Showing papers in "Ecological Psychology in 2003"

An Outline of a Theory of Affordances

Abstract: A theory of affordances is outlined according to which affordances are relations between the abilities of animals and features of the environment. As relations, affordances are both real and perceivable but are not properties of either the environment or the animal. I argue that this theory has advantages over extant theories of affordances and briefly discuss the relations among affordances and niches, perceivers, and events.

Affordances as Properties of the Animal-Environment System

Abstract: 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.

What Is an Affordance

Abstract: What should and should not be considered an affordance is still an open issue. At the 2002 North American meeting of the International Society for Ecological Psychology, a symposium was held concerning this topic. The articles in this special issue are expanded versions of the papers presented at that symposium. To set the stage for those discussions, this article presents an analysis of the evolution of J. J. Gibson's thinking on this issue, from some of his earliest writings (i.e., J. J. Gibson & Crooks, 1938) through his most recent writings (i.e., J. J. Gibson, 1979/1986). It is hoped that this forum will stimulate thinking concerning this important ecological concept.

Affordances: Four Points of Debate

Abstract: In this article, attention is given to 4 issues regarding affordances. The first relates to the ontological status of affordances: Affordances do not have to be perceived to exist. The second concerns whether affordances are necessarily related to (one's own) actions. The third considers the relation between affordances and effectivities. Finally, the nesting of affordances is addressed, as is whether some particular level of description should be considered privileged. Some issues seem settled; others require more theory and experimentation.

Affordances, Dynamic Experience, and the Challenge of Reification

Abstract: Why is it that affordances have received attention within psychology only in recent decades if they are supposedly what individuals perceive most fundamentally? This paradox can be explained, in part, by the fact that psychologists have usually considered the character of perceiving from a detached stance, and then reified the results of this analysis-an error that William James called the psychologist's fallacy-rather than attending to the immediate flow of perception-action. By the same token, if ecological psychologists were to take stimulus information as what is perceived, rather than as part of a conceptual framework offered to explain how we perceive, they would be committing a similar reification error. Ecological optics as a conceptual framework is always open to revision, even while the reality of affordances is assumed. Bearing in mind this distinction between what is perceived and how it is perceived, investigators need to return regularly to immediate experience, both as a means of verifying ...

The Agent-Environment Interface: Simon's Indirect or Gibson's Direct Coupling?

Abstract: A fundamental problem for ecological and cognitive psychology alike is to explain how agents are situated, that is, functionally coupled to their environments so as to facilitate adaptive actions. Herbert Simon (1969/1996) argued that such coupling is artifactual (rule governed), being mediated by symbol functions and necessarily involving information processing. An alternative to this computational approach is offered by James Gibson's (1979/1986) view that the interface is natural (law governed), being a direct informational coupling rather than a symbolically mediated one. This latter view necessarily involves the agent's awareness, whereas the former, being mechanistic, does not. I review the coupling problem from historical, logical, and semantic perspectives. I give arguments that the computational approach provides an inadequate account of situated adaptive actions and founders on the symbol grounding problem, whereas the ecological approach does a better job on both. Personal comments are interspe...

Beyond the Lens Model and Direct Perception: Toward a Broader Ecological Psychology

Abstract: Despite sharing the label ecological psychology, Brunswikian and Gibsonian research programs are virtually independent scientific activities conducted by a virtually independent pair of scientific communities. The purpose of this article is to provide a theoretical integration of these 2 lines of work. The lens model and the theory of direct perception can each be viewed as specific versions of a more general research program that distinguishes between distal structure (i.e., "thing") and proximal structure (i.e., "medium") and that is based on the metatheoretical commitment to understanding human behavior by focusing on adaptation to functionally significant environmental regularities. The lens model deals with probabilistic relations between proximal and distal that require judgment and decision making, whereas direct perception deals with direct specification between proximal and distal that permits an intimate coupling with the environment. By showing how these 2 lines of work can be integrated theore...

