Introduction to Cognitive ScienceLecture #2 : Mental Representations

Joe LauPhilosophy

HKU

Classical cognitive science

Assumption #1 : Mental states are constituted by mental representations.

Assumption #2 : Many mental states have complex structure.

Defending A1 Mental representations

Encode meaning and knowledge Explains how mental states can

interact with the brain and body No alternative way to explain

mental phenomena.

Defending A2 Structured representations :

Explain how we can have new thoughts that relate to old ones systematically.

Provides a good framework for studying various mental processes such as reasoning and language understanding.

White dog

Black cat

White cat

Black

dog

Theory of content 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?

Artificial representations Examples :

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.

“WHITE DOG”

Problem 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 Xnormally causes

represents

 Criticism #1 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 The attribution of representations

should be governed by bottom-up and top-down motivations. 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 The theory does not apply to

conceptual representations. Perceptual representations

Representations involved in perception. Detects real-time properties

Conceptual representations Representations involved in thinking and

reasoning. Do not function as detector

representations.