The measurement of sensory intensity has had a long history, attracting the attention of investigators from many disciplines including physiology, psychology, physics, mathematics, philosophy, and even chemistry. While there has been a continuing doubt by some that sensation has the properties necessary for measurement, experiments designed to obtain estimates of sensory intensity have found that a general rule applies: Equal stimulus ratios produce equal sensory ratios. Theories concerning the basis for this simple psychophysical rule are discussed, with emphasis given to (...) the physical correlate theory, which considers judgments of subjective magnitudes to be based upon estimates of physical dimensions that vary regularly with changes in degree of stimulation. For the most thoroughly investigated sensory scales, brightness and loudness, the physical correlate is considered to be distance. Our “tacit knowledge” of the sensory effects of changing distance plays an essential role in matching motor activities to environmental conditions and in ensuring accurate perceptual evaluations through brightness and loudness constancies. In psychophysical experiments, subjects apparently use this same tacit knowledge when required to estimate relative subjective magnitudes. The evidence related to the physical correlate theory is summarized, and it is concluded that, while under appropriate conditions we demonstrate considerable skill in evaluating environmental relationships, we are quite unable to estimate the neurophysiological nature or quantity of sensory response. A psychophysics devoted to studying conditions required for accuracy and conditions producing errors in the perception of environmental relationships would seem to be more valuable than one devoted to subjective magnitudes. (shrink)

Hintikka has criticized psychologists for "hasty epistemologizing," which he takes to be an unwarranted transfer of ideas from psychology (a discipline dealing with questions of fact) into epistemology (a discipline dealing with questions of method and theory). Hamlyn argues, following Hintikka, that Gibson's theory of perception is an example of such an inappropriate transfer, especially insofar as Hamlyn feels Gibson does not answer several important questions. However, Gibson's theory does answer the relevant questions, albeit in a new and radical way, (...) which suggests that the alleged distinction between psychology and epistemology is suspect. In fact, contrary to Hintikka and Hamlyn's claims, Gibson's theory of perception appears to be a valuable source of epistemological as well as psychological ideas. (shrink)

Central to contemporary cognitive science is the notion that mental processes involve computations defined over internal representations. This view stands in sharp contrast to the to visual perception and cognition, whose most prominent proponent has been J.J. Gibson. In the direct theory, perception does not involve computations of any sort; it is the result of the direct pickup of available information. The publication of Gibson's recent book (Gibson 1979) offers an opportunity to examine his approach, and, more generally, to contrast (...) the theory of direct perception with the computational/representational view. In the first part of the present article (Sections 2direct perceptioncase study”: the problem of perceiving the three-dimensional shape of moving objects is examined. This problem, which has been extensively studied within the immediate perception framework, serves to illustrate some of the inherent shortcomings of that approach. Finally, in Section 5, an attempt is made to place the theory of direct perception in perspective by embedding it in a more comprehensive framework. (shrink)

Efforts to bare the psychonomic nature of the semantic reference (representation) relation have been remarkably scanty; in fact, the only contemporary account developed with any care is the one proposed by Osgood. However, not even Osgood has looked deeply at the difficulties that beset any attempt to analyze reference in terms of common effects appropriately shared by a symbol and its significate.

It is proposed that the Darwinian theoretical approach and account of living systems has not yet been clearly given. A first approximation to this is attempted, focussing on behavior in evolving environments. A theoretical terminology is defined emphasizing the mutuality of organism and environment and the existence of biologically theoretical entities.

At the bottom of all human activities are “values,” the conviction that some things “ought to be” and others not. Science, however, with its immense interest in mere facts seems to lack all understanding of such‘requiredness.’… A science … which would seriously admit nothing but indifferent facts … could not fail to destroy itself.

