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Novicky F, Parr T, Friston K, Mirza MB, Sajid N. Bistable perception, precision and neuromodulation. Cereb Cortex 2024; 34:bhad401. [PMID: 37950879 PMCID: PMC10793076 DOI: 10.1093/cercor/bhad401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 10/04/2023] [Accepted: 10/05/2023] [Indexed: 11/13/2023] Open
Abstract
Bistable perception follows from observing a static, ambiguous, (visual) stimulus with two possible interpretations. Here, we present an active (Bayesian) inference account of bistable perception and posit that perceptual transitions between different interpretations (i.e. inferences) of the same stimulus ensue from specific eye movements that shift the focus to a different visual feature. Formally, these inferences are a consequence of precision control that determines how confident beliefs are and change the frequency with which one can perceive-and alternate between-two distinct percepts. We hypothesized that there are multiple, but distinct, ways in which precision modulation can interact to give rise to a similar frequency of bistable perception. We validated this using numerical simulations of the Necker cube paradigm and demonstrate the multiple routes that underwrite the frequency of perceptual alternation. Our results provide an (enactive) computational account of the intricate precision balance underwriting bistable perception. Importantly, these precision parameters can be considered the computational homologs of particular neurotransmitters-i.e. acetylcholine, noradrenaline, dopamine-that have been previously implicated in controlling bistable perception, providing a computational link between the neurochemistry and perception.
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Affiliation(s)
- Filip Novicky
- Department of Neurophysics, Radboud University, Heyendaalseweg 135, 6525 AJ, Nijmegen, Netherlands
- Faculty of Psychology and Neuroscience, Maastricht University, Universiteitssingel 406229 ER, Maastricht, Netherlands
| | - Thomas Parr
- Wellcome Centre for Human Neuroimaging, UCL, 12 Queen Square London WC1N 3AR, United Kingdom
| | - Karl Friston
- Wellcome Centre for Human Neuroimaging, UCL, 12 Queen Square London WC1N 3AR, United Kingdom
| | - Muammer Berk Mirza
- Department of Psychology, University of Cambridge, Downing Pl, Cambridge CB2 3EB, United Kingdom
| | - Noor Sajid
- Wellcome Centre for Human Neuroimaging, UCL, 12 Queen Square London WC1N 3AR, United Kingdom
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Perceptual Awareness and Its Relationship with Consciousness: Hints from Perceptual Multistability. NEUROSCI 2022. [DOI: 10.3390/neurosci3040039] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Many interesting theories of consciousness have been proposed, but so far, there is no “unified” theory capable of encompassing all aspects of this phenomenon. We are all aware of what it feels like to be conscious and what happens if there is an absence of consciousness. We are becoming more and more skilled in measuring consciousness states; nevertheless, we still “don’t get it” in its deeper essence. How does all the processed information converge from different brain areas and structures to a common unity, giving us this very private “feeling of being conscious”, despite the constantly changing flow of information between internal and external states? “Multistability” refers to a class of perceptual phenomena where subjective awareness spontaneously and continuously alternates between different percepts, although the objective stimuli do not change, supporting the idea that the brain “interprets” sensorial input in a “constructive” way. In this perspective paper, multistability and perceptual awareness are discussed as a methodological window for understanding the “local” states of consciousness, a privileged position from which it is possible to observe the brain dynamics and mechanisms producing the subjective phenomena of perceptual awareness in the very moment they are happening.
