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

processes are visual in nature: for instance, mental images can be scanned, inspected
at different apparent sizes, or rotated. The coupling of such processes with the depictive
structure of images is well-suited to solving visuospatial problems. Other structure-process
pairings—in particular, logical operations on propositional expressions
that describe spatial properties (Pylyshyn, 1973)—do not make spatial information
explicit and arguably will not be as adept at solving visuospatial problems. Kosslyn
(1980, p. 35) called the structural properties of images privileged because their possession
“[distinguishes] an image from other forms of representation.”
That the depictive theory makes claims about the primitive properties of mental
images indicates quite clearly that it is an account of cognitive architecture. That it
is a theory about architecture is further supported by the fact that the latest phase of
imagery research has involved the supplementing behavioural data with evidence
concerning the cognitive neuroscience of imagery (Kosslyn, 1994; Kosslyn et al.,
1995; Kosslyn et al., 1999; Kosslyn, Thompson, & Alpert, 1997; Kosslyn, Thompson,
& Ganis, 2006). This research has attempted to ground the architectural properties
of images into topographically organized regions of the cortex.
Computer simulation has proven to be a key medium for evaluating the depictive
theory of mental imagery. Beginning with work in the late 1970s (Kosslyn &
Shwartz, 1977), the privileged properties of mental images have been converted into
a working computer model (Kosslyn, 1980, 1987, 1994; Kosslyn et al., 1984; Kosslyn
et al., 1985). In general terms, over time these models represent an elaboration of
a general theoretical structure: long-term memory uses propositional structures to
store spatial information. Image construction processes convert this propositional
information into depictive representations on a spatial medium that enforces the
primitive structural properties of images. Separate from this medium are primitive
processes that operate on the depicted information (e.g., scan, inspect, interpret).
This form of model has shown that the privileged properties of images that define
the depictive theory are sufficient for simulating a wide variety of the regularities
that govern mental imagery.
The last few paragraphs have introduced Kosslyn’s (e.g., 1980) depictive theory,
its proposals about the privileged properties of mental images, and the success that
computer simulations derived from this theory have had at modelling behavioural
results. All of these topics concern statements about primitives in the domain of a
theory or model about mental imagery. Let us now turn to one issue that has not
yet been addressed: the nature of the primitives employed by the modelled subject,
the human imager.
The status of privileged properties espoused by the depictive theory has been
the subject of a decades-long imagery debate (Block, 1981; Tye, 1991). At the heart
of the imagery debate is a basic question: are the privileged properties parts of the
architecture or not? The imagery debate began with the publication of a seminal
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