The World Is So Full of a Number of Things: On Specification and Perceptual Learning

Abstract: Two basic concepts of James Gibson's ecological theory of perception are information and affordance. Discovering the information that specifies an affordance is a task confronting all of us and is an essential process in development. Information in the world is manifold and must be narrowed down to perceive what specifies an affordance. Perceptual learning is the process that we study to understand how this comes about.

Tufted Capuchins (Cebus apella) Use Weight and Sound to Choose Between Full and Empty Nuts

Abstract: Wild capuchins (Cebus apella) feed on high-energy husked fruits. Field researchers suggest that capuchins select beforehand the fruits that are worthwhile to crack open. We assessed whether captive capuchins use sound and/or weight as proximal causes to infer the fullness of a nut (full nuts are heavier and produce a low-pitched frequency sound when tapped). Two subjects had to choose between a nut shell containing food and another nut shell without food differing in weight and sound (Phase 1), or weight only (Phases 2 and 4), or sound only (Phase 3). Both subjects readily solved Phase 1 and 2. The only subject who spontaneously finger-tapped on the nut shells solved Phase 3. The minimal difference in weight perceived ranged between 2.1 and 3 g. Therefore, as expected by ecological psychology and optimal foraging theory, data suggest that capuchins seek information to discriminate effectively between full and empty nuts before going through the costly opening process.

Events as Changes in the Layout of Affordances

Abstract: In a target article that appeared in Ecological Psychology, Stoffregen (2000a) questioned the possibility of ecological event perception research. This article describes experiments performed to examine the perception of the disappearance of gap-crossing affordances, a variety of event as defined by Chemero (2000).We found that participants reliably perceive both gap-crossing affordances and the disappearance of gap-crossing affordances. Our findings provide empirical evidence in favor of understanding events as changes in the layout of affordances, shoring up event perception research in ecological psychology.

Constancy in Dynamic Touch: Length Perceived by Dynamic Touch Is Invariant Over Changes in Media

Abstract: Following a procedure employed by Pagano and Donahue (1999), participants reported the lengths of occluded rods wielded in air or water. In this experiment we manipulated moment of inertia-the resistance to angular rotation due to the rod's mass distribution-by varying the length and composition of the rods. We manipulated drag-the resistance to object movement due to the displacement of a fluid medium -by varying the length of the rods and by wielding them in air or in water. The rods were constructed such that moment of inertia and drag were decorrelated. Although the torques required to wield in water are substantially greater than those required to wield in air, the perceived lengths of rods wielded in the 2 media were equivalent. Perceived length was a function of inertia in both media conditions; there was no significant contribution of drag. The experiment demonstrated that perceivers can extract the physical invariant of inertia by attending to the time-varying patterns from the complex arrays of ...

Affordances Are Enough: Reply to Chemero et al. (2003)

Abstract: Chemero, Klein, and Cordeiro (this issue) present an argument about the utility of a concept of events within the ecological approach to perception and action. They define ecological events as changes in the layout of affordances, and they distinguish this concept from earlier definitions of event, which they refer to as physical events. They argue that changes in the layout of affordances should be perceived, that is, that their perception is motivated by the ecological approach to perception and action. They also argue that changes in the layout of affordances are perceived, and they offer an experiment that supports the hypothesis that humans are sensitive to changes in the layout of affordances. What they do not do, I argue, is offer any compelling reason why event should be applied to changes in the layout of affordances. I also argue that changes in the layout of affordances do not have a special ontological status that might merit a unique name or constitute a category of perceivables that is logic...

All That Glistens: II. The Effects of Reflective Surface Finishes on the Mouthing Activity of Infants and Toddlers

Abstract: A number of infants and toddlers have been observed to mouth and to lick the horizontal metal mirrors of toys on their hands and knees in a manner not unlike the way older children drink from rain pools in developing countries. Such mouthing of glistening surfaces by nursing-age children might characterize the precocious ability to recognize the glossy and sparkling features of water long before this information is useful later in development. Two experiments examined the frequency with which infants and toddlers mouthed lightweight 25.4-cm diameter dinner plates during 5 bouts of plate contact. Experiments were conducted in the natural context of toy handling during playtime at 10 day-care facilities in northern California. In the first experiment, 22 children divided into 2 age groups (13 between 6 and 12 months and 9 between 13 and 17 months) were examined as they handled or contacted a stainless steel plate with a mirror finish or a glossy white plastic plate. The stainless steel plate was mouthed at ...

