Affordances as Properties of the Animal-Environment System

In this article, I argue that affordances are properties of the animal-environment system, that is, that they are emergent properties that do not inhere in either the environment or the animal. I critique and review the formal definition of affordance offered by Turvey (1992). Turvey defined affordances as properties of the environment; I discuss some consequences of this and argue that Turvey's strategy of grounding the definition of affordance in terms of dispositional properties is problematic. I also suggest that Turvey's definition of affordance may lead to problems for the specification and direct perception of affordances. Motivated by these problems, I propose a new definition of affordance, in which affordances are properties of the animal-environment system. This definition does not rely on the concept of dispositional properties and is consistent with direct perception.     

Anorexia nervosa and oversized experiences

In this paper, I discuss what I call the oversized experiences that anorexic patients suffer from. It has been known for some time that anorexic patients mentally picture their bodies as larger than reality. While this constitutes one kind of oversized experience, I claim there is another, less explored kind. This is an experience of the body as oversized in relation to the affordances of its environment. I discuss recent evidence suggesting anorexic patients exhibit distorted affordance perception. I then discuss how this distorted affordance perception also constitutes an oversized experience of the body. Along with sociocultural influences, I claim oversized experiences ground negative propositional attitudes regarding body size.     

动允直接知觉的共鸣原理

传统认知理论认为我们只能间接知觉动允,而生态认知心理学则认为对动允的知觉是个体与环境信息直接共鸣的过程。生态认知心理学首先判定动允并不是存在于我们头脑中的认识,而是实际存在于个体-环境系统中的事实,对动允的直接知觉就是对动允的检测而非推测,是对动允信息的拾取而非对记忆内容的提取。这种直接知觉表现为身体的相关动作机制（动作神经元、肌肉组织等）与环境中动允信息的共鸣。进化与学习在共鸣的形成与发展中具有重要作用。     

关系属性:动允性概念的方法论蕴含

动允性是指环境提供给有机体的行动可能性。1977年,生态心理学家吉布森首次提出了“动允性”概念。这一概念有着深刻的方法论含义。首先,动允性超越了传统二元论思维的束缚。它既不是环境方面的物理属性,也不是动物方面的主观属性,而是环境与动物交互作用中的一个关系属性。其次,动允性所体现出来的价值和意义与动允性的关系属性是一致的。它主张意义既不外显于事物的外部,也不隐藏于事物的内部,而是嵌入于有机体和环境的互动互补关系之中。最后,这种关系属性使它免于被归结为物理的或心理的性质,从而超越了还原论的思维方式。     

Are Events and Affordances Commensurate Terms?

In this article, I argue that the dichotomy between events and affordances as Stoffregen (target article, this issue) devises is unwarranted and potentially misleading. I challenge the notion that the role of the actor distinguishes events from affordances in any useful way. The research labeled event perception is neither less ecological nor qualitatively different from research on affordances. Instead, the main distinction is constituted by affordance being a perceptual property, whereas event pertains to a different semantic category. Nonetheless, the contemplation of these concepts, in particular an elaboration of the concept of affordance, is desperately needed.     

The true and the false

A dispositional property is a tendency, or potency, to manifest some characteristic behaviour in some appropriate context. The mainstream view in the twentieth century was that such properties are to be explained in terms of more fundamental non-dispositional properties, together with the laws of nature. In the last few decades, however, a rival view has become popular, according to which some properties are essentially dispositional in nature, and the laws of nature are to be explained in terms of these fundamental dispositions. The supposed ability of fundamental dispositions to ground natural laws is one of the most attractive features of the dispositional essentialist position. In this paper, however, I cast doubt on the ability of dispositional essences to ground the laws of nature. In particular I argue that the dispositional essentialist position is not able to coherently respond—sympathetically or otherwise—to Cartwright's challenge that there are no true general laws of nature.     

Vision-for-action: The effects of object property discrimination and action state on affordance compatibility effects

When a person views an object, the action the object evokes appears to be activated independently of the person’s intention to act. We demonstrate two further properties of this vision-to-action process. First, it is not completely automatic, but is determined by the stimulus properties of the object that are attended. Thus, when a person discriminates the shape of an object, action affordance effects are observed; but when a person discriminates an object’s color, no affordance effects are observed. The former, shape property is associated with action, such as how an object might be grasped; the latter, color property is irrelevant to action. Second, we also show that the action state of an object influences evoked action. Thus, active objects, with which current action is implied, produce larger affordance effects than passive objects, with which no action is implied. We suggest that the active object activates action simulation processes similar to those proposed in mirror systems.     

