Cognitive Psychology and its Applications (XM_40010)
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Book summary: Cognitive Psychology - Goldstein and Van Hooff (2nd ed., 2021)
Chapter 5: Short-Term and Working Memory
Memory, like attention, comes in many forms. Two definitions:
● Memory is the process involved in retaining, retrieving and using information about
stimuli, images, events, ideas and skills after the original information is no longer
present.
● Memory is active any time some past experience has an effect on the way you think or
behave now or in the future (Joordens, 2011).
From these definitions, it is clear that memory has to do with the past affecting the present and,
possibly, the future. But while these definitions are correct, we need to consider the various
ways in which the past can affect the present to really understand what memory is.
5 types of memory
● The brief persistence of an image is one of the things that makes it possible to perceive
movies, is called sensory memory.
● Information that stays in our memory for brief periods, about 10 to 15 seconds if we don’t
repeat it over and over is short-term memory or working memory.
● Long-term memory is responsible for storing information for long periods of time—which
can extend from minutes to a lifetime.
○ Long-term memories of experiences from the past, like the picnic, are episodic
memories.
○ The ability to ride a bicycle, or do any of the other things that involve muscle
coordination, is a type of long-term memory called procedural memory.
○ Another type of long-term memory is semantic memory—memories of facts such
as an address or a birthday or the names of different objects.
5.1
The Modal Model of Memory
Models of how the mind works are central to a great deal of research in cognitive psychology.
We can appreciate this by remembering Broadbent’s (1958) filter model of attention, which
introduced the information processing approach and the use of flow charts to cognition. Ten
years after the introduction of Broadbent’s flow chart model, Atkinson and Shiffrin (1968)
launched the modal model of memory. Ten years after the introduction of Broadbent’s flow chart
model, Atkinson and Shiffrin (1968) launched the modal model of memory shown in Figure 5.2.
This model proposed three types of memory:
● Sensory memory is an initial stage that holds all incoming
information for seconds or fractions of a second.
● Short-term memory (STM) holds five to seven items for
about 15 to 20 seconds.
● Long-term memory (LTM) can hold a large amount of
information for years or even decades
The three types of memory listed above, each of which is indicated by a box in the model, are
called the structural features of the model. With respect to current standards, this model is
fairly basic, but it is a useful starting point to illustrate important principles about how different
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,Book summary: Cognitive Psychology - Goldstein and Van Hooff (2nd ed., 2021)
types of memory operate and interact. Indeed, this model has influenced researchers for more
than 50 years and it is one of the most cited models in cognitive psychology (Baddeley, Hitch, &
Allen, 2019). Besides these three types of memory, Atkinson and Shiffrin (1968) also proposed
control processes, which are dynamic processes associated with the structural features that can
be regulated by the person and may differ from one task to another. An example of a control
process that operates on short-term memory is rehearsal—repeating a stimulus over and over,
as you might repeat a telephone number in order to hold it in your mind after looking it up on the
internet. Rehearsal is symbolized by the blue arrow in Figure 5.2. Other examples of control
processes are strategies you might use to help make a stimulus more memorable, such as
relating the digits in a security code to a familiar date in history, and strategies of attention that
help you focus on information that is particularly important or interesting.
To illustrate how the structural features and
control processes operate together, let’s
consider what happens as Rachel looks up
the number for Mario’s Pizza Place on the
internet (Figure 5.3). When she first looks at
the screen, all of the information that enters
her eyes is registered in sensory memory
(Figure 5.3a). Rachel uses the control
process of selective attention to focus on
the number for Mario’s Pizza Place, so the
number enters her short-term memory
(Figure 5.3b), and she uses the control
process of rehearsal to keep it there (Figure
5.3c).
Rachel knows she will want to use the
number again later, so she decides that in
addition to storing the number in her mobile
phone, she is going to memorize the
number so it will also be stored in her mind.
The process she uses to memorize the
number, which involves control processes
we will discuss in Chapter 6, transfers the
number into long-term memory, where it is
stored more permanently (Figure 5.3d). The
process of storing the number in long-term
memory is called encoding. A few days later, when Rachel’s urge for pizza returns, she
remembers the number. This process of remembering information that is stored in long-term
memory is called retrieval (Figure 5.3e).
One thing that becomes apparent from our example is that the components of memory do not
act in isolation. Thus, the phone number is first stored in Rachel’s STM, but because information
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,Book summary: Cognitive Psychology - Goldstein and Van Hooff (2nd ed., 2021)
is easily lost from STM Rachel transfers the phone number into LTM (green arrow), where it is
held until she needs it later. When she then remembers the phone number later, it is returned to
STM (black arrow), and Rachel becomes again aware of the phone number. We will now
consider each component of the model, beginning with sensory memory.
5.2
Sensory memory is the retention, for brief periods of time, of the effects of sensory stimulation.
