Memory: Unit III Short-term Memory, a Presentation from Universidad Europea

Memory and Learning Processes

ue
2024/2025
David Prada CrespoCONTENTS

1. Short-term memory (STM)
2. Capacity
3. Duration
4. Towards a complex STM: Working memory
5. The phonological loop
6. The visuo-spatial sketchpad
7. The Central Executive
   Universidad EuropeaShort-term memory
   Universidad EuropeaSHORT-TERM MEMORY
   Short Term Memory
   (STM): A term applied
   to the retention of small
   amounts of material
   (verbal, visual, spatial ... )
   over periods of a few
   seconds (Baddeley, et.
   al. 2009).
   Capacity
   STM
   Duration
   Universidad EuropeaSHORT-TERM MEMORY
   Short Term Memory
   (STM): A term applied
   to the retention of small
   amounts of material
   (verbal, visual, spatial ... )
   over periods of a few
   seconds (Baddeley, et.
   al. 2009).
   Capacity
   STM
   Duration

Short-Term Memory Capacity

Measuring Short-Term Memory Capacity

Universidad EuropeaSHORT-TERM MEMORY: CAPACITY
How do we measure its capacity?

Digit Span Task

DIGIT SPAN TASK
Digit span task (Jacobs, 1887): the STM
6815
2794
capacity
>the longest sequence that
35147
41639
can be repeated without error.
625384
537416
3154279
4931527
15329687
81529341
725381974
351384921
8136249217
3829153794
This task requires:
•
Remembering what the items are.
· Remembering the order in which
they are presented.
Universidad EuropeaACTIVITY 2INSTRUCTIONS
Now, you will hear different number sequences.
After hearing every sequence, you must
write it down.
Sequences will be progressively longer.PART 1
Direct sequencesPART 2
Inverse sequencesSpan Dígitos Directo (WMS-III)
Pt
1-7
1
6- 3
5-8-2
2
6-9-4
3
6-4-3-9
7-2-8-6
4-2-7-3-1
4
7-5-8-3-6
5
3-9-2-4-8-7
5-9-1-7-4-2-8
6
4-1-7-9-3-8-6
7
5-8-1-9-2-6-4-7
3-8-2-9-5-1-7-4
8
2-7-5-8-6-2-5-8-4
7-1-3-9-4-2-5-6-8
Puntuación directa (16)
6-1-9-4-7-3Span Dígitos Inverso (WMS-III)
Pt
2- 4
1
5-7
6-2-9
2
4-1-5
3-2-7-9
3
4-9-6-8
1-5-2-8-6
4
6-1-8-4- 3
5
5-3-9-4-1-8
7-2-4-8-5-6
6
8-1-2-9-3-6-5
4-7-3-9-1-2-8
7
9-4-3-7-6-2-5-8
7-2-8-1-9-6-5-3
Puntuación inversa (
14)SHORT-TERM MEMORY: CAPACITY
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> The short-term memory amplitude is the length of the
series that was repeated without making any errors in
either the repeated digits or the order of presentation.
THE MAGICAL NUMBER 7 +/- 2 (Miller, 1956) > Interval:
5-9 elements.
- Our STM allows us to store about 7 elements for a few
seconds.
- Conclussion: STM has a limited capacity.
Universidad EuropeaSHORT-TERM MEMORY: CAPACITY
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> The short-term memory amplitude can be impaired in
some patients suffering from different diseases (e.g.,
depression, dementia, brain damage, etc.).
Giro precentral;corteza
motora primaria (área 4)
Giro poscentral; corteza somatosensorial
¿ primaria (áreas 1, 2 y 3)
Corteza
premotora (área 6)
Corteza
prefontal
Corteza visual primaria (área 17)
Broca's area (left
hemisphere)
Corteza auditiva primaria
Giro temporal (áreas 41 y 42)
superior
Wernicke's area (left
hemisphere)
A.R = articulatory rehearsal
P.S = Phonological store

Patient Attentional Span Examples

Universidad EuropeaSHORT-TERM MEMORY: CAPACITY
E.g., Patient 1 > Attentional spam (ST capacity): ?
Span Dígitos Inverso (WMS-III)
Pt
2- 4
> 2, 4
V
1
5-7
-> 5,7
2
6-2-9
> 6, 2, 7
XX
3-2-7-9
3
4-9-6-8
4
6-1-8-4-3
5
7-2-4-8-5-6
6
8-1-2-9-3-6-5
4-7-3-9-1-2-8
7
9-4-3-7-6-2-5-8
7-2-8-1-9-6-5-3
Puntuación inversa (14)
4-1-5
> 1, 4, 2
1-5-2-8-6
5-3-9-4-1-8SHORT-TERM MEMORY: CAPACITY
E.g., Patient 2 > Attentional spam (ST capacity): ?
Span Dígitos Inverso (WMS-III)
Pt
1
2- 4
-> 2, 4
V
5-7
-> 5,7
2
4-1-5
-> 4, 1, 5
3-2-7-9
> 3, 2, 1, 9
3
4-9-6-8
-> 4, 9, 8, 3
4
6-1-8-4-3
5
7-2-4-8-5-6
6
8-1-2-9-3-6-5
4-7-3-9-1-2-8
7
9-4-3-7-6-2-5-8
7-2-8-1-9-6-5-3
Puntuación inversa (14)
6-2-9
-> 6, 3,9
XXX
X
V
1-5-2-8-6
5-3-9-4-1-8

