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.     

Extending the notion of affordance

Post-Gibson attempts to set out a definition of affordance generally agree that this notion can be understood as a property of the environment with salience for an organism’s behavior. According to this view, some scholars advocate the idea that affordances are dispositional properties of physical objects that, given suitable circumstances, necessarily actualize related actions. This paper aims at assessing this statement in light of a theory of affordance perception. After years of discontinuity between strands of empirical and theoretical research, the time is ripe for addressing the question of whether the dispositional interpretation of affordance is in accordance with some recent evidence from cognitive science and neuroscience. Following this line, I clarify that there are some cases of affordance-related effects that neither require the actualization of an action, nor the presence of an action-related property bearer in the environment, and that the identification of affordance with physical properties provides only a partial explanation of the wide range of affordance-related effects. Accordingly, I argue in favor of a more general account of affordance perception based on the ability to directly detect perceptual patterns in the environment.     

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。     

Affordance Types and Affordance Tokens: Are Gibson’s Affordances Trustworthy?†

Late in their paper on hypersets, Chemero and Turvey characterize affordances as “quicksilvery,” prone to rapid appearance and disappearance. We contrast this view with Gibson’s emphasis on the stability of affordances. We argue that this apparent discrepancy can be resolved by appeal to the distinction between affordances as indefinite abstract types and definite affordance tokens (instances of the type that share the resemblance relation). These issues will be discussed in the context of their consistency with ecological realism, where Platonic idealism is eschewed in favor of a more Aristotelian process theory. These ideas will be examined in the broader context of the domain ontology to ensure that Gibson's seminal affordance concept has its greatest theoretical utility. Finally, we develop a process theory of ontological descent by which indefinite affordance possibilities become more definite affordance potentialities and these eventuate in the most definite affordance actualizing actions.     

Gibson's Affordances and Turing's Theory of Computation

The concept of affordance is a central component of the ecological psychology of J. J. Gibson (1966, 1977, 1979/1986). Affordances are properties of the environment taken relative to an observer. Ecological theorists have developed formal models for the analysis of affordances. Models proposed by Shaw and Turvey (1981), Turvey (1992), and Greeno (1994) are described and evaluated, and another approach, using Turing's (1936-1937/1965) theory of computation, is outlined. Affordances are characterized as the configurations of Turing machines. It is shown that Turing's work provides a natural vehicle for exploring Gibson's ideas.     

Heideggerian Meditations on an Alternative Ontology for Ecological Psychology: A Response to Turvey's (1992) Proposal

In his last book, Gibson (1979/1986) clearly described crucial elements for an ontology for ecological psychology, but left his overarching ontology implicit and incomplete. As a partial remedy, Turvey (1992) presented a compact, well- packaged outline of an ontology for ecological psychology derived in part from the work of Bunge. In appreciation of Turvey's pioneering and thought-provoking attack on this difficult issue, we offer our own reflections on Turvey's propertied realism. In reviewing Turvey's work we use both the insights of Heidegger and recent experimental findings in ecological psychology to argue for the need for a different ontological foundation. We argue that a Heideggerian ontology can provide us with a broader and more complete ontological foundation with which to deal with complex issues, such as prospective control, than can Turvey's proposed ontology. Also, we suggest that a Heideggerian ontology can be used to supply what is missing or understated in Gibson. We argue against propertied realism as a basis for ecological psychology's ontology and contend that a proper conception of intentionality provides a way to transcend traditional object-subject ontologies. We propose that fields should be considered real ontological entities that differ from matter. Finally, we reflect on how the highly nonscientific language of Heidegger might possibly be formalized to make it more suitable for scientific use.     

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.     

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).     

Social Affordances and the Possibility of Ecological Linguistics

This paper includes an effort to extend the notion of affordance from a philosophical point of view the importance of ecological approach for social psychology, ethics, and linguistics. Affordances are not always merely physical but also interpersonal and social. I will conceptualize affordance in general and social affordance in particular, and will elucidate the relation between intentional action and affordances, and that between affordances and free will. I will also focus on the relation between social institution and affordance. An extended theory of affordances can provide a way to analyze in concrete ways how social institution works as an implicit background of interpersonal interactions. Ecological approach considers social institution as the producer and maintainer of affordances. Social institutions construct the niches for human beings. Finally, I will argue the possibility of the ecological linguistics. Language is a social institution. The system of signs is the way to articulate and differentiate interpersonal affordances. Language acquires its meaning, i.e. communicative power in the interpersonal interactions, and interpersonal interactions, in turn, develop and are elaborated through the usage of signs. Communication is seen as never aimed to transmit inner ideas to others, but to guide and adjust the behaviors of others thorough articulating the affordance of responsible-ness.     

