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 | |||
| Kristina Kastner | CV | ||
Research
- Relations between brain functional states and mental
states
- Methods of analysis of brain electrical activity
- Subjective experience and perception of time
- Subjective geometry of visual space
- 'Anomalous' dyadic communication processes
- Theoretical aspects of psychophysics
Relations between brain functional states and mental states
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, focussing on EEG correlates of multi-modal Ganzfeld induced imagery and on the influence of Ganzfeld stimulation with varied colours on the brain's functional state.
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.
Recent publications
C. Allefeld, H. Atmanspacher, and J. Wackermann: Mental states as macrostates emerging from EEG dynamics. Chaos 19: 015102 (2009).
P. Pütz and J. Wackermann: Effects of coloured light on brain functional states. International Journal of Psychophysiology 69(3): 211 (2008).
J. Wackermann, P. Pütz, and C. Allefeld: Ganzfeld-induced hallucinatory experience, its phenomenology and cerebral electrophysiology. Cortex 44(10): 1364–1378 (2008).
Methods of analysis of brain electrical activity
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, consecutive EEG segments 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.
Recent publications
J. Wackermann and C. Allefeld: State space representation and global descriptors of brain electrical activity. In Electrical Neuroimaging: A Systematic Introduction, ed. by C.M. Michel, Th. Koenig, D. Brandeis, L.R.R. Gianotti, and J. Wackermann, Cambridge University Press, 2009, pp. 191–214.
J. Wackermann and C. Allefeld: On the meaning and interpretation of global descriptors of brain electrical activity. Including a reply to X. Pei et al. International Journal of Psychophysiology 64: 199–210 (2007).
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.
Recent publications
M. Wittmann, Virginie van Wassenhove, A.D. Craig and M.P. Paulus: The neural substrates of subjective time dilation. Frontiers in Human Neuroscience 4.2: 1–9 (2010).
J. Wackermann: Measure of time: a meeting point of psychophysics and fundamental physics. Mind and Matter 6(1): 9–50 (2008).
J. Wackermann, M. Wittmann, F. Hasler, and F.X. Vollenweider: Effects of varied doses of psilocybin on time interval reproduction in human subjects. Neuroscience Letters 435: 51–55 (2008).
Subjective geometry of visual space
Experimental studies and mathematical modeling of so-called "geometric-optical" illusions. These studies provide insight into the organization laws of visual field and its subjective metric.
Recent publications
J. Wackermann and K. Kastner: Paradoxical form of filled/empty visual illusion. Acta Neurobiologiae Experimentalis 69: 560–563 (2009).
Anomalous dyadic communication processes
Since the early 1970s dyadic communication in the Ganzfeld ("Ganzfeld telepathy") is an established paradigm in experimental parapsychology. Results of these studies have often been considered as experimental evidence of "anomalous information transfer", but there is no consensus regarding the interpretation of these findings. We investigated the possibility of anomalous dyadic communication between human subjects in a Ganzfeld-induced altered state of consciousness. In contrast to previous studies, we did not instruct the participants to "transfer information", but nonetheless obtained hit-rates exceeding mean chance expectation. As of present there is no plausible explanation for this result.
Recent publications
P. Pütz, M. Gäßler, and J. Wackermann: Ein Experiment mit "verborgener" Ganzfeld-Telepathie, Zeitschrift für Anomalistik 8(1–3): 10–31 (2008).
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.Recent publications
J. Wackermann: Psychophysics as a science of primary experience. Philosophical Psychology 23: 189–206 (2010).
J. Wackermann: Anthropological turn: a missed chance for psychophysics? In Fechner Day 2009, ed. by Mark A. Ellliott et al., Galway: International Society for Psychophysics, 2009, pp. 143–148.
C. Allefeld: The Hollow of Being: What can we learn from Merleau-Ponty's ontology for a science of consciousness? Mind and Matter 6(2): 235–255 (2008).
J. Wackermann: Jenseits der psychophysischen Dualität: Wirklichkeit des Geistes. In Geist als Ursache? Mentale Verursachung im interdisziplinären Diskurs, ed. by M.F. Peschl and A. Batthyany, Würzburg: Königshausen & Neumann, 2008, pp. 189–221.
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. Hans Primas, ETH Zurich
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 and November 2006.