In lieu of an abstract, here is a brief excerpt of the content:James J. Gibson's Ecological Approach:Perceiving What ExistsWilliam M. Mace (bio)Environmental Philosophy and EpistemologyThe purpose of this paper is to help an audience attracted to environmental philosophy get to the core of Gibson's system in a compact form and to appreciate the necessity for an account of the environment in epistemology. I hope to show that Gibson's is a consistent and scientifically progressive account of knowing that gives the environment (...) its due and that this is not a simple matter of fiat but a call to extended scientific investigation. I want to stress that Gibson's work is scientifically progressive in the sense that it has consistently opened new avenues for research. If one could be assured tomorrow that Gibson was correct and his critics wrong, the ecological psychology enterprise would not have to be shut down with nothing left to do. The goal of the enterprise, certainly for Gibson, was not to be declared a winner but to open doors for discovery. Because Gibson has developed a theory of perceiving the environment, it would be worth exploring as an important topic for environmental philosophers covering a wide range of issues. It offers an intriguing, environmentally based, grounding for epistemology; it offers ways to deal [End Page 195] with practical issues within "pure science"; and it is open to reorganizing ways to conceptualize problems beyond epistemology.Gibson developed a richly articulated system that grew steadily over a period of 50 years, 1929 to 1979, which he devoted to "puzzling over" the "perplexities" of vision (1979, xiii). From Gibson's standpoint, knowledge begins with perception, and perception is perceiving the environment. The environment, for Gibson, is at least as essential as the brain to the existence and exercise of "the mind."As an empiricist, knowledge is based on perception for Gibson. But perception, at root, turns out to be perception of the environment. Entities like sense data and representations become "after the fact" curiosities for Gibson, and have no role to play in the foundations of perceptual experience and, a fortiori, knowledge. If Gibson is correct, then scientific accounts of perception must converge on environmental perception. A philosopher whose primary focus is epistemology, and who works within Gibson's system, would perforce be an environmental philosopher—not (first) because of a special concern for the environment, but because an adequate appreciation of relevant facts requires it. Of great importance to environmental philosophers is that Gibson not only provides an account of perceiving grounded in access to environmental properties, but he establishes a basis for perceiving this particular world as a specific arrangement of surfaces. The world we perceive, according to Gibson, is a connected, public world that we share. It is, again, the world, the logical individual world and not an abstraction. This is not an account of the experience of abstract shapes, distances, and motions. It is a system in which travelers can visit the pyramids and in which I can trip over your garbage.Is there a symmetric direction of influence? Just as a commitment to understanding knowledge scientifically and philosophically can lead one to focal considerations of the environment, could a deep concern for the environment as a value lead to the serious study of perception and, more broadly, epistemology? It seems entirely plausible. Gibson's is a "yin and yang" system of scientific complementarities beginning with animal and environment and extending to knowledge and value (in his concept of affordance). In each complementarity, the terms are differentiable but not entirely independent. Animals and their environments are different entities and should not be confused with one another, but they also are so [End Page 196] mutually dependent that one should not imagine a thorough account of one without the other. In like manner, objects and value (first through use) are not independently comprehensible in Gibson's system. This is a theme worthy of careful examination of detailed examples. I am not doing that in this paper, but hope that enough of the flavor of Gibson's work will come through to allow a reader to understand how one might be steered to epistemology from an initial concern with environment and values and... (shrink)

In this paper, I suggest that some tales (or narratives) developed in the literature of embodied and radical embodied cognitive science can contribute to the solution of two longstanding issues in the cognitive neuroscience of perception and action. The two issues are (i) the fundamental problem of perception, or how to bridge the gap between sensations and the environment, and (ii) the fundamental problem of motor control, or how to better characterize the relationship between brain activity and behavior. In both (...) cases, I am going to propose that cognitive neuroscience could incorporate embodied insights—coming from the sensorimotor approach to perception and action, and from ecological psychology—to advance the solution for each issue without the need for abandoning or undergoing a substantial revision of its core assumptions. Namely, cognitive neuroscience could incorporate the forgotten tales of embodiment without undergoing through a complete revolution. In this sense, I am proposing not a call but a farewell to arms. (shrink)

