Cognition – 2/e
Dr. Daniel B. Willingham
Chapter 4:
Sensory & Primary Memory
PowerPoint by Glenn E. Meyer, Trinity University
©2004 Prentice Hall
What is Sensory Memory?
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Early Span of Apprehension Studies
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Sperling’s Partial Report Procedure
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Characteristics of Iconic Memory
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What is Iconic Memory For?
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Echoic Memory
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Early Span of Apprehension Studies
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Span of apprehension:
The amount of information that can enter consciousness at
once.
Early Studies:
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Jevons (1871) – counted beans thrown into a small box. Accuracy
was usually perfect at < 4 beans. 95% at 5 beans. Declined above
that as seen in Fig. 4.1. Using 50% criteria, span of apprehension =
9 beans.
Point made by others that subjects could perceive seeing more than
they could report – Glanville and Dallenbach (1929), Woodworth
(1938)
Lead to Sperling’s work
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Sperling’s Partial Report Procedure
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Developed by Sperling (1960) to examine iconic memory
Participants are shown an array of stimuli (usually letters or numbers) very
briefly. Array can contain 4 to 12 items
They are given a cue (visual or auditory) telling them which subset of the
stimuli to report. This is the Partial Report
The cue delay can vary. Since subjects don’t know which items will be cued,
the percent of the subset reported estimates the percent of items available at a
given time after the cue
This method showed that participants perceive most of the stimuli in a
complex array.
Sperling argued the items held in a large capacity iconic memory
A Q 6 8
Typical Sperling Display
T P W 1
2 Y 6 L
Immediate Report – 4 correct – 33%
of array
Immediate Cue of Row -3 correct –
implying 75% of array available
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Characteristics of Iconic Memory
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Large Capacity
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Up to 17 letters, 2 seconds
Depends on stimulus conditions – dark fields enhance, bright pre
and post fields cut down duration
Spontaneous Decay and Potential to be Erased
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Loss of info due to spontaneous decay
Decay begins at onset of target, not offset (DiLollo, 1980) as seen in Fig 4.3.
Information can also be lost due to a following stimulus acting as a mask
(Breitmeyer & Ganz, 1976; Turvey, 1973)
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Brief Duration – 500 milliseconds to 1 second typically
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Representation – Initially thought to be a physical representation as
selection of items on physical characteristics (ex. color) possible but not
on semantic characteristics (digits vs. letters) (Sperling , 1960). This
has been challenged and there may be some semantic info in iconic
memory
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What is Iconic Memory For?
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Haber (1983) argues against Iconic Memory as a
useful concept
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Icon supposed to maintain stable image of the world through eye
movements – Not supported by Irwin et al. (1983) as seen in Fig.
4.4 where iconic information not useful in integrating across
saccades (rapid eye movements)
Haber suggests the only thing the icon would be useful for is trying
to read at night during a thunder storm
Loftus (1983) argues that the iconic experimental
paradigm is a useful tool and the real world argument of
Haber is not appropriate as in many sciences lab situations
don’t mirror the real world but give us insights
Iconic research has been robust and an important tool for
examining the visual system and is still on-going.
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Echoic Memory
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Auditory variety of sensory memory.
Experimental Evidence:
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Massaro (1970) – identification of a short tone was
masked by a random auditory stimulus. If the tone was
delayed identification improved. Echoic memory
duration was estimated to be 250 milliseconds
Efron (1970a) – estimated echoic duration of 30 ms tone
to be 130 ms
Neural Representation:
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Lu, et al. (1992) – Echoic memory is the lifetime of
neural activity in auditory sensory cortex by measuring
activity with magnetoencephalography as seen in Box 42
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What are the Characteristics of
Primary Memory?
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Impetus to Study Primary Memory
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How Forgetting Occurs
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Representation
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Capacity
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Impetus to Study Primary Memory
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Broadbent (1958) likened mind to an electronic information processing system.
Flow of information was:
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Miller (1956)
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Large capacity sensory memory
Filter
Primary memory – associated with consciousness and fades if not rehearsed
Reviewed literature suggesting what became known as the magic number 7+ 2 – the
limited capacity of primary memory
Suggested the process of chunking : A unit of knowledge that can be decomposed
into smaller units of knowledge. Similarly, smaller units of knowledge can be
combined (“chunked”) into a single unit of knowledge (e.g., chunking the numbers
1, 9, 0, and 0 into a unit to represent the year 1900). This is a way to get around the
primary memory limit above
Brown (1958) and Peterson & Peterson (1959) demonstrated the difference
between primary and secondary memory by suggesting the forgetting
processes of primary memory was decay and not interference.