示能性:基于镜像神经元视角的理解

示能性(affordance)概念解释了人的行为与物体功能之间互动、互补的关系。但是,有关示能性生理基础却很少被提及。镜像神经元的发现为示能性生理基础提供了可能的解释。文章根据研究将示能性分为结构示能性和功能示能性,探讨了不同示能性和镜像神经元之间的关系,并提出不同神经通路中的镜像神经元是示能性生理基础的结论。背-背侧分流中的镜像神经元是结构示能性的神经基础,而腹-背侧分流中的镜像神经元是功能示能性的神经基础。     

Turning up the volume on the property view of sound

In the present article, I show that sounds are properties that are not physical in a narrow sense. First, I argue that sounds are properties using Moorean-style arguments and defend this property view from various arguments against it that make use of salient disanalogies between sounds and colors. The first disanalogy is that we talk of objects making sounds but not of objects making colors. The second is that we count and quantify over sounds but not colors. The third is that sounds can survive qualitative change in their auditory properties, but colors cannot survive change in their chromatic properties. Next, I provide a taxonomy of property views of sound. As the property view of sound has been so rarely discussed, many of the views available have never been articulated. My taxonomy will articulate these views and how they are related to one another. I taxonomize sounds according to three characteristics: dispositional/non-dispositional, relational/non-relational and reductive/non-reductive. Finally, mirroring a popular argument in the color literature, I argue that physical views in the narrow sense are unable to accommodate the similarity and difference relations in which sounds essentially stand. I end replying to three objections.     

On Stoffregen's Definition of Affordances

Stoffregen (2003) has proposed a formal definition of affordances as emergent or relational properties of animal-environment systems. This definition contrasts with Turvey's (1992) formal definition of affordances as properties of the environment. In this commentary, my purpose is not to take sides on this issue but instead to bring to light what I believe to be a crucial flaw in Stoffregen's definition. Specifically, I show that Stoffregen's definition places no constraint on which relational or emergent properties legitimately deserve to be counted as affordances, thus allowing any relational property that can be predicated of an animal-environment system to be considered as an affordance. As such, Stoffregen's definition lacks any substantive linkage to the "opportunity for action" notion that has accounted for the scientific utility of the concept to date, a linkage I suggest should be preserved in any definition of affordances.     

Potentiation of action by undetected affordant objects

The physical attributes of objects that are relevant to motor behaviour, or action, are referred to as affordances (Gibson, 1979). Recent evidence has shown that an object's affordance can potentiate an unrelated motor response even when there is no intention to respond to it (e.g., Tucker & Ellis, 1998). In the five experiments, we examined whether conscious perception of an affordance is necessary to produce motor priming by presenting images of affordant objects (e.g., hammer) under conditions which cause them to be undetectable: Brief masked exposure (BME) and attentional blink (AB). We successfully demonstrated that conscious perception is not necessary for an object's affordance to produce motor priming. Since these findings are consistent with the abilities/disabilities of patients with blindsight and visual form agnosia, it is possible that processing accomplished by the dorsal stream produced this effect, though more research is needed to confirm this assertion.     

Impact of Postural Stability and Modality on the Perception of Passage and Surface Climbing

The foundation for this study is the belief that an accurate understanding of affordance perception requires consideration of the observer-ground surface interface. More specifically, it is argued that variations in the organism-environment interface will affect postural stability that, in turn, will affect affordance judgments. It is further expected that the impact of variations in postural stability should be independent of the perceptual system employed by the perceiver. Participants in this study wore shoes meant to create varying degrees of postural stability and used either vision or sound to determine whether a gap afforded passage or a surface could be stepped upon. The results revealed that the manipulation of postural stability significantly affected judgments of passage and climbability. Although modality alone did not influence affordance judgments, it did so in combination with postural stability. Discussion is given to the notion that an accurate understanding of perception requires consideration of the perceiver and the environment as a single unit.     

行动语义、客体背景和判断任务对客体动作承载性的影响

客体动作承载性指人们知觉客体时同时激活的针对客体的行动。当Gibson最初提出动作承载性概念时, 他认为客体的这种属性是可以自动激活的。然而近年来越来越多的证据显示, 在知觉和行动的关系中, 行动语义知识和客体所处背景对客体动作承载性具有调节作用, 表现在人们可以根据这些自上而下的信息选择针对客体的适当的行动。此外, 不同的判断任务在引发客体动作承载性效应上具有特异性, 表现在若判断任务仅需知觉客体表层属性时, 不能激活对客体的动作, 进而不能产生客体动作承载性; 若判断任务需要对客体进行深层加工时, 才会激活对客体的动作。未来研究还需要进一步探究行动语义知识和客体所处背景影响客体动作承载性发生的原因和机制, 以及不同判断任务中出现结果特异性的原因。     

Goal orientation, motivational climate, and dispositional flow of high school students engaged in extracurricular physical activity

The purpose of this study was to examine the role of goal orientation, motivational climate, and dispositional flow in physical education lessons on extracurricular involvement in physical activity. Questionnaires were administered to 1,103 (792 athletes; 311 nonathletes) secondary school students (M age = 14.3 yr., SD = 0.7). Analysis showed significant mean differences between groups on goal orientation and dispositional flow in physical education lessons, but none for perception of motivational climate. These findings suggest that dispositional variables are related to extracurricular involvement in physical activity.     