Information is a central notion for cognitive sciences and neurosciences, but there is no agreement on what it means for a cognitive system to acquire information about its surroundings. In this paper, we approximate three influential views on information: the one at play in ecological psychology, which is sometimes called information for action; the notion of information as covariance as developed by some enactivists, and the idea of information as minimization of uncertainty as presented by Shannon. Our main thesis is (...) that information for action can be construed as covariant information, and that learning to perceive covariant information is a matter of minimizing uncertainty through skilled performance. We argue that the agent’s cognitive system conveys information for acting in an environment by minimizing uncertainty about how to achieve her intended goals in that environment. We conclude by reviewing empirical findings that support our view and by showing how direct learning, seen as instance of ecological rationality at work, is how mere possibilities for action are turned into embodied know-how. Finally, we indicate the affinity between direct learning and sense-making activity. (shrink)

I am an emeritus professor of theoretical psychology at the University of Portsmouth. I was introduced to Gestalt Psychology as a student back in the 1960s. My professor, Tim Miles, knew Michotte and had translated his book on Causality. Tim once showed us Michotte’s remarkable displays of perceived causality and animal movement based on the simplest of equipment. I liked the way that demonstrations can themselves play an important scientific role in the study of perception. My start with the Gestalt (...) Psychologists led me to the work of James Gibson who although influenced by the Gestaltists was grudging to admit it. In fact, I have spent a large part of my long career commenting on, and sometimes criticising, his radical challenge to mainstream psychology. Thanks mainly to my students, I have been involved in research across a wide range of topics. These include developmental psychology, autism, children’s drawings, “false memories”, speech perception, community care for schizophrenics, old-age care. What, for me, holds this research together is the “ecological approach” we have taken to these issues. (shrink)

Psychophysical scaling models of the form R = f, with R the response and I some intensity of an attribute, all assume that people judge the amounts of an attribute. With simple biases excepted, most also assume that judgments are independent of space, time, and features of the situation other than the one being judged. Many data support these ideas: Magnitude estimations of brightness increase with luminance. Nevertheless, I argue that the general model is wrong. The stabilized retinal image literature (...) shows that nothing is seen if light does not change over time. The classification literature shows that dimensions often combine to produce emergent properties that cannot be described by the elements in the stimulus. These and other effects cannot be adjusted for by simply adding variables to the general model because some factors do not combine linearly. The proposed alternative is that people initially judge the entire stimulus – the object in terms of its environment. This agrees with the constancy literature that shows that objects and their attributes are identified through their relations to other aspects of the scene. That the environment determines judgments is masked in scaling studies where the standard procedure is to hold context constant. In a typical brightness study the essential stimulus might be the intensity of the light or a difference between the light and the background. The two are perfectly confounded. This issue is examined in the case of audition. Judgments of the loudness of a tone depend on how much that tone differs from the previous tone in both pitch and loudness. To judge loudness people first seem to process the stimulus object in terms of differences between it and other aspects in the situation; only then do they assess the feature of interest. Psychophysical judgments will therefore be better interpreted by theories of attention that are based in biology or psychology than those that are based in classical physics. (shrink)

After writing my response to the commentaries, I sat back and reflected on the fascination and frustration of work on this topic. There is the ancient fascination of trying to understand the nature of the sensory bridge linking us to the external world. Also, discussing the measurability of sensation brings to the surface concepts we use and take for granted when we are working in other areas of psychology; and it holds them before us for critical examination. The frustration lies (...) chiefly in the difficulty of formulating concepts clearly, in a way understood by all. At least when constructing the original Tower of Babel, workers hearing strange words knew that communication was not occurring. The psychophysical Tower of Babel sometimes has workers using the same words, but with different meanings. Much of my response is based on attempts to clarify concepts and clear up confusions. (shrink)