According to Kepler and Descartes, the geometry of the triangle formed by the two eyes when focused on a single point affords perception of the distance to that point. Kepler characterized the processes involved as associative learning. Descartes described the processes as a “ natural geometry.” Many interpreters have Descartes holding that perceivers calculate the distance to the focal point using angle-side-angle, calculations that are reduced to unnoticed mental habits in adult vision. This article offers a purely psychophysiological interpretation of (...) Descartes’s natural geometry. In his account of perceived limb position from the Treatise on Man, he envisioned a central brain state that controls ocular convergence and thereby co-varies with the distance from observer to object. A psychophysiological law relates the visual perception of distance to this brain state. Descartes also invokes more traditional theories of distance and size perception based on unnoticed judgments, yielding a hybrid account. (shrink)

How does Descartes characterize the peculiar way in which each of us is aware of our bodies? I argue that Descartes recognizes a sense of bodily ownership, such that the body sensorily appears to be one's own in bodily awareness. This sensory appearance of ownership is ubiquitous, for Descartes, in that bodily awareness always confers a sense of ownership. This appearance is confused, in so far as bodily awareness simultaneously represents the subject as identical to, partially composed by, and united (...) to her body, without distinguishing these relations. Finally, the appearance of ownership is grounded in multiple other ways in which the body sensorily appears: namely, in the fact that the body appears to be inescapable, modified by bodily sensations, and an object of special concern. (shrink)

Malebranche holds that visual experience represents the size of objects relative to the perceiver's body and does not represent objects as having intrinsic or nonrelational spatial magnitudes. I argue that Malebranche's case for this body-relative thesis is more sophisticated than other commentators—most notably, Atherton and Simmons —have presented it. Malebranche's central argument relies on the possibility of perceptual variation with respect to size. He uses two thought experiments to show that perceivers of different sizes—namely, miniature people, giants, and typical human (...) beings—can experience the very same objects as having radically different sizes. Malebranche argues that there is no principled reason to privilege one of these ways of experiencing size over the others and, more specifically, that all three kinds of perceivers experience size veridically. From the possibility of this kind of veridical perceptual variation, Malebranche infers that visual experience represents only body-relative size. (shrink)

It is natural to assume that the fine-grained and highly accurate spatial information present in visual experience is often used to guide our bodily actions. Yet this assumption has been challenged by proponents of the Two Visual Systems Hypothesis , according to which visuomotor programming is the responsibility of a “zombie” processing stream whose sources of bottom-up spatial information are entirely non-conscious . In many formulations of TVSH, the role of conscious vision in action is limited to “recognizing objects, selecting (...) targets for action, and determining what kinds of action, broadly speaking, to perform” . Our aim in this study is to show that the available evidence not only fails to support this dichotomous view but actually reveals a significant role for conscious vision in motor programming, especially for actions that require deliberate attention. (shrink)

Mary Astell (1666-1731) relies on a Cartesian account of the self to argue that both men and women are essentially thinking things and, hence, that both should perfect their minds or intellects. This account of the self might seem to ignore the inescapable fact that we have bodies. I argue that Astell accommodates the self’s embodiment along three dimensions. First, she tempers her sharp distinction between mind and body by insisting on their union. Second, she argues that the mind-body union (...) is good, at least when the body obeys the mind. Third, though Astell identifies the self with the mind, she identifies the person with the combination of mind and body. (shrink)