1: Brown-Peterson Paradigm
2: Intro to the Working Memory Model
Psychology 355: Cognitive Psychology
Instructor: John Miyamoto
4/23/2015: Lecture 04-4
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Outline
• Mention Friday section & essay quiz
• Duration of information retention in STM
The Brown-Peterson Paradigm
• Retroactive & proactive interference (a cause of forgetting)
• Proactive interference & the Brown-Peterson Paradigm
• Introduction to the Working Memory (WM) Model
♦
Contrast between the STM model & the WM model
♦
Three components of the WM model:
Phonological Loop (PL); Visuospatial Sketch Pad (VSP);
Central Executive (CE)
Lecture probably
ends here
• Evidence that WM has a PL component
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What Causes Forgetting from WM/STM?
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What Causes Forgetting from WM/STM?
• Why is information lost from STM?
How long does information last in STM without active processing?
• Two hypotheses
♦
Decay – representations of information simply "fall apart."
♦
Interference – other information "bumps" information out of STM.
• Brown-Peterson paradigm – an attempt to measure how long
information is retained in STM without active processing.
♦
The Brown-Peterson paradigm will be discussed on the next slide.
• General Conclusion: Without active processing, all information
is lost after 15 – 20 seconds.
• What causes the loss of information?
♦
Interference - one very likely cause.
♦
Decay - hard to prove convincingly that decay occurs; maybe it does.
Psych 355, Miyamoto, Spr '15
The Brown-Peterson Paradigm - Example
3
Brown-Peterson Paradigm
• Brown-Peterson paradigm – an attempt to measure how long
information is retained in STM without active processing.
♦
The Brown-Peterson task is this past week’s Coglab.
• Example of the Task:
Remember three letters:
P N R
Count backwards by 3’s
from the given number:
108
Stop counting and report
the letters when the
experimenter tells you to do so.
Psych 355, Miyamoto, Spr '15
Duration of delay is
different, e.g., 5 second,
10 second, 15 seconds,
...., on different trials.
Brown-Peterson Paradigm – Summary of the Task
4
What is the Purpose of the Brown-Peterson Paradigm?
• Brown-Peterson paradigm – an attempt to measure how long
information is retained in STM without active processing.
♦
Remember three letters, e.g., “P N R"
♦
Count backwards by 3's from a given number
♦
Report the letters after a delay
• Goal: Measure decay characteristics of STM.
Assumption 1: While you are
counting backwards, you
cannot rehearse “P N R”.
Assumption 2: Counting
backwards by 3's does not
interfere with retention of
"P N R".
• Counting backwards by 3’s is an example of articulatory suppression.
♦
Later when we discuss working memory, we will say that
counting backwards by 3’s suppresses activity in the phonological loop (PL).
Psych 355, Miyamoto, Spr '15
Results for Brown-Peterson Task – Averaged Results
5
Results for the Brown-Peterson Paradigm
Delay in Seconds
• IMPORTANT FACT: These results are averaged over many trials.
• Superficially, the results support the hypothesis that without active
processing, almost all information is lost after about 15 – 20 seconds.
Psych 355, Miyamoto, Spr '15
Keppel & Underwood: Reanalysis for 3rd & 18th Trial
6
Keppel & Underwood’s Reanalysis of Brown-Peterson Results
Delay in Seconds
Delay in Seconds
Delay in Seconds
• Panel (b): Performance on the 1st trial of Brown-Peterson task.
• Panel (c): Performance on the 3rd trial of Brown-Peterson task.
• Performance at 18 second delay gets worse as subject performs more
memory trials!
Psych 355, Miyamoto, Spr '15
Same Graph – Hypothesis That Proactive Interference Causes Forgetting
7
Keppel & Underwood’s Reanalysis of Brown-Peterson Results
Delay in Seconds
Delay in Seconds
Delay in Seconds
• Why does performance at 18 second delay get worse as subject
performs more memory trials?
• Proactive interference – explained on next slide
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Interference – Definition; Proactive & Retroactive Interference
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Interference – a Cause of Forgetting
• Interference as a cause of forgetting – something you learn
or already know makes it difficult to remember something else.
• Retroactive Interference (RI):
New learning interferes with recall of previous learning.
♦
Example: What did you see when you walked to school 7 days ago?
Everything you have seen since then interferes with access to that memory.
♦
Example: Julie used to go out with Tom and now she goes out with Ted.
Memory of Julie/Ted interferes with memory of Julie/Tom.
• Proactive Interference (PI):
Old learning interferes with recall of new learning.
♦
Example: If you already play tennis, it is harder to learn to play
badminton than if you already play basketball (not tennis).
♦
Example: It is hard to remember where I parked my car today
because I have many memories of parking my car in various places.
