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Introduction to Cognitive Science
Lecture #2 :
Mental Representations
Joe Lau
Philosophy
HKU
Classical cognitive science
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Assumption #1 : Mental states are
constituted by mental representations.
Assumption #2 : Many mental states
have complex structure.
Defending A1
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Mental representations
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Encode meaning and knowledge
Explains how mental states can interact
with the brain and body
No alternative way to explain mental
phenomena.
Defending A2
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Structured representations :
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Explain how we can have new thoughts that relate
to old ones systematically.
White
dog

Black
cat
Whit
e cat
Black
dog
Provides a good framework for studying various
mental processes such as reasoning and language
understanding.
Theory of content
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Mental representations have content.
Philosophical question : what is it that
determines the content of a
representation?
How can we tell whether a state of the
brain has content or not?
“WHITE DOG”
Artificial representations
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Examples :
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Diagrams, signs, natural languages,
gestures
The assignment of meaning is arbitrary
in that there is no necessary connection
between a representation and its
meaning.
Depends on conventional usage.
Problem
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A theory of content that invokes
conventions is not applicable to mental
representations.
Conventions depend on the beliefs,
which is what mental representations
are supposed to explain.
Visual Perception
Topographical
representation of
visual stimulus in
area V1
Causal correlation?
A simple causal theory of meaning
 X represents Y in a creature Z = when Z
is functioning normally, X is caused by Y
and only by Y.
Y
normally causes
represents
X
Criticism #1
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Not all causal correlations involve
representations.
For example, the pumping of the heart
normally causes blood circulation, but
the latter is not a representation of the
former.
Response
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The attribution of representations
should be governed by bottom-up and
top-down motivations.
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It should be part of a theory that explains
where the content of the representation
derives from and how the content is used.
Representations are supposed to play an
informational role.
Criticism #2
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The theory does not apply to
conceptual representations.
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Perceptual representations
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Representations involved in perception.
Detects real-time properties
Conceptual representations
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Representations involved in thinking and
reasoning.
Do not function as detector representations.