The information that enters our senses is incomplete, noisy and to varying degrees ambiguous. Our perceptual system needs to disambiguate and interpret this restricted information in order to construct plausible conscious percepts. Ambiguous figures, like the well-known Necker cube, are paradigmatic in this context. During prolonged observation of such an ambiguous figure our perception becomes unstable and alternates spontaneously between two or more about equally probable interpretations. In this workshop five experts coming from different disciplines (physics, engineering, biology, medicine, cognitive science) and working with different methodological approaches (psychophysics, modeling, EEG and fMRI) will provide different viewpoints (first person perspective, predictive coding approaches, quantum inspired models) on the phenomenon of multistable perception. We will focus on how our perceptual system constructs a stable and reliable conscious endogenous world out of a priori low-quality exogenous sensory information.
Institute of Physics
University of Freiburg, Germany
Jürgen Kornmeier (chair)
Department of Psychiatry and Psychotherapy,
Medical Center, University of Freiburg, Germany
Perceptual Systems Laboratory
Ecole Normale Supérieure Paris, France
Department of Psychiatry and Psychotherapy
Charite Universitätsmedizin Berlin, Germany
Chair for Consciousness Studies
Alanus University of Arts and Social Sciences, Mannheim, Germany
A quantum model for bistable perception
The Necker-Zeno model for the perception of ambiguous stimuli is based on a quantum formalism for so-called 2-state systems. The model predicts a sharp relation between three time-scales: the average dwell time (i.e. the inverse reversal rate), a time-scale related to our ability to sequence perceived events in a temporal order (the “order threshold”), and a time-scale related to our conscious awareness of perceptions. There are several ways to test the predictions of the Necker-Zeno model using mild assumptions about the quantitative identification of the mentioned time-scales.
Thomas Filk studied Physics in Bonn, Germany. After he received his PhD in 1982 with a thesis on String Theory he had a two-year fellowship of the Japanese Society for the Promotion of Science in Tokyo, Japan. Since 1985 he is at the Physics Department of the University of Freiburg, first as a scientific assistant, since 1994 as a lecturer and since 2000 as an associated professor. His main fields of interest are related to learning mechanisms of neural networks, the foundations of quantum theory, the application of quantum methods to cognitive studies, and the didactics of physics.
Can I Trust in What I See? EEG Evidence for Reliability Estimations of Perceptual Outcomes
During observation of an ambiguous figure perception becomes unstable and alternates between different interpretations. Tiny low-level changes can disambiguate an ambiguous figure and thus stabilize its percept. We compared ERPs evoked by ambiguous stimuli and by disambiguated stimulus variants across different visual categories (geometry, motion) and complexity levels (up to emotional face expressions).
Disambiguated stimulus variants cause stable percepts and evoke much larger amplitudes of two positive ERP components than ambiguous stimuli (d > 1). This pattern of results is highly consistent across very different categories and complexity levels.
The generality of our findings points to higher-level mechanisms: We postulate that a meta-perceptual/cognitive inference unit evaluates the reliability of perceptual constructs beyond sensory details. Small ERP amplitudes reflect high small amplitudes low perceptual reliability. I will discuss our results with respect to what perceptual (in)stability can tell us about mental (in)stability and the contents of perceptual awareness.
Jürgen Kornmeier studied Biology and Mathematics at the University of Freiburg, Germany. In his PhD at the Biology Department in Freiburg he studied instabilities in visual perception and continued in this research area as a postdoc at the University Medical Center in Freiburg. Currently he is the head of the Perception and Cognition Research Group at the Institute for Frontier Areas of Psychology and Mental Health in Freiburg and scientific associate at the Department of Psychiatry and Psychotherapy at the University of Freiburg. His research interests include perceptual and mental instabilities, altered states of consciousness and quantum cognition. His review paper (together with Michael Bach) about perceptual instabilities from 2012 is one of the most often downloaded articles of the Frontiers Journal Family.
