Perception and Cognition

The information available via our senses is restricted and to varying degrees ambiguous. It needs to be disambiguated and continuously interpreted in order to construct stable and reliable percepts. The discrimination between reality and illusion is thus to a large a Necker cube, is maximally ambiguous, and percepts become unstable and alternate repeatedly between possible outcomes although the underlying stimulus stays unchanged. We use this phenomenon of perceptual instability to study the psycho-physical relations and altered states of consciousness.


PD Dr.rer. nat. Jürgen Kornmeier +49 (0)761 20721 21
Emanuela Liaci +49 (0)761 20721 15
Dr. Monika Intaite --
Ellen Joos -
Dr. Sebastian Philipp --
Elena Morone --
Stefan Gutmann --
Stefan Lemke --


  1. EEG-Correlates of Altered States of Consciousness Through Meditation
  2. How long lasts a moment? The answer to this question is important for the understanding of perceptual processes, of consciousness and also of altered states of consciousness. The estimated duration of a moment - about 3 s - corresponds to the duration of a temporal Gestalt in music, to the duration of a linguistic element and also to the average duration of perceptual stability ("dwell time") of an ambiguous figure. In the xx Achtsamkeitsmeditation meditators focus on the present moment in order to achieve an altered state of consciousness with increased attention and high emotional control. It is assumed that the duration of a moment will be extended in such an altered state of consciousness. Confirmation comes from experienced meditators. They show longer ambiguous figure dwell times compared to non-meditating controls.
    The recently presented Necker-Zeno-model of bistable perception presents a mathematical relation between dwell times and two other basic time scales of cognitive relevance: (a)the order threshold, (i.e. the minimal temporal distance of about 30 ms between two successive stimuli to identify their order) and (b) the duration of about 300 ms between stimulus onset and perceptual awareness of the stimulus. This model predicts that the temporal extension of a moment correlates with a deceleration of perceptual awareness and/or a shortening of the order threshold (Atmanspacher et al. 2008). In an EEG study on the perception of ambiguous figures with meditators and non-meditator controls we test these model predictions by focusing on the temporal patterns of event related potentials that are specific to the perception of ambiguous figures (Kornmeier & Bach 2012).

  3. Neural Processing of Sensory Ambiguity - Basic Research
  4. Perception of ambiguous figures is unstable and alternates between different interpretations. Tiny figural changes can disambiguate an ambiguous stimulus and stabilize its percept. Recently, we found an ERP ambiguity effect, consisting of two event-related potentials, a fronto-central P200 and a parieto-central P400, with the following features: (a) the ERP amplitudes increase monotonously with decreasing stimulus ambiguity, (b) the ERP latencies and spatial distributions are very similar across highly different visual categories (geometry, motion and semantics, see Figure below).

    Neuronale Verarbeitung sensorischer Ambiguität

    We interpret these effects in the context of the following model: Our perceptual system weights the sensory information with concepts from perceptual memory in order to construct stable and reliable percepts. A probabilistic inference unit estimates the reliability of the perceptual constructs and the P200 and P400 amplitudes reflect the result. In a series of current projects we test the generalization of the ERP ambiguity effect across modalities (visual, auditory and tactile). Further we plan to compare brain sources of the P200 and P400 signatures between visual categories.

  5. Neural Processing of Sensory Ambiguity in Psychiatric Disorders
  6. Perceptions result from a weighting of exogenous sensory information with endogenous memory concepts (see above). This weighting can be biased in either direction, depending on the quality of the sensory information. Patients with Asperger Autism Spectrum Disorder put more weight on sensory information and less weight on endogenous memorized concepts. In a cooperation project with the Clinic for Psychiatry and Psychotherapy of the University Freiburg we study whether such perceptual differences between patients and healthy controls are reflected in an altered ERP ambiguity effect (see above). We further plan a project where we compare the ERP ambiguity effect in patients with Schizophrenia Spectrum Disorder and healthy controls.


Liaci E, Fischer A, Heinrichs M, Tebartz van Elst L, Kornmeier J (submitted) Mona Lisa’s happiness is up to 34% in the beholder’s eye –relations between emotional and geometric ambiguity

Kornmeier J, Wörner R, Riedel A, Tebartz van Elst L (submitted) A different view on the Necker cube – differences in multistable perception dynamics between Asperger and Non-Asperger observers

Intaite M, Castelo-Branco M, Heinrich S, Bach M, Kornmeier J (submitted) Visual working memory load reduces the perceptual orientation bias of ambiguous Necker cube

Sosic-Vasic Z, Hille K, Kröner J, Spitzer M, Kornmeier J (in revision) When learning disturbs memory – temporal profile of retroactive interference of learning on memory formation

Kornmeier J, Friedel E, Wittmann M, Atmanspacher H (2017) EEG Correlates of Cognitive Time Scales in the Necker-Zeno Model for Bistable Perception. Consciousness and Cognition 53, 136 - 150. [PDF-request?@]

Liaci E, Fischer A, Heinrichs M, Tebartz van Elst L, Kornmeier J (2017) Mona Lisa is always happy – and only sometimes sad. Scientific Reports 7, 43511

Kornmeier J, Wörner R, Bach M (2016) Can I trust in what I see? – EEG Evidence for a Cognitive Evaluation of Perceptual Constructs. Psychophysiology 53 (10), 1507-1523

Liaci E, Wörner R, Bach M, Tebartz van Elst L, Heinrich SP, Kornmeier J (2016) Ambiguity in visual and tactile apparent motion perception. PLoS ONE 11(5): e0152736.

