Introduction to Cognitive Science Lecture #2 : Mental Representations

1. Introduction to Cognitive ScienceLecture #2 : Mental Representations Joe Lau Philosophy HKU

2. Classical cognitive science • Assumption #1 : Mental states are constituted by mental representations. • Assumption #2 : Many mental states have complex structure.

3. 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.

4. 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

5. 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?

6. “WHITE DOG” 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.

7. 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.

8. Visual Perception Topographical representation of visual stimulus in area V1

9. 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 X represents

10.  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.

11. 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.

13. 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.