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Kornmeier J, Bhatia K, Joos E. Top-down resolution of visual ambiguity - knowledge from the future or footprints from the past? PLoS One 2021; 16:e0258667. [PMID: 34673791 PMCID: PMC8530352 DOI: 10.1371/journal.pone.0258667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 10/01/2021] [Indexed: 11/18/2022] Open
Abstract
Current theories about visual perception assume that our perceptual system weights the a priori incomplete, noisy and ambiguous sensory information with previous, memorized perceptual experiences in order to construct stable and reliable percepts. These theories are supported by numerous experimental findings. Theories about precognition have an opposite point of view. They assume that information from the future can have influence on perception, thoughts, and behavior. Several experimental studies provide evidence for precognition effects, other studies found no such effects. One problem may be that the vast majority of precognition paradigms did not systematically control for potential effects from the perceptual history. In the present study, we presented ambiguous Necker cube stimuli and disambiguated cube variants and systematically tested in two separate experiments whether perception of a currently observed ambiguous Necker cube stimulus can be influenced by a disambiguated cube variant, presented in the immediate perceptual past (perceptual history effects) and/or in the immediate perceptual future (precognition effects). We found perceptual history effects, which partly depended on the length of the perceptual history trace but were independent of the perceptual future. Results from some individual participants suggest on the first glance a precognition pattern, but results from our second experiment make a perceptual history explanation more probable. On the group level, no precognition effects were statistically indicated. The perceptual history effects found in the present study are in confirmation with related studies from the literature. The precognition analysis revealed some interesting individual patterns, which however did not allow for general conclusions. Overall, the present study demonstrates that any future experiment about sensory or extrasensory perception urgently needs to control for potential perceptual history effects and that temporal aspects of stimulus presentation are of high relevance.
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Affiliation(s)
- Jürgen Kornmeier
- Institute for Frontier Areas of Psychology and Mental Health, Freiburg, Germany
- Department of Psychiatry and Psychotherapy, Medical Center, University of Freiburg, Freiburg, Germany
- Faculty of Medicine, Freiburg, Germany
| | - Kriti Bhatia
- Experimental Cognitive Science, Eberhard Karls University Tübingen, Tübingen, Germany
| | - Ellen Joos
- INSERM U1114, Cognitive Neuropsychology and Pathophysiology of Schizophrenia, University of Strasbourg, Strasbourg, France
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White PA. The extended present: an informational context for perception. Acta Psychol (Amst) 2021; 220:103403. [PMID: 34454251 DOI: 10.1016/j.actpsy.2021.103403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 08/04/2021] [Accepted: 08/19/2021] [Indexed: 01/29/2023] Open
Abstract
Several previous authors have proposed a kind of specious or subjective present moment that covers a few seconds of recent information. This article proposes a new hypothesis about the subjective present, renamed the extended present, defined not in terms of time covered but as a thematically connected information structure held in working memory and in transiently accessible form in long-term memory. The three key features of the extended present are that information in it is thematically connected, both internally and to current attended perceptual input, it is organised in a hierarchical structure, and all information in it is marked with temporal information, specifically ordinal and duration information. Temporal boundaries to the information structure are determined by hierarchical structure processing and by limits on processing and storage capacity. Supporting evidence for the importance of hierarchical structure analysis is found in the domains of music perception, speech and language processing, perception and production of goal-directed action, and exact arithmetical calculation. Temporal information marking is also discussed and a possible mechanism for representing ordinal and duration information on the time scale of the extended present is proposed. It is hypothesised that the extended present functions primarily as an informational context for making sense of current perceptual input, and as an enabler for perception and generation of complex structures and operations in language, action, music, exact calculation, and other domains.
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Sato F, Laeng B, Nakauchi S, Minami T. Cueing the Necker cube: Pupil dilation reflects the viewing-from-above constraint in bistable perception. J Vis 2020; 20:7. [PMID: 32293651 PMCID: PMC7405692 DOI: 10.1167/jov.20.4.7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
We hypothesized that a perceptually ambiguous or bistable object (Necker cube) can be more effectively biased to assume a point of view-from-above (VFA) than from below the object by cueing attention. Participants viewed a Necker cube in which one surface was temporarily shaded so as to prime a specific perspective on the cube. Subsequently, the standard (wireframe) Necker cube was viewed for 3 seconds, and participants reported what perspective they had seen initially and whether their perception shifted to the alternative perspective during the brief viewing. Concomitantly, pupil size was monitored with an eye-tracker to obtain an index of cognitive effort. There were two conditions: passive viewing and forced attention to sustain the initially primed perspective. We confirmed the presence of a VFA bias with forced attention, which was accompanied by reduced attentional effort, as indexed by a reduced pupil diameter, compared with the view-from-below. Participants showed no bias during passive viewing. We suggest that the level of intensive attention, when retrieving and maintaining a specific view from memory, is mirrored in the size of the eye pupils and may reflect ecological constraints on visual perception.
