temporal lobes. These two streams are then pooled in an associative
memory system (in the posterior superior temporal lobes), which also
contains conceptual information, where they are matched to stored data.
At this stage object recognition may well take place. But if recognition is
not immediately achieved, a search through stored data, guided by the
partial object-information already available, then occurs. Object-repre-
sentations are projected back down through the visual system to the
occipital lobes, shifting visual attention, and asking relevant questions of
the visual input. This last stage is subserved by a rich network of back-
ward-projecting neural pathways from the ‘higher’, more abstract, visual
areas of the brain to the occipital cortex. And it is this last stage which is
exploited in visual imagination, on Kosslyn’s account. A conceptual or
other non-visual representation (of the letter ‘A’, as it might be) is projec-
ted back through the visual system in such a way as to generate activity in
the occipital cortex (just as if a letter ‘A’ were being perceived). This
activity is then processed by the visual system in the normal way to yield a
quasi-visual percept.
Note that hardly anyone is likely to maintain that visual imagery is a
mere epiphenomenon of central cognitive reasoning processes, playing no
real role in those processes in its own right. On the contrary, it seems likely
that there are many tasks which cannot easily be solved by us without
deploying a visual (or other) image. Thus, suppose you are asked (orally)
to describe the shape which is enclosed within the capital letter ‘A’. It seems
entirely plausible that success in this task should require the generation of
a visual image of that letter, from which the answer (‘a triangle’) can then
be read oV. So it certainly appears that central cognition functions, in part,
by co-opting the resources of the visual system to generate visual represen-
tations, which can be of use in solving a variety of spatial-reasoning tasks.
And this then opens up the very real possibility that central cognition may
alsodeploy the resources of thelanguagesystem to generate represen-
tations of natural language sentences (in ‘inner speech’), which can similar-
ly be of use in a variety ofconceptualreasoning tasks.
The third reason mentioned above for denying that natural language is
constitutively involved in central cognition – namely that non-linguistic
animals are in fact capable of thought – also establishes little. For everyone
is prepared to allow that there are thought-processes distinctive of hu-
mans. (One candidate would beexplicitas opposed toimplicitly enter-
tainedthoughts, tokened in such a way as to be promiscuously available to
other cognitive processes; another would beconsciousas opposed to
non-consciousthoughts, which are available to higher-order reXection; and
there are presumably also a number of particular domains which can only
be thought about by humans, with their distinctive conceptual resources
210 Forms of representation