Effects of Affordance Perception on the Initiation and Actualization of Action

Studies have shown information specifying some affordances may be faster or easier to perceive than others. This article investigates the effect of affordance perception on the time taken to initiate and perform an action. In particular it focuses on how action timing varies as a function of a continuum of afforded action, that is, around an action-boundary. In Experiment 1, participants made judgments regarding whether they could fit a small ball through a series of different size apertures. Judgments were quick and accurate at the extremes of the affordance scale; however, at the perceived action-boundary longer, more variable initiation times (ITs) were observed. Trials repeated over 3 consecutive days revealed a systematic change in the IT distribution and demonstrated that IT is highly sensitive to changes in location of the perceived action-boundary. In Experiment 2 effects of action-scaling were observed on IT and movement time of afforded actions: around the perceived action-boundary the afforded action took longer to be both perceived and acted upon. The results highlight that affordance perception influences not only action selection and preparation but also the action itself. The findings are discussed in terms of the informational basis of action responses.     

LAWS AND ESSENCES

Those who favour an ontology based on dispositions are thereby able to provide a dispositional essentialist account of the laws of nature. In part 1 of this paper I sketch the dispositional essentialist conception of properties and the concomitant account of laws. In part 2, I characterise various claims about the modal character of properties that fall under the heading ‘quidditism’ and which are consequences of the categoricalist view of properties, which is the alternative to the dispositional essentialist view. I argue that quidditism should be rejected. In part 3, I address a criticism of a strong dispositional essentialist view, viz. that ‘structural’ (i.e. geometrical, numerical, spatial and temporal) properties must be regarded as categorical.     

Visual guidance of walking through apertures: body-scaled information for affordances

A necessary condition for visually guided action is that an organism perceive what actions are afforded by a given environmental situation. Warren (1984) proposed that an affordance such as the climbability of a stairway is determined by the fit between properties of the environment and the organism and can be characterized by optimal points, where action is most comfortable or efficient, and critical points, where a phase transition to a new action occurs. Perceiving an affordance, then, implies perceiving the relation between the environment and the observer's own action system. The present study is an extension of this analysis to the visual guidance of walking through apertures. We videotaped large and small subjects walking through apertures of different widths to determine empirically the critical aperture-to-shoulder-width ratio (A/S) marking the transition from frontal walking to body rotation. These results were compared with perceptual judgments of "passability" under static and moving viewing conditions. Finally, we tested the hypothesis that such judgments are based on intrinsic or body-scaled information specifying aperture width as a ratio of the observer's eyeheight. We conclude (a) that the critical point in free walking occurs at A/S = 1.30, (b) that static monocular information is sufficient for judging passability, and (c) that the perception of passability under such conditions is based on body-scaled eyeheight information.     

Scaffolds for Social Meaning

The perception of social meanings traditionally deemed to be private is addressed by contrasting the perception of social affordances with the perception of the physical affordances of environmental objects. Assuming that (a) affordances are defined by relationships between properties of the environment and properties of an actor and that (b) information must exist to specify this relationship for the perception of affordances, the question is whether and how private social meanings can fulfill these criteria. The attack is twofold. First, one needs to take seriously the ontology of the social world by considering social environment properties and actors' social roles as real and embodied—existing in the world and not just in mental representations. Second and more problematically, one needs to understand how information exists that specifies these more abstract and temporally extended aspects of the environment and actor. I propose that these problems can be averted by taking seriously as conceptual scaffolds the reality of functionally defined properties of the environment and actor, J. J. Gibson's primacy of events, and his notion of the occluding edge (1979/1986).     

Shoemaker on Phenomenal Content

Sydney Shoemaker has given a sophisticated theory of phenomenal content, motivated by the transparency of experience and by the possibility of spectrum inversion without illusion (1994, 2000, 2001, 2002). It centers on the idea that color experiences represent what he calls “appearance properties”. I consider the different sorts of appearance properties that Shoemaker has suggested might enter into phenomenal content – occurrent appearance properties, dispositional appearance properties, and higher-order dispositional appearance properties – and argue that none of them are plausibly represented by color experiences. I argue that Shoemaker's theory faces a dilemma – either it makes misperception too difficult, or it does not truly accommodate veridical spectrum inversion. I then examine some alternative Russellian theories of phenomenal content that might be consistent with Shoemaker's motivations, including a different sort of proposal recently suggested by Shoemaker (forthcoming). I argue that these views are also lacking, for similar reasons as the appearance property view. Finally, I conclude that in order for a representationalist theory to properly accommodate spectrum inversion without illusion, phenomenal content must include an indexical element. Such a view requires the adoption of a broadly Fregean theory of phenomenal content, according to which sameness of phenomenal character does not entail sameness in extension. What phenomenally identical experiences have in common is not what they represent, but how they represent.     

Why Colours Do Look Like Dispositions

In recent years philosophers such as Paul Boghossian, David Velleman and Colin McGinn have argued against the view that colours are dispositional properties, on the grounds that they do not look like dispositional properties, and in particular that they are not represented in visual experience as dispositions to present certain kinds of appearances. Rather colours are represented as being these appearances, i.e., simple, non-dispositional properties. I argue that a proper understanding of how visual experiences represent physical objects as being coloured shows that colours do look like dispositions. In particular, I argue that if visual experiences are to represent properties as properties of physical objects, they must distinguish between these properties and their appearances, and thus cannot represent such properties as colours as being identical with their corresponding appearances.