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PSYC 101 Chapter Notes -Long-Term Memory, Iconic Memory, Sensory Memory


Department
Psychology
Course Code
PSYC 101
Professor
Barbara Cox

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PSYC 101 007 CHPT.8 MEMORY
I. Overview of Memory
Like learning, memory can’t be measured directly. Again, we have to indirectly measure it based on performance.
Early Understanding of Memory: Associative Models
Associationism- belief that memory results from mental connections between ideas and concepts
First systematically studied by Herman Ebbinghaus in the late 1800’s
Ebbinghaus memorized strings of nonsense syllables & tried to figure out the basic rules of memory
Used himself as the only subject, prolonged study over several years
Memory & Information Processing
Starting in the ‘80s it become more popular to look at memory processes like a computer
Broke down memory into processes
Memory- the cognitive processes of encoding, storing & retrieving information
Encoding- process by which sensory info is converted into a form that can be used by the brain’s
memory system
Storage- process of maintaining info in memory
Retrieval- active processes of locating and using the stored information
Active/latent distinction between retrieval of info
Donald Hebb used this distinction to suggest the brain remembered info in 2 different ways
Known as dual trace theory
Info in active state b/c of neurons firing continuously- feedback circuits of neurons
Repeated firing strengthened the synaptic efficiency of the circuit, leading to structural changes in the neurons
involved
This structural change persists after the activity has ceased- latent structural state
The brain retains traces of an experience either in an active state or latent structural state
Richard Atkinson & Richard Shiffrin later proposed that memory takes 3 forms:
1. Sensory Memory-memory in which representations of the physical features of a stimulus are stored for
very brief durations
Difficult to distinguish from act of perception
Corresponds to memory systems that retain active traces
Info contained here represents original stimulus fairly accurately & contains all or most of the info that
has just been perceived
2. Short Term Memory- immediate memory for stimuli that have just been perceived
Limited both in terms of capacity (5-9, usually 7 chunks of info) and duration (less than 20 secs)
Remember the info by keeping it active, such as repeating it
Let the info become inactive, then might not remember it later
Unless info stored in long term memory, it will be lost forever
3. Long Term Memory- info is represented on a permanent or near permanent basis
Retains latent traces
Has no known limits, is relatively durable
Occurs b/c of physical changes that take place in the brain
Info here need not be continually rehearsed like in short term memory
Can retrieve info from here for future use
Implication that info flows from one type of memory to another called modal model of memory

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II. Sensory Memory
We become aware of sensory memory only when info is presented very briefly so that we can perceive its after-
effects
Ex. thunderstorm at night provides an opportunity to become aware of visual sensory memory
When flash of lightening reveals a scene, we see things before we recognize them
2 most important forms: iconic (visual) & echoic (audio) memory
Iconic Memory- a form of sensory memory that holds a brief visual image of a scene that has just been perceived
Aka visible persistence b/c representation is closely tied to perception
Sperling studied this form by flashing a set of 9 letters on the screen for 50 milliseconds
He then asked people to recall as many letters as they could- known as whole-report procedure
On average, they could remember on 4 or 5 letters, they saw more than that but image of the letters faded too
quickly for people to identify them all
Sperling used the partial-report procedure to determine whether the capacity of iconic memory accounted for
this limitation
Hebb sounded low, medium or high tone immediately after matrix disappeared
tone signaled 1 row to report
recall was almost perfect
when he delayed the tone signalling which row to remember, recall only 50%
Showed people could not report more than 5 letters not b/c they didn’t have enough time to view all the letters
When visual stimulus is presented for a brief flash, all the info is available for a short time & people can
see and recall the info momentarily
BUT image of visual stimulus fades quickly from iconic memory
The people had to scan their iconic memory, identify each letter, & name it verbally
During this process, the letters were fading & the info becoming unreliable
Although their iconic memory contained all 9 letters, they had time to recognize & report only 4-5 before the
mental image disappeared
Echoic Memory- a form of sensory memory for sounds that have just been perceived
we hear individual sounds one at a time when we hear a word pronounced
we cannot identify the word until we have heard all the sounds
acoustical info must be stored temporarily until all the sounds have been received
Appears to operate similar to iconic memory
III. Short Term or Working Memory
Encoding of Information in the Short Term: Interaction with Long Term Memory
Sensory memory forms automatically, without attention or interpretation
Attention is needed to transfer information to short term memory
Information can also enter short term memory from long term memory
When performing a task, some info that we require to do it is available
in our long term memory
This info is moved into short term memory & then recalled
So short term memory contains both new info & info retrieved from long term memory
Led to preference for the term working memory
Working Memory- memory for new info & info retrieved from long term memory
Represents our ability to remember what we have just perceived & to think about it in terms of what
we know
A sort of behaviour that we use to maintain info over the short term
Primacy and Recency Effects

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Primacy effect- tendency to remember initial info
In memorization of a list of words, the effect is evidenced by better recall of words early in the list
Caused by words earlier in a list having the opportunity to be rehearsed more than others words later in
the list
The rehearsal permits the beginning words in long term memory-> remembered better
Recency Effect- tendency to recall later info
In memorization of a list of words, the effect is evidenced by better recall of the last words in the list
Last words to be heard still in short term memory
Shows that memory follows predictable patterns & is dependent on the contributions of rehearsal & short term
memory
The Limits of Working Memory
Maintenance rehearsal- mental or verbal repetition of info
Allows info to remain in working memory longer than the usual 30 secs
Memory decays quickly if prevented from using maintenance rehearsal
Consider the following experiment:
Nonsense syllable presented
BUT, have to count backwards from 1,000 by sevens (i.e., 1014, 1007, 1000 … etc.)
The backward counting prevents rehearsal
Stimuli remain in working memory for less than 20 secs unless they are rehearsed
Petersons pointed out that working memory may be even more limited
Found that unexpected distractions seriously disrupted working memory
Most people found it hard to recall 3 letters after only 2 secs
Capacity of working memory: people can retain on average about 7 pieces of info in their short term memories
Chunking- process by which info is simplified by rules, which make it easily remembered once the rules are
learned
Ex. Easier to remember sequence of letters “MBIASUAICIBF” when organize them into smaller chunks “
FBI CIA USA IBM”
Capacity for verbal material depends on how much meaning the info has
When items are related, we can store many more of them
Chain unrelated words together by imaging a story involving them to improve short term memory of those
words
Varieties of Working Memory
Working memory can contain a variety of sensory info & motor memories
Baddeley suggested that working memory consists of several components all coordinated by a “central
executive” function
Phonological short term memory- short term memory for verbal info
Phonological coding involves both the auditory system of the brain (auditory association cortex) & the system
that controls speech
People read the letters, encode them acoustically & remember them by rehearsing the letters as sounds
During this process, may easily make acoustic errors
Reflects a form of acoustical coding in working memory
Subvocal articulation prevents decay of phonological short term memory
Best neurological evidence for existence of phonological short term memory comes from a disorder called
conduction aphasia
Conduction aphasia- inability to remember words that are heard, although they usually can be understood &
responded to appropriately
Caused by damage to a region of the left parietal lobe (Wernicke’s & Broca’s areas)
b/c brain damage that produces this disorder disconnects regions of the brain involved in speech perception &
production, perhaps the damage disrupts acoustical short term memory
making subvocal verbal rehearsal difficult or impossible
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