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Polgári P, Causin JB, Weiner L, Bertschy G, Giersch A. Novel method to measure temporal windows based on eye movements during viewing of the Necker cube. PLoS One 2020; 15:e0227506. [PMID: 31940327 PMCID: PMC6961897 DOI: 10.1371/journal.pone.0227506] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 12/19/2019] [Indexed: 11/18/2022] Open
Abstract
Bistable stimuli can give rise to two different interpretations between which our perception will alternate. Recent results showed a strong coupling between eye movements and reports of perceptual alternations with motion stimuli, which provides useful tools to objectively assess perceptual alternations. However, motion might entrain eye movements, and here we check with a static picture, the Necker cube, whether eye movements and perceptual reports (manual responses) reveal similar or different alternation rates, and similar or different sensitivity to attention manipulations. Using a cluster analysis, ocular temporal windows were defined based on the dynamics of ocular fixations during viewing of the Necker cube and compared to temporal windows extracted from manual responses. Ocular temporal windows were measured also with a control condition, where the physical stimulus presented to viewers alternated between two non-ambiguous versions of the Necker cube. Attention was manipulated by asking subjects to either report spontaneous alternations, focus on one percept, or switch as fast as possible between percepts. The validity of the ocular temporal windows was confirmed by the correspondence between ocular fixations when the physical stimulus changed and when the bistable Necker cube was presented. Ocular movements defined smaller time windows than time windows extracted from manual responses. The number of manual and ocular windows both increased between the spontaneous condition and the switch condition. However, only manual, and not ocular windows, increased in duration in the focus condition. Manual responses involve decisional mechanisms, and they may be decoupled from automatic oscillations between the two percepts, as suggested by the fact that both the number and duration of ocular windows remained stable between the spontaneous and focus conditions. In all, the recording of eye movements provides an objective measure of time windows, and reveals faster perceptual alternations with the Necker cube and less sensitivity to attention manipulations than manual responses.
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Affiliation(s)
- Patrik Polgári
- INSERM U1114, Strasbourg, France
- University of Strasbourg, Strasbourg, France
| | - Jean-Baptiste Causin
- INSERM U1114, Strasbourg, France
- University of Strasbourg, Strasbourg, France
- Psychiatry Department, University Hospital of Strasbourg, Strasbourg, France
| | - Luisa Weiner
- INSERM U1114, Strasbourg, France
- University of Strasbourg, Strasbourg, France
- Psychiatry Department, University Hospital of Strasbourg, Strasbourg, France
| | - Gilles Bertschy
- INSERM U1114, Strasbourg, France
- University of Strasbourg, Strasbourg, France
- Psychiatry Department, University Hospital of Strasbourg, Strasbourg, France
| | - Anne Giersch
- INSERM U1114, Strasbourg, France
- University of Strasbourg, Strasbourg, France
- Psychiatry Department, University Hospital of Strasbourg, Strasbourg, France
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Kornmeier J, Friedel E, Hecker L, Schmidt S, Wittmann M. What happens in the brain of meditators when perception changes but not the stimulus? PLoS One 2019; 14:e0223843. [PMID: 31647833 PMCID: PMC6812751 DOI: 10.1371/journal.pone.0223843] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 09/30/2019] [Indexed: 11/30/2022] Open
Abstract
During the observation of an ambiguous figure our perception alternates between mutually exclusive interpretations, although the stimulus itself remains unchanged. The rate of these endogenous reversals has been discussed as reflecting basic aspects of endogenous brain dynamics. Recent evidence indicates that extensive meditation practice evokes long-term functional and anatomic changes in the brain, also affecting the endogenous brain dynamics. As one of several consequences the rate of perceptual reversals during ambiguous figure perception decreases. In the present study we compared EEG-correlates of endogenous reversals of ambiguous figures between meditators and non-meditating controls in order to better understand timing and brain locations of this altered endogenous brain dynamics. A well-established EEG paradigm was used to measure the neural processes underlying endogenous perceptual reversals of ambiguous figures with high temporal precision. We compared reversal-related ERPs between experienced meditators and non-meditating controls. For both groups we found highly similar chains of reversal-related ERPs, starting early in visual areas, therewith replicating previous findings from the literature. Meditators, however, showed an additional frontal ERP signature already 160 ms after stimulus onset (Frontal Negativity). We interpret the additional, meditation-specific ERP results as evidence that extensive meditation practice provides control of frontal brain areas over early sensory processing steps. This may allow meditators to overcome phylogenetically evolved perceptual and attentional processing automatisms.