Letter Sequence Repetition

SHORT-TERM MEMORY: CAPACITY
WHAT HAPPENS IF WE PRESENT LETTERS INSTEAD?
Try to repeat in the same order:
HBIETRTGOLAMLO
Universidad EuropeaSHORT-TERM MEMORY: CAPACITY
WHAT HAPPENS IF WE PRESENT LETTERS INSTEAD?
Try to repeat in the same order:
ROOMTABLELIGHT
Universidad EuropeaSHORT-TERM MEMORY: CAPACITY
WHAT HAPPENS IF WE PRESENT LETTERS INSTEAD?
Try to repeat in the same order:
HBIETRTGOLAMLO
ROOMTABLELIGHT
The second case is much easier because we can create
subgroups or chunks.
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Chunking in Short-Term Memory

SHORT-TERM MEMORY: CHUNKING
Chunking: The process of combining a number of
items into a single chunk.
This technique allows us to improve our STM capacity.
However, the number 7 +/- 2 still works: It is no about
the number of items but the number of chunks.
The process of chunking is usually related to our LONG
TERM MEMORY, showing that STM is linked to LTM.
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Primacy and Recency Effects

SHORT-TERM MEMORY: PRIMACY AND RECENCY
What happens if the STM capacity is exceded?
Try to remember the following list:
Ape, goal, hurricane, plane,
glass, soldier, phoenix, house, carpet,
sunlight, phone, menu, children, journey,
archer, doorbell.
Free recall task: Participants are presented with a sequence of items and
are required to recall in any order they wish.
Universidad EuropeaSHORT-TERM MEMORY: PRIMACY AND RECENCY
100
- Immediate recall
Recency
Primacy
% Correct
0
Presentation order
Seri
The effect of better remembering the first and last items in the list is called the
primacy and recency effects, respectively.
Universidad EuropeaSHORT-TERM MEMORY: PRIMACY AND RECENCY
How can we explain these effects?
Universidad EuropeaSHORT-TERM MEMORY: PRIMACY AND RECENCY
ue
Primacy: It seems to be due to the fact that more attention is
paid to the first elements and they are also more repeated.
> When an item is presented, we try to repeat it until a new one
appears. When this new element appears, we try to retain it, but
at the same time, we try to repeat the previous elements.
> This effect is explained by the greater repetition of the first
elements of the series (Rundus, 1971) and indicates that the first
elements have been transferred to the LTM.
Recency: The last elements of a series are best remembered
because they are still contained in the STM (Waugh and Norman,
1965).
Universidad EuropeaSHORT-TERM MEMORY: PRIMACY AND RECENCY
ue
The results of the serial position curve allowed Waugh and Norman
to propose that in these tasks of free memory, two types of
memory stores are shown.
100
- Immediate recall
Recency
Primacy
% Correct
LTM
STM
0
Presentation order
Universidad EuropeaSHORT-TERM MEMORY: PRIMACY AND RECENCY
What would it happen if we
delayed the recall?
Universidad EuropeaSHORT-TERM MEMORY: PRIMACY AND RECENCY
100
-
Immediate recall
Delayed
Recency
Primacy
% Correct
0
Presentation order
A brief filled delay (for
instance, asking people
to count backwards after
the list presentation) is
sufficient to eliminate
the Recency effect.
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Summary of Short-Term Memory Capacity

SHORT-TERM MEMORY
In summary, related to the capacity of STM:
· It is limited.
· The capacity for adults, on average, varies
between 5 and 9 elements.
· If we use "chunks" it is posible to
memorize 7+/-2 units.
. There are primacy and recency effects.
7 +/- 2 >Magic number!
HBIETRTGOLAMLO
V
ROOMTABLELIGHT
100
- Immediate recall
Recency
% Correct
Primacy
0
Presentation order
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Short-Term Memory Duration

Measuring Short-Term Memory Duration

SHORT-TERM MEMORY
Short Term Memory
(STM): A term applied
to the retention of small
amounts of material
(verbal, visual, spatial ... )
over periods of a few
seconds (Baddeley, et.
al. 2009).
Capacity
STM
Duration
Universidad EuropeaSHORT-TERM MEMORY: DURATION
How do we measure its duration?
Forgetting tasks (Brown and Peterson paradigm,
1959): how long is the information avaliable in our
memory?
Key point-> avoiding strategies
such as the rehearsal.
Short-term
memory
Rehearsal
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Brown-Peterson Paradigm

SHORT-TERM MEMORY: DURATION
Brown-Peterson Paradigm
1. The experiment began as follows. Each participant had to be seated in front
of a black box that had a green and a red light.
2. The experimenter read aloud a trigram of letters consisting of three
consonants such as MHP, followed by a number consisting of three digits as
358.
3. The participant had to count backwards by 3 or 4 from the original number
until a light was turned on inside the black box. That was the moment when
the participant had to remember the trigram of letters. All the participants
individually performed 48 experimental trials.
>
The independent variable was the number of seconds that the
distracting task of counting back from the number indicated by the
experimenter lasted. (3, 6, 9, 12, 15 and 18 seconds of distraction).
Universidad EuropeaSHORT-TERM MEMORY: DURATION
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Peterson and Peterson (1959)
100
% Trigrams Correct
80
80
40
20
0
3
6
9
12
15
18
Interval (seconds)
>Over time, the information stored in short-term memory fades
(Decay theory of immediate memory).
>To prevent this: rehearsal process.
Universidad EuropeaSHORT-TERM MEMORY: DURATION
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. The function of the distracting task is precisely to avoid the
repetition of the material.
· The average duration of the short-term information would be
about 18 seconds.
. Decay is specific from STM. Forgetting in LTM occurs due to
other mechanisms (interference).
. This fits perfectly with the structural memory model. It would
be a proof of the existence of two types of memory, STM and
LTM, with different characteristics.
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