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Papers by Thomas Ditzinger

Physical Review E, 1994

Responses of two models of autonomous nonlinear systems, one bistable and the other monostable in... more Responses of two models of autonomous nonlinear systems, one bistable and the other monostable in certain parameter regions, to additive white noise are investigated numerically. We show that the additive white noise can induce coherent oscillations, and both autonomous systems show optimum responses, represented by the maximum signal-to-noise ratio of the output for certain noise strengths. This phenomenon is thus termed as stochastic resonance without external periodic force.

Ambiguity in Mind and Nature, 1995

In this chapter we describe a mathematical model of a synergetic computer that represents a numbe... more In this chapter we describe a mathematical model of a synergetic computer that represents a number of results found by psychophysical experiments in which multistable patterns are shown to subjects. Our model is derived from basic principles of synergetics where the concept of order parameters describing complex patterns was introduced. The differential equations describing pattern recognition depend on a set of parameters which may be interpreted as attention parameters. According to a psychological finding of Kohler (1940), we allow that these attention parameters saturate once a specific percept has been realized. By this the observed oscillations between percepts can be modelled. The lengths of the reversion times may be different for different percepts and depend on different parameters of the stimulus patterns. Our model is based on three parameters which can be put in direct relationship to the experimental data and a psychological meaning can be attributed to these parameters. In a generalization of our model we are also able to simulate some properties of the perception of the stroboscopic alternative movement (SAM), which was the topic of several experimental contributions to this conference.

Physical Review E, 2000

Autostereograms can be perceived in different well-defined spatial levels. Therefore they are an ... more Autostereograms can be perceived in different well-defined spatial levels. Therefore they are an excellent tool with which to examine spatiotemporal processes of multistable three-dimensional perception. We study properties of spatial ambiguity such as phase transitions between different spatial levels and hysteresis in perception with and without noise. We show that the perception of physical noise-which is added to the autostereograms in the form of a random dot pattern-is dependent on the perceived spatial level. We demonstrate that noise can be helpful for the perception of depth in some cases. We show that the signal-to-noise ratio of depth perception is enhanced at an intermediate level of noise strength that is the signature of stochastic resonance in depth perception.

Physical Review Letters, 2000

The propagation of material interfaces is investigated under the action of a localized moving sou... more The propagation of material interfaces is investigated under the action of a localized moving source which deposits or removes material. Among others the latter process applies to beam cutting techniques. We develop a Kuramoto-Sivashinsky-type model and find a new type of ripple forming mechanism. This theory offers a new explanation for the occurrence of striation patterns which often degrade the quality of cutting edges.

Physical Review Letters, 1993

A model of a two-dimensional autonomous system subject to external noise is investigated. Without... more A model of a two-dimensional autonomous system subject to external noise is investigated. Without noise the system has a stable limit cycle in a certain region of control parameter. Various noise-induced eAects have been found numerically, such as a noise-induced frequency shift in the presence of the deterministic limit cycle, and noise-induced coherent oscillations in the absence of the deterministic limit cycle. An interesting result is that the stochastic resonance phenomenon appears in a system without an external signal and when the asymptotic state of the deterministic system is stationary.

Illusions of Seeing, 2021

ABSTRACT Dieser Erlebnisreiseführer der besonderen Art begleitet Sie in die wunderbare Welt des S... more ABSTRACT Dieser Erlebnisreiseführer der besonderen Art begleitet Sie in die wunderbare Welt des Sehens. Er präsentiert eine Vielzahl bekannter und ganz neuer optischer Täuschungen und fantastischer Bilder. Jedes dieser Reiseerlebnisse eröffnet einen neuen, ganz individuellen Weg zum Bestaunen und zum Verständnis Ihrer eigenen Wahrnehmung. Warum brauchen wir zwei Augen? Warum sind nachts alle Katzen grau und erscheinen schneller als bei Tag? Warum ist der Himmel blau und was ist der grüne Strahl? Warum sehen Frauen anders als Männer? Antworten auf diese und viele andere Fragen führt dieses anschauliche Buch des Sehens vor Augen. Schritt für Schritt können Sie die wunderbaren Leistungen und Fehlleistungen Ihrer Wahrnehmung genauer kennen und schätzen lernen. Die vorliegende überarbeitete Neuauflage zeigt Ihnen in einer neuen Reise in unseren Alltag eindrückliche Täuschungen in unserem täglichen Leben, beim Einkaufen, beim Zahnarzt, im Fußballstadion oder im Urlaub. Dieses lebendige Buch liefert zu jedem der vorgeführten Wahrnehmungserlebnisse eine fundierte Erklärung. Es verbindet auf einmalige Weise das pure Staunen über viele kleine Bilder mit großartigen Eigenschaften und verständlichen und spannend erzählten Erklärungen „direkt an der Täuschung“. Das Buch verkörpert dadurch den Ansatz einer Erlebniswissenschaft – „Learning by doing - and fun“. Es bietet eine Gesamtschau über unsere fantastischen Wahrnehmungsleistungen und letztlich über uns selbst.

Illusionen des Sehens, 2013