DaeWon Kim

Contents
1. Primary Memory
① Broadbent’s Model
② Waugh and Norman’s Model
③ Atkinson and Shiffrin’s Dual-Store Model

2. The Serial Position Curve and the

Modal Model
3. Problems with the Modal Model
① Continual distractor paradigm
② Ratio rule
③ Changing distractor effect

4. Summary of the Modal Model

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1. Primary Memory
Dividing memory into multiple stores
One store specialized for briefly holding information : primary memory, working memory, short-term memory and short-term store. Computer mataphor of memory
The resultant of two-store conception of

memory :
(1974))

Modal Model (termed by Murdock
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1. Primary Memory

① Broadbent’s Model
Human processor as a series of systems

through which information flows
S-system : a preattentive sensory store, the

forerunner of iconic and echoic memory
P-system : the site of awareness, limited capacity store

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1. Primary Memory

① Broadbent’s Model
Three assumptions of Broadbent’s

view
1) Primary and secondary memory involve

separate memory systems.
2) Primary memory has a limited capacity.
3) Because information fades quickly in primary memory, information is retained only when it is actively rehearsed.
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1. Primary Memory

① Broadbent’s Model
“The Magical Number Seven, Plus or

Minus Two” [George Miller (1956)]
Absolute identification experiment
Hear a set of nine tones that vary only in frequency On each trial, one of these tones is played, then tries to identify it.
The subject is informed whether the response is correct and, if not, what the correct response should have been.
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1. Primary Memory

① Broadbent’s Model

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1. Primary Memory

① Broadbent’s Model
Generally speaking, once the number of

items reaches about eight or nine, subjects become unable to perform the task without errors
When stimuli vary along more than one

dimension, identification is much better.
Ex) 26 letters of the alphabet

A a

Bb Cc Dd Ii

O o ….
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1. Primary Memory

② Waugh and Norman’s Model
• Perceived information first enters primary

•

•
•

•

memory, a limited capacity structure
Some information is lost by displacement, as newly arriving items “bump out” already existing items. Other information might be rehearsed and thus remain in primary memory longer.
Rehearsal also caused the information to be transferred to secondary memory, which has no capacity limitation.
Recall can be based on information in primary 9

1. Primary Memory

③ Atkinson and Shiffrin’s Dual-Store Model

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1. Primary Memory

③ Atkinson and Shiffrin’s Dual-Store Model
• Assumed that transfer began and

continued during the entire time an item was in STS.
• Experiment [ Hebb (1966) ]
• Presented a series of nine-item lists to 40 subjects. • The lists were made up of the digits 1-9, presented in random order, and the task was recall the items in order.
• Most of the lists contained novel orderings, but
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one list was repeated every third trial.

1. Primary Memory

③ Atkinson and Shiffrin’s Dual-Store Model

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2. The Serial Position Curve and the Modal Model
Many experiments that tested

predictions of the modal model concerned the serial position function observable with free recall.
Murdock(1962) reported a free recall

experiment in which he presented lists of items that varied in length.
Lists of 10, 15, and 20 items.

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2. The Serial Position Curve and the Modal Model

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2. The Serial Position Curve and the Modal Model
Recency effect : excellent recall of the

last few items
Due to the dumping of items from STS

Primacy effect : batter recall of the first

few items
Due to the extra rehearsal the first few items

get, which copies them into LTS

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2. The Serial Position Curve and the Modal Model
• A strong prediction of the model is that if

recall is delayed, the primacy effect should remain unaltered but the recency effect should disappear.
• To test this prediction, Glanzer and

Cunitz(1966) presented 15-item lists to subjects. • In the control