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Affiliation(s)
- Jürgen Kornmeier
- Institute for Frontier Areas of Psychology and Mental Health, Freiburg, Germany
- Department of Psychiatry and Psychotherapy, Medical Center, University of Freiburg, Freiburg, Germany
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Evelyn. Friedel
- Department of Psychiatry and Psychotherapy, Medical Center, University of Freiburg, Freiburg, Germany
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Lukas Hecker
- Institute for Frontier Areas of Psychology and Mental Health, Freiburg, Germany
- Department of Psychiatry and Psychotherapy, Medical Center, University of Freiburg, Freiburg, Germany
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Eye Center, Medical Center, University of Freiburg, Freiburg, Germany
| | - Stefan Schmidt
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Department of Psychosomatic Medicine and Psychotherapy, Medical Center, University of Freiburg, Freiburg, Germany
| | - Marc Wittmann
- Institute for Frontier Areas of Psychology and Mental Health, Freiburg, Germany
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Linares Gutierrez D, Kübel S, Giersch A, Schmidt S, Meissner K, Wittmann M. Meditation-Induced States, Vagal Tone, and Breathing Activity Are Related to Changes in Auditory Temporal Integration. Behav Sci (Basel) 2019; 9:bs9050051. [PMID: 31067755 PMCID: PMC6562910 DOI: 10.3390/bs9050051] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 05/04/2019] [Accepted: 05/05/2019] [Indexed: 11/30/2022] Open
Abstract
This study is based on the relationship between meditation, the present moment, and psychophysiology. We employed the metronome task to operationalize the extension of the present moment. A pre-post longitudinal study was conducted. The performance in the metronome task was compared before and after the interventions (meditation, story). The aim was to assess whether physiological changes (heart, breathing) during meditation influence the temporal-integration (TI) of metronome beats. Mindfulness meditators either meditated (n = 41) or listened to a story (n = 43). The heart and breathing activity were recorded during the intervention and compared to a resting-state condition. By applying path analyses we found that meditation led to an increase of the duration of integration intervals at the slowest metronome frequency (inter-stimulus interval, ISI = 3 s). After meditation, the higher the heart-rate variability (i.e., the root mean square of successive differences, RMSSD), the longer the duration of integration intervals at the fastest frequency (ISI = 0.33 s). Moreover, the higher the breathing rate during meditation, the greater the integration of intervals at ISI = 1 s. These findings add evidence to meditation-induced changes on the TI of metronome beats and the concept of the embodiment of mental functioning.
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Affiliation(s)
| | - Sebastian Kübel
- Institute for Frontier Areas of Psychology and Mental Health, 79098 Freiburg, Germany.
| | - Anne Giersch
- INSERM U1114, 67091 Strasbourg, France.