Understanding phenomenological differences in how affordances solicit action. An exploration

Affordances are possibilities for action offered by the environment. Recent research on affordances holds that there are differences in how people experience such possibilities for action. However, these differences have not been properly investigated. In this paper I start by briefly scrutinizing the existing literature on this issue, and then argue for two claims. First, that whether an affordance solicits action or not depends on its relevance to the agent’s concerns. Second, that the experiential character of how an affordance solicits action depends on the character of the concern to which it is relevant. Concerns are conceived of as bodily forms of responsiveness, and solicitations are experienced through this responsiveness. The main aim of this paper is to make clear that an understanding of experiential differences in solicitations has to be based on a phenomenological appreciation of how one experiences one’s responsiveness to those solicitations. In the remainder of the paper I show how such a phenomenological appreciation reveals several characteristics of our responsiveness and I briefly explore three of them: valence, force and mineness. In the final section I discuss the self-referentiality of affordances in light of the current proposal, and argue that this self-referentiality is broader than is typically acknowledged.     

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.     

Human Echolocation as a Basic Form of Perception and Action

In this article we discuss known and possible uses of echolocation by humans. We argue that echolocation may be a basic perception-action ability of humans. We review studies which suggest that both blind and sighted humans are capable of substantial precision in the perception of properties of distal objects, such as distance, size, shape, substance, and relative motion. We analyze relations between acoustic pulse and echo that may provide information to support these percepts and others. Our analysis predicts echolocation-based sensitivity in humans and other animals to a number of properties of the animal-environment interaction. We also discuss echolocation-based acoustic specification of time-to-contact. We develop a new variable that provides this information and discuss acoustic Τs recently developed by Shaw, McGowan, and Turvey (1991) and by Lee, van der Weel, Hitchcock, Matejowsky, and Pettigrew (1992).Our analysis suggests that there may be important insights to be gained from an ecological study of echolocation in humans and other species. We end with suggestions for research derived from our analysis.     

Judging the 'passability' of dynamic gaps in a virtual rugby environment

Affordances have recently been proposed as a guiding principle in perception–action research in sport (Fajen, Riley, & Turvey, 2009). In the present study, perception of the ’passability’ affordance of a gap between two approaching defenders in rugby is explored. A simplified rugby gap closure scenario was created using immersive, interactive virtual reality technology where 14 novice participants (attacker) judged the passability of the gap between two virtual defenders via a perceptual judgment (button press) task. The scenario was modeled according to tau theory (Lee, 1976) and a psychophysical function was fitted to the response data. Results revealed that a tau-based informational quantity could account for 82% of the variance in the data. Findings suggest that the passability affordance in this case, is defined by this variable and participants were able to use it in order to inform prospective judgments as to passability. These findings contribute to our understanding of affordances and how they may be defined in this particular sporting scenario; however, some limitations regarding methodology, such as decoupling perception and action are also acknowledged.     

von Uexküll’s Theory of Meaning and Gibson’s Organism–Environment Reciprocity

Abstract

Jakob von Uexküll is mostly known for his concept of Umwelt—the meaningful surrounding of animals. von Uexküll insisted vehemently on the fact that Umwelt vindicated Kant’s subjectivist epistemology in the biological domain. However, we argue that a crucial yet widely overlooked development in von Uexküll’s theory of meaning implies a more radical vision strikingly germane to J. J. Gibson’s own direct realist epistemology-ontology and in tension with his own subjectivist concept of Umwelt. Gibson argued that organism and environment are complementary and meaning is not constructed via a subjective act but is directly available in the world as opportunities for action, namely, affordances. We show that von Uexküll’s notion of “functional tone” is similar to Gibson’s concept of affordance in that it includes action in perception. More important, von Uexküll introduces the musical metaphor of harmony to characterize the relationship between animal and environment. Like Gibson’s reciprocity, harmony implies an unmediated isomorphism between the dispositions of the animal and those of the environment that allows for direct perceptual contact with the world and action upon it.     

