Empirical and Analytical Psychophysics

Overview

The department of Empirical and Analytical Psychophysics (EAP) is one of four research departments of the IGPP; it evolved from the former "Psychophysiology Laboratory" (1998–2001). Our research involves experimental studies, using methods and techniques of psychophysics and psychophysiology, as well as analytical studies and mathematical modelling. The department's activities are regularly evaluated by an advisory board.

Personnel

Head
Dr. Jiří Wackermann	+49 (0)761 20721 71		CV
Secretary / Technical Assistant
Oksana Gutina	+49 (0)761 20721 70		CV
Research Staff Members
Dr. Peter Pütz	+49 (0)761 20721 76		CV
Dr. Marc Wittmann	+49 (0)761 20721 73		CV
Student Research Assistant
Jakob Pacer	+49 (0)761 20721 73		CV

Research

• Theoretical aspects of psychophysics
• Subjective experience and perception of time
• Subjective geometry of visual space
• Relations between brain functional states and mental states
• Methods of analysis of brain electrical activity
• 'Anomalous' dyadic communication processes

Theoretical aspects of psychophysics

Psychophysics, according to the classic definition by G.Th. Fechner (1860), should be "an exact theory of functional relations between the material and the mental, the physical and the psychological worlds." We understand psychophysics as a mathematical study of invariant structures of primary experience, which should supersede the traditional notion of "psychophysical laws." Our theoretical efforts aim at a conceptual extension of the discipline into an "integral psychophysics," combining the foundational ideas of Fechner and Mach with phenomenological and anthropological approaches.

Subjective experience and perception of time

Temporality is one of the fundamental dimensions of human experience of the world. It is known that subjective estimates of temporal intervals often differ from objective (clock) time measure. Especially in so-called "altered states of consciousness" the subjective experience of time may be greatly distorted, or abolished at all. In our studies we focus on human perception of temporal durations in the supra-second region. We proposed a model of internal representation of duration, based on integration of internal (neural) event flows in "leaky accumulators" or, metaphorically, "klepsydrae." This "dual klepsydra model" (Wackermann and Ehm, 2006) fits well with experimental data on discrimination of temporal durations, and naturally reproduces phenomena such as subjective shortening of intervals in the remote past and presentation-order error. Further studies investigate neural mechanisms of internal representation and perception of time, using brain imaging and electrophysiological methods.

Subjective geometry of visual space

Experimental studies and mathematical modeling of so-called "geometric-optical illusions" (GOI). These phenomena are not random errors of the visual system; they are rather lawful manifestations of their functioning principles. Systematic studies of GOI thus provide insight into the organization of visual field and its subjective metric. Of special interest is the Oppel–Kundt phenomenon, a special case of the "filled space expansion" effect.

Relations between brain functional states and mental states (CLOSED)

Correlations between objectively measurable brain states and subjectively experienced mental states are of interest for neuroscience and psychological/medical disciplines. On the experimental side, we study changes of the brain's electrical activity related to changes of the state of consciousness, focusing on EEG correlates of multi-modal Ganzfeld induced imagery. On the methodological side, we work on novel conceptual approaches to the understanding of the relation between neurophysiological and mental states. In the development of methods for the identification of brain functional states from EEG data, we combine concepts of theoretical physics with traditional ideas of electrophysiological signal analysis.

Methods of analysis of brain electrical activity (CLOSED)

For more than a decade we have been developing a methodology for a global quantitative assessment of brain functional states, based on multichannel recordings of brain electrical activity (EEG). In our approach, segments of EEG data are characterized by three "global descriptors", reflecting geometrical properties of the EEG trajectory in the state space: integral field strength (Σ), generalized frequency (Φ), and spatial complexity (Ω). Variations of the brain functional state in time can thus be studied in the three-dimensional "macro-state" space, in terms of the original descriptors or derived state variables. Since its inception in late 1990s, the method has been applied in numerous studies in experimental and clinical neurophysiology, neuro/psychopharmacology, sleep research, and developmental studies. Of special interest are relations between global properties of the brain's electrical activity and corresponding states of consciousness. The approach has been included into EEG training courses and represented in standard textbooks.

Anomalous dyadic communication processes (CLOSED)

Since the early 1970s dyadic communication in the Ganzfeld ("Ganzfeld telepathy") has been an established paradigm in experimental parapsychology. Results of these studies have been often interpreted as experimental evidence of "anomalous information transfer". We were studying anomalous dyadic communication in the Ganzfeld, using a modified experimental paradigm ('covert telepathy').

Advisory board

Prof. Dr. Dr. h.c. Jürgen Kurths, Humboldt University of Berlin
Prof. Dr. Nikos K. Logothetis, Max Planck Institute for Biological Cybernetics, Tübingen
Prof. Dr. Günter Mahler, University of Stuttgart
Prof. Dr. Wolfgang Skrandies, Justus-Liebig-University, Giessen
Prof. Dr. Herbert Witte, Friedrich-Schiller-University, Jena

The advisory board acts jointly for the departments for Theory and Data Analysis and Empirical and Analytical Psychophysics. Activities of the department EAP were evaluated by the advisory board in October 2001, November 2006, and December 2011.