain
Prefrontal cortex involved in working memory
Gets inputs from the sensory areas
Gets inputs from areas involved in action
Connected to areas involved in long-term memory
Physiological evidence
Delayed-response task in monkeys
Single-cell recording in monkeys
Brain imaging evidence

88. Working Memory and the Brain
Physiological evidence based on similirities between monkey and human brain
Delayed-response: Monkeys can remember a location over a delay. When monkeys have PFC removed, they can’t do that very well any more.
Funahashi and coworkers (1989) Single-cell recording: When monkeys have to remember a location over time, cells in the PFC remain active

89. Working Memory and the Brain
Brain imaging studies with humans: PFC is active when we use working memory
BUT it isn’t the only area that’s active!
Other areas in the frontal lobe
Areas in the parietal lobe
Areas in the cerebellum
Activity occurs in many areas simultaneously

90. Working Memory and the Brain