Note: There are 2 slides at the end of this lecture file that were not presented during the lecture.

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Note There are 2 slides at the end of this
lecture file that were not presented during the
lecture. This material may be tested on the
upcoming midterm (particularly the last slide),
so you will want to look at your text for
information on these issues. Any questions, feel
free to ask...
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Memory
What is memory?
The mechanism by which information is moved
forward in time
Computers magnetic / optical data storage
Humans - ??? We know a lot about the properties
of memory, but not a lot about the underlying
physiological mechanism(s)
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Memory
Memory as Information Processing
Encoding how does information get into memory?
Storage how is information retained over time?
Retrieval how is information in memory accessed?
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Memory
3 stage processing model of memory
Sensory memory sensory information immediately
recorded
Short-term memory initial information processing
Long-term memory permanent (?) and limitless
(?) information storage
Extensive filtering at each stage
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Memory
Working Memory
Similar idea to short-term memory
Visual and verbal components are somewhat
independent
Analogous to RAM in a computer
- size limitations
- integration of new and stored info
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Memory
Encoding
Effortful vs Automatic processing
For most of you, reading this sentence involves
automatic processing
For most of you, reading this sentence involves
effortful processing
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Memory
Encoding
Effortful vs Automatic processing
With practice, effortful processes can become
automatic (e.g., riding a bicycle)
Effortful processing frequently involves rehearsal
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Memory
Encoding
Rehearsal is the conscious repetition of
information
Ebbinghaus and nonsense words
- subjects had to memorize a list of 3 letter
non-words (e.g., CUG, WUX)
- same list of non-words memorized again on the
second day (and third day, etc...)
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Memory
Encoding
The more rehearsal on Day 1, the less time it
took to relearn the list again on Day 2
Spacing effect the longer the time between
rehearsal sessions, the better the retention of
the information
Massed rehearsal much less effective
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Memory
Encoding
Serial Position Effects
Primacy effect the first item in a list will
show better retention than other items
Recency effect the last item in a list will
show better retention than other items
Recency effect dominant immediately after
rehearsal, primacy effect dominant after delay
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Memory
Encoding
What gets encoded?
For example, remember this word
BLIND
What properties of the word did you encode?
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Memory
Encoding
Visual encoding encoding the image of the
written word
Acoustic encoding encoding the sound of the
spoken word
Semantic encoding encoding the meaning of the
word
Semantic encoding allowed for the best retention
in experimental subjects
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Memory
Chunking
Memorize the following lists
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Memory
Chunking
Information to be encoded is divided into
meaningful units (chunks)
Depending on the context, chunks could be
individual letters, words, or complete sentences
Expertise / practice allows for larger chunks and
more chunks to be encoded and retained
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Memory
Chunking
ball soft lean
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Memory
Retention
Information in working memory is retained only
for a very short time unless rehearsal is used to
maintain it
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Memory
Retention
Retention in long-term memory appears to be
limitless (your brain does not get full)
Everything that makes it from working memory into
long-term memory stays there
Accessing that information, however, is another
matter
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Memory
Retention
While the physiological basis of memory retention
is still unclear, one phenomenon that has
received much attention is Long Term Potentiation
(LTP)
LTP involves the strengthening of synaptic
connections through mutual activation of the
presynaptic and postsynaptic neurons
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Memory
Retention
neurons that fire together, wire together
Feedback from the postsynaptic neuron to the
presynaptic neuron increases strength of the
connection
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Memory
Implicit and Explicit Memories
Implicit Memory
- procedural memory (how to do things)
- non-declarative memory
- includes motor skills and conditioned behaviors
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Memory
Implicit and Explicit Memories
Explicit Memory
- declarative memory (what you are consciously
aware of knowing)
- you may be consciously aware that you can ride
a bicycle (explicit memory), but actually riding
it requires an implicit memory of the required
sequence of actions
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Memory
Implicit and Explicit Memories
Explicit memory can be further divided into
Semantic memory encyclopedic knowledge of facts
/ meanings
Episodic memory memory of personally
experienced events
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Memory
Implicit and Explicit Memories
In some amnesic patients new implicit memories
can be formed, but new explicit memories cannot
These patients can learn new skills (procedural),
but remain unaware that they have learned them
(declarative)
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Memory
The Role of the Hippocampus
- structure in the limbic system (midbrain)
- hippocampus is lateralized (one in each
hemisphere)
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Memory
The Role of the Hippocampus
- damage to hippocampus can result in the loss of
the ability to form new explicit memories
- lateralization
- left hippocampal damage ? loss of explicit
verbal memory
- right hippocampal damage ? loss of explicit
spatial memory
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Memory
The Role of the Hippocampus
The hippocampus plays a role in memory
consolidation
- damage / loss of hippocampus in monkeys
resulted in loss of explicit memory of events in
the month prior to the damage, as well as the
loss of new explicit memories
Hippocampus also active during memory playback
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Memory
Other brain regions are involved in long-term
explicit memory storage
Active recall of stored memories into working
memory involves activity in the frontal and
temporal lobes
Lateralization also seen here
verbal memory ? left frontal cortex
visual memory ? right frontal cortex
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Memory
Other brain regions are involved in long-term
explicit memory storage
The amygdala, also in the limbic system, provides
the emotional content associated with explicit
memories
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Memory
Storage of implicit memories
the cerebellum
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Memory
Storage of implicit memories
Damage or loss of the cerebellum prevents the
acquisition of many conditioned behaviors in
classical and operant conditioning
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Memory
Retrieval
3 types of test
recall
e.g., the amygdala is part of the _________
system
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Memory
Retrieval
3 types of test
recognition

• e.g., the amygdala is part of
• the royal family of Sweden
• the limbic system
• a canoe

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Memory
Retrieval
3 types of test
relearning
e.g., repeatedly solving a puzzle or problem
(such as memorizing Ebbinghaus lists of nonsense
words)
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Memory
Retrieval
Cues and Contexts
- memory as a web of linked items
- activation of one item can lead to activation
of closely linked items
- memory can be primed to make certain links
active without conscious awareness
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Memory
Retrieval
Retrieval is often better if it takes place in
the same context as was present when the
information was originally encoded
Context as a cue for memory activation
Can also be true for implicit memory (e.g.,
state-dependent learning)
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Memory
Spreading Activation Networks
- each node is linked to many other nodes
- activation of one node in memory by current
experience leads to spread of activation to
nearby nodes
- strength of activation decreases with
distance
- why does my cat make me think of Arnold
Schwarzenegger, The English Patient, and Winnie
the Pooh (among other things)?
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inside my head...
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Memory
Forgetting
Why is memory not perfect?
3 possible sources of memory failure
- encoding failure
- decay while in storage
- retrieval failure
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Memory
Forgetting
Encoding failure is the result of information
being lost between working memory and long-term
memory
- info lost between sensory encoding and working
memory considered filtered, rather than
forgotten
Some memories require effortful processing in
order to be encoded (others may be encoded
automatically)
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Memory
Forgetting
Encoding failure is the result of information
being lost between working memory and long-term
memory
- result of insufficient / interrupted rehearsal
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Memory
Forgetting
Storage decay is evident in the forgetting curve
The greatest decay in memory storage occurs early
in retention
physiological reason ???
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Memory
Forgetting
Retrieval failure occurs when info in long-term
memory cannot be found and brought back into
working memory
storage decay may just reflect loss of
accessibility, not loss of information
Cues / context can sometimes help
Retrieval failure may be due to interference
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Memory
Forgetting
Proactive Interference
- previous learning interferes with newer learning
Retroactive Interference
- newer learning interferes with previous learning