Program & Proceedings

2000 North American Meeting

The International Society for Ecological Psychology

June 23-24, 2000

Clemson University

Clemson, SC

 

 

 

 

 

Organized by:

Christopher C. Pagano & Thomas R. Alley

Sponsored by:

Clemson University Department of Psychology

PROGRAM

Thursday, June 22

20:00 - 23:00 Informal gathering at "Joe’s Place" (a pub located on the Madren Conference Center site)

 

Friday, June 23

8:30 - 9:00 Morning Refreshments & Registration

9:00 - 10:30 Friday Symposium: Events and Affordances, How Are They Related?

John Pittenger, moderator

Thomas A. Stoffregen
Affordances and events in perception and action

Michael T. Turvey
Ecological facts and efficiency of information

Robert E. Shaw
Effective action against affordance imperialism

10:30 - 11:00 Break

11:00 - 12:30 Friday Symposium continued

Leonard S. Mark
Challenges in conducting research on the perception of events and affordances

Anthony Chemero, Wil Cordeiro, & Colin Klein
Perceiving Events Related to Gap-Crossing: An Empirical and Ontological Study

Thomas A. Stoffregen & John Pittenger
Reply & Discussion

12:30 - 13:30 Lunch

13:30 - 15:00 Poster Session (with refreshments beginning 14:30)

15:00 - 17:00 Individual Talks

Ted Cochran
An Ecological Perspective on Crisis Management in Automated Systems: Why Can't Operators Push the Big, Red 'Emergency Shutdown' Button When the Plant Catches Fire?

Donald H. Mershon
Interpreting Eyewitness Descriptions of Aircraft Accidents

John R. Hajdukiewicz & Kim J. Vicente
Inducing Coordinative Structures through Ecological Interface Design

R. C. Schmidt & Robyn Sysko
Perceptual-Motor Coordination and Handedness in Endoscopic Surgery

19:00 - 21:30 Dinner (with cash bar)

21:30 - 24:00 Social interaction at "Joe’s Place"

Saturday, June 24

8:30 - 9:00 Morning Refreshments & Registration

9:00 - 11:00 Saturday Symposium: Issues in Transportation

Richard A. Tyrrell, moderator

Leo Gugerty, Joseph C. Jenkins, & Rebecca Morley
Coordination of Egocentric and Exocentric Reference Frames in Cardinal Direction Judgments

D. Alfred Owens
Vision and Driving: An Example of Perception-in-Action

Richard A. Tyrrell & Chad W. Patton
The Nighttime Visibility of Pedestrians: The Pedestrians' Perspective

Jeffery T. Andre

A User-Centered Description of the Illumination Provided by Automobile Headlamp Systems

11:00 - 11:30 Break

11:30 - 12:30 Individual Talks

Eugene C. Goldfield, Ignatius Calalang, Kimberly Lee & Douglas Richardson
Smart Bottle: A Preliminary Clinical Trial

Eugene C. Goldfield, Arden Hill, Kara Fletcher, Athos Bousvaros & Carlo Buonomo
Tau of Swallowing Viscous Fluids During a VideoFlouroscopic Swallow Study: Adult Data With Implications for Premature Infants

12:30 - 13:30 Lunch

13:30 - 15:00 Individual Talks

Leonard S. Mark & Marvin J. Dainoff
Toward a method for Drawing Performance-Based reach Envelopes

Michael K. Russell
Influences of Auditory Experience on Reachability Perception

William Mace
Homeokinetics for Ecological Psychology: The Physics of Everyday Life

15:00 - 15:30 Break

15:30 - 17:00 Individual Talks

Leslie R. Cohen & Thomas F. Shipley
Detecting Invariants in Point-light Walker Displays

Jeffrey B.Wagman
Affordances and Dynamic Touch: Implications for Tool Use

Christopher C. Pagano
Invariants and Selective Attention: Some Recent Experiments Involving the Inertia Tensor

PROCEEDINGS

 

FRIDAY SYMPOSIUM:

Events and Affordances: How are they related?

Moderator

John Pittenger

University of Arkansas at Little Rock

Speakers

Tom Stoffregen

University of Cincinnati

Affordances and events in perception and action

Michael Turvey

CESPA, University of Connecticut

Ecological facts and efficiency of information

Robert Shaw

CESPA, University of Connecticut

Effective action against affordance imperialism

Leonard S. Mark

Miami University

Challenges in conducting research on the perception of events and affordances

Anthony Chemero, Wil Cordeiro, & Colin Klein

Franklin & Marshall College

Perceiving Events Related to Gap-Crossing: An Empirical and Ontological Study

 

A significant proportion of the theoretical and empirical work performed by ecological psychologists has concerned perception of events and perception of affordances. Our leadership on these topics has been one of the factors distinguishing ecological research from research guided by other approaches. However, despite the importance of these topics to ecological psychologists, we have not yet developed a statement of the relation between events and affordance upon which we are in general agreement.

This topic is the subject of a special issue of Ecological Psychology (vol. 12, no.1). Tom Stoffregen’s target article questions the role of event perception in ecological theory, arguing that it is not clear why ecologists should expect animals, including humans, to perceive events. Two key points in his arguments are that (1) events should be defined without reference to the animal’s behavior and should not be scaled to action-relevant properties of the animal and (2) ecological theory assumes that perception exists to facilitate adaptive action by the animal. Stoffregen’s conclusions as to the relation between events and affordances clearly have strong implications for ecological theory. He also suggests implications for research by raising the possibility that the research we have long supposed to demonstrate perception of events may actually constitute studies of the perception of affordances.

Commentaries published in the special issue of Ecological Psychology include both agreement and disagreement with Stoffregen’s ideas. It is, however, notable that these commentaries reveal diversity in the definitions of "event" and "affordance" and in the supposed relations between events and affordances. Therefore, whether or not one agrees with Stoffregen, his paper has revealed that we in the ecological camp have yet to achieve a consensus on this issue, one that is central to our approach.