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Had subjects learn a trigram (ex. TPW) and then count backwards by threes from a
large number
Plotted percent correct recall as time of counting varied
As seen in Fig 4.5 ,recall was very low by 18 seconds, suggesting decay of primary
memory
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How Forgetting Occurs
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Two types of interference also contribute to forgetting:
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Proactive Interference - Earlier learning interferes with new learning.
Retroactive Interference - Later learning interferes with earlier learning
Keppel and Underwood (1962) demonstrated in the Brown-Peterson &
Peterson task that repeated trials produced more forgetting of the target –
suggesting a role for proactive interference in primary memory
Reitman (1971) – varied type of activity during the delay period in BrownP&P and found matching types of activity to the target type increased
forgetting, demonstrated the role of retroactive interference in primary
memory
Decay Again
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Baddeley and Scott (1971) demonstrated decay on one trial as seen in Fig
4.8 when there is no chance for proactive interference
Researchers suggest decay necessary or interference would overwhelm the
system. Altmann and Gray (2002) demonstrate such in a rule based
categorization task as seen in Fig. 4.9.
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Representation
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Material in Primary Memory Can Be Coded:
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Visuospatially
Acoustically
Semantically
Perhaps also with a tactile representation
Early Research Suggested Primary Memory Was Solely
Acoustic
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Baddeley (1966) found primary tasks hurt if all items sounded
similar (ex. Mad, man, mat, cap, cad, can,cat)
Conrad (1964) demonstrated acoustic confusion errors in primary
memory:
Errors in primary memory based on sound (e.g., thinking one
heard g instead of d). The presence of such errors indicates that
participants use an acoustic code in primary memory on the task .
For example, they might mistake an “M” for “N” when they hear
it.
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Representation - Continued
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Spatial Information in Primary Memory:
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Baddeley, et al. (1975) reports a secondary tracking task interfered
with subjects remembering a visuospatial instruction set for
imagining a matrix. The secondary task did not interfere with a
nonvisual task
Semantic Information in Primary Memory
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Demonstrated by Release from Proactive Interference
Refers to the effect in which proactive interference dissipates if one
changes the stimulus materials.
Experimental test
Uses Brown-Peterson paradigm with repeated trials. Target words are
used instead of trigrams
There are up to 5 trials with the first trials semantically related, the last
item wasn’t (for example: trial 1 = apple, 2 = orange, 3 = pear, 4 = doctor)
Recall declined over the first 3 trials (Proactive Interference) but the recall
of the last item was significantly increased ( release from PI), indicating
that semantic context was present in primary memory
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Capacity
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Miller (1956) - magic number 7 + 2, also known as digit
span at turn of the century (1900’s)
Capacity of Different Primary Memory codes
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Acoustic code best described as the number of items you can say in
two seconds as found in the word length effect (Baddeley, et al.
1975). Subjects can remember more short than long words.
Semantic code best described by chunks - Simon (1974) - as seen in
Fig. 4.11, subjects can remember more total words if organized into
semantically related chunks - but chunk number in primary
member seems fairly constant
Visuospatial code about 4 objects (Luck and Vogel, 1997; Lee and
Chun, 2001). For example, which is easier to remember? The
object on the left or its 9 component lines on the right?
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How does Primary Memory Work?
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Models of Primary Memory
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Working Memory
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Primary Memory Contributions to
Secondary Memory Tasks
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Working Memory as a Workspace
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Models of Primary Memory
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Modal Memory (Murdock, 1974) based on sensory, shortterm and long-term systems as seen in Fig. 4.13.
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Attended info from Sensory Memory moves into Short Term
Memory
Information remains in Short Term Memory for 30 seconds unless
rehearsed
More processing in STM leads to information being sent to Long
Term Memory
Information can also enter Short Term Memory from Long Term
Memory
Information can be forgotten from Sensory Memory and Short
Term Memory through decay. Long Term Memory loss due to
interference
Model now seen as inadequate for several reasons.
