"A picture is worth a thousand words" refers to the imagery debate;
therefore, whether mental imagery is best explained by depictive (ie,
similar to actual pictures or images, they resmble the spatial
features of an object physically) or propositional (ie, symbol
strings, which similar to words, share the fact that they are only
arbitrarily related to an object) representations. Pylyshyn argued
that mental imagery cannot be pictorial since he believed that
images, unlike propositions, require a homonculus ("a little man in
the head") to look at them, and to interpret and understand them.
Hence, to Pylyshyn a "picture" is worth nothing on its own, since it
objectively means nothing without a propostionally-based
interpretation. Instead he saw images as "epiphenomenal"; an
unimportant by-product of some other underlying process, images
themselves are of no consequence during the actual act of processing
information. Basically, propositionalists, perhaps rightfully,
advocated the possibility of using symbols in any task which Kosslyn
believed necessitated the "priveleged properties" of depictive
representations; with the additional advantage that propositions can
"stand alone", without the necessity of an internal viewer, since as
in a machine, the computation involved in symbol manipulation does
not require a "mind's eye". Therefore, it is possible to argue that
a propositional representation can offer as much information as would
be avaliable in a picture. However, as an end-product, propositions
are cumbersome. Pictures can encompass a vast amount of information
in a more immediately avaliable and accessible form, whereas to
represent certain things symbollically would require a vast amount of
additional symbolically-based information. Eg, when we perform a
task such as identifying a face, we do so by directly picturing the
face, rather than labouriously working through a list of descriptive
features. Clearly the latter would prove innappropriate. Therefore,
although experiments such as the "mental scanning" studies did reveal
that propositions, in the form of "mental lists", were equally
capable of supposedly visually-based tasks; as a usable
end-product(regardless of trhe processes that may create it), an
image-based representation is preferable for such a task. Therefore,
in this respect a picture may prove worth a thousand words, although
it appears that the worth of both types of representation (which each
appear equally probable), may be task dependent.
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