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SATURDAY SYMPOSIUM:

Issues in Transportation

Moderator

Richard A. Tyrrell

Clemson University

Speakers

Leo Gugerty, Joseph C. Jenkins, & Rebecca Morley

Clemson University

Coordination of Egocentric and Exocentric Reference Frames in Cardinal Direction Judgments

D. Alfred Owens

Franklin and Marshall College

Vision and Driving: An Example of Perception-in-Action

Richard A. Tyrrell & Chad W. Patton

Clemson University

The Nighttime Visibility of Pedestrians: The Pedestrians' Perspective

Jeffery T. Andre

Lewis and Clark College

A User-Centered Description of the Illumination Provided by Automobile Headlamp Systems

 

This symposium will start with a discussion of issues pertaining to the use of maps to facilitate navigation. Specifically, new research will be presented which examines the ability to coordinate egocentric and exocentric reference frames in order to make cardinal direction judgments. To address this issue empirically, Gugerty et al. asked both novices and pilots to make direction judgements while "flying" an uninhabited aerial vehicle (UAV) from a PC workstation. Results of these studies have implications both for understanding the use of maps in navigation and for the design of the UAV piloting task.

In the second presentation, Fred Owens will discuss recent driving-related research and will assert that driving is a rich context from which to study perception and action. He will discuss both theoretical and practical implications that have emerged from studying perception, action, and driving simultaneously. Of particular emphasis will be night driving when, as Owens says, we "see more than we notice but less than we think."

Following up on the general problem of night driving, Tyrrell and Patton will discuss the specific problem of pedestrian safety. While researchers have long known that drivers have difficulty seeing pedestrians at night, pedestrians appear not to appreciate this fact. Pedestrians also appear not to appreciate the extent to which the use of retroreflective markings or high beam illumination can increase their visibility. To test this hypothesis, pedestrians’ estimates of their own nighttime visibility were measured under a variety of conditions. Particularly surprising were the results of several attempts to educate pedestrians of the nighttime visibility problems.

The final presentation will discuss a user-centered approach to describing automotive headlamp systems. Despite the fact that the purpose of headlamps is to provide useful illumination in the three-dimensional space in front of the vehicle, conventional descriptions of the illumination provided by headlamp systems are two-dimensional photometric descriptions. Jeff Andre will employ the concept of civil twilight to develop a user-centered description of the visibility that is afforded by headlamps. He will also show that new cars exhibit surprising variability in their "twilight envelopes."

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INDIVIDUAL TALKS (in alphabetical order):

 

Perceiving Events Related to Gap-Crossing: An Empirical and Ontological Study

Anthony Chemero, Wil Cordeiro, & Colin Klein

Franklin and Marshall College

In a recent Ecological Psychology target article Stoffregen (2000) argues that animals do not perceive events. This result, if it turned out to be true, would have widespread consequences, both methodological and ontological, for ecological psychology. In a response to that target article, Chemero (2000) argues that, despite the fact that a good deal of what Stoffregen says is true, his main claim is incorrect: we do perceive events. To see that this is the case, however, requires a new conceptualization of events, in which events are not merely changes in the physical surrounds of an animal; instead, events are taken to be changes in the layout of affordances of the animal-environment system. Chemero (2000) also proposes an experiment that could determine whether humans actually do perceive events as he has described them. This presentation describes the results of that experiment.

The experiment, which builds on the work of Burton (1992, 1993) and Corbus, Montagne and Laurent (1999), was designed to determine whether subjects could perceive changes in the layout of gap-crossing affordances. It consisted of four different tasks. First, subjects judged whether they would be able to step across static gaps of varying length between a stationary, raised platform on which they were standing and a second stationary, raised platform. Second, subjects stood on a stationary, raised platform and were asked to press a button as soon as they judged that they were no longer able to step onto a raised platform that was moving away from them at a constant speed. Third, subjects stood on a stationary, raised platform and were asked to press a button as soon as they judged that they were able to step onto a raised platform that was moving toward them at a constant speed. Finally, subjects were asked to physically step across static gaps of various lengths.

References

Burton, G. (1992). Nonvisual judgement of the crossability of path gaps. Journal of Experimental Psychology: Human Perception and Performance, 18, 698-713.

Burton, G. (1993). Non-neural extensions of haptic sensitivity. Ecological Psychology, 5, 105-124.

Chemero, A. (2000). What events are. Ecological Psychology, 12, 37-42.

Cornus, S., Montagne, M., & Laurent, M. (1999). Perception of a stepping-across affordance. Ecological Psychology, 11, 249-267.

Stoffregen, T. (2000). Affordances and events. Ecological Psychology, 12, 1-32.

 

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An Ecological Perspective on Crisis Management in Automated Systems: Why Can't Operators Push the Big, Red 'Emergency Shutdown' Button When the Plant Catches Fire?

Ted Cochran

Honeywell Technology Center

As automated systems in aviation, industrial process control, and related areas become more complex, their human designers and operators are faced with significant, and sometimes intractable, problems. Over the past several years, human interface designers have developed a variety of techniques to simplify interaction with complex systems, to increase the salience of displays, and to make the underlying relations between system attributes more apparent. These techniques work: Given both rigorous and systematic attention to interface issues in system design and implementation, and consistent execution of best practices in the operation of automated systems, significant improvements can be made in operational reliability. However, these improvements have led systems designers to incorporate still more complexity in their projects, leading to diminishing returns. Worse, the increased reliability of these systems has begun to lead to a different kind of problem, in that operators rarely encounter serious problems, and may not respond appropriately when they do. In industries in which simulators are impractical, operators frequently have deal with significant problems that they have never encountered before, and will never encounter again. This raises a host of issues for those taking an ecological approach to systems design. Among the most perplexing is the problem of ensuring that operators will, in the midst of an obvious emergency, actually take emergency measures.

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Detecting Structural Invariants in Point-light Walker Displays

Leslie R. Cohen & Thomas F. Shipley

Temple University

Since Johansson (1973) generated the first point-light biological motion displays by attaching small lights at major human joints and then filming people as they engaged in various movements in a darkened room, human observers have been shown to readily detect a number of invariant relations in these and similar motion displays.

