Skill theory v2.0: dispositions,emulation, and spatial perception

An attempt is made to defend a general approach to the spatial content of perception, an approach according to which perception is imbued with spatial content in virtue of certain kinds of connections between perceiving organism’s sensory input and its behavioral output. The most important aspect of the defense involves clearly distinguishing two kinds of perceptuo-behavioral skills—the formation of dispositions, and a capacity for emulation. The former, the formation of dispositions, is argued to by the central pivot of spatial content. I provide a neural information processing interpretation of what these dispositions amount to, and describe how dispositions, so understood, are an obvious implementation of Gareth Evans’ proposal on the topic. Furthermore, I describe what sorts of contribution are made by emulation mechanisms, and I also describe exactly how the emulation framework differs from similar but distinct notions with which it is often unhelpfully confused, such as sensorimotor contingencies and forward models.     

面部特征空间关系、肤色亮度对卡通面孔吸引力的影响

选取88名大班儿童（43名女童和45名男童）及90名在校大学生（42名男生和48名女生）为实验被试,通过心理量表评分,探讨面部特征空间关系、肤色和亮度对儿童卡通面孔吸引力影响。结果显示：（1）幼儿与成人对卡通面孔最佳面部特征空间关系评价存在差异;（2）幼儿评价女童卡通面孔眼嘴间距离占面长24%时吸引力最优,两眼间距离占面宽41%时吸引力最优,但未达显著。成人评价女童卡通面孔也存在纵向“黄金比例（19%）”现象;（3）男童卡通面孔不存在最佳比例;（4）幼儿偏爱偏白肤色,而成人偏好白里透红;（5）受众性别与卡通形象性别均对肤色偏好有影响;（6）亮度高的儿童卡通面孔更具吸引力。结论：卡通面孔吸引力受面部特征空间关系、肤色与亮度等因素显著影响,卡通设计需针对不同年龄、性别受众来设定面部特征空间关系与肤色等要素。     

Perception of the color red enhances the force and velocity of motor output

The present research examined whether perception of the color red influences basic motor functioning. Prior research on color and motor functioning has been guided by ill-defined theoretical statements, and has been plagued by methodological problems. Drawing on theoretical and empirical work on the threat-behavior link in human and nonhuman animals, we proposed and tested the prediction that perceiving red enhances the force and velocity of motor output. Experiment 1 demonstrated that red, relative to gray (matched to red on lightness), facilitates pinchgrip force. Experiment 2 demonstrated that red, relative to gray (matched to red on lightness) and blue (matched to red on lightness and chroma) facilitates handgrip force and the velocity of that force. These findings clearly establish a link between red and basic motor action, illustrate the importance of rigorous experimental methods when testing color effects, and highlight the need to attend to the functional, as well as aesthetic, value of color.     

The perception of lightness in 3-D curved objects

Lightness constancy in complex scenes requires that the visual system take account of information concerning variations of illumination falling on visible surfaces. Three experiments on the perception of lightness for three-dimensional (3-D) curved objects show that human observers are better able to perform this accounting for certain scenes than for others. The experiments investigate the effect of object curvature, illumination direction, and object shape on lightness perception. Lightness constancy was quite good when a rich local gray-level context was provided. Deviations occurred when both illumination and reflectance changed along the surface of the objects. Does the perception of a 3-D surface and illuminant layout help calibrate lightness judgments? Our results showed a small but consistent improvement between lightness matches on ellipsoid shapes, relative to flat rectangle shapes, under illumination conditions that produce similar image gradients. Illumination change over 3-D forms is therefore taken into account in lightness perception.     