- FMTS, Psychiatry Department, University Hospital of Strasbourg, 67200 Strasbourg, France.
| | - Stefan Schmidt
- Department of Psychosomatic Medicine and Psychotherapy, Medical Faculty, Medical Center-University of Freiburg, 79104 Freiburg, Germany.
| | - Karin Meissner
- Division of Integrative Health Promotion, Department of Social Work and Health, University of Applied Sciences, 96450 Coburg, Germany.
- Institute of Medical Psychology, Ludwig-Maximilian University Munich, 80336 Munich, Germany.
| | - Marc Wittmann
- Institute for Frontier Areas of Psychology and Mental Health, 79098 Freiburg, Germany.
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Hupé JM, Signorelli CM, Alais D. Two paradigms of bistable plaid motion reveal independent mutual inhibition processes. J Vis 2019; 19:5. [PMID: 30943533 DOI: 10.1167/19.4.5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Perception is sometimes bistable, switching between two possible interpretations. Levelt developed several propositions to explain bistable perception in binocular rivalry, based on a model of competing neural populations connected through reciprocal inhibition. Here we test Levelt's laws with bistable plaid motion. Plaids are typically tristable, either a coherent pattern, transparent with one component in front, or transparent with the opposite depth order. In Experiment 1, we use a large angle between component directions to prevent plaid coherence, limiting the ambiguity to alternations of grating depth order. Similar to increasing contrast in binocular rivalry, increasing component speed led to higher switch rates (analogous to Levelt's fourth proposition). In Experiment 2, we used occlusion cues to prevent one depth order and limit bistability to one transparent depth order alternating with coherence. Increasing grating speed shortened coherent motion periods but left transparent periods largely unchanged (analogous to Levelt's second proposition). Switch dynamics showed no correlation between the experiments. These data suggest that plaid component speed acts like contrast in binocular rivalry to vary switch dynamics through a mutual inhibition model. The lack of correlation between both experiments suggests reciprocal inhibition mediates bistability between a variety of neural populations across the visual system.
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Affiliation(s)
- Jean-Michel Hupé
- Centre de Recherche Cerveau et Cognition, Université de Toulouse Paul Sabatier and Centre National de la Recherche Scientifique, Toulouse, France
| | - Camilo Miguel Signorelli
- Centre de Recherche Cerveau et Cognition, Université de Toulouse Paul Sabatier and Centre National de la Recherche Scientifique, Toulouse, France.,Present addresses: Department of Computer Science, University of Oxford, Oxford, UK Cognitive Neuroimaging Unit, INSERM U992, NeuroSpin, Gif-sur-Yvette, France
| | - David Alais
- School of Psychology, The University of Sydney, Sydney, New South Wales, Australia
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A different view on the Necker cube-Differences in multistable perception dynamics between Asperger and non-Asperger observers. PLoS One 2017; 12:e0189197. [PMID: 29244813 PMCID: PMC5731733 DOI: 10.1371/journal.pone.0189197] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 11/21/2017] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND During observation of the Necker cube perception becomes unstable and alternates repeatedly between a from-above-perspective ("fap") and a from-below-perspective ("fbp") interpretation. Both interpretations are physically equally plausible, however, observers usually show an a priori top-down bias in favor of the fap interpretation. Patients with Autism spectrum disorder are known to show an altered pattern of perception with a focus on sensory details. In the present study we tested whether this altered perceptual processing affects their reversal dynamics and reduces the perceptual bias during Necker cube observation. METHODS 19 participants with Asperger syndrome and 16 healthy controls observed a Necker cube stimulus continuously for 5 minutes and indicated perceptual reversals by key press. We compared reversal rates (number of reversals per minute) and the distributions of dwell times for the two interpretations between observer groups. RESULTS Asperger participants showed less perceptual reversal than controls. Six Asperger participants did not perceive any reversal at all, whereas all observers from the control group perceived at least five reversals within the five minutes observation time. Further, control participants showed the typical perceptual bias with significant longer median dwell times for the fap compared to the fbp interpretation. No such perceptual bias was found in the Asperger group. DISCUSSION The perceptual system weights the incomplete and ambiguous sensory input with memorized concepts in order to construct stable and reliable percepts. In the case of the Necker cube stimulus, two perceptual interpretations are equally compatible with the sensory information and internal fluctuations may cause perceptual alternations between them-with a slightly larger probability value for the fap interpretation (perceptual bias). Smaller reversal rates in Asperger observers may result from the dominance of bottom-up sensory input over endogenous top-down factors. The latter may also explain the absence of a fap bias.