Gibsonian theory provides a useful framework for interpreting recent results from point-light walker research: observers consistently provide more accurate and detailed accounts of the objects and actions present in human walker displays, as opposed to those featuring animals or unfamiliar forms in motion (Pinto&Shiffrar, 1999;Neri, et.al.1998); observers are poorer at detecting upside-down point-light walkers. (Sumi, 1984; Bertenthal & Pinto, 1994). Detecting the structural invariants in these displays, seeing a human appears to require picking up higher-order relationships between action and the ground. (Gibson,1986)

We are looking at the effect of two kinds of experience on information pick-up in biological motion displays. In the first experiment we tested expert animal trainers to see if their years of experience observing and interacting with animals would improve their ability to recognize and detect animals in masked point-light displays. It was found that seal trainers and dog trainers were not better at detecting their own animals in such displays, nor did they show an orientation effect; both groups showed an orientation effect for human walker displays--they were also better at recognizing and detecting upright humans.

In a second experiment, we looked at the effect of experience on detecting complex human actions (e.g., sports). If previous experience engaging in an action aids detection in point-light displays, one would expect that people who had played and watched a given sport would perform better than those who had not. Our preliminary findings showed that experience with basketball was correlated with a higher rate of reporting coherent actions and forms in point-light scenes generated from basketball footage. We have also found that the removal of a point corresponding to the ball appears to remove critical information about human/environment relations: Observers rarely reported seeing coordinated action and were less likely to report coherent figures.

Biological motion displays provide an opportunity to examine the critical invariant relations that may help co-ordinate our actions with those of other humans. An examination of properties of point-light displays may suggest what kinds of information might be more or less readily picked up in 2D media. The talk will provide an overview of the most recent findings from research on point-light walkers in light of related work within the field of ecological psychology. We will also provide a more detailed presentation of our experimental findings and suggest how they may relate to the presentation of information in , video, and electronic interactive media.

References

Bertenthal, B. I. & Pinto, J. (1994) Psychological Science, 5, 4, 221-225.

Gibson, J.J. (1986). The Ecological Approach to Visual Perception.

Johansson, G. (1973). Perception and Psychophysics, 14, 201-211.

Pinto, J. & Shiffrar, M. (1999). Abstracts of the Psychonomic Society. 4, 1.

Neri, P. et. al. (1998). Nature. 395, 894-896.

Sumi, S. (1984). Perception. 13, 283-286.

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Smart Bottle: A Preliminary Clinical Trial

Eugene C. Goldfield, Ignatius Calalang, Kimberly Lee, & Douglas Richardson

Children's Hospital, Boston, Beth Israel Deaconess Medical Center; Harvard Medical School

Of the 4 million live births in the United States, more than 436,000 are born at gestational ages less than 37 weeks. Many of these preterm infants have spent some time in neonatal intensive care, and are delayed in hospital discharge by difficulty with oral feeding. Thus, in this country alone, the feeding difficulty of preterm infants constitutes a major health problem. What is the nature of this problem? Studies have shown that these infants have difficulty in breathing at the same time they suck and swallow fluid. Especially when they are very hungry, infants try to suck and swallow milk as vigorously as they can, even if they must briefly interrupt their breathing. This promotes poor coordination of swallowing and breathing, choking on the milk, and feeding apnea. One solution to this problem has been to provide infants with constant restricted milk flow. However, such a strategy doesn’t help infants to learn on their own to regulate their sucking and swallowing so that it doesn’t interfere with breathing. This suggests that using a device that regulates milk flow for the infant, based upon their breathing patterns, might help them learn to feed more effectively, and hence reduce the amount of time they must spend in the hospital.

This study presents the results of a preliminary clinical trial of a device designed to regulate the flow of milk available to an infant, depending upon their breathing pattern (see Figure 1). This device, called "Smart Bottle" (U.S. Patent 09/132,015), uses a nasal air flow sensor to detect respiratory patterns. A computer controller monitors each breath as well as sucking demand. A pump provides milk at one of four flow rates: none, low, moderate, and high. The particular rate is determined by the infant’s sucking amplitude. When an inspiration exceeds the threshold set for inspiration amplitude, the computer sends a signal to a pump to provide milk flow at the level demanded by the infant. However, if the inspiration does not exceed threshold, milk flow is reduced to the next lowest level, and then to no flow until breathing returns to threshold. The decision by the controller to pump milk is made ten times each second.

The data presented here are from the first phase of the clinical trial. During this phase, there is only a "virtual" pump being controlled by the computer. Using Labview software (National Instruments, Austin TX), all of the functions of an infusion pump have been recreated in software so that signals to the pump based upon the infants breathing could be evaluated. The rationale for using a virtual pump is that it allows us to demonstrate the safety of the decision rules by which the computer sends signals for controlling milk flow. Our hypothesis is that the virtual pump will be turned on only when a recorded inspiratory signal crosses the threshold we established. Even when the infant sucks vigorously, unless inspirations cross the threshold, only minimal milk flow is provided. The test of the hypothesis is whether, for each "on" signal to the pump, the concurrent breath has crossed threshold. Figure 2 presents a sample of the results for one of the infants tested thus far. Over the period of ten seconds sampled, the infant inspired 16 times (1.6 breaths per sec). Of these 16 breaths, 14 crossed the established threshold, and 2 did not. The virtual pump signaled "on" for 14/14 of the breaths that crossed threshold, and signaled "off" for 2/2 breaths that did not cross threshold. For the entire recording of five minutes of feeding for one infant, for nearly 500 breaths, the pump never signaled "on" unless the infant’s inspiration at that moment exceeded the established threshold value. The results, therefore, are promising. After we test more infants, we will move to the next phase that allows us to use an actual pump to provide rates of milk flow appropriate to the infant’s respiratory patterns.

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Tau of Swallowing Viscous Fluids During a Videoflouroscopic Swallow Study: Adult Data with Implications for Premature Infants

Eugene C. Goldfield, Arden Hill, Kara Fletcher, Athos Bousvaros, & Carlo Buonomo

Children's Hospital, Boston; Harvard Medical School

The coordination of the tongue and pharyngeal structures during swallowing is one of the earliest motor patterns observable in human infants. This behavioral pattern is well organized at term (38 to 40 weeks Gestational Age, (GA) but poorly developed among preterm infants, especially those born less than 28 weeks GA. A consequence of poor coordination of swallowing is that some of the fluid taken into the mouth enters the airway, a process called aspiration. Chronic aspiration places the infant at risk of pneumonia. The problem has not yet been studied from the standpoint of motor control and perceptual regulation. In this study of an adult subject, we use the technique of videofluoroscopy to examine the relationship between the rate of flow of fluids of different viscosities, and the timing of the contact between the tongue and soft palate.