Sellars and Nonconceptual Content

In this paper I take up the question of whether Wilfrid Sellars has a notion of non‐conceptual perceptual content. The question is controversial, being one of the fault lines along which so‐called left and right Sellarsians diverge. In the paper I try to make clear what it is in Sellars' thought that leads interpreters to such disparate conclusions. My account depends on highlighting the importance of Sellars' little discussed thesis that perception involves a systematic form of mis‐categorization, one where perceivers mistake their sensory states to be properties of physical objects. I argue that the counterpart color and shape attributes of these states, which become ‘point of viewish’ when organized by the productive imagination, provides perceptual experience with its non‐conceptual representational content. I then argue that this content is not a form of the mythical Given because one can only have a non‐conceptual point of view on an object when an object is introduced into one's perceptual experience through the conceptual mis‐taking of one's sensory states. So, while Sellars has a notion of non‐conceptual representational content, it can only be salient in the context of a perceptual act that is conceptual overall.     

When does perceived lightness depend on perceived spatial arrangement?

Experiments have recently been reported in which a decisive change in perceived lightness was produced by a change in perceived spatial position, with no important change in the retinal image. A number of previous studies had found little or no such effect. Experiments of the kind that produced these effects and of the kind that do not produce these effects are presented here. The main differences between these two kinds of experiments are discussed. One difference is whether the display allows the target to be part of one ratio in one spatial position but another in the other spatial position. Another difference concerns the range of luminances within the display. Also discussed are the implications of these findings for cognitive vs. S-R theories, the order of processing depth and lightness, laboratory data vs. experience, the role of lateral inhibition in lightness perception, and theories of lightness perception in general.     

The Real Foundation of Fictional Worlds

I argue that judgments of what is ‘true in a fiction’ presuppose the Reality Assumption: the assumption that everything that is (really) true is fictionally the case, unless excluded by the work. By contrast with the more familiar Reality Principle, the Reality Assumption is not a rule for inferring implied content from what is explicit. Instead, it provides an array of real-world truths that can be used in such inferences. I claim that the Reality Assumption is essential to our ability to understand stories, drawing on a range of empirical evidence that demonstrates our reliance on it in narrative comprehension. However, the Reality Assumption has several unintuitive consequences, not least that what is fictionally the case includes countless facts that neither authors nor readers could (or should) ever consider. I argue that such consequences provide no reason to reject the Reality Assumption. I conclude that we should take fictions, like non-fictions, to be about the real world.     

An empirical study of the traditional Mach card effect

The traditional achromatic Mach card effect is an example of lightness inconstancy and a demonstration of how shape and lightness perception interact. We present a quantitative study of this phenomenon and explore the conditions under which it occurs. The results demonstrate that observers show lightness constancy only when sufficient information is available about the light-source position, and the perceptual task required of them is surface identification rather than direct colour-appearance matching. An analysis and comparison of these results with the chromatic Mach card effect (Bloj et al 1999 Nature 402 877-879) demonstrate that the luminance effects of mutual illumination do not account for the change in lightness perception in the traditional Mach card.     

Photometric, geometric, and perceptual factors in illumination-independent lightness constancy

It has been shown that lightness constancy depends on the articulation of the visual field (Agostini & Galmonte, 1999). However, among researchers there is little agreement about the meaning of "articulation." Beyond the terminological heterogeneity, an important issue remains: What factors are relevant for the stability of surface color perception? Using stimuli with two fields of illumination, we explore this issue in three experiments. In Experiment 1, we manipulated the number of luminances, the number of reflectances, and the number of surfaces and their spatial relationships; in Experiment 2, we manipulated the luminance range; finally, in Experiment 3 we varied the number of surfaces crossed by the illumination edge. We found that there are two relevant factors in optimizing lightness constancy: (1) the lowest luminance in shadow and (2) the co-presence of patches of equal reflectance in both fields of illumination. The latter effect is larger if these patches strongly belong to each other. We interpret these findings within the albedo hypothesis.     

