Cognitive Psychology, 2nd Ed.
Chapter 8
Semantic Memory
Representing Concepts
Concepts are general ideas that enable
the categorization of unique stimuli as
related to one another.
Concepts are characterized by
dimensions of variation among
exemplars.
Contrasting Types of Concepts
Rule governed concepts
specify the features and
relations that define
category membership
on an all or none basis.
Classical view holds
assumes defining
features are related by
a conjunctive rule.
Object concepts refer to
natural kinds and
artifacts that violate the
classical view.
Characteristic features
are disjunctively
related, creating a
family resemblance
structure and a fuzzy
boundary.
Prototype
The best or most typical example of a
category that serves in the mental
representation of a concept.
The range of feature variation on a stimulus
dimension and feature frequency of
occurrence define in part the gradient of
category membership.
The gradient creates typicality effects in
categorization speed, acquisition order, and
priming.
Schema
A schema is a cognitive structure that
organizes related concepts and integrates
past events.
Frames organize the physical environment
(e.g., an office frame).
Scripts represent routine activities (e.g., a
restaurant script). Cumulative recall of script
events is linear whereas object exemplars
follow a negatively accelerated curve.
Meta-Representation
Defined as a mental representation of
another mental representation. Thinking
about thinking requires meta-representation.
Pretending a banana is a telephone requires a
meta-representation linking the two object
concepts. Meta-representation thus affords
flexible and creative cognition.
Between ages 2-4 the use of metarepresentation develops.
Theory of Mind
Theory of mind refers to the human ability to
infer that others, like ourselves, have mental
states. It helps account for why we are not
all adherents of solipsism.
By age 4 children can not only pretend but
can predict the consequences of another
having false beliefs.
Mindblindness is an inability to understand
that others possess mental representations
and is characteristic of autism. An autistic
child is socially isolated and treats others as
robots without feelings and thoughts.
Propositions vs. Images
Abstract means of
mental representation.
Schematic and verbal.
Each proposition is an
assertion that may be
true or false.
Coded as a relation and
arguments (e.g., Fred is
tall).
Perceptual means of
mental representation.
Concrete and
nonverbal.
One image conveys
Represent multiple
features and relations.
Can images be
decomposed into
propositions?
Functional Equivalence
Hypothesis
Visual imagery, while not identical to
perception, is mentally represented and
functions the same as perception.
An image is isomorphic to the referent object
(second-order), meaning spatial relations are
analogous.
An image is an analog representation of the
object, as shown by mental rotation and
image scanning.
The Nature of Propositions
“Fred is tall” is a single proposition coded as a
relation with two arguments (is, Fred, tall).
“The ants ate the sweet jelly that was on the
table” expresses four propositions.
Latent Semantic Analysis is a mathematical
procedure for extracting and representing the
meanings of propositions expressed by a text.
It represents the co-occurrence of words and
their contexts. Using a database of cooccurrence relations, it can compute the
similarity in meaning of two words or texts.
Semantic Network vs. Feature
Comparison Models
Hierarchical network
of concepts .
Cognitive economy
stipulates features
are represented only
once in the
hierarchy.
Used in WordNet to
represent word
meanings.
Feature vector defines
each concept for each
level (e.g., robin, bird,
animal).
Stages of feature search
(characteristic
vs. defining) explains
typicality effects.
Category Size Effect
“All collies are dogs” faster than “All collies are
animals.”
Network model
assumes that
feature search must
proceed from level 0
to level 1to confirm
dog.
Must proceed to
level 2 to confirm
animal, taking more
time.
Feature comparison
assumes search of
characteristic
features is sufficient
to confirm dog.
Must proceed to
Stage 2 search of
defining features to
confirm animal.