March 22 - 23, 1996
Life Sciences Auditorium
Trinity College
Hartford, CT USA


7:30 p.m. -- 9:30 p.m. (19:30 -- 21:30) Mounting of posters and informal gathering of participants who are present. Lobby of Life Sciences Building, Trinity College. We encourage as many people as possible to attend this session to visit with one another and to get the posters up.


8:45 a.m. -- Informal gathering; coffee

9:20 a.m. -- Welcome and introduction to the meeting

9:30 a.m. -- 10:00 a.m. Dynamics of Clapping: Modeling Strategies for Adults and Children

Paula Fitzpatrick
CESPA, University of Connecticut

Coupled oscillator dynamics was proposed as a candidate dynamical model in a task appropriate for developmental study -- clapping. The appropriateness of coupled oscillator dynamics in characterizing adult clapping patterns under manipulation of frequency of oscillation and limb weighting was presented to establish a comparative baseline of skilled behavior. Clapping patterns of children aged four, five, and seven years suggested that a stable oscillatory dynamic was not exhibited until seven years. Evidence for relative coordination, however, was found for younger clappers, indicative of coupled oscillator attractors underlying their coordination patterns. In spite of high variability, nonstationarity, and individual differences of the children's data, coupled oscillator dynamics can be used to successfully model their interlimb coordination in clapping.

10:00 -- 10:30 a.m. -- Dynamics of 1:2 Coordination in Rhythmic Interlimb Movement

Dagmar Sternad
Pennsylvania State University
Department of Kinesiology

Treating synchronized rhythmic interlimb movements as two coupled oscillations, stable performance can be characterized by relative phase between the two limbs. The modeling strategy, verified for 1:1 coordination, was generalized to 1:2 and n:m coordination. Four predictions were derived and evaluated in 3 experiments using the wrist-pendulum task. Experiment 1 contrasted 1:2 and 1:1 coordination establishing the model's generalizability. In Experiment 2, the additional task asymmetry as posed by the task's frequency ratio was highlighted. In Experiment 3, subjects performed two phase modes, paced by 3 metronome frequencies. The two modes proved equally stable. Phase entrainment was identified with perturbations from the 1:1 regime. Loss of stable phase locking was identified with intermittent behavior in dynamical systems.

10:30 - 11:00 BREAK

11:00 -- 11:30 The sampling of optical flow by eye movements

Nam Gyoon Kim
CESPA, University of Connecticut

When an animal moves rectilinearly with its eyes and head fixed, the retinal motion flows radially from a point, the focus of expansion. The animal can steer its locomotion in the direction of the focus of expansion. When the animal moves along a circular path, the focus of expansion vanishes and retinal flow becomes inherently curvilinear. We constructed various graphic simulations depicting the effect of eye rotation during circular translation. When gaze direction coincides with circular heading, every velocity vector in the image plane becomes linearized. Under these conditions the velocity vectors in the image plane are tangent vectors of the corresponding flow lines of optical flow. The animal's path can be determined by connecting all the tangent vectors lying perpendicular in the image plane. The same solution can be further generalized to linear translation.

11:30 -- 12:00 Motion sickness induced through postural stabilization of vision

Thomas A. Stoffregen & L. Jay Smart
University of Cincinnati

Motion sickness usually is associated with large magnitude imposed motions, such as occur in vehicles or in vehicle simulators. Attention to such situations has lead to the sensory conflict theory of motion sickness. Riccio & Stoffregen (1991) developed an alternative theory, in which motion sickness is not associated with particular kinds of sensory stimulation, but is caused by instabilities in the control of bodily orientation. This theory predicts that the body is destabilized by imposed motions whose frequencies resemble the frequencies of self-generated motions that are used to control orientation. It further predicts that motion sickness will be preceeded by detectable instabilities in the control of orientation. To evaluate this theory we exposed standing subjects to low-amplitude ( <2.0 cm) large field optical oscillations. The oscillations comprised a sum of ten sinusoids ranging between 0.1 and 0.3 Hz. Subjects were exposed for up to 40 minutes. In the main experimental group the incidence of motion sickness was near 50%. Postural motion was measured using a 6-df tracking device. Preliminary analyses of the postural motion data will be presented.

