The Imagery Debate is all about whether the images that we all know and
experience through introspection are useful entities which we can
investigate and ground in theories, or whether they are really
something of a private illusion that has no formal role in anything or
at best a minor role. We believe that there have to be some form of
representations in our head, but are any of them in the form of an
The homunculus fallacy is all about the conferring of human attributes
to something that is not human or is only part of a human and using
that something as an actor in a process. Not only is this incoherent,
but all that is added to any explanation is an extra unhelpful step. If
we are driven by an homunculus, who drives the homunculus.?
An extreme case would be to describe a process as our mind seeing and
scanning pictures on our visual cortex and telling our legs to start
running, a less obvious case would be to say that the brain interprets
and understands messages sent to it by our sensory organs. Metaphors
should be acknowledged for what they are and never extrapolated to
become real entities.
Pylyshyn criticises the use mental imagery for memory representations,
suggesting that it is adequate to propose abstract mental structures or
symbolic descriptions which are not accessible to our consciousness. He
suggests that propositions are likely to be more robust representations
than appearances of images, and that representations of images are more
like descriptions than pictures. This suggests that our introspection
of an image is something of a construct. Stored images would need to be
scanned by something, a set of propositions would not, they could be
part of an information processing model.
Kosslyn defends imagery by acknowledging that the primitive picture
metaphor should be rejected because of the need for a second, third etc
processing system to interpret the information from the previous
process, but pleading the case for quasi-pictorial images as a "special
kind of functional representation in human memory".
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