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Working Memory - Baddeley, 1986
Phonological
Loop
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Central
Executive
Visuospatial
Sketchpad
Secondary Memory & Sensory Memory - slaves to Central Executive, not
shown
Phonological Loop: The part of the working memory model in which auditory
information is stored. It has two components:
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Phonological store: The part of the phonological loop that can store about 2 s of
auditory information.
Articulatory Control Processes: The process that allows one to enter information
into the phonological store; it is literally the process of talking to yourself.
Evidence for the Phonological loop comes from Articulatory Suppression studies:
Refers to demanding that participants keep the articulatory system busy with
nonsense during encoding (usually by saying “thethethethe” or something similar),
thereby ensuring that they will not code stimuli in the phonological store.
Speech can gain access to the Articulatory Store through obligatory access which
refers to the fact that verbal information (but not all sounds) appear to be entered
into the phonological loop by its mere presence, even if the participant does not
want it to enter.
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Working Memory - Continued
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Visuospatial sketchpad is the visual analog of the phonological loop.
Conceived as a buffer on which visual or spatial information can be
manipulated and briefly stored. It is thought to be similar to visual imagery.
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Central Executive - Baddeley suggests Norman and Shallice’s (1986) model of
attention is a good starting place for the central executive. The model is seen in
Figure 4.15. Model has two important selection processes:
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Spatial Information (where things are) and visual information (what they look like)
are separable according to Baddeley (as seen in Baddeley and Lieberman (1980)
Contention Scheduling:The process by which the relative importance of two tasks is
weighed if executing the tasks simultaneously is not possible.
Supervisory Attentional System:The SAS selects action when a task must be
planned in advance; when automatic processes appear to be having negative or
unexpected consequences; when a new, unfamiliar action must be taken or ; when
or a strong habit must be suppressed.
Model is supported by:
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Baddeley (1966) - subjects unable to produce random letter strings as speed
increased as the SAS couldn’t keep up
Neural imaging - MacDonald et al. (2000) using modified Stroop task found
evidence for control processes in the dorsolateral frontal cortex and monitoring in
the anterior cingulate cortex
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Primary Memory Contributions to Secondary
Memory Tasks
% Recall
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Primacy
Serial Position Effect
Recency
Serial position:
The position of a word (or other stimulus)
in a list, usually of to-be-remembered
stimuli.
First
Last
Position in the List
• Experimental Evidence
Glanzer and Cunitz (1966)
Delay of recall weakens Recency as
primary memory had supposedly faded
as seen in Fig. 4.17
Increasing time between items enhances
primacy as more time given for item
rehearsal and entry into secondary
memory
Recency effect: Refers to the fact that
memory for items at the end of a list is
quite good in a task demanding immediate
free recall. Thought to be due to retrieval
from Primary Memory.
Primacy Effect: Refers to the fact that
memory for items at the beginning of a list
is good (relative to that for items in the
middle of the list). Thought to be due to
first words being more likely to enter
secondary memory.
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Working Memory as a Workspace
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Phonological Loop: Important in acquiring new
vocabulary (Baddeley, Gathercole, & Papagno, 1998): In
children digit span (measure of phonological loop)
positively correlates with vocabulary size
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Daneman & Carpenter (1980): Working memory span is
good predictor of reading comprehension in college
students
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Working memory span is good predictor of performance
on reasoning tasks and may be seen in age related deficits
(Salthouse, 1992)
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Neurological Findings of Interest
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Counting and Subitizing:
The latter is process for recognizing the number of items in a display
in an effortless manner. It usually can be done for a set of 1 to 4 items.
Piazza, et al. (2002) found that counting and subitizing had similar
patterns of cortical activation (see Box 4-1) using PET scans.
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Brain Components of the Phonological Store:
Paulseu, et al. (1993) attempted to localized the two components of the
phonological loop – 1) phonological store and 2) the articulatory
control process. As seen in Box 4-3 some patients indicate separation of
processes. Ventrolateral prefrontal cortex (Broca’s area) critical for the
maintenance of phonological material
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Brain Basis of the Central Executive:
Dorsolateral prefrontal cortex – manipulation of phonological material
 Petrides (1989)
 D’Esposito, et al. (1999, 2000) – concludes ventrolateral prefrontal
cortex contributes to maintenance, dorsolateral to manipulation.
Not clear if the latter contributes to maintenance.
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