Mind, Body, World- Foundations of Cognitive Science, 2013a

with embodied cognitive science. Pylyshyn’s theory also accounts for such actions,
because FINSTs are presumed to exist in different sensory modalities. In particular,
ANCHORs are analogous to FINSTs and serve as indices to places in motor-command
space, or in proprioceptive space (Pylyshyn, 1989). The role of ANCHORs is
to serve as indices to which motor movements can be directed. For instance, in the
1989 version of his theory, Pylyshyn hypothesized that ANCHORs could be used to
direct the gaze (by moving the fovea to the ANCHOR) or to direct a pointer.
The need for multimodal indexing is obvious because we can easily point at
what we are looking at. Conversely, if we are not looking at something, it cannot
be indexed, and therefore cannot be pointed to as accurately. For instance, when
subjects view an array of target objects in a room, close their eyes, and then imagine
viewing the objects from a novel vantage point (a rotation from their original
position), their accuracy in pointing to the targets decreases (Rieser, 1989).
Similarly, there are substantial differences between reaches towards visible objects
and reaches towards objects that are no longer visible but are only present through
imagery or memory (Goodale, Jakobson, & Keillor, 1994). Likewise, when subjects
reach towards an object while avoiding obstacles, visual feedback is exploited to
optimize performance; when visual feedback is not available, the reaching behaviour
changes dramatically (Chapman & Goodale, 2010).
In Pylyshyn’s (2003b, 2007) theory of visual cognition, coordination between
vision and action occurs via interactions between visual and motor indices, which
generate mappings between the spaces of the different kinds of indices. Requiring
transformations between spatial systems makes the location of indexing and tracking
mechanisms in parietal cortex perfectly sensible. This is because there is a great
deal of evidence suggesting that parietal cortex instantiates a variety of spatial mappings,
and that one of its key roles is to compute transformations between different
spatial representations (Andersen et al., 1997; Colby & Goldberg, 1999; Merriam,
Genovese, & Colby, 2003; Merriam & Colby, 2005). One such transformation could
produce coordination between visual FINSTs and motor ANCHORs.
One reason that Pylyshyn’s (2003b, 2007) theory of visual cognition is also concerned
with visually guided action is his awareness of Goodale’s work on visuomotor
modules (Goodale, 1988, 1990, 1995; Goodale & Humphrey, 1998; Goodale et al.,
1991), work that was introduced earlier in relation to embodied cognitive science.
The evidence supporting Goodale’s notion of visuomotor modules clearly indicates
that some of the visual information used to control actions is not available
to isotropic cognitive processes, because it can affect actions without requiring or
producing conscious awareness. It seems very natural, then, to include motor indices
(i.e., ANCHORs) in a theory in which such tags are assigned and maintained
preattentively.
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