The study is guided by a model of perceptual guidance of intrinsic motor timing patterns. According to the model, swallowing coordination is characterized by the time to contact (tau) between anatomical surfaces that open and close the pharynx, relative to the rate of fluid flow. Swallowing difficulty among some infants may arise because the rate of closure and contact between tongue and soft palate occurs too slowly to prevent some fluid from being aspirated. Preterm infants with a motor deficit that results in a slow rate of closure of tongue and soft palate may be more prone to swallowing problems and aspiration. During videofluoroscopic swallow studies (VFSS) at Children’s Hospital, Boston, clinicians report anecdotally that at term, some preterm infants tend to have more difficulty swallowing and are more likely to aspirate thin fluids. Videofluoroscopy is a procedure that uses an x-ray machine and videorecorder for diagnosis of swallowing disorders. Clinicians also report that thickening the radio-opaque medium, barium sulfate, both improves swallowing and reduces aspiration. Fluid viscosity was measured with a rheometer, a highly sensitive device that measures the resistance of a fluid to spinning forces. An implication of the theory is that brain immaturity may interfere with the perceptual regulation of action, and that interventions that thicken swallowed fluids may be successful because they slow the rate of fluid flow.

Recent advances in computer-assisted motion analysis make it possible to measure the coordination of pharyngeal structures involved in swallowing and airway protection following VFSS. Motion analysis uses a cross-hair cursor to mark x,y coordinates of anatomical structures viewed on each digitized video frame. Software calculates displacement, velocity, and acceleration of the markers over a sequence of video frames. To evaluate the rate of closure of tongue and soft palate during swallowing, we use motion analysis to examine (a) the timing of tongue contact with the soft palate, relative to the rate of flow of fluids during swallowing, and (b) the effects of fluid thickening procedures that slow rate of flow during swallowing.

We present a video illustration and examine data from a healthy adult. We calculated the value of time to contact between the tongue to the soft palate during each of several swallows. We also calculated the transit time of the head of the barium sulfate bolus between anatomical landmarks. The computation of tau for each of these indicated that coordination was achieved by coupling the taus.

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Inducing Coordinative Structures through Ecological Interface Design

John R. Hajdukiewicz & Kim J. Vicente

University of Toronto

The concept of coordinative structures has its origins in motor control, and it has generated a great deal of productive research on that specific problem (Turvey, 1990). As far as we know, however, the concept has not been used outside of motor control. In previous work, we postulated that it may be possible to develop a general theory of the generic systems problem of coordination that is applicable to both biological and human-machine systems (Yu et al., 1997). In this research, we test that conjecture by using the concept of coordinative structures to make predictions about the impact of interface design on human performance in DURESS II, a process control simulation. This simulation requires mediated rather than direct interaction with the environment, has slow dynamics, and requires people to engage in problem solving activities. Thus, it allows us to assess the generalizability of the concept of coordinative structures to a new domain with a different set of properties from motor control.

To investigate the use of coordinative structures in DURESS II, a study was conducted with 16 participants, using one of two different interfaces to control the process system. The P interface, designed using a more traditional rote instrument approach (i.e., mimic design), displayed primarily physical information about the work domain. The P+F interface, designed using the smart instrument approach of ecological interface design (EID; Vicente & Rasmussen, 1990), displayed both physical and functional information about the work domain derived from an abstraction hierarchy (AH; Rasmussen, 1985) analysis of DURESS II. The hypothesis was that the P+F interface would better support the use of coordinative structures, compared with P interface, in the face of global, dynamic perturbations. Participants were given a great deal of practice controlling the process, and then their ability to achieve the task goals in the face of global changes in component time constants was examined. The data were analyzed using measures that assess adaptive performance, coupling to the work domain, and stability. Evidence for the use of coordinative structures for these conditions would be indicated by lower variability in completion times, coupling at higher-order variables of the work domain, and more robust control. The results did in fact show that P+F participants had faster and less variable completion times, coupling to higher-order variables of the work domain, and more robust control, compared with P participants.

In conclusion, this study suggests that the problem of how to coordinate a complex system with many degrees of freedom in a goal-directed fashion in the face of limited resources may have a generic solution, whether it is implemented biologically (as in the case of motor control) or in a well-designed human-machine system (as in the case of the P+F interface for DURESS II). Therefore, it seems worthwhile to explore the connections between theories of motor control and cognitive engineering (Vicente, 1999). The result may very well be progress towards a general theoretical account of the generic systems problem of coordination.

Acknowledgements

This research was sponsored by a contract from Sytronics Inc. (Robert Eggleston, contract monitor), and a grant from the Natural Sciences and Engineering Research Council of Canada.

References

Rasmussen, J. (1985). The role of hierarchical knowledge representation in decision making and system management. IEEE Trans. on Systems, Man, and Cybernetics, 15, 234-243.

Turvey, M. T. (1990). Coordination. American Psychologist, 45, 938-953.

Vicente, K. J. (1999). Cognitive work analysis: Toward safe, productive, and healthy computer-based work. Mahwah, NJ: Erlbaum.

Vicente, K. J., & Rasmussen, J. (1990). The ecology of human-machine systems II: Mediating 'direct perception' in complex work domains. Ecological Psychology, 2, 207-250.

Yu, X., Lau, E., Khayat, R., Vicente, K. J., & Carter, M. W. (1997). Ecological interface design and long-term adaptation: Information, coordination, and execution-driven control. In Proceedings of the International Symposium on Artificial Intelligence, Robotics and Intellectual Human Activity Support for Nuclear Applications (pp. 81-92).

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Homeokinetics for Ecological Psychology: The Physics of Everyday Life

William Mace

Trinity College

My goals in this talk are (1) to provide ideas about directions for empirical research in psychology especially suited to homeokinetic thinking and (2) to provide an orderly "gist" of what the fundamental features of homeokinetics are. It will be important to keep separate distinct ways to be comprehensive. Iberall's goals are breathtakingly ambitious in their scope, but the homeokinetic framework does NOT promise insight into arbitrarily selected problems in psychology.

