By further distinguishing between primary and secondary epistemic seeing, we try
to analyze the subtle ways in which an individual’s knowledge arises from visual per-
ception and how visual knowledge interacts with non-visual knowledge. In Chapter 6,
we argue that the key towards understanding the modularity of visuomotor representa-
tions is that in a visuomotor representation of a target for action, the visual information
about the shape, size and orientation of the target is trapped in a representation of its
location coded in an egocentric frame of reference. Only by recoding the location of an
object in allocentric coordinates can the visual information about the shape, size and
orientation of an object be available for perceptual processing.
In the early 1980s, electrophysiological and behavioral evidence from macaque
monkeys demonstrated the existence of two separate pathways in the primate visual
system: the ventral pathway and the dorsal pathway. Then in the early 1990s, the
in-depth neuropsychological study of brain-lesioned human patients provided evidence
for the view that the former underlies visual perception, whereas the latter underlies
the visuomotor transformation. We depart from the earlier model of the distinction
between vision-for-perception and vision-for-action in several respects. First of all, as we
have already said, humans can see a great variety of things (including, rivers, substances,
clouds, vapors, smoke, movies, events and actions), only a few of which they can
also grasp and manipulate. On our view, the dualistic model of human vision, accord-
ing to which one and the same object can be visually processed either for the purpose
of visual perception or for the purpose of visual action, primarily applies to the vision
of objects that can be perceived, reached and grasped. As it turns out, seeing human
actions raises issues that cannot be properly understood on the basis of the restricted
duality between the visual perception of objects and the visuomotor trans-
formation. Second, we emphasize the fact that, in the visual life of normally sighted
human adults, perceptual and motor processing of visual inputs do almost always
collaborate. Thirdy, we think that the anatomical distinction between the ventral path-
way and the dorsal pathway, which, according to the earlier dualistic model, underlies
vision-for-perception and vision-for-action, must accommodate the distinction between
the visuomotor transformation and the perceptual processing of spatial properties and
relations among objects. In particular, it must accommodate the dual role of the parietal
lobe, which is both involved in the visuomotor transformation and in the perception of
spatial relationships. Finally, in our view, the visuomotor transformation is but a first
lower level component of the human ‘pragmatic processing’ of objects. We contrast this
lower level pragmatic processing with a higher level pragmatic processing of objects
involved in the skilled use and manipulation of complex cultural tools and artifacts.
Thus, in our view, there is a parallelism between levels of semantic processing and
levels of pragmatic processing. Lower level visuomotor processing stands to higher
level pragmatic processing of objects somewhat as non-epistemic seeing stands to
epistemic seeing on the perceptual side. This parallelism is corroborated by the
neuropsychological evidence. The term ‘agnosia’ was coined by Sigmund Freud to refer
to a visual perceptual impairment. Neuropsychologists make a distinction between
‘apperceptive’ agnosic patients and ‘associative’ agnosic patients. Apperceptive agnosic
patients have a deeper perceptual impairment than associative agnosic patients: the
former fail to process the elementary visual attributes of objects. Although the latter can
process most of the elementary visual attributes of objects (such as their size, shape and
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