Psych 355, Miyamoto, Spr '15
Experimental Design for Wicken’s Exp Showing Release from PI
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Forgetting in Brown-Peterson Paradigm Is Due in Part to PI
Simplified Version of Figure 6.6 (p. 157):
Wicken's Study of Influence of Proactive Interference on Brown-Peterson Task
• Wicken’s experiment uses the Brown-Peterson paradigm.
• Experiment has 3 groups, but only two are important.
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Same Slide – Emphasis Rectangle on Fruit Group
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Forgetting in Brown-Peterson Paradigm Is Due in Part to PI
Simplified Version of Figure 6.6 (p. 157):
Wicken's Study of Influence of Proactive Interference on Brown-Peterson Task
• Fruit Group: Every trial requires subject to remember 3 fruit.
• Meat Group: Trials 1 – 3 require remembering meat words.
Trial 4 requires remembering fruit words.
Psych 355, Miyamoto, Spr '15
Results of Wicken’s Experiment
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Forgetting in Brown-Peterson Paradigm Results in Part from PI
Fruit Group
Meat Group
Trial 1: banana, peach, apple
Trial 1: salami, pork, chicken
Trial 2: plum, apricot, lime
Trial 2: bacon, hot doc, beef
Trial 3: melon, lemon, grape
Trial 3: hamburger, turkey, veal
Trial 4: orange, cherry, pineapple
(same category)
Psych 355, Miyamoto, Spr '15
Remember list of fruits
after remembering
other lists of fruits.
Trial 4: orange, cherry, pineapple
(switch category)
Meat Group
Remember list of fruits
after remembering
lists of meats.
% Recalled After 20 s Delay
% Recalled After 20 s Delay
Fruit Group
Same
Same Graph Without the Colored Boxes
12
Forgetting in Brown-Peterson Paradigm Results in Part from PI
Fruit Group
Mean Group
Trial 1: banana, peach, apple
Trial 1: salami, pork, chicken
Trial 2: plum, apricot, lime
Trial 2: bacon, hot doc, beef
Trial 3: melon, lemon, grape
Trial 3: hamburger, turkey, veal
Trial 4: orange, cherry, pineapple
(same category)
Trial 4: orange, cherry, pineapple
(switch category)
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Meat Group
Remember list of fruits
after remembering
lists of meats.
% Recalled After 20 s Delay
% Recalled After 20 s Delay
Fruit Group
Remember list of fruits
after remembering
other lists of fruits.
Same Graph: Define “Release from PI”
13
Forgetting in Brown-Peterson Paradigm Results in Part from PI
• PI: Previous trials with same category (fruit or meat) interferes with STM retention
on current trial.
• Release from PI: Improved STM retention on trial where PI no longer
influences performance.
Psych 355, Miyamoto, Spr '15
Meat Group
Remember list of fruits
after remembering
lists of meats.
% Recalled After 20 s Delay
% Recalled After 20 s Delay
Fruit Group
Remember list of fruits
after remembering
other lists of fruits.
Summary: What Causes Forgetting from WM/STM?
14
Conclusion re Forgetting in the Brown-Peterson Paradigm
Delay in Seconds
Delay in Seconds
Delay in Seconds
• Proactive interference is a major cause of forgetting in the Brown-Peterson
paradigm.
• Brown-Peterson paradigm attempts to measure decay of memory in STM,
but the measurement is confounded with PI (proactive interference).
Psych 355, Miyamoto, Spr '15
Bottom-Line re Forgetting in STM
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Bottom Line re Duration of Storage in WM/STM
• To keep information in WM/STM, you need to actively process the
information.
♦
Phonological rehearsal & forming mental images
♦
Associating contents of WM/STM with information in LTM (thinking)
• Without active processing, information in WM/STM is lost
after 15 – 20 seconds.
♦
In everyday life, information may be lost from WM/STM even more quickly,
e.g., after a few seconds, if some new information interferes
with the contents of WM/STM.
• Why is information lost from WM/STM?
♦
Interference – well-established cause of forgetting from WM/STM.
♦
Decay – no one has yet proved definitively that decay does or does not occur.
Psych 355, Miyamoto, Spr '15
Overview of WM versus STM
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Overview of the STM and WM Models
Short-Term Memory (STM)
Working Memory (WM)
• STM is a single component
• WM has multiple components
• Main theoretical issue:
How much information can
be stored in STM and how
long does it last?
• Main theoretical issues:
How is information represented
in WM? How is information
manipulated in WM?
o
The issue of the duration and quantity
of information storage is still
important for WM, ....
but question of how WM manipulates
information is the central focus of
research.