In the 1960's, the physicist / engineer Arthur Iberall, was encouraging biologists to look for periodic phenomena in behavior wherever possible, to be sensitive to limit cycle organization, and to elaborate in the framework of nonlinear dynamics. This was done in the name of "Systems Science." The problem area was called "homeokinesis" in order to pair it with "homeostasis." The core of Iberall's ideas for psychology was presented in a 1969 paper co-authored with Warren McCulloch. Stimulated by an ethological orientation to animal behavior as described by J.P. Scott, Iberall and McCulloch offered a classification of all mammalian "routines" [my word choice] with rough proportions of recurrence. These temporally nested routines, from fastest to slowest, make up the empirical "foot in the door" for including psychology in a consistent science that for Iberall spans physics, biology, psychology, politics, economics, and the study of civilizations. In recent years, Iberall has pressed the idea that the nested cyclic activity of the universe can best be comprehended through a recursive application of the principles of statistical mechanics and thermodynamics. The unity he presented in the 1960's as "systems thinking" is now developed solely as physics (period) and homeokinetics has been elaborated as the physics of complex systems.

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Toward a Method for Drawing Performance-Based Reach Envelopes

Leonard S. Mark & Marvin J. Dainoff

Miami University, OH

The specification of reach envelopes that accommodate specified working populations is an important component of ergonomic guidelines, and standards. The transition between two reach modes (such as from arm only to arm plus shoulder reach) typically occurs prior to the limit set by anthropometric dimensions. Actors appear to avoid this limit, possibly in an attempt to maximize comfort or minimize energy expenditure and/or strain. This study attempts to predict the distances at which these preferred critical boundaries occur using a methodology based on the work of Cesari and Newell (1999). Preliminary results indicate similar predictions are possible for reach, and could provide a principled basis for determining action-based reach envelopes. We are currently attempting to use the resultant reach envelopes to determine their adequacy in predicting the reach modes used by computer operators to reach for objects at different distances.

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Interpreting Eyewitness Descriptions of Aircraft Accidents

Donald H. Mershon

North Carolina State University

Eyewitness descriptions of aircraft accidents (or aircraft behavior prior to an accident) can be important in the process of reconstructing the event. Eyewitness statements often provide compelling descriptions of tragic events. This was particularly true for two recent air accidents: the crash of TWA Flight 800 off the coast of Long Island, New York (1996) and the deaths of 20 skiers when a US Marine jet severed the cables supporting their gondola near Cavalese, Italy (1998). In the first case, witnesses described what appeared to be the track of a missile launched from a beach or from the water just offshore. In the second case, many witnesses described a military jet flying excessively low (possibly recklessly) in the time shortly before the fatal crash. To what degree should investigators depend upon such descriptions in their reconstruction?

The difficulty arises, of course, when such descriptions are assumed to be exact reflections of reality. Psychologists like Dr. Elizabeth Loftus have ably considered the malleability of human memory, especially following frequent repetition of an account and/or exposure to media descriptions. The current presentation will focus instead, not on issues of memory, but on some basic perceptual processes which can affect the original experience of an eyewitness. In particular, the discussion will center on how these processes can create significant errors in the spatial percepts experienced by human observers.

Laboratory studies over many years have shown conclusively that restrictions of visual information lead to predictable types of errors in the perception of both egocentric and exocentric distance. It is relatively easy to find examples of such errors in everyday situations, especially when information has been restricted in some way (e.g., by the involvement of great physical distance, the observation through some sort of aperture or the separation of objects from the ground plane). Under conditions in which information is limited, two characteristic biases produce significant errors in distance perceptions: 1) objects tend to appear too close to the observer in distance, and 2) objects tend to appear too close to each other in depth. Although independent, these two factors may sometimes combine to create more serious misperceptions.

The usefulness of these two key biases in understanding and interpreting the statements of eyewitnesses to air accidents will be discussed.

 

 

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Invariants and Selective Attention: Some Recent Experiments Involving the Inertia Tensor

Christopher C. Pagano

Clemson University

Two sets of experiments regarding the perception of length by wielding will be discussed. Participants in the first set of experiments reported the lengths of occluded rods wielded in air or water. Moment of inertia (the resistance to angular rotation due to mass distribution) was manipulated by varying the length and composition of the rods. Drag (the resistance to angular rotation due to the displacement of a fluid medium) was manipulated by wielding in air or water. Although the torques required to wield in water are substantially greater than those required to wield in air, it is possible for the perceived lengths of rods wielded in the two be identical. These experiments demonstrate that perceivers can extract the physical invariant of inertia from the complex arrays of forces created by the denser medium of water. These results underscore the importance of invariants in perception.

The second set of experiments investigated the perception of object length in a condition where participants are allowed to view the objects during wielding. The results of these experiments indicate that participants tend to use actual length–a geometric variable available through vision–rather than inertia–a mass-based parameter available through touch–when perceiving the lengths of wielded rods that they can see. Thus when asked to perceive a geometric property of the wielded object the participants attended to use the more accurate geometric information available via vision rather than the mass-based information available via dynamic touch.

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Influences of Auditory Experience on Reachability Perception

Michael K. Russell

Kutztown University

 

 

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Perceptual-Motor Coordination and Handedness in Endoscopic Surgery

R. C. Schmidt & Robyn Sysko

College of the Holy Cross

Over the past ten years, endoscopic surgery has become an increasingly common procedure within the medical community. Endoscopic surgery involves the insertion of a camera and surgical instruments into the body through small incisions and controlling the procedure on a video monitor. Using this procedure, discomfort and recovery time have been dramatically reduced for patients. However, the remote control nature of the perceptual processes needed to perform endoscopic surgery are different from that of traditional procedures, and can in turn produce complications. The remote-control perceptual processes needed to perform endoscopic surgery are unusual because the canonical relationship between the hands and the eyes is disturbed by the intermediary of the remote-sensing device. Previous research has demonstrated that different camera and monitor positions differentially disturb this canonical relationship and affect the difficulty of remote sensing manual task. In a series of preliminary experiment using a number of different tasks, the differential effects of monitor and camera positions on task difficulty were replicated. Asymmetries in the results led to subsequent studies that explored the interaction of monitor and camera positions with the handedness of the subject. Experiments using right-handed participants found that the participants needed greater amount of time to complete the task when either the monitor or camera were located on the right of the body (240° or 300°). Experiments using left-handed participants that the monitor or camera positioned on the left side of the body caused the greatest task difficulty (120° and 60°). Thus, at least for subjects with minimal training, body asymmetries due to handedness result in that an asymmetry in the perceptual-motor work space that in turn affect the timing of movements in this remote sensing task.