Duval CZ, Goumon Y, Kemmel V, Kornmeier J, Dufour A, Andlauer O, Vidailhet P, Poisbeau P, Salvat E, Muller A, Mensah-Nyagan AG, Schmidt-Mutter C, Giersch A (2016) Neurophysiological evidence of enhanced pain sensitivity in patients with schizophrenia. Scientific Reports 6, 22542, 1-10

Wernery J, Atmanspacher H, Kornmeier J, Candia V, Folkers G, Wittmann M (2015) Temporal processing in bistable perception of the Necker cube. Perception 44(2), 157-168.

Kornmeier J. Mayer G. (2014) The alien in the forest OR when temporal context dominates perception. Perception 43(11), 1270-1274.

Mayer G. & Kornmeier J. (2014). Rätselhafte Objekte auf den Bildern einer Wildkamera oder: die Tücken der Wahrnehmung. Zeitschrift für Anomalistik Band 14, 7-24.

Kornmeier J. & Bach M. (2014). EEG correlates to perceptual reversals of Boring's ambiguous Old/Young Woman. Perception 43(9), 950-962-A.

Kornmeier J., Wörner R., Riedel A. & Tebartz van Elst L. (2014). A different view on the checkerboard? Alterations in early and late visually evoked EEG potentials in Asperger observers. PLoS ONE 9(3): e90993.

Kornmeier J., Spitzer M. & Sosic-Vasic Z. (2014). Very similar spacing-effect patterns in very different learning/practice domains. PLoS ONE 9(3): e90656.

O'Shea R., Kornmeier J. & Roeber U. (2013). Predicting visual consciousness electrophysiologically. PLoS ONE 8(10): e76134.

Kornmeier J. & Sosic-Vasic Z. (2012). Parallels between spacing effects during behavioural and cellular learning. Frontiers in Human Neuroscience 6(203): 1-5.

Kornmeier J. & Bach M. (2012). Ambiguous figures - What happens in the brain if perception changes but not the stimulus. Frontiers in Human Neuroscience 6(51): 1-23.

Kornmeier J., Pfäffle M. & Bach M. (2011). Necker cube: Stimulus-related (low-level) and percept-related (high-level) EEG signatures early in occipital cortex. Journal of Vision 11(9):12, 1-11.

Kornmeier J. & Sosic-Vasic Z. (2011). Hirngymnastik nach Plan - Gibt es ein Trainingsprogramm für effizientes Lernen? Nervenheilkunde 30: 613-620. [PDF-request?@]

Ehm W., Bach M. & Kornmeier J. (2010). Variability in gamma activity during observation of ambiguous figures. In: Fechner Day 2010, ed. by A. Bastianelli and G. Vidotto, International Society for Psychophysics, Padua 2010, pp. 439-444. [PDF-request?@]

Ehm W., Bach M. & Kornmeier J. (2010). Ambiguous figures and binding: EEG frequency modulations during multistable perception. Psychophysiology 48: 547-558. [PDF-request?@]

Ehm W., Kornmeier J. & Heinrich SP. (2010). Multiple testing via successive subdivision. Electronic Journal of Statistics 4: 461-471.

Kornmeier J. & Bach M. (2009). Object perception: When our brain is impressed but we do not notice it. Journal of Vision 9(1): 7, 1-10.

Kornmeier J., Hein CM. & Bach M. (2009). Multistable Perception: When bottom-up and top-down coincide. Brain & Cognition 69: 138-147. [PDF-request?@]


PD Dr. H. Atmanspacher (IGPP, Freiburg & Collegium Helveticum, Zürich, Schweiz)

Prof. M. Bach (Universitäts-Augenklinik, Freiburg)

Prof. M. Castelo-Branco (University of Coimbra, Portugal) /

PD Dr. T. Filk (Physik, Universität Freiburg)

Prof. G. Folkers (Collegium Helveticum, Zürich, Schweiz)

Dr. A. Giersch (Psychiatrie der Universität Strasbourg)

PD Dr. SP. Heinrich (Universitäts-Augenklinik, Freiburg)

Prof. R. O'Shea (Southern Cross University, Coffs Harbour, Australien)

Dr. Z. Sosic-Vasic (Psychiatrie der Universität Ulm)

Prof. M. Spitzer (Psychiatrie der Universität Ulm)

Prof. T. Stieglitz (Technische Fakultät der Universität Freiburg)

PD Dr. R. Roeber (Institut für Psychologie, Universität Leipzig)

Prof. L. Tebartz van Elst (Psychiatrie der Universität Freiburg)

PD Dr M. Wittmann (IGPP)