We can demonstrate this brief retention for the effects of visual stimulation with two familiar
examples: the trail left by a moving sparkler and the experience of seeing a film.
The Sparkler’s Trail and the Projector’s Shutter
It is dark out on New Year’s Eve, and you put a match to the tip of a sparkler. As sparks begin
radiating from the tip, you sweep the sparkler through the air, creating a trail of light (Figure 5.4).
Although it appears that this trail is created by light left by the sparkler as you wave it through
the air, there is, in fact, no light along this trail. The lighted trail is a creation of your mind, which
retains a perception of the sparkler’s light for a fraction of a second. This retention of the
perception of light in your mind is called the persistence of vision.
Persistence of vision is the continued perception of a visual stimulus even after it is no longer
present. This persistence lasts for only a fraction of a second, so it isn’t obvious in everyday
experience when objects are present for long periods. However, the persistence of vision effect
is noticeable for brief stimuli, like the moving sparkler or rapidly flashed pictures in a movie
theatre.
While you are watching a movie, you may see actions moving smoothly across the screen, but
what is actually projected, for traditional films at least, is quite different. First, a single film frame
is positioned in front of the projector lens, and when the projector’s shutter opens and closes,
the image on the film frame flashes onto the screen. When the shutter is closed, the film moves
on to the next frame and during that time the screen is dark. When the next frame has arrived in
front of the lens, the shutter opens and closes again, flashing the next image onto the screen.
This process is repeated rapidly, 24 times per second, with 24 still images flashed on the screen
every second and each image followed by a brief period of darkness. A person viewing the film
doesn’t see the dark intervals between the images because the persistence of vision fills in the
darkness by retaining the image of the previous frame.
Sperling’s Experiment: Measuring the Capacity and Duration of the Sensory Memory Store
The persistence of vision effect has been known since the early days of psychology (Boring,
1942). To extend on this, Sperling (1960) wondered how much information people can take in
from briefly presented stimuli. He determined this in a famous experiment in which he flashed
an array of letters, like the one in Figure 5.5a, on the screen for 50 milliseconds (50/1000
second) and asked his participants to report as many of the letters as possible. This part of the
experiment used the whole report method; that is, participants were asked to report as many
letters as possible from the entire 12-letter display. Given this task, they were able to report an
average of 4.5 out of the 12 letters.
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, Book summary: Cognitive Psychology - Goldstein and Van Hooff (2nd ed., 2021)
At this point Sperling could have concluded that because the exposure was brief, participants
saw only four or five of the 12 letters. However, some of the participants in his experiment
reported that they had seen all of the letters, but that their perception had faded rapidly as and
when they were reporting the letters. That is, by the time they had reported four or five letters,
they could no longer see or remember the other letters. Perhaps you recognize this feeling as
when you are briefly aware of your last night’s dream but seem to forget it at the moment you try
to write it down or tell someone else about it.
Sperling reasoned that if participants couldn’t report the 12-letter display because of fading,
perhaps they would do better if they were told to just report the letters in a single four-letter row.
To test this idea, he devised the partial report method. Participants saw the 12-letter display
for 50 ms, as before, but immediately after it was flashed, they heard a tone that told them
which row of the matrix to report. A high-pitched tone indicated the top row; a medium-pitch
indicated the middle row; and a low-pitch indicated the bottom row (Figure 5.5b).
Importantly, because the tones were presented immediately after the letters were turned off, the
participants’ attention was directed not to the actual letters, since they were no longer present.
Instead, their attention could only be directed to whatever trace remained in the participant’s
mind after the letters were turned off. When the participants focused their attention on one of the
rows in their mind, they correctly reported an average of about 3.3 of the four letters (82 per
cent) in that row. Because this occurred no matter which row they were reporting, Sperling
concluded that immediately after the 12-letter display was presented, participants had access to
an average of 82 per cent of all of the letters but were not able to report all of them (when asked
to do so in the whole report method) because they rapidly faded as the initial letters were being
reported.
To determine the time course of this fading, Sperling devised an additional experiment using a
delayed partial report method. In this method, letters were flashed on and off like before but
the cue tone was presented after a short delay (Figure 5.5c). The result of the delayed partial
report experiments was that when the cue tones were delayed for one second after the flash,
participants were able to report only slightly more than one letter in a row. Figure 5.6 plots this
result, showing the percentage of letters available to the
participants from the entire display as a function of time
following presentation of the display. This graph
indicates that immediately after a stimulus is presented,
all or most of the letters presented are available for
perception (82 per cent). This is sensory memory. Then,
over the next second, sensory memory fades quickly.
That is, after 0.1 seconds only about 60 per cent of the
letters displayed were available for recall and after 0.3
seconds this had dropped to 50 per cent.
Sperling concluded from these results that a short-lived sensory memory registers all or most of
the information that hits our visual receptors, but that this information decays within less than a
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