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The Perception of Affordances of Hand-Held Tools

Jeffrey B. Wagman

CESPA, University of Connecticut

In the ecological approach to perception and action, in the tradition of James Gibson (1966/1986; 1979), affordances are the entry point into the interaction between an animal and its environment, and a tool is an object attached to the body in such a way as to extend the organism's capacity for perceiving and acting. Thus, there is an intrinsic link between the concept of affordance and the concept of tool use. Since tool use in humans has far surpassed known use of tools in other species the bulk of research on tool use has been on hypothetical internal cognitive mechanisms (e.g., schemas) associated with human tool use.

The use of most hand-held tools (consider, for example, the use of a hammer, screwdriver, or wrench) often involves firmly grasping an object and manipulating it via muscular effort, a process known as dynamic touch (Gibson, 1966). The physical bases of perception of object properties via dynamic touch is the object's rotational inertia (see Turvey, 1996 as well as Turvey & Carello, 1995 for a review). Dynamic touch then, provides a means for an animal to: (1) perceive the properties of a hand-held tool and (2) regulate the generation and application of torques in manipulating that tool so as to satisfy a given intention. Furthermore, dynamic touch provides a means for the study of particular instances of tool use without strict reliance on internal cognitive mechanisms.

In three experiments, we attempt to uncover the physical bases of the perception of the affordance of hand-held objects for two common functions: hammering (i.e., pounding) and poking (i.e., displacing). In all three experiments, participants rated nine wielded (but unseen) objects as to how well they would be able to "hammer" or "poke" another object with them.

In Experiment 1, we found that ratings of hammers were dependent upon a particular parsing of the inertia tensor of the objects. Additionally, ratings of pokers were dependent on a very different parsing of the tensor for those participants who were able to successfully differentiate between hammers and pokers. In Experiment 2, ratings of hammers were dependent on the same parsing of the inertia tensor observed in Experiment 1, and selection of the point along the object at which to strike another object was dependent on the major eigenvalue of the objects. In Experiment 3, we found that the physical dependencies of ratings of both hammers and pokers change after experience completing a task involving hammering or poking. Furthermore, these changes are in a direction that seem to suggest "attunement" to inertial properties of the objects that may promote successful completion of the given task.

These findings suggest that: (1) perception of affordance of hand-held tools (at least tools to be used in hammering or poking) is perceptible via dynamic touch (2) the physical basis of these perceptions is the object rotational inertia, and (3) such perception can be "tuned" via experience with a particular task.

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POSTER PRESENTATIONS

 

Affordances and the Accuracy of Visual Estimates of Size

Thomas R. Alley & Theodora S. Passinos

Clemson University

Two methods of estimating size (linear extent) were compared. One required adjustment of the distance between a point created by a laser beam and a fixed reference line; the other involved adjusting the separation of two vertical posts. Two groups of adults were instructed to use these methods to indicate either simple linear extent ("width") or the affordance of passability (minimal opening) for identical dimensions of objects and their own bodies. Higher accuracy was expected for both the method (posts) and instructions ("opening") that should foster affordance-based judgements. Despite the greater ease and precision of the laser-based method, more accurate estimates were made using two vertical posts.

 

 

 

The Doctoral Students of James J. Gibson and Eleanor J. Gibson

Patrick A. Cabe

University of North Carolina at Pembroke

Scholars are often noted both because of the work they produce and because of the students they train. Between them, James J. Gibson and Eleanor J. Gibson, over long academic careers, supervised approximately 40 doctoral dissertations. This poster presents a compilation of the names and dissertation titles of those students. Because some gaps remain in this list, it should be considered a work in progress. While some of the Gibsons' students have pursued aims other than academia or research, a number of those individuals have gone on to establish respected research careers of their own in perception and perceptual development. Some other individuals who have had a close working relationship with one or the other of the Gibsons, but whose dissertations were not supervised by either James or Eleanor Gibson, are also listed.

 

 

 

Detecting Surface Aberrations in a Tool Task by Capuchin Monkeys (Cebus Apella)

Sarah E. Cummins-Sebree & Dorothy M. Fragaszy

University of Georgia

We examined four capuchins' abilities to accommodate their actions to surface aberrations when manipulating a hoe to slide food across a platform. The platforms presented varied in being a) flat, b) containing a hole, and c) containing a barrier. Capuchins avoided barriers more than holes in early testing. They succeeded with both plain and barrier platforms throughout testing. By the conclusion of testing, two capuchins accommodated their actions sufficiently to succeed with hole platforms. Capuchins learn the affordances of varying surfaces and actions for successful use of tools.

 

 

 

Three Perspectives of AIDS

Judith Effken & Mary Koithan

University of Arizona College of Nursing

We describe three perspectives relevant to assessing patients with HIV. The clinician's perspective is biomedically driven, based on goals, skills, and the healthcare reimbursement environment. Patients offer two additional perspectives. The cognitive perspective is found in patients' stories, colored by education, culture and family history. The perceptual perspective, reflecting embodied experience in the world, is not typically accessed and is best captured through aesthetic representations. A sample of visual representations of persons living with HIV revealed a number of shared properties (shape, color, space & spacing, symmetries). We speculate that these similarities represent the invariant structure of their world.

Detection of Aperture Size and Location using Echolocation

Terri Erwin & Danielle Wassam

Wheeling Jesuit University

The acoustic perception of spatial layout by sighted humans was investigated in two experiments. Specifically, participants' ability to use reflected sound to apprehend the dimensions of an enclosure was examined. Inside a chamber with sound reflecting walls, subjects produced "hooting" sounds and used the acoustic reflection to judge the size (Experiment 1) and location (Experiment 2) of an aperture in the wall facing them. Congruent with past research with blind and sighted subjects, we found variability in participants' ability to echolocate successfully; however, our data indicate systematic performance for many participants in aperture size and location ranking, though absolute accuracy was not achieved.

