PSYC1002 Lecture Notes - Lecture 4: Wilder Penfield, Semantic Memory, Semantic Network
19 May 2018
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Department
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Ch 7 Weiten p282-6
20170731T
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Unlimited capacity store that can hold info over lengthy periods of time
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Stores info indefinitely
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Forgetting only occurs because people sometimes can't retrieve needed information
from LTM
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Triggered memories through electrical stimulation of the brain (ESB) during brain
surgeries
▪
Mapped brain function in patients undergoing surgery for epilepsy
▪
Found stimulation of temporal lobe sometimes elicited vivid descriptions of events
long past
▪
Patients described exact playbacks of long-lost memories unearthed by electrical
stimulation of the brain
▪
Later scrutiny showed that the memories activated by ESB often included major
distortions or factual impossibilities
▪
The ESB-induced recollections apparently were hallucinations, dreams or loose
reconstructions of events, not exact replays of the past
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Wilder Penfield 1960
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Unusually vivid and detailed recollections of the circumstances in which people
learned about momentous, newsworthy events
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e.g. adults remembering exactly where they were, what they were doing and how
they felt when Pres JKF was assassinated
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Flashbulb memory phenomenon
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May be permanent
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Long term memory
Although memories are strong, studies suggest they are not that accurate
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The memories become less detailed and complete with time and are often
inaccurate
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Flashbulb memories not distinguished by their accuracy or longevity, but by
people believing that these memories are exceptionally vivid, so have exceptional
confidence in their accuracy and attach more emotional intensity to them
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No convicting evidence that memories are stored permanently and that forgetting is due
to retrieval failure
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Knowledge takes a variety of forms depending on the nature of the material that needs to be
tucked away in memory
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Subjects memorised a list of 60 words presented in a scrambled order
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Each of the words in the list fit into 1 of 4 categories
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Showed subjects used clustering to recall list
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People spontaneously organise information into categories for storage in memory
(Bousfield 1953)
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Clustering and conceptual hierarchies
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Representation and organisation of knowledge in memory
L4 - structure of LTM
Monday, 7 August 2017
8:28 AM
Cognitive Page 1
Showed subjects used clustering to recall list
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Clustering = the tendency to remember similar or related items in groups
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Multilevel classification system based on common properties among items
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Screen clipping taken: 7/08/2017 10:49 AM
Conceptual hierarchy
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Schema = an organised cluster of knowledge about a particular object or event
abstracted from previous experience with the object or event
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e.g. college students have schemas for what classrooms are like
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Tested recall of 30 subjects who had briefly visited an office
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Most subjects recalled desks and chairs
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Few recalled other features e.g. wine bottle, picnic basket, which don't belong to
typical office schema
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9 subjects falsely recalled books
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Brewer and Treyens 1981
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Suggests people more likely to remember things consistent with their schemas than
things that aren't
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Attracts attention and deeper processing, so more memorable
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People can also exhibit better recall of things that violate schema-based expectations
(ie. Unusual)
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Schemas
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Semantic network = consists of nodes representing concepts joined together by
pathways that link related concepts
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Length of each pathway represents the degree of association between 2 concepts,
shorter pathway = stronger association
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When people think about a word, their thoughts naturally go to related words
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Spreading activation within a semantic network
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Assume an activation spreads out along the pathways of the semantic network
surrounding the word
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Strength of activation decreases as it travels outward
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e.g. for word "red", words that are closely linked e.g. orange, should be easier to
recall than words that have longer links
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Collins and Loftus 1975
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Semantic networks
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Cognitive Page 2
Document Summary
Unlimited capacity store that can hold info over lengthy periods of time. Forgetting only occurs because people sometimes can"t retrieve needed information from ltm. Triggered memories through electrical stimulation of the brain (esb) during brain surgeries. Mapped brain function in patients undergoing surgery for epilepsy. Found stimulation of temporal lobe sometimes elicited vivid descriptions of events long past. Patients described exact playbacks of long-lost memories unearthed by electrical stimulation of the brain. Later scrutiny showed that the memories activated by esb often included major distortions or factual impossibilities. The esb-induced recollections apparently were hallucinations, dreams or loose reconstructions of events, not exact replays of the past. Unusually vivid and detailed recollections of the circumstances in which people learned about momentous, newsworthy events e. g. adults remembering exactly where they were, what they were doing and how they felt when pres jkf was assassinated. Although memories are strong, studies suggest they are not that accurate.