Psych 355, Miyamoto, Spr '15
Modal Memory Model
17
Modal Model of Memory (circa 1970)
Control
Processes
Input
Sensory
Memory
Short-Term
Memory
Long-Term
Memory
Output:
Speech/Actions
Psych 355, Miyamoto, Spr '15
Diagram for the Baddeley-Hitch Working Memory Model
18
Baddeley-Hitch Working Memory (WM) Model
Think of the diagram to the
right as an expansion &
revision of the standard
STM model.
1. Phonological Loop (PL)
♦
♦
♦
Storage of sounds
Rehearsal
Manipulation of verbal
information
2. Visuospatial Sketch Pad (VSP)
♦
Storage & manipulation of visual images and spatial information.
3. Central Executive (CE)
♦
♦
Directs activity within the PL or VSP.
Coordinates activity between PL, VSP, and LTM.
Psych 355, Miyamoto, Spr '15
Same Slide Without the Emphasis Rectangles - END
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Baddeley-Hitch Working Memory (WM) Model
Think of the diagram to the
right as an expansion &
revision of the standard
STM model.
1. Phonological Loop (PL)
♦
♦
♦
Storage of sounds
Rehearsal
Manipulation of verbal
information
2. Visuospatial Sketch Pad (VSP)
♦
Storage & manipulation of visual images and spatial information.
3. Central Executive (CE)
♦
♦
Directs activity within the PL or VSP.
Coordinates activity between PL, VSP, and LTM.
Psych 355, Miyamoto, Spr '15
What Justifies the Hypothesis: PL is Part of WM?
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What Justifies the Hypothesis: PL Is Part of WM?
Summary of Evidence for PL (Phonological Loop)
• Phonological similarity effect: Lists of words that are similar
in sound are harder to remember than lists of words that sound
different, even with a visual presentation of stimuli.
♦
Example 1: Remember the list, D B C T P G
(harder)
♦
Example 2: Remember the list, K F Y L R Q
(easier)
• Word length effect: People are better at remembering lists
of short words than lists of long words.
• Articulatory suppression experiments
• Neuropsychological evidence (later - not in this lecture)
Psych 355, Miyamoto, Spr '15
Demo of the Phonological Similarity Effect
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Demo of Phonological Similarity Effect:
Memory Span for Words
• On each trial, you will see a sequence of words
presented one after the other.
• Your Task: Write down all of the words in the order in which they
were presented.
• For example, if you see
ORANGE  LOOSE  GRIP  TUESDAY
Write down: ORANGE, LOOSE, GRIP, TUESDAY.
Note that ORANGE, TUESDAY, GRIP, LOOSE is incorrect.
• On each trial, make a mental note of how hard it was to
do the task.
Psych 355, Miyamoto, Spr '15
Fixation Point
22
Word Span Trial with 5 Words: How Hard Is This?
*
Note to Self: The following slides advance automatically on a timer, i.e., don't advance the slides
manually.
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Next: On Click – Display Stimulus Words on a Timer, 1 Slide per second
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Digit
EASE
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Digit
GONE
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Digit
SING
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Digit
TOP
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Digit
CRISP
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What Were the Words?
• Correct Answer:
EASE, GONE, SING, TOP, CRISP
• Remember how hard was that task.
Next: Repeat task but with different stimulus words.
Psych 355, Miyamoto, Spr '15
Fixation Point
29
Word Span with 5 Words: How Hard is This?
*
Note to Self: The following slides advance automatically on a timer, i.e., don't advance the slides
manually.
Psych 355, Miyamoto, Spr '15
On Click, Display Stimulis on Timer, 1 Slide per Second
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Digit
RAKE
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Digit
FATE
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Digit
TASTE
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Digit
BREAK
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Digit
BAIT
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What Were the Words?
• Correct Answer: RAKE, FATE, TASTE, BREAK, BAIT
• Which word list was harder to remember?
List 1: The words are not similar in sound.
List 2: The words are similar in sound.
List 2 is harder to remember.
This is the phonological
similarity effect.
Psych 355, Miyamoto, Spr '15
Theoretical Analysis of the Phonological Similarity Effect
36
Interpretation of Phonological Similarity Effect
Phonological similarity effect: Memory span is smaller for similar
sounding words than for dissimilar sounding words.
What does this show about working memory?
• Basic assumption of PL: One way that people maintain information
in STM is by rehearsing the sound of words.
• Prediction: Similar-sounding words are more confusable
in a sound-based rehearsal. Therefore memory span should
be smaller for lists of similar-sounding words because
the similarity in sound causes errors.
♦
Prediction is confirmed.
• This evidence supports: (a) PL exists; (b) people use rehearsal to
maintain information in WM/STM.
Psych 355, Miyamoto, Spr '15
Demo of the Word Length Effect
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Thursday, April 23, 2015: The Lecture Ended Here
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