 

 

 

Role of Dynamic Touch in Tool Use Development

Paula Fitzpatrick

Assumption College

During the toddler and preschool years children gain proficiency using a variety of tools-spoons, crayons, and shovels, for example. Lacking, however, is an understanding of the role of perception-particularly dynamic touch-in tool use development. Knowing the location of the end of a hand-held object is fundamentally crucial for successfully using it. In this experiment, perceptual measures were taken of children's ability to perceive the length of an unseen, hand-held object. Drawing ability was used as an index of tool-use skill level. Results indicate that children are able to perceive the extent of a hand-held object, with subtle changes in perceptual sensitivity as a function of skill level. In addition, perception of extent was shown to vary as a function of the inertia of the object.

 

 

 

Perceiving the Lengths of Nonrigid Objects by Dynamic Touch

Desiré GrandPre & Claudia Carello

Center for the Ecological Study of Perception and Action, U of Connecticut

Haptically perceiving the lengths of rigid objects is constrained by the inertia tensor. When the wielded objects are nonrigid, however, tissue is deformed by more than the object’s mass distribution (e.g., oscillatory motions of an object, influenced by its stiffness, are superimposed on exploratory movements). Two experiments examined perception of spring length by dynamic touch. As with rigid objects, perceived length approximated actual length and was constrained by two moments of inertia whose exponents were opposite in sign. Moreover, the contribution of an index of stiffness was significant (with a negative exponent) for both plain springs and springs attached to rigid handles.

 

 

 

Adapting to Change in Complex Work Environments

John R. Hajdukiewicz

University of Toronto

The purpose of this research is to assess the impact of human-computer interfaces on an operator's ability to adapt to change. A study was conducted using DURESS II, a thermal-hydraulic microworld environment. Participants used one of two interfaces to control the process system, developed using different design principles. After a great deal of practice, their abilities to achieve the target states, in the face of global, dynamic perturbations, were examined. The data were analyzed using measures of adaptive performance, coupling to the work environment, and stability. The results show that information and experience are key factors to success in adapting to change.

Identification of Positive and Negative Behaviours Associated with Operating a Cellular or Mobile Phone Whilst Driving

Philip Hovea, Gillian H. Gibbsb, & Jeff K. Cairda

aUniversity of Calgary bSimon Fraser University

Although using a cellular or mobile phone while driving is likely to increase accident risk (Goodman, et al., 1997, Redelmeier and Tibshirani, 1997; Violanti and Marshall, 1996), little is actually known about when and why drivers use their phones while driving. Dialing a long number or arguing with a spouse on the phone when the traffic environment is particularly demanding exemplify several behaviours not suited to driver safety. However, being able to call the police after an accident occurs or requesting a tow truck after breaking down are positive behaviours associated with using a mobile phone (Goodman, et al., 1997). On a situation by situation basis, some drivers may and others may not attempt to balance the attentional demands of using the phone with the varying demands of driving. Others may make strategic decisions when it is or is not safe to use a phone such as not in high traffic urban areas or at intersections. We hypothesized that those that are willing to commit violations in high risk driving situations such as running yellow lights (see, e.g., berg, et al., 1998; Parker, et al., 1992; 1995; Reason, et al., 1990) would also be more likely to use mobile phones when it was less safe to do so. The purpose of this study was to develop and test a measurement instrument that could test this hypothesis.

 

 

 

Age-Related Variation in Driving behavior At Night

D. Alfred Owensa, Justin M.. Owensa, Joanne Woodb, Daniel Whittamb, & Mark Woolfb

aFranklin & Marshall College

bQueensland University of Technology

Road fatality rates are 3 to 4 times higher at night than in the day, and impaired vision is a major contributing factor. Moreover, problems of night vision are greater for older drivers, the fastest-growing segment of the driving population. Accordingly, this study tested performance during driving on a closed road course to assess the effects of age and low illumination, the two factors that most commonly impair vision when driving. Visual recognition of naturalistic targets is degraded during night driving, and this problem increases with advancing age. Risks for pedestrians, who are especially difficult to see at night, are minimized by biological motion markings. Measures of speed and lane keeping suggest that older drivers attempted to compensate for age-related impairments of night vision through more cautious behavior. All ages drove more slowly in low light, but none slowed enough to compensate for decreased visibility. These findings support the hypothesis that driving behavior depends less on visual recognition (focal) than on visual guidance (ambient) processes, which evolved to provide efficient control of actions.

 

 

 

Relating Errors in Verbal and Reaching Responses to Visual Targets

Christopher C. Pagano, Richard P. Grutzmacher, & Joseph C. Jenkins

Clemson University

It has recently been suggested that different responses to visually perceived targets, such as verbal responses and blind walking, are directed by a single internally represented perceived depth. Evidence for this is provided by the fact that verbally reported distances are essentially a single-valued function of distance reported by an action response. An alternative procedure is to compare verbal and action responses that are made at the same time (i.e. within-trial). Specifically, participants can be asked to make a verbal judgment to a given target distance which is immediately followed by an action response. The results suggest that ‘cognitive’ and motor responses to visually perceived targets, such as verbal responses and blind reaches, respectively, are not directed by a single internally represented perceived depth when those responses are initiated immediately. With a delay, however, it is possible that the two responses may become correlated.

Visual Judgements of Wheelchair Passability: Influence of Control and Point of View

Michael K. Russellab & Stacy Lopresti a

aKutztown University bBucknell University

Flascher, Kadar, Garrett, Meyer, and Shaw (1995) have shown that passability judgments of physical extensions of the body (e.g., cars, wheelchairs) are a function of the observer's intention and can be as accurate as body-scaled judgments. In the present studies, participants were given the task of judging whether a gap affords passage for a wheelchair. The contributions of chair control (own versus another's control) and point of observation were evaluated. Results revealed that while passability judgments were essentially independent of the point of observation, the control of the wheelchair was a significant factor. The importance of perspective and intention are discussed.

