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Chapter 5

Chapter 5 notes

Course Code
Gabriela Ilie

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PSYB57- Chapter 5- Memory Structures
The Echo
Sensory memory for auditory material
Moray, Bates and Barnett gave participants a four eared listening task, similar to
the dichotic listening task. Strings of random letters were presented in each of the 4
channels. In one condition participants were asked to recall all the letters that were
presented (whole report condition) and in the other condition, they were asked to
partially report the letters from one of the channels, indicated by a light
corresponding to a channel. Like Sperling, they found that participants were able to
recall more letters in the partial report condition, suggesting that echo, like icon,
stores information only briefly
Crowder said that echoic memory has a larger capacity than iconic memory
Suffix effect- you are presented with a list of digits or letters auditorily and if there
is an auditory recall cue such as a spoken word or specific item, recall of the last few
items on the list is hindered
The recall cue, called the suffix, functions as an auditory mask because when the
suffix is simply a beep or a tone or a visual stimulus, there is usually not much
effect. Nor is there any effect if the items on the list are presented visually
The more auditory similarity there is between the suffix and the items on the list,
the greater the suffix effect
Sensory memories are modality specific: visual sensory memory contains visual info,
Sensory memories capacities appear larger for visual than auditory sensory memory,
but the length of time info can be stored is longer in the auditory store
Information that can be stored appears relatively unprocessed, meaning that most
has to do with physical aspects of the stimuli rather than with meaningful ones
Short term memory
Free recall experiment- people are presented with a list of words and are just asked
to recall all the words. Results show that people recall more words at either the
beginning or the end of the list than they do words in the middle. This is known as
the serial position effect

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The improved recall of words at the beginning of the list is called the primacy
effect ; that at the end of the list is the recency effect
Rehearsal or repetition of items helps info enter long term storage
If the experimenter reads the list rapidly to prevent rehearsal of items, the primacy
effect disappears but the recency effect remains
The recency effect d thought to result from participants’ using either sensory
memory or STM.
If the experimenter prevents the participant from reporting words right away, by
having her first perform an unrelated task, the recency effect (but not the primacy
effect) disappears
Incoming info. First passes through this rapidly decaying storage system (sensory
memory). If attended to, this info next moves into STM. To be held for longer than a
min or 2 the info must be transferred to LTM
STM lasts typically for a min or 2, if rehearsal is not prevented
Short term store- capacity
7 seems to be the max number of independent units we can hold in STM. We call this
the capacity of STM
You can remember a long string of letters by chunking the info into sets
Chunking depends on knowledge; Miller regarded chunking as a fundamental
process of memory- a powerful means of increasing the amount of info we can
process at any given time
Short term store- Coding
Coding refers to the way in which info is mentally represented- the form in which
info is held
Study by Conrad- he presented a list of consonants for later recall. Although the
letters were presented visually, participants were likely to make errors that were
similar in sound to the original stimuli. For ex, if the letter P was presented, they
would recall another letter that sounded like P (like G or C) than to report a letter
that looked like P. They were forming a mental representation of the stimuli that
involved the acoustic rather than the visual properties

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Baddeley confirmed this finding by using words instead of letters
Short term store- Retention duration and forgetting
If not rehearsed, info is lost from STM in 20 sec. that length of time is called the
retention duration of the memory
Brown- Peterson task- they presented participants with a 3 letter trigram (ex. BKG)
and 3 #s (347) and asked them to count backwards from the # by threes. The purpose
of the counting task was to prevent the participant from rehearsing the letters. The
length of time a participant must count varies. If asked to count backward for only 3
seconds, 80% of participants can recall the trigram. If asked to count for 18 seconds,
only 7% can recall.
They concluded that the memory trace- the encoded mental representation of the
to0be-remebered info that is not rehearsed- decays, or breaks apart, within about
20 sec
Interference- some info can displace other info making the former hard to retrieve
In the Brown- Peterson task, the counting task actually interferes with the STM of
the trigram, as well as prevent participants from rehearsing
Other evidence suggests that interference, not decay accounts for forgetting in STM
Proactive interference- material learned first can disrupt retention of
subsequently learned material. Keppel and Underwood said that forgetting in the
Brown- Peterson task doesnt happen until after a few trials. They said that
overtime, proactive interference builds up
Others argued that if STM, like LTM is subject to proactive interference, then STM
like LTM should also be subject to a related phenomenon called release from
proactive interference
So if you learn a # of pieces of similar info, after a while any new learning becomes
more difficult because the old learning interferes with the retention of new (because
of proactive interference)
The greater the similarity among the pieces of info the greater the interference. This
implies that if a new and distinct piece of info were presented, the degree of
interference would be sharply reduced
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