Scared stiff: The influence of anxiety on the perception of action capabilities

Influences on the perception of affordances (i.e., opportunities for actions) have been primarily studied by manipulating the functional morphology of the body. However, affordances are not just determined by the functional morphology of the perceiver, but also by the physiological state of the perceiver. States of anxiety have been shown to lead to marked changes in individuals’ physiological state and their behaviour. To assess the influence of emotional state on affordance perception, the perception of action capabilities in near space was examined after participants completed an anxiety-provoking task. Anxiety was induced immediately prior to tasks that assessed participants' perceived reaching ability in Experiment 1, grasping ability in Experiment 2, and the ability to pass their hands through apertures in Experiment 3. Results indicated that those participants who experienced changes in anxiety underestimated their reaching, grasping, and passing ability compared to non-anxious participants. In other words, anxious participants were more conservative in their estimations of their action capabilities. These results suggest that anxiety influences the perception for affordances in near space and are consistent with the notion that anxiety induces withdrawal behaviours.     

Direct Perception Requires an Animal-Dependent Concept of Specificity and of Information

Specificity and information are at center stage in ecological psychology. Nevertheless, the usual theorizing on these concepts may have made the problem of accounting for perception and action more difficult by so far underestimating the role of animals as both meaning-detectors and meaning-determiners. The usual understanding of information and specificity in ecological psychology seems neither necessary nor even compatible with ecological premises and empirical findings. I argue that a reframing of these concepts to fully take animals into account is necessary to explain perception of action-specific meanings. The reframing proposed converges on ideas from developmental systems theory and in no way concedes to inputs-followed-by-processing-followed-by-representation models. Fully acknowledging the animal for properly defining information over the animal-environment system poses no threat lawfulness, realism, or direct perception. It also invites serious consideration of self-organization and interactivism as sources for further development of ecological science.     

THOMAS REID ON ACQUIRED PERCEPTION

Thomas Reid's distinction between original and acquired perception is not merely metaphysical; it has psychological and phenomenological stories to tell. Psychologically, acquired perception provides increased sensitivity to features in the environment. Phenomenologically, Reid's theory resists the notion that original perception is exhaustive of perceptual experience. James Van Cleve has argued that most cases of acquired perception do not count as perception and so do not pose a threat to Reid's direct realism. I argue that acquired perception is genuine perception and as direct as original perception. Perception is grounded in a productive and developing relationship between the mind and world.     

Body-scaled affordances in sensory substitution

The research field on sensory substitution devices has strong implications for theoretical work on perceptual consciousness. One of these implications concerns the extent to which the devices allow distal attribution. The present study applies a classic empirical approach on the perception of affordances to the field of sensory substitution. The reported experiment considers the perception of the stair-climbing affordance. Participants judged the climbability of steps apprehended through a vibrotactile sensory substitution device. If measured with standard metric units, climbability judgments of tall and short participants differed, but if measured in units of leg length, judgments did not differ. These results are similar to paradigmatic results in regular visual perception. We conclude that our sensory substitution device allows the perception of affordances. More generally, we argue that the theory of affordances may enrich theoretical debates concerning sensory substitution to a larger extent than has hitherto been the case.     

To Cross or Not to Cross: The Effect of Locomotion on Street-Crossing Behavior

Perception of some affordances requires action scaling rather than simply body (size) scaling. Crossing a road safely is such an affordance. Perceiving accurately whether crossing in front of oncoming traffic is possible entails perceiving the relation between environmental properties (the to-be-crossed distance and the available time) and one's walking abilities. Only while walking is perceptual information about walking abilities available; hence, a more accurate perception of whether crossing is possible is expected than when stationary. We observed crossing behavior (stopping, staying, and crossing) at a crosswalk and related this behavior to the time that was available before the next vehicle arrived. The critical time gap that separated not crossing (stopping or staying) and crossing was smaller, that is, closer to the actual crossing time, when walking than when standing still. Thus, crossing from standstill entailed a larger safety margin. This suggests that information about ongoing action can yield more accurate perception of the affordance in question.