Uncertainty in Visual Perception
Visual perception is severely affected by uncertainty. This uncertainty comes in various forms, from the ambiguity of the relationship between a retinal image and the three-dimensional world, up to the limitations and noises sources inherent to the visual system. All these sources of uncertainty make it harder for us to determine the shape and color of objects, their distance to us, or the speed at which they travel. And yet, we do not struggle much to interpret the images that impinge on our retinas, and except in some rare cases of visual illusions, we are rarely aware of their alternative interpretations.
In the recent past, we have been using the framework of Bayesian probabilistic inference to better understand how the visual system copes with uncertainties. We have shown that observers rely on prior knowledge such as that light comes from above our head to interpret the shape of objects. When observers have to interpret ambiguous oriented or moving images, they are influenced by the history of their past perceptual decisions and they exhibit strong consistent biases with very slow dynamics. But surprisingly, in spite of all these uncertainties and biases, observers are very precise at monitoring their own performance.
Pascal Mamassian was born in Lyon (France) and was trained in Telecommunication Engineering (Sup' Télécom, Paris, France) followed by a PhD in Experimental and Biological Psychology (Univ. of Minnesota, Minneapolis, USA). He has worked at the Max-Planck Institute for Biological Cybernetics (Tübingen, Germany) and New York University (New York, USA). He was at the University of Glasgow (Glasgow, UK) as senior lecturer before taking a researcher position at the CNRS (France) where he is now heading a research unit at the Ecole Normale Supérieure, Paris. His main research interests are in the psychophysical investigation of basic visual perceptual phenomena in combination with computational modeling.
A Bayesian Account of Perceptual Multistability
Perceptual inference is the process by which current beliefs are used to give rise to conscious perception by inferring the probable causes of the incoming sensory signals. When sensory signals are perceptually ambiguous, inference may result in spontaneous alterations between two or more conscious perceptual states, a phenomenon called multistable perception. The neural mechanisms of the underlying inferential processes have remained controversial. Whereas some authors argue that multistable perception is governed by local processes in sensory cortices, others have proposed a role for higher-level frontoparietal brain regions in driving perceptual inference. Here, I will propose an account of multistable perception that may reconcile these apparently contradictory views within the computational framework of Bayesian inference. I will also present results from behavioral experiments, computational modeling and model-based fMRI that support the proposed account. Finally, I will discuss how these findings may contribute to our understanding of the neural mechanisms underlying conscious perception.
Philipp Sterzer studied medicine at Ludwig-Maximilians-Universität in Munich and Harvard Medical School in Boston, USA. He started his scientific work on visual perception and consciousness during his PhD at the Universities of Munich, which he later continued at the University of Frankfurt and as a postdoctoral fellow at University College London. Currently he is Professor of Psychiatry and Computational Neuroscience at Charité - Universitätsmedizin Berlin. He uses functional neuroimaging, psychophysics and computational modeling to investigate the neural processes underlying visual perception and their alterations in psychiatric disorders. Recent publication: Sterzer et al., The predictive coding account of psychosis. Biological Psychiatry 84(9): 634-643 (2018).
From Perceptual Irritation to the Functional Layer Theory of Mental Action
I will give an overview of my current research on the first-person perspective in perceptual reversals during observation of ambiguous visual situations. By means of life-worldly examples and with short perceptual exercises for the audience, two complementary experimental tasks will be explained and discussed with regard to methodological issues such as introspective data acquisition. Furthermore, it shall be indicated how a structure-phenomenologically informed account can bring the observed aspects of mental activity into a conceptual context, which also allows references to the brain-physiological level of perceptual reversals.
Johannes Wagemann studied electrical engineering, physics, mathematics, pedagogy and philosophy in Berlin (Germany). After temporarily being engaged in digital image processing research he worked as a Waldorf school teacher. In 2010 he completed his PhD on a trans disciplinary approach to the mind-brain problem at University Witten-Herdecke. After being Assistant Professor for Consciousness Research at Alanus University Alfter (Germany) he moved to Campus Mannheim where he has held a full professorship of Consciousness Studies with focus on Pedagogical Anthropology since 2018. His main interest is in developing experimental designs for psychological first-person research on cognitive processes and in conducting studies on perception, social interaction and other topics.