Robert E. Shaw

Ecological laws of perceiving and acting: In reply to Fodor and Pylyshyn (1981 )*

This paper is both a reply to Fodor and Pt_lyshyn (198 1) and a systematic explication of one of Gibson’s (1979) basic claims, namely, that there are ecological laws relating organisms tc the a.ffordances of the environment. Gibson’s theory of affordances holds great promise for psychology for a number of reasons: it provides a framework for the precise formulation and testing of hypotheses about behavior and perception (e.g. E. J. Gibson, in press; Johnston and Turvey, 1980; Lee, 19110; Shaw and Bransford, 1977); it suggests a way to integrate theOphenomenological and mechanistic aspects of psychology without succumbing to either one-sided point of view (Reed, 1980; Runeson, 1977;Shaw et al., in press;Tua-:rey and Shaw, 1979); and it promises to put psychology back on the track of seeking lawful relations-as Gibson (1967, p. 122) once said, in science: “You either find causal relations or you do not’“.

Aging faces as viscal-elastic events: implications for a theory of nonrigid shape perception

A theory for the perception of events is proposed using the concepts of transformational and structural invariants. This approach involves the application of a method of spatial coordinate transformation to characterize the remodeling of faces by growth. By construing growing faces to the viscal-elastic events, the perception of the relative age level faces in made amenable to the proposed event perception analysis. Shear and strain transformation are compared as alternative formulations of growth-produced changes in the shape of human profiles. Thes studies indicate that profiles transformed by strain elicit more reliable rank-order age judgments than those transformed by shear, although shear had a small significant effect. It is also shown that subjects are highly sensitive to small changes in strain, and that perceived identity of a shape is preserved under the strain transformation. The explanatory adequacy of the event perception theory of age information is compared to that of more traditional feature analytic theories.

The intentional spring : a strategy for modeling systems that learn to perform intentional acts

In motor task learning by instruction, the instructors skill and intention, which, initially, are extrinsic constraints on the learners perceiving and acting, eventually become internalized as intrinsic constraints by the learner. How is this process to be described formally? This process takes place via a forcing function that acts both as an anticipatory (informing) influence and a hereditary (controlling) influence. A mathematical strategy is suggested by which such intentions and skills might be dynamically learned. A hypothetical task is discussed in which a blindfolded learner is motorically instructed to pull a spring to a specific target in a specific manner. The modeling strategy involves generalizing Hookes law to the coupled instructor-spring-Learner system. Specifically, dual Volterra functions express the anticipatory and hereditary influences passed via an instructor-controlled forcing function on the shared spring. Boundary conditions (task goals) on the instructor-spring system, construed as a mathematical (self-adjoint) operator, are passed to the learner-spring system. Psychological interpretation is given to the involved mathematical operations that are passed, and mathematical (Hilbert-Schmidts and Greens function) techniques are used to account for the release of the boundary conditions by the instructor and their absorption by the learner, and an appropriate change of their power spectra.

Principles of Self-Organization: Learning as Participation in Autocatakinetic Systems

Modem science has been built on a Cartesian or Newtonian (mechanical) world view giving rise to an artifactual view of mind and suggesting that particles (learners) are continuously working to destroy order (are recalcitrant), which can only be maintained by an external artificer (the teacher). At the core of the Cartesian worldview is the absolute separation of mind and matter. Beginning with the separation of mind and body, Cartesianism is grounded in a set of dualisms that separate individual from environment and leads to the belief that knowledge refers to a self-sufficient immaterial substance that can be understood independently from the individual, environment, and context in which it is situated. In contrast, we make the argument for an alternative set of assumptions predicated on a relational ontology and grounded in recent developments in the understanding of self-organizing systems. In our view, knowing, meaning, and cognition are actualized through the dynamic between learner (self) and enviro...

