According to an influential philosophical view I call “the relational properties view”, “perspectival” properties, such as the elliptical appearance of a tilted coin, are relational properties of external objects. Philosophers have assessed this view on the basis of phenomenological, epistemological or other purely philosophical considerations. My aim in this paper is to examine whether it is possible to evaluate RPV empirically. In the first, negative part of the paper I consider and reject a certain tempting way of doing so. In (...) the second, positive part of the paper I suggest a novel way of evaluating RPV empirically, relying on the influential object files framework. (shrink)

A judge springs out of his car on the way to court in downtown Chicago and takes photographs of an inflatable rat. A while later he inserts these photographs into a decision involving another inflatable rodent. Judges now regularly insert pictures in judgments, but there is no study either of the genres or the precedential status of these modern visual emblemata, these pictorial interventions in the record. Using a comparative visual corpus of over three hundred images extracted from diverse common (...) law jurisdictions, the practice of retinal justice, the novelty of vision in decision, is here anatomized, choreographed, and critically classified. (shrink)

How does neuronal activity give rise to cognitive capacities? To address this question, neuroscientists hypothesize about what neurons “represent,” “encode,” or “compute,” and test these hypotheses empirically. This process is similar to the assessment of hypotheses in other fields of science and as such is subject to the same limitations and difficulties that have been discussed at length by philosophers of science. In this paper, we highlight an additional difficulty in the process of empirical assessment of hypotheses that is unique (...) to the cognitive sciences. We argue that, unlike in other scientific fields, comparing hypotheses according to the extent to which they explain or predict empirical data can lead to absurd results. Other considerations, which are perhaps more subjective, must be taken into account. We focus on one such consideration, which is the purposeful function of the neurons as part of a biological system. We believe that progress in neuroscience critically depends on properly addressing this difficulty. (shrink)

It may be possible, one day, to use gene therapy to treat diseases whose genetic defects have been discerned. Because many genes responsible for inherited eye disorders within the retina have been identified, diseases of the eye are prime candidates for this form of therapy. The eye also has the advantage of being highly accessible with altered immunological properties, important considerations for easy delivery of virus and avoidance of systemic immune responses. Currently, adenovirus, adeno‐associated virus and lentivirus have been used (...) to successfully transfer genetic material to retinal pigment epithelium and photoreceptor cells. By harnessing therapeutic genes to these viruses, researchers have been able to demonstrate rescue in rodent models of retinitis pigmentosa, providing evidence that this form of therapy can be effective in delaying photoreceptor cell death. Future challenges include confirming therapeutic effects in animal models with eyes more anatomically similar to those of humans and demonstrating long‐term rescue with minimal toxicity. BioEssays 23:662–668, 2001. © 2001 John Wiley & Sons, Inc. (shrink)

Metamorphosis in frogs is a critical developmental process through which a tadpole changes into an adult froglet. Metamorphic changes include external morphological transformations as well as important changes in the wiring of sensory organs and central nervous system. This review aims to provide an overview on the events that occur in the visual system of metamorphosing amphibians and to discuss recent studies that provide new insight into the molecular mechanisms that control changes in the retinal growth pattern as well (...) as the formation of new axonal pathways in the central nervous system. BioEssays 23:319–326, 2001. © 2001 John Wiley & Sons, Inc. (shrink)

Diseases causing inherited retinal degeneration in humans, such as retinitis pigmentosa and macular dystrophy, are genetically heterogeneous and clinically diverse. More than 40 genes causing retinal degeneration have been mapped to specific chromosomal sites; of these, at least 10 have been cloned and characterized. Mutations in two proteins, rhodopsin and peripherin/RDS, account for approximately 35% of all cases of autosomal dominant retinitis pigmentosa and a lesser fraction of other retinal conditions. This target article reviews the genes and (...) mutations causing retinal degeneration and proposes mechanisms whereby specific mutations lead to particular clinical consequences, that is, the relationship between genotype and phenotype. Retinitis pigmentosa and macular dystrophy are genetically heterogeneous diseases that cause retinal degeneration in humans and often result in severe visual impairment or blindness. Although many of the genes causing these diseases have not been identified, three photoreceptor-specific proteins have been implicated: rhodopsin, peripherin/RDS, and the P-subunit of rod phosphodiesterase. Mutations in the genes for these three proteins can cause either dominant retinitis pigmentosa, recessive retinitis pigmentosa, dominant congenital stationary night blindness, or dominant macular degeneration. Why this multiplicity of clinical phenotypes? Our target article summarizes the genetic and biochemical background to this question and proposes a number of possible explanations. Discussion focuses mainly on 73 distinct disease-causing mutations of rhodopsin. We feel that rhodopsin and other photoreceptor proteins can serve as model systems for unraveling the connection between genotype and phenotype, not only for inherited retinal diseases but for other degenerative disorders as well. (shrink)