Color perception involves color representations firstly at a semantic level and then at a lexical level

Studies and models have suggested that color perception first involves access to semantic representations of color. This result leads to two questions: (1) is knowledge able to influence the perception of color when associated with a color? and (2) can the perception of color really involve only semantic representations? We developed an experiment where participants have to discriminate the color of a patch (yellow vs. green). The target patch is preceded either by a black-and-white line drawing or by a word representing a natural object associated with the same or a different color (banana vs. frog). We expected a priming effect for pictures because, with a 350-ms SOA, they only involve access to semantic representations of color, whereas words seem only elicit an access to lexical representations. As expected, we found a priming effect for pictures, but also for words. Moreover, we found a general slowdown of response times in the word-prime-condition suggesting the need of an additional processing step to produce priming. In a second experiment, we manipulated the SOA in order to preclude a semantic access in the word-prime-condition that could explain the additional step of processing. We also found a priming effect, suggesting that interaction with perception occurs at a lexical level and the additional step occurs at a color perception level. In the discussion, we develop a new model of color perception assuming that color perception involves access to semantic representations and then access to lexical representations.     

Lightness compression and hue changes

Two experiments were performed to relate the Bezold-Brücke (B-B) and lightness compression effects. The first used a calibrated screen to present an achromatic luminance staircase. In addition, it reproduced, the methodology and the essential aspects the lightness compression effect discovered by Cataliotti and Gilchrist (1995). That is, observers perceived a truncated grey scale (from white to medium grey) when the staircase was the only stimulation in the near background (Gelb condition), but not when presented on a Mondrian background, because of the high articulation level provided by this background. Experiment 1 design also included two other backgrounds that produced a partial compression effect. In Experiment 2, two chromatic staircases were used. Employing a naming task, changes in hue perception were only observed for the susceptible staircase. The observed changes were of two types. First, for the full staircase presentations, a Gelb background produced maximum lightness compression (more similarity in the lightness of the staircase stimuli) and, also, a minimum B-B effect (fewer differences in hue). Second, only for the Gelb condition, there were changes in the hue of the lowest luminance staircase stimuli depending on the staircase extension. Results are discussed in the framework of the anchoring theory of lightness perception.     

Aesthetic response to color combinations: preference, harmony, and similarity

Previous studies of preference for and harmony of color combinations have produced confusing results. For example, some claim that harmony increases with hue similarity, whereas others claim that it decreases. We argue that such confusions are resolved by distinguishing among three types of judgments about color pairs: (1) preference for the pair as a whole, (2) harmony of the pair as a whole, and (3) preference for its figural color when viewed against its colored background. Empirical support for this distinction shows that pair preference and harmony both increase as hue similarity increases, but preference relies more strongly on component color preference and lightness contrast. Although pairs with highly contrastive hues are generally judged to be neither preferable nor harmonious, figural color preference ratings increase as hue contrast with the background increases. The present results thus refine and clarify some of the best-known and most contentious claims of color theorists.     

The effects of global grouping laws on surface lightness perception

Previous studies of lightness perception have shown that local surface grouping laws such as proximity and T junction were powerful determinants of target surface lightness. Recent lightness theories also emphasize the importance of local grouping of surfaces. In this study, we further examined the effects of three global grouping laws--symmetry, repetition, and alternation--on lightness perception. Local surface grouping laws such as proximity and good continuation were controlled across all of our stimulus displays. Participants' lightness perception consistently depended on a given surface's belongingness as determined by these laws--that is, global grouping laws affected a target surface's lightness perception. Our results indicate that global grouping laws determine a target surface's lightness when local surface grouping does not produce any distinct surface belongingness. Implications of our basic results are discussed in terms of a recent lightness theory.     