The Role of Rotational Inertia in the Haptic and Haptic + Visual Size-Weight Illusions

Abstract: In 2 experiments, the role of rotational inertia in perceiving heaviness was investigated. Rotational inertia has been shown previously to be responsible for one's perception of heaviness and the size-weight illusion when the perceiver is using dynamic touch. In both of the experiments reported here, participants rated the heaviness and volume of a set of stimuli that varied in both mass and volume. In Experiment 1, participants were able to grasp but not view the stimuli (haptic touch). In Experiment 2, participants were able to both grasp and view the stimuli (haptic touch + vision). Because the stimuli were lifted by the participants in each experiment, dynamic touch was available. In each case, reports of perceived heaviness were a function of rotational inertia. As additional information became available through haptic touch or vision, however, perceivers became more sensitive to the variations in rotational inertia. These results suggest that perceivers use rotational inertia to perceive heaviness i...

An Interview With Eleanor Gibson

Abstract: (2003). An Interview With Eleanor Gibson. Ecological Psychology: Vol. 15, No. 4, pp. 271-281.

Twist and Shout: Audible Facing Angles and Dynamic Rotation

Abstract: In 2 experiments, blindfolded listeners estimated the facing direction of a sound source from 2 different listening distances. In Experiment 1, listeners estimated the stationary facing angle of a loudspeaker that projected a speech stimulus while facing 1 of 8 different directions. In Experiment 2, the loudspeaker sounded while rotating and also while stationary at its terminal orientation. Listeners then made judgments of the final facing angle. Although performance fell short of that typically found in minimum audible angle experiments, listeners made relatively accurate estimates of loudspeaker orientation and showed a significant advantage when dynamic rotation information was available. Listeners were also significantly better at perceiving facing angles when closer to the source and when the loudspeaker was directly facing the listener (0�). The enhanced sensitivity to this egocentric source orientation may be the result of the use of redundant binaural and monaural information at a facing angle of...

What Psychology Is About: Ruminations of an Opinionated Aged Psychologist

Abstract: (2003). What Psychology Is About: Ruminations of an Opinionated Aged Psychologist. Ecological Psychology: Vol. 15, No. 4, pp. 289-295.

Inertial Eigenvectors Play a Role in Proprioception: Comment on Craig and Bourdin (2002)

Abstract: Craig and Bourdin (2002) called into question the role of the limbs' inertial eigenvectors in perceiving limb position. In this commentary we respond to some of the issues Craig and Bourdin raised with respect to previous studies that established a role for the limbs' inertial eigenvectors in proprioception. We then discuss some conceptual and methodological features of Craig and Bourdin's work. The discussion is focused on 2 primary points: (a) Some of Craig and Bourdin's experimental conditions required participants to produce very large shoulder angles, which could have lessened the role of the inertial eigenvectors; and (b) excluding those extreme conditions, their data actually appear to support the inertial eigenvector hypothesis, rather than contradict it.

Haptically Perceiving Whole and Partial Rod Length at the Small Scale

Abstract: Exteroception by dynamic touch has been studied for the most part using large (30-120 cm, 20-65 g) handheld stimulus objects. Only one study, Santana and Carello (1999), has looked at the perception of small-scale objects (15-25 cm, 0.75-1.3 g) by dynamic touch. The purpose of this article is to extend the theory of dynamic touch to the perception of small-scale objects. We explore whether the power-law scaling of perceived magnitudes to object inertial properties observed at the large scale held at the small scale, and whether partial and whole-length perceptions of small-scale objects were perceptually independent. Results indicated accurate whole-length perceptions but a change in the scaling of perceived whole length to the principal moment of inertia. Results also indicated inaccurate perceptions of partial length that were uncorrelated with object inertial properties. Perceptual independence of whole- and partial-length perceptions was observed.