Transcript BHS 499-07 Memory and Amnesia

BHS 499-07
Memory and Amnesia
Semantic Long-Term
Memory
Semantic Memory
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Semantic memory is general knowledge
of the world.
• Are dogs safe?
• What happens in a restaurant?
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Generalizations that can apply to a
variety of situations – built from previous
experiences.
Semantic Priming
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Priming – thinking about one concept
brings related memories closer to
awareness.
• People respond faster to a concept after it has
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been primed.
The prime comes first, then the target
(associated item), and response times (RTs)
are measured.
Memory Structure
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Semantic memory is structured based on
shared meaning, not prior associations.
• Similar concepts in terms of meaning are
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stored closer to each other.
Semantic “closeness” is metaphoric, based on
response times.
Activation spreads to related items.
A great deal of repeated use moves
items from episodic to semantic memory.
Controlled Priming
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In general, priming is automatic (does
not require conscious effort).
Conscious expectations can change
priming (Neely).
• In the Category Shift Expected condition, the
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prime signaled the appearance of a different
category which was then primed.
It took a while for the different expectation to
develop so priming occurs after several trials.
Mediated Priming
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How far does activation spread during
priming?
• Lion  Tiger  Stripes
• Does activation spread to Stripes via Tiger?
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This phenomenon is called mediated
priming – smaller than regular priming.
• The further you go from the original prime, the
smaller the activation and less likely the
priming.
Semantic Interconnectivity
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No fan effect in semantic memory –
more associations speed up, not slow
down retrieval.
• Direct and indirect connections provide more
ways to retrieve info, making it more reliable.
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As with episodic memory, inhibition
occurs, but mostly during active retrieval,
not when passively reading.
Semantic Memory is Embodied
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In addition to capturing abstract
relationships among words, storage
reflects how we relate to the world.
Concrete nouns tend to activate the
sensory cortex because they are things
we see and feel – perceptual effort.
Verbs tend to activate the motor cortex
because they are things we do.
Categorization
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Similarity-based grouping in which two or
more entities are treated as equivalent.
• Concept – a mental construct that contains
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information associated with an idea (a dog).
Category – a class of concepts to which a set
of assertions applies (a dog has four legs,
may bite).
Categories are generalized from
repeated instances of concepts.
Properties of Categories
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Levels of categorization:
• Basic, subordinate (detailed), superordinate.
• We operate on the basic level most often –
items on that level retrieved better & faster.
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Central tendency – there is an averaged
ideal or best member of the category.
Graded membership – some members
are better than others (robin vs penguin)
Definition of the Category
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Categories are defined in different ways:
• Rules – things that are used at the beach,
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numbers divided by 2, kinship (bachelor).
Shared features or family resemblance –
birds, furniture.
Categories defined by rules or specific
features are called classical categories.
• Classical theories don’t explain graded
membership and typicality effects.
Prototype Theory
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Categories based on similarity or shared
features may arise inductively from
unconscious mental statistics.
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The typical member may be a statistical average of all
category members, called a prototype.
This theory does not explain how categories
change over time or how we know their extent.
Caricatures emphasizing distinctive features
are better for comparing across categories.
Exemplar Theory
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Rather than reasoning from a derived
prototype, we use all category members
to make decisions.
• Explains sensitivity to context effects (priming
of pony mane greater than lion’s mane).
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Circularity is a problem
• How can members define a category if the
category is needed to identify the members?
Explanation-Based Theory
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When a category is formed, people try to
explain why its members go together.
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Why do wings and feathers go together? Feathers
help creatures to fly.
Ad hoc categories – explanations created for a
group of objects (e.g., things that stink).
Psychological essentialism – the items
grouped form natural kinds based on their
nature, pragmatics, or causality (purpose).
Stereotypes & Prejudice
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Stereotypes are categories for various
groups of people.
• When use of a stereotype causes someone to
treat an individual inappropriately that is
prejudice.
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Use of stereotypes is natural and part of
normal thinking, but we must monitor our
use of them for fairness.
Ordered Relations
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Semantic Distance Effect – the time it
takes to make a judgment is
proportionate to their distance.
Semantic Congruity Effect – items are
easier to judge when they are similar
with respect to some dimension.
Serial Position Effect – items at either
end are easier to judge than the middle.
Schemas & Scripts
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Commonly experienced aspects of life form
schemas – these make it easier to understand
new situations.
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What happens at a birthday party?
What happens at a restaurant?
Scripts are schemas with a sequence of events
that occur in a stereotyped fashion.
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Organized in time, like a script for a play or TV show.
5 Primary Schema Processes
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Selection – which components are
important and which are peripheral.
• Knowing what schema to apply to a situation
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tells you what to pay attention to (Droodles).
Ambiguous passages are clarified by
schemas (washing clothes).
Abstraction – the surface form is
converted to an abstract meaning.
• Drawings change in the direction of meaning.
Schema Processes (Cont.)
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Interpretation – We infer missing info
during reading or movies based on the
schema (e.g., on/off airplane, infer flight)
Integration – When we receive info
piecemeal, the schema lets us put it all
together (e.g., mysteries).
Reconstruction – fill in gaps at recall
from schema (War of the Ghosts).
Scripts
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Temporally ordered schemas structured by the
main components of the event.
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It takes longer to read a script when the next
step is further along in sequence.
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Preference for going in the forward order.
People scan the steps in the script.
Even when parts are presented in random
order they are remembered in proper order.
Limits on Schema Use
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Schemas are not always used.
• Causes may be inferred from schemas but
not necessarily effects because a number of
outcomes may be possible.
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When a schema is discredited, people
will ignore it.
• Escaped convict/deer hunter schema
changed when subjects were told the title was
wrong – fewer schema-related intrusions.
Semantic Illusions
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How many animals of each kind did
Moses take on the ark?
• 81% of UCSD students got this wrong.
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What was the famous line uttered by
Louis Armstrong on the moon?
3 explanations: (1) general focus; (2)
partial assessment; (3) similar language
components giving illusion it is known.
Naïve Physics
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A semantic illusion of nonverbal memory.
Mental models of how the world works do not
conform to real life physics.
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Similar to Medieval theories of motion.
Less likely to occur with moving models, more likely
with static drawings.
People set thermostat higher so it will heat the
house faster – temperature accelerator.
Vision involves emissions from eyes.