Book Reviews

Abstract

The aim of this paper is to identify what I take to be the main conceptual problem in Lewis’ semantics for counterfactuals when the Limit Assumption (LA) is not satisfied, what I call the Discrimination Problem (DP), and to present and discuss a modification of Lewis’ semantics that aims at solving DP. First, I outline Lewis’ semantics, highlighting the aspects that will be relevant for our discussion. Second, I present DP and discuss it with a heuristic example. Third, I present the new proposal and comment some formal consequences and the objections they give rise to. Fourth, I present an allegedly equivalent version of the proposal and discuss the difference between counterfactuals and strict conditionals. Finally, I defend that the two proposals are different and argue for the first one as the best way of capturing two intuitions that seem in conflict when the LA is not satisfied. I conclude with a dilemma: either the proposal here defended works or LA is inescapable. Thus, if the proposal doesn’t work, the paper must then be considered as an indirect defense of the Limit Assumption.     

The Senses as Signalling Systems

A central goal of the philosophy of perception is to uncover the nature of sensory capacities. Ideally, we would like an account that specifies what conditions need to be met in order for an organism to count as having the capacity to sense or perceive its environment. And, on the assumption that sensory states are the kinds of things that can be accurate or inaccurate, a further goal of the philosophy of perception is to identify the accuracy conditions for sensory states. In this paper I recommend a novel approach to these core issues, one that draws heavily on game-theoretic treatments of signalling in nature. A benefit of the approach is that it helps us to understand why biologists attribute sensory powers to such a diverse range of organisms, including plants, fungi, and algae.     

FREE WILL AND LUCK

I present an account of how agents can know what they are doing when they intentionally execute object-oriented actions. When an agent executes an object-oriented intentional action, she uses perception in such a way that it can fulfil a justificatory role for her knowledge of her own action and it can fulfil this justificatory role without being inferentially linked to the cognitive states that it justifies. I argue for this proposal by meeting two challenges: in an agent's knowledge of her action perception can only play an enabling role (and no justificatory role) for the agent's knowledge and if perception has a justificatory role, then the agent's knowledge must be inferential.     

Perceptual organization and White's illusion

The apparent lightness of a surface can be strongly modulated by the spatial context in which it is embedded. Early theories of such context dependence emphasized the role of low-level mechanisms that sense border contrast, whereas a number of recent authors have emphasized the role of perceptual organization in determining perceived lightness. One of the simplest and most theoretically challenging lightness illusions was described by White. This illusion has been explained with a variety of different models, ranging from low-level filter outputs to computations underlying the extraction of mid-level representations of surfaces. Here, I present a new method for determining the organizational forces that shape this illusion. I show that the spatial context of White's pattern not only transforms the apparent lightness of homogeneous target patches. but can also induce dramatic inversions of figure-ground relationships of textured target regions. These phenomena provide new evidence for the role of scission in causing the lightness illusion experienced in White's effect.     

The Relationship Between Visual Illusion and Aesthetic Preference – an Attempt to Unify Experimental Phenomenology and Empirical Aesthetics

Experimental phenomenology has demonstrated that perception is much richer than stimulus. As is seen in color perception, one and the same stimulus provides more than several modes of appearance or perceptual dimensions. Similarly, there are various perceptual dimensions in form perception. Even a simple geometrical figure inducing visual illusion gives not only perceptual impressions of size, shape, slant, depth, and orientation, but also affective or aesthetic impressions. The present study reviews our experimental phenomenological work on visual illusion and experimental aesthetics, and examines how aesthetic preference is influenced by stimulus factors determining visual illusions including anomalous surface and transparency as well as geometrical illusion. Along with line figures producing geometrical illusions, illusory surface figures inducing neon color spreading and transparency effects were used as test patterns. Participants made both of psychophysical judgments and of aesthetic judgments for the same test pattern. Both of geometrical illusions and aesthetic preferences were found to change similarly as a function of stimulus variables such as the number of filling lines and the size ratio of the inner and outer figural components. Also, following specific stimulus variables such as lightness contrast ratio and spatial interval between inducing figural elements (so called ``packmen''), strong effects of color spreading and transparency were accompanied with strong preferences. It seems that the paradigm to investigate aesthetic phenomena along with perceptual dimensions is useful to bridge the gap between experimental phenomenology and experimental aesthetics.