Theory and Experiment papers

[Hans-Otto Carmesin]

   Two corresponding experimental and theoretical papers concerning
  -- Continuous Phase Transitions in Multistable Perception:
               Neural Network and Experiment --
are now available.
Based on a neural network theory, we predicted a continuous phase
transition for multistable perception (H.-O. Carmesin: Theorie
neuronaler Adaption, Koester, Berlin 1994,1996).
Then we discovered this continuous transition experimentally,
observed additional dynamical effects at the sensitive continuous
transition and improved the neural network model accordingly.

The full neural network theory is presented in the paper
  - A neural network model for stroboscopic alternative motion -
by Hans-Otto Carmesin and Stefan Arndt in
Biological Cybernetics 75, 239-251 (1996).
ABSTRACT:
A neural network which models multistable perception is presented.
The network consists of sensor and inner neurons.
The dynamics is established by a stochastic neuronal dynamics, a
formal Hebb-type coupling dynamics and a resource mechanism that
corresponds to saturation effects in perception.
>From this a system of coupled differential equations is derived and
analyzed. 
Single stimuli are bound to exactly one percept, even in ambiguous
situations where multistability occurs.
The network exhibits discontinuous as well as continuous phase
transitions and models various empirical findings, including the
percepts of succession, alternative motion and simultaneity; the
percept of oscillation is explained by oscillating percepts at a
continuous phase transition. 

The experimental methods and results are presented in the paper
  - Continuous phase transitions in the perception of
                multistable visual patterns -
by Peter Kruse, Hans-Otto Carmesin, Lars Pahlke, Daniel Strber and
  Michael Stadler in Biological Cybernetics 75, 321-330 (1996).

ABSTRACT:
The phenomenon of alternative stroboscopic motion exhibits five
different percepts that are seen with an increase in frequency of
presentation: (a) succession, (b) fluttering motion, (c) reversible
clockwise and counterclockwise motion, (d) oppositional motion and (e)
simultaneity. From a synergetic point of view the increase in
frequency is a control parameter and different percepts are order
parameters with phase transitions in between. The neural network
theory of Carmesin and Arndt is applied to receive predictions about
hysteresis and phase transitions between these order
parameters. Empirical data show the different motion percepts (b),
(c) and (e) have lognormal distributions. Following the theoretical
model, it is argued that there are three different phases, (a), (c)
and (e), with two continuous phase transitions, (b) and (d), between
them. The experimental data substantially match the theoretical
assumptions. 


Some free reprints are available and can be requested via email
from carmesin at theo.physik.uni-bremen.de.
Moreover, two related papers are available online in the www at
http://schoner.physik.uni-bremen.de/~carmesin/docs/zkw9505.ps and
http://schoner.physik.uni-bremen.de/~carmesin/docs/cyber2u.ps.

Hans-Otto Carmesin
Institute for Theoretical Physics,
University Bremen,
28334 Bremen,
Germany,
WWW: http://schoner.physik.uni-bremen.de/~carmesin/