Wrinkling and head shape as coordinated sources of age-level information

Changes in the shape of a human head and the development of facial wrinkles were examined as potential sources of information about age level. In Experiment 1, subjects estimated the ages of faces that had been produced by systematically manipulating characteristic head shapes and levels of wrinkles associated with ages 15, 30, 50, and 70 years. The results indicated that observers used both sources of craniofacial change in making age estimates; but the effect of either source of change on perceived age depended upon the level of the other source of change. In Experiment 2, subjects’ ratings of the apparent conflict between levels of head shape and wrinkles further substantiated the conclusion that observers are sensitive to the coordination of products of the two sources of change. These findings suggest that the information specifying perceived age level is a complexrelationship among different types of craniofacial change.

Making the constraints visible: testing the ecological approach to interface design

A haemodynamic monitoring and control task was used to evaluate the ecological approach to interface design for complex high-technology environments. Guidelines proposed by Bennett and Flach (1992) were used to design multilevel displays that made visible (a) anatomical constraints, and (b) causal constraints on haemodynamic systems. These displays were compared with a traditional display that showed pressure and flow values in five separate graphs. Simulations of clinical problems were generated by a computer model and presented in an interactive computer environment. Critical care nurses and nursing students observed changes in pressures and flow corresponding to certain disease states and corrected those states using simulated drugs. For both groups, speed and accuracy were progressively improved by the enhanced, multilevel displays.

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

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 Gibsons (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 agents 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 interspersed throughout, providing an autobiographical perspective on issues germane to these topics.

Inadequacies of the Computer Metaphor

One of the most popular tacks taken to explain cognitive processes likens them to the operations of a digital computer. Indeed, the tasks for the cognitive scientist and the artificial intelligence scientist are often seen as indistinguishable: to understand how a machine or a brain “can store past information about the world and use that memory to abstract meaning from its percepts” (Solso, 1979, p. 425). The fact that there are machines that appear to do this, to varying degrees of success, is often taken to imply, almost by default, that cognition would have to embody the same steps in order to achieve the same results. In what folIows, we outline our objections to this attitude and briefly consider some alternatives.

Perception of growth: a geometric analysis of how different styles of change are distinguished.

Although there have been many demonstrations that human observers can accurately recognize a variety of styles of change, such as rolling, walking, or growing, there are no existing theories capable of explaining how one style of change is distinguished from another. The present article offers a hypothesis that any recognizable style of change is uniquely specified by geometric invariants- the abstract properties of a visual display that are preserved by the change. In an effort to provide an empirical test of this hypothesis, several experiments involving the perception of growth were performed. Observers were required to make perceptual judgments of consequences of facial profiles, each of which was constructed by using a different mathematical transformation. The same pattern of results was obtained on both a free response task and a growth rating task: All transformations that were consistently identified as growth preserved the same geometric invariants.

Inquiry into intentional systems I: Issues in ecological physics

SummaryThe role of intention in guiding the behavior of goal-directed systems is a problem that continues to challenge behavioral science. While it is generally agreed that intentional systems must be consistent with the laws of physics, there are many obvious differences between inanimate, physical systems and sentient, intentional systems. This suggests that there must be constraints over and above those of physics that govern goal-directed behavior. In this paper it is suggested that generic properties of self-organizing mechanisms may play a central role in the origin and evolution of intentional constraints. The properties of self-organizing systems are first introduced in the context of simple physical systems and then extended to a complex (biological) system. Whereas behavior of an inanimate physical system is lawfully determined by force fields, behavior of an animate biological system is lawfully specified by information fields. Biological systems are distinguished from simple physical systems in terms of their ubiquitous use of information fields as special (biological and psychological, social, etc.) boundary conditions on classical laws. Unlike classical constraints (boundary conditions), informational constraints can vary with time and state of the system. Because of the nonstationarity of the boundary conditions, the dynamic of the system can follow a complex trajectory that is organized by a set of spatially and temporally distributed equilibrium points or regions. It is suggested that this equilibrium set and the laws that govern its transformation define a minimal requirement for an intentional system. One of the benefits of such an approach is that it suggests a realist account for the origin of semantic predicates, thereby providing a basis for the development of a theory of symbolic dynamics. Therefore, the principles of self-organization provide a comprehensive basis for investigating intentional systems by suggesting how it is that intentions arise, and by providing a lawful basis for intentional behavior that reveals how organisms become and remain lawfully informed in the pursuit of their goals.