Chapter 4 Short-Term and Working Memory Flashcards
(33 cards)
What Is Memory?
● Memory: processes involved in
retaining, retrieving, and using
information about stimuli, images,
events, ideas, and skills after the
original information is no longer
present
● Aka mental time travel
Working memory
● The brief, immediate memory for material you are currently
processing
● Also coordinates your ongoing mental activities.
Short-term memory
● The “old” terminology for what we now refer to as working memory.
Long-term memory
● The large-capacity memory that contains our memory for experiences
and information that we accumulate over a lifetime.
Extract from Clive Wearing’s diary in 1990, where he records the moment he woke up over and over again
● At the beginning of his illness, Clive would sometimes be
confounded at the bizarre things he experienced. Deborah [his wife]
wrote of how, coming in one day, she saw him holding something in
the palm of one hand, and repeatedly covering and uncovering it
with the other hand as if he were a magician practicing a
disappearing trick. He was holding a chocolate. He could feel the
chocolate unmoving in his left palm, and yet every time he lifted his
hand he told me it revealed a brand new chocolate.
“Look!” he said. “It’s new!” He couldn’t take his eyes off it.
“It’s the same chocolate,” I said gently.
“No . . . look! It’s changed. It wasn’t like that before . . .” He
covered and uncovered the chocolate every couple of seconds,
lifting and looking.
“Look! It’s different again! How do they do it?”
● ~ New Yorker: Oliver Sacks
Clive Wearing
● English musician, conductor, tenor
● Viral encephalitis that afflicted his central nervous system (parts of his
temporal lobe)
● Functioning STM (only what happened during the last 60-120 s), but unable
to form new memories
○ Suffering from both anterograde and retrograde amnesia
● spends constantly ‘waking up’ every 60 seconds, re-launching’ his
consciousness once the time span of his short term memory elapses
moment-to-moment consciousness
● Procedural memory intact
Atkinson and Schiffrin (1968): Modal Model of Memory
● Atkinson and Shiffrin (1968)
● Computer as a model for human
cognition
● Memory is an integrated system that
processes information
○ Acquire, store, and retrieve information
○ Components of memory do not act in
isolation
● Memory has a limited capacity
○ Limited space
○ Limited resources
○ Limited time
● Control processes: active
processes that can be
controlled by the person
○ Rehearsal
○ Strategies used to make a
stimulus more memorable
(remember chapter on
“Becoming a better
learning”)
○ Strategies of attention
Modal Model of Memory: Sensory Memory
● Holds large amount of information for a short period of time
○ Collects information
○ Holds information for initial processing
○ Fills in in the blank
● Measuring the capacity and duration of sensory memory (Sperling, 1960)
○ Array of letters flashed quickly on a screen
○ Participants asked to report as many as possible
Modal Model of Memory: Sensory Memory
● Whole report: participants asked to report as many as could be seen
○ Average of 4.5 out of 12 letters (37.5%)
● Partial report: participants heard tone (in our case seeing an arrow)
that told them which row of letters to report
○ Average of 3.3 out of 4 letters (82.5%)
○ Participants could report any of the rows
● Delayed partial report: presentation of tone (cue, in our case arrow)
delayed for a fraction of a second after the letters were extinguished
○ Performance decreases rapidly
Sensory Memory
● Stores huge amount of information, however the information is retained for
only fractions of a second
Short-Term Memory
● Stores small amounts of information for a brief duration
● Includes both new information received from the sensory stores and information recalled from long-term memory
The Magical Number
● George Miller (1956)
● “The Magical Number Seven, Plus or
Minus Two”
○ STM Capacity is 7 +/- 2!
○ Suggested that people can remember
about 7±2 items
○ Each memory unit is a chunk
○ We can engage in internal mental
processes in order to convert stimuli
into a manageable number of chunks
Modal Model of Memory: Short-Term Memory
● Capacity of short-term memory
○Digit span: how many digits a person can
remember
■Typical result: 5-9 items
How is it then possible to hold in memory more information than 4 items?
Chunking!
● The capacity of the working memory may be increased by “chunking.”
● Chunk is a collection of elements strongly associated with one another
but weakly associated with elements in other chunks
Modal Model of Memory: Short-Term Memory
●The Brown/Peterson & Peterson Technique
Technique involves:
1. Presentation of three items
2. Count backwards by threes for specified period of time
3. Recall originally presented items
● Counting backwards prevents rehearsal
● The silent, mental repetition of the items
● Revealed that material is held in memory for less
than a minute
Brown-Peterson task
Results
●After three seconds of counting, participants
performed at 80%
●After 18 seconds of counting, participants
performed at 10%
● Short-term memory, when rehearsal is
prevented, is about 15-20 seconds
RESULTS OF Peterson and Peterson’s (1959) duration of STM experiment
(a) The result originally presented by Peterson and Peterson, showing a large drop in memory for letters with a delay of 18 seconds between presentation and test.
These data are based on the average performance over many trials.
(b) Analysis of Peterson and Peterson’s results by Keppel and Underwood, showing little decrease in performance if only the first trial is included.
Explaining Brown Peterson Task: Serial
Position Effect
● Tendency to recall best the first and last items in a list
● Consists of both a primacy and a recency effec
Why does this occur? Serial position effect
● Primacy effect:
● Ability to accurately recall first
items presented
● Occurs because items rehearsed
more and stored in LTM
● Recency effect
● Ability to accurately recall last
items/items at the end of a list
presented
● Occurs because items are still
available/present in WM
● When there is a delay in recall of
last items, however, recency effect
disappears
factors affecting working memory capacity
● Factors Affecting Working Memory’s Capacity
1. Chunking
2. Pronunciation Time
3. Semantic Similarity
Pronunciation Time
● The longer it takes to
pronounce the items, the lower
our capacity
● Results have been found with:
● Short names vs. long names
● Numbers in different
languages
● This effect is due to the
acoustic properties of stimuli
● The “sound” of the stimuli
Semantics refers to the meaning of the
words/items
● Wickens and colleagues (1976)
○ Proactive interference (PI)
■ disruptive effect of prior learning on
ability to encode new information
○ However, switching the category/type
of new information can result in a
release from proactive interference
● Wickens and colleagues (1976)
○ Brown/Peterson & Peterson task
○ Varied semantic similarity on Trial 4
○ The semantic similarity of the items in Trial 4
influenced the ability to recall those items
■ Less similar items were more easily
recalled
Results of Wickens et al.’s (1976) proactive inhibition experiment.
(a) Fruit group, showing reduced
performance on trials 2, 3, and 4 caused at least partially by proactive interference (indicated by dark points).
(b) Professions group, showing reduced performance on trials 2 and 3 but improved performance on trial 4. The increase in performance on trial 4 represents a release from proactive
interference caused by the change of category from professions to fruits.
more details about Wickens et al.’ study
Wickens and colleagues (1976) conducted a study that demonstrated the phenomenon
of proactive interference and how it can be released under certain conditions. In their
experiment, participants were asked to memorize lists of words belonging to the same
semantic category (e.g., fruits). With each successive list, participants’ recall
performance worsened, indicating that earlier learned material was interfering with the learning of new material.
However, when the category of words was switched (e.g., from fruits to professions),
there was a significant improvement in recall. This phenomenon is known as release from proactive interference, suggesting that proactive interference can be reduced when there is a shift in the nature of the information being processed, such as a change in category.
This study highlights the role of semantic categories in memory interference and
demonstrates that the brain is better able to retain new information when it is
sufficiently distinct from previously learned material.