 

 

 

Auditory Perception of Reachability: Interaction Between Earheight and Traditional Information Factors

Michael K. Russellab & Kerri Schulera

aKutztown University bBucknell University

Eye height has been shown to affect visual perception. While the present study revealed that ear height influenced auditory perception, visual and auditory judgments of reachability were found to be differentially affected by the manipulation of the point of observation. The extent to which binaural differences, sound intensity, and the ratio of direct to indirect sound influenced distance judgments when ear height and target height were not equivalent was also determined. The results suggest that it is only the amount of direct sound energy reaching the ear that is informative about source distance when target height is below ear height.

 

 

 

Auditory Perception of Reachability: Sound Intensity and Ratio of Direct-to-Indirect Sound

Michael K. Russellab & Kerri Schulera

aKutztown University bBucknell University

It has been previously shown that observers are highly capable of judging the reachability of an unseen sound source. The present study sought to determine the extent to which sound intensity and the ratio of direct to indirect sound influence reachability judgments. While the results suggest that both factors affect perceptual judgments, sound intensity appears to be a scaling factor whereas this was not the case for direct:indirect sound energy. The possibility exists that a higher-order variable, a variable capturing both factors, serves as the basis of auditory distance perception.

 

 

 

The Effect of the Hand in the Body Cavity on a Laporoscopic Surgical Task

Richard Schmidt, Nicole Gribbons, & Brian Eckert

College of the Holy Cross, Worcester, MA

This study investigated whether the performance of a video-guided surgical task using the dominant hand is enhanced by the presence of the nondominant hand inside of the body cavity. In a series of experiments, performance of a manual task using one hand alone was compared to the performance of the task when the participants had their nondominant hand inside the body cavity either invisibly, or visibly and playing a passive role or visibly and playing an active role in the task. Results using three different manual tasks suggest that having the hand play an active role decreased the difficulty of the task whereas having the hand in a position invisible to the participant caused a deficit in task performance. The results have implications for the use of the HandPort Surgical System developed recently by Smith and Nephew Endoscopy.

 

Variations of Mass and Static Moment are Not Necessary for Variations in Perceived Heaviness: An Affordance Perspective on the Inertia Tensor

Kevin D. Shockley, Claudia Carello, & M. T. Turvey

Center for the Ecological Study of Perception & Action, University of Connecticut

Haskins Laboratories

Two scalars derived from the inertia tensor have been shown to play a role in heaviness perception: Inertia ellipsoid volume relates to the mean level of torque needed to move an object; inertia ellipsoid symmetry concerns how that torque should be directed. Previous research has found that the influences of these scalars on perceived heaviness are additive. Since static moment, SM, also varied, three new experiments assessed whether perceived heaviness varies in the absence of variations of mass and SM. The tensor hypothesis was supported. Given their relevance to the human movement system, symmetry and volume provide an affordance-based description of objects.

 

 

 

 

Tell Me How to Move

Kevin D. Shockleyab, Marie-Vee Santanaa, & Carol Fowlerb

aCenter for the Ecological Study of Perception & Action, University of Connecticut

bHaskins Laboratories

Biological organisms exhibit phase-locking or synchronization at different time scales. The behavior of fireflies, for instance, as well as that of other biological organisms has been observed to exhibit collective patterns (c.f., Strogatz & Stewart, 1993, Schmidt & O_Brien, 1997). The present research will report evidence of entrainment as a function of speech and communication using the wrist-pendulum paradigm and postural activity (measured using 6-D motion capture technology). The experiments discussed here utilize independent and cooperative speech tasks to investigate the influence of these on action. Our goal is to better understand the constraints that oral communication imposes on coordination.

 

 

 

 

Postural Stabilization of Vision with Imposed Optical Flow

Mei Sia, Gregory K. Nelsona, Philip Hovea, Thomas A. Stoffregena, & Benoit G. Bardyb

aUniversity of Cincinnati bUniversity of Paris XI

Are postural responses to imposed optical flow functionally related to the demands of simultaneous supra-postural tasks? Standing subjects were exposed to imposed optical flow in a moving room. In Experiment 1 subjects were instructed to intentionally resist the effects of room motion on stance; this effort yielded a significant reduction in coupling. In Experiments 2 and 3 subjects performed an explicit supra-postural visual task, either fixation of a textured target, or scanning a text for target letters. Targets either shared the room's motion or were stationary relative to the earth. Coupling of body sway to room motion was reduced with stationary targets.

Clinical Utility of Postural Dynamics

L. James Smart, Jr. & Dean L. Smith

Miami University, OH

Recently, evidence linking behavioral and health research has emerged from the study of posture and postural dynamics. Studies examining the relation between postural control and motion sickness has shown that motion sickness is preceded and predicted by postural instability (Stoffregen & Smart, 1998; Stoffregen et al, in press; Smart, 2000). Motion sickness is characterized by maladaptive response to unusual motion events (Reason & Brand, 1975). Symptomology is non-specific and variable. While the Postural instability theory of motion sickness proposed by Riccio and Stoffregen (1991) predicted that instability should precede sickness, they did not make any claims regarding the symptomology associated with it. Chiropractic literature has emphasized the effects of vertebral subluxation on neurological dysfunction. Vertebral subluxation is a condition that is postulated to interfere with neurological processes and may influence organ system function and general health. As in the case of motion sickness, symptomology is non-specific and variable (and in some instances the person may be asymptomatic). So what do these disorders have in common? In each instance the disruptions lead to inefficiency in the system. We will discuss this link in the poster.

 

 

 

The Affordances of Conversation: Interrupting and Self-Disclosure

S. Stavros Valenti

Hofstra University

Gibson's ecological approach has much to offer the study of social development because it redirects attention away from hypothetical mental representations and steps of information processing. Instead, it stresses the discovery of what people actually do together and the informational bases of social behavioral regulation. In this presentation I will discuss recent thinking on the nature of social affordances as entities distinct from the affordances of places, pathways, dwellings, and objects. The idea of social (communicative) affordances will be illustrated with two lines of research: Dunn and Shatz's 1989 study of young children's interrupting, and our own research on the sequential structure of self-disclosure in the conversations of adolescent friends.