Psych1000- Chapter 8 Memory.doc

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14 Nov 2012
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Chapter 8
Memory
H.M.
Hippocampus and surrounding brain tissue removed to reduce his epileptic seizures
Operation successful, but left HM with amnesia
Can discuss childhood, teens, and early twenties.
Forgotten some events that occurred within the two year prior to surgery
Lost the ability to form new memories
He cannot remember new facts, nor retain the meaning of words that have entered the English
language since his operation
Once an experience leaves his immediate train of though he cannot remember it
Depart for a couple minutes, he will not recognize you.
Forgets his favourite uncle died, and has relearned it and experienced the grief many times over
again
Memory: refers to the processes that allow us to record and later retrieve experiences and information
Memory as Information Processing
Ebbinghaus- rate at which new information is forgotten
Galton- investigated peoples memories for personal events.
Encoding refers to getting information into the system by translating it into a neural code that
your brain processes.
Storage involves retaining information over time. Once in a system, information must be filed
away and saved, as happens when a computer stores information on a hard drive.
Finally, there must be a way to pull information out of storage when we want to use it, a process
called retrieval.
Analogy between humans and computers is crude because humans routinely forget and often
remember things that never happened.
A Three-Component Model
Atkinson and Shiffrin proposed that memory has three major components: sensory memory,
short-term or ―working‖ memory, and long-term memory
Model does not assume that each component corresponds to a specific structure within the brain
The components may involve interrelated neural sites, and memory researchers use these terms
in a more abstract sense
Sensory Memory
Sensory memory: holds incoming sensory information just long enough for it to be recognized
It is composed of different subsystems, called sensory registers, which are the initial
information processors
Visual sensory register is called the iconic store
Time course for visual sensory memory is very brief
It is difficult, perhaps impossible, to retain complete information in purely visual form for more
than a fraction of a second
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The auditory sensory register, called the echoic store, is studied by asking participants to recall
different sets of numbers or letters that are simultaneously presented to their left and right ears
via headphones
Echoic memory lasts longer than iconic memory
A nearly complete echoic trace may last about two seconds and a partial trace may linger for
several more
Short-Term/Working Memory
Because our attentional capabilities are limited, most information in sensory memory simply
fades away
But through selective attention, a small portion enters short-term memory, which hold the
information that we are conscious of at any given time
Short-term memory also is referred to as working memory, because it consciously processes,
codes, and ―works on‖ information
Mental Representations:
Once information leaves sensory memory, it must be represented by some type of code if it is to
be retained in short-term and eventually long-term memory
Mental representations, or memory codes, can take various forms
We may try to:
o Form a mental image- visual encoding
o Code something by sound- phonological encoding
o Focus on the meaning of a stimulus- semantic encoding
o For physical actions, such as learning sports, we code patterns of movement- motor
encoding
The form of a memory code often does not correspond to the form of the original stimulus
When you read this you are not storing the way that the letters look, you use phonological code,
which is saying the words to yourself.
When people are presented with lists of words or letters and asked to recall them immediately,
the errors that they make often are phonetic
Likewise, given word lists such as (1) main, mad, cap, can, map; (2) old, late, thin, wet, hot; and
(3) big, huge, broad, long, tall people become most confused recalling the first list, in which
the words sound similar
Capacity and Duration
Can hold only a limited amount of information at a time
Most people can hold no more than five to nine meaningful items at ―the magical number
seven, plus or minus two‖
The limit on short term memory capacity concerns the number of meaningful units that can be
recalled, and the original 17 letters have been combined into five meaningful words.
Combining individual items into larger units of meaning is called chunking, and it can greatly
aid recall
Short term memory is limited in duration as well as capacity
Be rehearsing information we can extend its duration in short-term memory indefinitely
This simple repetition of information is called maintenance rehearsal
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In contrast, elaborative rehearsal involves focusing on the meaning of information or relating
it to other things we already know.
Both types of rehearsal keep information active in short term memory, but elaborative rehearsal
is more effective in transferring information into long term memory which is out more
permanent memory state.
Putting Short-Term Memory “To Work”:
Items that remain in the short-term loading dock enoughsuch as through maintenance
rehearsaleventually get transferred into the long-term library
The original three-stage model of memory focused on short-term memory primarily as a
loading platform or holding station for information along the route from sensory to long-term
memory
Instead, they view short-term memory as a working memory—a ―mental workspace‖
that actively and simultaneously processes different types of information and supports other
cognitive functions, such as problem solving and planning
Working memory ―is instead more like the office of a bust librarian, who is energetically
categorizing, cataloguing, and cross-referencing new material‖
One model divides working memory into three components
First, we maintain some information in an auditory working memory (the ―phonological
loop‖), such as when you repeat a phone number, name or new vocabulary terms to yourself
mentally
A second component, visual-spatial working memory (the ―visuo-spatial sketchpad‖), allows
us to temporarily store and manipulate images and spatial information, as when forming mental
―maps‖ of the route to some destination
Finally, a control process, called the central executive, directs the action
It decided how much attention to allocate to mental imagery and auditory rehearsal, calls up
information from long-term memory, and integrated the input
Prefrontal cortex is heavily involved in directing the processing of information in working
memory
Long-Term Memory
Long-Term Memory: our vast library of more durable stored memories
We remain capable of forming new long term memories until we die.
Long term storage capacity is unlimited
Words at the end and beginning of list are the easiest to recall
This U-shaped pattern is called the serial position effect, meaning that recall is influenced by a
word‘s position in a series of items
The serial position effect has two components, a primary effect, reflecting the superior recall
of early words, and a recency effect, representing the superior recall of the most recent words
As the first few words enter short-term memory, we can quickly rehearse them and transfer
them into long-term memory
However, as the list gets longer, short-term memory rapidly fills up
The last few words have the benefit of not being ―bumped out‖ of short-term memory by any
new information
The primacy effect is due to the transfer of early words into long-term memory, whereas the
recency effect is due to short-term memory
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