Transcript Chap6b

Cognitive Processes
PSY 334
Chapter 6 – Human Memory:
Encoding and Storage
Criticisms of STM
 Rate of forgetting seemed to be quicker
than Ebbinghaus’s data, but is not really.
 Amount of rehearsal appeared to be
related to transfer to long-term memory.
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Later it was found that the kind of
rehearsal matters, not the amount.
Passive rehearsal does little to achieve
long-term memory.
 Information may go directly to LTM.
Depth of Processing
 Craik & Lockhart – proposed that it is not
how long material is rehearsed but the
depth of processing that matters.
 Levels of processing demo.
Working Memory
 Baddeley – in working memory speed of
rehearsal determines memory span.
Articulatory loop – stores auditory input
(speech) for 1.5 to 2 seconds.
 Visuopatial sketchpad – rehearses
images.
 Central executive – controls other
systems.
Articulatory Loop
 The word-length effect provides
evidence of the existence of the
articulatory (phonological) loop.
 When a list of words is read, the number
recalled depends on how long the words
are:
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Wit, sum, harm, bay top = 4.5 words
University, opportunity, aluminum,
constitutional, auditorium = 2.6 words
Delayed Matching Task
 Delayed Matching to Sample – monkey
must recall where food was placed.
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Monkeys with lesion to frontal cortex
cannot remember food location.
Human infants can’t do it until 1 year old.
 Regions of frontal cortex fire only during
the delay – keeping location in mind.

Different prefrontal regions are used to
remember different kinds of information.
Activation
 Activation – how available
information is to memory:
Probability of access – how likely you
are to remember something.
 Rate of access – how fast something
can be remembered.

 From moment to moment, items
differ in their degree of activation in
memory.
Factors Affecting Activation
 How recently we have used the
memory:
Loftus – manipulated amount of delay
 1.53 sec first time, then 1.21, 1.28,
and 1.33 with 3 items intervening.

 How much we have practiced the
memory – how frequently it is used.
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Anderson’s study (sailor is in the park)
Spreading Activation
 Activation spreads along the paths
of a propositional network:
Dog – c
 Bone – m
 1.41 sec
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Gambler – c
bone – m
1.53 sec
 Associative priming – involuntary
spread of activation to associated
items in memory.
Associative Priming
 Meyer & Schvaneveldt – spreading
activation affects how fast words
are read.
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Subjects judged whether pairs of
related & unrelated items were words.
 Ratcliff & McKoon – priming
influences word recognition.
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Subjects identified words from
sentences faster with priming.
Practice and Strength
 Amount of spreading activation
depends on the strength of a
memory.
 Memory strength increases with
practice.
 Greater memory strength increases
the likelihood of recall.
Power Function
 Each time we use a memory trace,
it gradually becomes a little
stronger.
 Power law of learning:
T = 1.40 P-0.24
 T is recognition time, P is days of
practice.
 Linear when plotted on log-log scale.
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Long Term Potentiation (LTP)
 Neural changes may occur with
practice:
Long-term potentiation (LTP) in
hippocampus.
 Repeated electrical stimulation of
neurons leads to increased
sensitivity.
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 LTP changes are a power function.