12:15 p.m. -- 1:30 p.m. LUNCH -- catered on site

1:30 -- 2:00 Gap Crossing in the Rat is Influenced by Vibrissa Length Even When Vision is Available

Gregory Burton, Michael Vigorito and Crista Trippodi
Seton Hall University

Previous research (Hutson & Masteron, 1986) shows that blinded rats with intact vibrissae will cross longer elevated gaps than when their vibrissae are clipped. The vibrissae may provide metrical dynamic touch information, or vibrissal contact may provide an either/or signal that the surface to be reached is within a familiar range. To test these possibilities, four vibrissa lengths were employed: full, none, and also quarter-length, and extended, in which fine bristles were glued to either side of the muzzle to existing vibrissae. Rats were trained to cross raised gaps and then tested in the four length conditions, first in the light, then in total darkness.

A significant effect of vibrissa length was found; post-hoc tests showed the difference to reside between full-length and trimmed vibrissae. Rats did not cross longer gaps when their whiskers were extended; in fact, rats crosssed shorter distances in the light in the extended condition compared to the full-length condition. There was no effect of light-vs.-dark, and the advantage for full-length whiskers was present in both conditions, suggesting that the conventional practice of blinding rats to reveal vibrissal use may not always be necessary.

2:00 -- 2:05 Introductory remarks on Brunswik and Gibson

Kim Vicente
Cognitive Engineering Laboratory
Department of Industrial Engineering
University of Toronto

2:05 -- 2:35 How to exploit the structure of environments to achieve near-optimal reasoning.: Satisficing algorithms that stand up to 'rational' favorites.

Daniel Goldstein and Gerd Gigerenzer
Center for Adaptive Behavior and Cognition
Max Planck Institute for Psychological Research
Leopoldstr. 24
80802 Munich GERMANY

We support Egon Brunswik's ecological conception of the mind, namely, that the mind and its environment evolve in tandem, and his view of how the mind exploits the structure of the environment via vicarious functioning with probability cues. However, humans and animals make inferences about the world under limited time and knowledge. Despite this, many Brunswikian and other models of rational inference treat the mind as a computational demon equipped with unlimited time, knowledge, and computational might. This can be seen, for example, in Brunswik's analogy between vicarious functioning and multiple regression. Following Herbert Simon's notion of satisficing, we propose a family of cognitive algorithms based on a simple psychological mechanism which exploits the structures of natural environments: one-reason decision making. These fast and frugal algorithms violate fundamental tenets of classical rationality: they neither look up nor integrate all information, and they are non-compensatory. By computer simulation, we held a competition between the satisficing Take The Best algorithm and various "rational" decision procedures (such as multiple regression). Take The Best matched or outperformed all competitors in inferential speed and accuracy. This result is an existence proof that cognitive mechanisms capable of successful performance in natural environments do not need to satisfy the classical norms of rational inference.

2:35 -- 2:45 Summary remarks by Kim Vicente

2:45 -- 3:00 Discussion

3:00 -- 3:45 BREAK


Participants -- Frank Hassler, Harry Soodak, and Michael T. Turvey

Dr. Frank L. Hassler is the Director of the Office of Transport and Information Resources of the Volpe National Transportation Systems Center, an element of the Research and Special Programs Administration of the U.S. Department of Transportation in Cambridge, Massachusetts. This Office provides planning for and central management of Volpe Center large scale information technology, and advanced concepts development projects, especially those in support of the Departments of Defense and Energy. He also serves as the executive agent for the Technology Committee of the National Defense Transportation Association.

Dr. Harold Soodak is a Professor of Physics at City College of New York. Trained at Duke University and CCNY, Dr. Soodak holds patents on nuclear energy and is the author of numerous books and articles on nuclear reactors and on the physics of complex systems. He has been recognized as an Outstanding Teacher of Physics at CCNY.

[ For a description of homeokinetics and some background on the physicists, Hassler and Soodak, see the link to it from the ISEP home page on the World Wide Web] or Click Here

5:30 -- 7:00 -- Poster Viewing

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