Colour constancy with change of viewing distance under water

Colour constancy is commonly considered to be the product both of high-order (cognitive) and of lower-order (retinal) mechanisms. A study is reported of colour appearance in situations where the spectral radiance of an object changes significantly with viewing distance. Subjects were instructed to match the colour appearance of a number of coloured tiles in air and at various viewing distances in different types of water. Colour-constancy ratios were calculated by comparing the visual data with simultaneously obtained spectroradiometric and photometric data. The obtained constancy ratios were attributed to the role of distance estimation in the determination of colour appearance, an effect that is presumably masked under normal viewing conditions, where long viewpaths are necessary to produce significant radiance changes. A similarity to the size-distance invariance hypothesis is noted.     

Ambiguous figures and representationalism

Ambiguous figures pose a problem for representationalists, particularly for representationalists who believe that the content of perceptual experience is non-conceptual (MacPherson in Nous 40(1):82–117, 2006). This is because, in viewing ambiguous figures, subjects have perceptual experiences that differ in phenomenal properties without differing in non-conceptual content. In this paper, I argue that ambiguous figures pose no problem for non-conceptual representationalists. I argue that aspect shifts do not presuppose or require the possession of sophisticated conceptual resources and that, although viewing ambiguous figures often causes a change in phenomenal properties, this change is accompanied by a change in non-conceptual content. I illustrate the case by considering specific examples.     

Colour constancy in goldfish and man: influence of surround size and lightness

Colour constancy was investigated by using a series of 10 simultaneously presented surface colours ranging in small steps from green through gray to red-purple. Goldfish were trained to select one medium test field when the entire setup was illuminated with white light. In the tests, either red or green illumination was used. Colour constancy, as inferred from the choice behaviour, was perfect under green illumination when the test fields were presented on a gray or a white background, but imperfect on a black background. Under red illumination and a white background, however, colour constancy was overcompensated. Here, a colour contrast effect was observed. The influence of background lightness was also found when the surround was restricted to a narrow annulus of 4-11 mm width (test field diameter: 14 mm). By applying colour metrics it could be shown that the von Kries coefficient law can describe the overall effect of colour constancy. For an explanation of the effect of surround size and lightness, lateral inhibitory interactions have to be assumed in addition, which are also responsible for simultaneous colour contrast. Very similar results were obtained in experiments with the same colours in human subjects. They had to name the test field appearing 'neutral' under the different illumination and surround conditions, as tested in the goldfish experiment.     

Visual prominence and representationalism

A common objection to representationalism is that a representationalist view of phenomenal character cannot accommodate the effects that shifts in covert attention have on visual phenomenology: covert attention can make items more visually prominent than they would otherwise be without altering the content of visual experience. Recent empirical work on attention casts doubt on previous attempts to advance this type of objection to representationalism and it also points the way to an alternative development of the objection.     

Ambiguous figures and representationalism

Macpherson (Nous 40(1):82–117, 2006) argues that the square/regular diamond figure threatens representationalism, construed as the theory which holds that the phenomenal character is explained by the nonconceptual content of experience. Her argument is the claim that representationalism is committed to the thesis that differences in the experience of ambiguous figures, the gestalt switch, should be explained by differences in the NCC of perception of these figures. However, with respect to the square/regular diamond and some other ambiguous figure representationalism fails to offer a unified account of how representational content makes them ambiguous. In this paper, I aim, first, to offer a representationalist account of ambiguous figures and, second, to examine and rebut Macpherson’s arguments. My main point is that in each ambiguous figure Macpherson discusses there are differences in representational content that can explain differences in phenomenal character or content. The representational differences are due to the ways the Cartesian frame of reference in which perceptual content is always cast cuts the figure, underlying different properties of the figure with respect to the axes of the Cartesian frame of reference.     

Sameness of Fregean sense

This paper develops a criterion for sameness of Fregean senses. I consider three criteria: logical equivalence, intensional isomorphism, and epistemic equipollence. I reject the first two and argue for a version of the third.     

Fregean Quantification Theory

Frege’s system of first-order logic is presented in a contemporary framework. The system described is distinguished by economy of expression and an unusual syntax.     

Strong representationalism and centered content

I argue that strong representationalism, the view that for a perceptual experience to have a certain phenomenal character just is for it to have a certain representational content (perhaps represented in the right sort of way), encounters two problems: the dual looks problem and the duplication problem. The dual looks problem is this: strong representationalism predicts that how things phenomenally look to the subject reflects the content of the experience. But some objects phenomenally look to both have and not have certain properties, for example, my bracelet may phenomenally look to be circular-shaped and oval-shaped (and hence non-circular-shaped). So, if strong representationalism is true, then the content of my experience ought to represent my bracelet as being both circular-shaped and non-circular-shaped. Yet, intuitively, the content of my experience does not represent my bracelet as being both circular-shaped and non-circular-shaped. The duplication problem is this. On a standard conception of content, spatio-temporally distinct experiences and experiences had by distinct subjects may differ in content despite the fact that they are phenomenally indistinguishable. But this undermines the thesis that phenomenal character determines content. I argue that the two problems can be solved by applying a version of an idea from David Chalmers, which is to recognize the existence of genuinely centered properties in the content of perceptual experience.     

Relativized Propositions and the Fregean Orthodoxy

This paper answer the question how propositions whose truth is relativized to times, places, asserters or assessers can, despite their relativity, be used to represent the world.     

非严格弗雷格自由逻辑

莱曼(S.Lehmann)的1994年的论文从三值逻辑角度处理语言中的空词项。弗雷格认为句子的所指是真值,包含空词项的句子缺乏所指,而只有涵义,那么这样的句子不真也不假。莱曼的文章刻画了弗雷格这一思想,但有两点不尽人意之处:其一、对量词进行特殊处理,使得量词公式是二值的;其二,把包含空词项的复合句一概归于第三值。针对上述两点,本文以一度衍推系统为基础,在语义上,以偏解释函数为基础构造了一个非严格弗雷格中性自由逻辑表列系统,使得量词公式是三值的,同时使得一部分包含空词项的复合公式或真或假。     

论广义弗雷格谜题

在过去50年中,语言哲学家提出了众多新指称理论,似乎我们对名字有了极好的理解,因为克里普克这样的哲学家让我们相信,名字没有涵义,只有指称。①然而,弗雷格1892年的论文《论涵义和所指》中提出的弗雷格之谜,却成了指称论天空上的一朵乌云。弗雷格之谜引起了许多哲学家