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What is Short-Term Memory?
How can you fit more information into STM?
Is STM different from LTM?
How does STM compare to Working Memory?
Lasts about 18 seconds without rehearsal
(Peterson & Peterson,1959): count backwards by
threes and then remember a set of letters
 Capacity is 7 +/- 2 chunks
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The amount of information in a chunk can vary
 543149290210 (12 chunks)
 543 1492 90210 (3 chunks)
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You can use mnemonics to make very large
chunks
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Primacy Effect – LTM
Recency Effect – STM
Double-dissociation:
 H.M.: loss of LTM with intact STM
 K.F.: loss of STM with intact LTM
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Letters that sound similar (b and v) are more
likely to be confused than letters that look similar
(q and p) (Conrad, 1963)
Bilingual Welsh-English speakers can remember
more digits in English than in Welsh - the names
for numbers are longer in Welsh (Baddeley, 1982)
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Two letters are presented with a brief delay
between them. Time to say whether the letters
are the same is less when they match visually
(Posner & Keele, 1967)
Faster to match A-A or a-a than A-a
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Different view of STM
Emphasizes processing ability
Need to coordinate storage and processing
“Mary and John got into a fight and she refused to
speak to him”
Central
Executive
Phonological
Loop
- makes decisions
- coordinates
rehearsal
Visual
- Spatial
Scratchpad
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Phonological loop
 Phonological similarity effect (Conrad,1964)
 Word length effect (Baddeley et al.,1984)
 Articulatory suppression (Baddeley et al.,1984)
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Visual-Spatial Scratchpad
 Pointing to a yes-no response interferes with
performance on a visual task but not on a verbal task
(Brooks, 1968)
 Neurons in primary visual cortex active in monkeys
during delayed-response task (Super et al., 2001)
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What is the adaptive value of working memory?