A number of philosophers have held that we visually experience objects’ occluded parts, such as the out-of-view exterior of a voluminous, opaque object. That idea is supposed to be what best explains the fact that we see objects as whole or complete despite having only a part of them in view at any given moment. Yet, the claim doesn’t express a phenomenological datum and the reasons for thinking we do experience objects’ occluded parts, I argue, aren’t compelling. Additionally, I anticipate and reply to attempts to salvage the idea by appeal to perceptual expectation and amodal completion. Lastly, I address potential concerns that the only way to capture the phenomenal character of perceiving voluminous objects is to say experience outstrips what’s in view, providing a description of such experience without any implication of that idea.

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 (1990) and Simmons (2003)—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.

Use of virtual reality (VR) is considered beneficial for reviewing 3D models throughout product design. However, research on its usability in the design field is still explorative, and previous studies are often contradictory regarding the usability of VR for 3D model review. This paper argues that the usability of VR should be assessed by analysing human factors such as spatial perception and taking into consideration the complexity of the reviewed product. Hence, a comparative evaluation study has been conducted to assess spatial perception in desktop interface-based and VR-based review of 3D models of products with different levels of complexity. The results show that participants in VR more could perceive the fit of user interface elements, and estimation of the model dimensions had a lower relative error than in desktop interface. It has been found that various sensory cues are used to perceive the model size and that the employed sensory cues depend on the level of complexity. Finally, it is proposed that differences between a desktop interface and VR for reviewing models are more evident when reviewing models of higher complexity levels.

Proffitt, Stefanucci, Banton, and Epstein (2003) reported a set of studies showing that the perceived distance to a target is influenced by the effort required to walk to its location. Hutchison and Loomis (H&L) reported an experiment that failed to find a significant influence of effort on indices of apparent distance. There were numerous important differences between the design and methods of H&L's study and those of Proffitt et al. Moreover, there are important theoretical reasons to believe that these differences were responsible for the different results. The theoretical motivation of H&L's studies was also brought into question.

While acknowledging that their design and methods were different from the original Proffitt, Stefanucci, Banton, and Epstein (2003) study, Hutchison and Loomis (H&L) continue to argue that their findings qualify our account of energetic influences on distance perception. This reply provides a brief and focused discussion of the methodological differences between their study and ours and why these differences were likely responsible for the different results. It is also argued that the measures employed by H&L are assessments of apparent location, not apparent distance.

Posterior parietal cortex has traditionally been considered to be a sensory association area in which higher-order processing and intermodal integration of incoming sensory information occurs. In this paper, evidence from clinical reports and from lesion and behavioral-electrophysiological experiments using monkeys is reviewed and discussed in relation to the overall functional organization of posterior parietal association cortex, and particularly with respect to a proposed posterior parietal mechanism concerned with the initiation and control of certain classes of eye and limb movements. Preliminary data from studies of the effects of posterior parietal lesions on oculomotor control in monkeys are reported.

The behavioral effects of lesions of posterior parietal cortex in monkeys have been found to be similar to those which follow analogous damage of the minor hemisphere in humans, while behavioral-electrophysiological experiments have disclosed classes of neurons in this area which have functional properties closely related to the behavioral acts that are disrupted by lesions of the area. On the basis of current data from these areas of study, it is proposed that the sensory association model of posterior parietal function is inadequate to account for the complexities of the present evidence. Instead, it now appears that many diverse neural mechanisms are located in part in parietal cortex, that some of these mechanisms are involved in sensory processing and perceptual functions, but that others participate in motor control, and that still others are involved in attentional, motivational, or emotional processes. It is further proposed that the elementary units of these various neural mechanisms are distributed within posterior parietal cortex according to the columnar hypothesis of Mountcastle.