Lecture 3 Psyco 350, A1 Fall, 2006

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Lecture 3 Psyco 350, A1Fall, 2006

• N. R. Brown

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Outline

• Aspects of Modal Model
• STM vs LTM Serial Position Curve
• Properties of STM
• Capacity Span Task
• Duration/Forgetting Brown-Peterson Task
• Retrieval Sternberg Task
• Problems w/ Modal Model

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Measuring STM Capacity Digit-Span Task

• Instructions Recall the digits in the order
  presented.

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Measuring STM Capacity Digit-Span Task

• Span Test
• Materials random digits, words, etc
• Task serial recall
• Span Defined list length that produces accurate
  performance on 50 of trials

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Free Recall the Serial Position Curve
Memory Tests
Recall
Recognition
Cued
Uncued
FREE
Serial
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In-Class Digit Span

• List 1 3825
• List 2 94318
• List 3 596382
• List 4 7918546
• List 5 86951372
• List 6 163874952
• List 7 7154856193

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Capacity Span Task

• Digit Span Defined of digits accurately
  recalled 50 of the time
• Standard Span 72 digits
• Modal Model Interpretation (Miller, 1956)
• STM Capacity 7 chunks

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Modal Model w/ 7 Slots 1 chunk/slot
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Chunking Demo

• CDHAOETGN
• C D H
• A O E
• T G N

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Chunking

• Chunking the process of combining information
  so that it takes up as little as possible of the
  limited space in STM
• Klatzky, p. 74
• Chunking ? span
• Why not a limitless STM?
• Chunk chunked chunks?
• Required
• Chunking scheme
• Time to apply scheme

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Extraordinary Digit-Span SF

• Materials
• random digits
• auditory presentation
• 1 digit/s
• Results
• After 45 days of practice span 83

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SF Digit Span
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How did he do it?

• Chunk (and elaborated) groups of digits into
  running times (or historical dates)
• Devised in used retrieval structure to guide
• Parsing of list in to units
• retrieval of items at test

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SF Chunking
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SF Retrieval Structure
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Duration Forgetting in STM

• Brown-Peterson Task
• Initial attempt to measure duration of STM
• Procedure
• hear sub-span target set 3 letters
• count backwards for X s
• recall target
• Manipulation length of retention interval
• Assumption
• Counting task knocks out rehearsal
• Measure of the rate of forgetting

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Brown-Peterson Main Finding

• In the absence of rehearsal, sub-span material is
  forgotten very rapidly from STM
• Initial interpretation information rapidly
  decays from STM
• Note w/ 0-delay, only 80 accuracy.

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A Test of Decay Hypothesis

• Waugh Norman (1965) -- Serial Probe Task
• Method
• auditory, 16 digit list, followed by probe digit
• TASK name the digit that followed the probe
• Manipulation
• location of probed item
• Presentation time 1digit/s vs 4 digits/s
• Decay prediction
• recall 1 digit/s lt 4 digits/s
• Interference prediction
• recall 1 digit/s 4 digits/s

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Waugh Norman (1965)

• Results
• Recall ? w/ of intervening items
• consistent w/ both decay interference
• Recall (more or less) unaffected by presentation
  rate
• Consistent only w/ interference

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Evidence for PI in Brown-Peterson Task

• Keppel Underwood (1962)
• Competing Predictions
• Decay prediction Does delay affect recall? NO
• Interference prediction Performance decline
  across trials? YES
• Conclusion
• Interference causes forgetting in STM

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STM Retrieval 3 Possiblities

• Issue
• How do we access information in STM?
• Is Item X in STM?
• Three possibilities
• Parallel simultaneous access to all items.
• Serial consider 1 item at a time.

Retrieval Models
Parallel
Serial
Self- Terminating
Exhaustive
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STM Retrieval 3 Possiblities

• Three possibilities
• Parallel simulators access to all items.
• Serial consider 1 item at a time.
• Self-terminating
• Stop when
• target content
• Exhaustive
• Check each item on list

Retrieval Models
Parallel
Serial
Self- Terminating
Exhaustive
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Selecting between Retrieval Model The Sternberg
Task

• Task
• Materials
• Memory Set N letters
• Probe target letter
• Question Is probe in memory set?
• Manipulations
• Set Size 1 to 6 letters
• Probe Type
• positive (in memory set)
• negative (not it set)

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Sternberg Task Method
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Competing Retrieval Model Predictions
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Why Serial Models Make Different
PredictionsAdditive Factors Logic (Radvansky,
pp. 58-60)
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Sternberg Task Results

• RT ? w/ set size
• Implication serial
• Negative Positive
• Implication exhaustive

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Sternbergs Model