The world perceived by a person undergoing vision without inversion of the retinal image has traditionally been described as inverted. Drawing on the philosophical work of Maurice Merleau-Ponty and the empirical research of Hubert Dolezal, I argue that this description is more reflective of a representationist conception of vision than of actual visual experience. The world initially perceived in vision without inversion of the retinal image is better described as lacking in lived significance rather than inverted; vision without (...) inversion of the retinal image affects the very content of the perceived world, including, importantly, its expressions and conducts, and not merely the orientation of this content. Moreover, I argue that the enactive approach, rather than a representationist approach, is best able to account for the perception of the world, after prolonged vision without inversion of the retinal image, as both normal and upright, yet still different from the world seen previously. Finally, in their attention to the perception of other people’s facial expressions, I argue that Merleau-Ponty and Dolezal draw out the existential significance of the enactive approach. In encountering another person, the most pressing task is generally not to observe this person’s features but, instead, to engage with this person’s expressions. (shrink)

Sensorimotor theorists of perception have argued that eye movement is a necessary condition for seeing on the basis that subjects whose retinal images do not move undergo a form of blindness. I show that the argument does not work.

La personalità di Shitao, pittore cinese attivo durante l’inizio della dinastia Qing, merita di essere compresa nella comparazione della sua particolare vita, del suo lavoro artistico – soprattutto nella fase di piena espressione, – e dei pensieri filosofici che ha rivelato nei suoi Discorsi sulla pittura. A partire dall’unione di questi fattori, Shitao stesso stabilì un legame tra l’«unico tratto di pennello» e l’olistica fusione del suo spirito con la natura.

This paper argues that the distinctiveness of the Hering primary hues—red, green, blue, and yellow—is already evident at the retina. Basic features of spectral sensitivity provide a foundation for the development of unique hue perceptions and the hue categories of which they are focal examples. Of particular importance are locations in color space at which points of minimal and maximal spectral sensitivity and extreme ratios of chromatic to achromatic response occur. This account builds on Jameson and D’Andrade’s (1997) insight about (...) the relationship between the Hering primaries and chromatic/achromatic ratios, Romney and Chiao’s (2009) color appearance model, and Thornton’s (1971, 1999) research on artificial lighting. (shrink)

Cognition or higher brain activity is sometimes seen as a phenomenon greater than the sum of its parts. This viewpoint however is largely dependent on the state of the art of experimental techniques that endeavor to characterize morphology and its association to function. Retinal ganglion cells are readily accessible for this work and we discuss recent advances in computational techniques in identifying novel parameters that describe structural attributes possibly associated with specific function. These parameters are based on calculating wavelet (...) gradients from cell images followed by the extraction of meaningful measures including 2nd wavelet moment, entropy of orientation, and curvature. For the three cell types analyzed, the mean 2nd wavelet moment, which relates to the field of influence of the dendritic-tree segments was significantly different. cells had the highest mean 2nd wavelet moment, followed by the and cells (134 ± 22, 93 ± 19 and 63 ± 12, respectively). There was no significant difference between cells for entropy of orientation, indicating no class with a preferential orientation of their dendritic tree. Curvature provided similar results to the 2nd wavelet moment with cells having the highest curvature followed by and the cells (mean ± SD: 161 ± 15; 134 ± 22; 121 ± 15). Our feature space analysis also indicated a difference between these cell types. No difference was found between the and cell types and their physiological counterparts the Y and X cells based on wavelet analysis. Both the X and Y cells can be divided into two subtypes, the ON- and OFF-center cells based on the stratification level of the dendritic tree within the retina. Using 2nd wavelet moment, a difference in their morphological attributes, not reported previously, was noted for these subtypes. The 2nd wavelet moment and curvature are further discussed with respect to explaining regularity of spacing and coverage associated with retinal ganglion cell mosaics. (shrink)