Re: Pylyshyn's Critique of Mental Imagery

From: HARNAD Stevan (
Date: Tue May 28 1996 - 17:37:32 BST

> From: "Phillips Barbara" <>
> Date: Tue, 21 May 1996 08:51:28 GMT
> There are two theories as to how mental images are represented. The
> first is by depictive representations. This is where mental images
> look exactly like the real image of the object. I.e the same size,
> shape and orientation.

"Exactly" is a bit strong. Resemble is more like it... You should
mention analog representation and explain how it differs from symbolic

> The second theory is that mental images are
> propositional representations. These are sentences that represent
> the real objects using symbols. These do not look like the object -
> they just describe the object through symbols.

What are symbols? What is computation? Pylyshyn is a computationalist.

> Each concept has supporting and contradictory evidence. Some of
> which involves mental scanning and PET experiments.

Would a kid-sibling know what you were talking about here? What were the
findings and what did they show?

> Pylyshyn (1973)
> disagreed with the idea of depictive representations. He maintains
> that if mental images were depictive a 'little man' would be needed
> to look at the pictures to interpret them. This is the homunculus
> problem. If a man looks at the pictures and sees and interprets the
> pictures - how do we interpret what is going on in the little man's
> head? This is Pylyshyn's critique of mental imagery. For this
> reason, Pylyshyn believes in propositional representations.

There are a few more reasons than that, such as the power of
computation. Read the Kosslyn chapter carefully to get a stronger basis
for your reply.

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