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Kornmeier J, Friedel E, Wittmann M, Atmanspacher H. EEG correlates of cognitive time scales in the Necker-Zeno model for bistable perception. Conscious Cogn 2017; 53:136-150. [PMID: 28666186 DOI: 10.1016/j.concog.2017.04.011] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 04/07/2017] [Accepted: 04/15/2017] [Indexed: 11/25/2022]
Abstract
The Necker-Zeno model of bistable perception provides a formal relation between the average duration of meta-stable percepts (dwell times T) of ambiguous figures and two other basic time scales (t0, ΔT) underlying cognitive processing. The model predicts that dwell times T covary with t0, ΔT or both. We tested this prediction by exploiting that observers, in particular experienced meditators, can volitionally control dwell times T. Meditators and non-meditators observed bistable Necker cubes either passively or tried to hold their current percept. The latencies of a centro-parietal event-related potential (CPP) were recorded as a physiological correlate of t0. Dwell times T and the CPP latencies, correlated with t0, differed between conditions and observer groups, while ΔT remained constant in the range predicted by the model. The covariation of CPP latencies and dwell times, as well as their quadratic functional dependence extends previous psychophysical confirmation of the Necker-Zeno model to psychophysiological measures.
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Affiliation(s)
- J Kornmeier
- Institute for Frontier Areas of Psychology and Mental Health, Wilhelmstraße 3a, 79098 Freiburg, Germany; Center for Mental Disorders, Medical Center, University of Freiburg, Hauptstraße 5, 79104 Freiburg, Germany; Eye Center, Medical Center, University of Freiburg, Killianstraße 5, 79106 Freiburg, Germany; Faculty of Medicine, University of Freiburg, Freiburg, Germany.
| | - E Friedel
- Institute for Frontier Areas of Psychology and Mental Health, Wilhelmstraße 3a, 79098 Freiburg, Germany; Center for Mental Disorders, Medical Center, University of Freiburg, Hauptstraße 5, 79104 Freiburg, Germany; Eye Center, Medical Center, University of Freiburg, Killianstraße 5, 79106 Freiburg, Germany; Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - M Wittmann
- Institute for Frontier Areas of Psychology and Mental Health, Wilhelmstraße 3a, 79098 Freiburg, Germany
| | - H Atmanspacher
- Institute for Frontier Areas of Psychology and Mental Health, Wilhelmstraße 3a, 79098 Freiburg, Germany; Collegium Helveticum, Schmelzbergstraße 25, 8092 Zürich, Switzerland; University of Zürich, Rämistraße 71, 8006 Zürich, Switzerland; ETH Zürich, Rämistraße 101, 8092 Zürich, Switzerland
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Liaci E, Bach M, Tebartz van Elst L, Heinrich SP, Kornmeier J. Ambiguity in Tactile Apparent Motion Perception. PLoS One 2016; 11:e0152736. [PMID: 27171276 PMCID: PMC4865082 DOI: 10.1371/journal.pone.0152736] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Accepted: 03/19/2016] [Indexed: 11/18/2022] Open
Abstract
Background In von Schiller’s Stroboscopic Alternative Motion (SAM) stimulus two visually presented diagonal dot pairs, located on the corners of an imaginary rectangle, alternate with each other and induce either horizontal, vertical or, rarely, rotational motion percepts. SAM motion perception can be described by a psychometric function of the dot aspect ratio (“AR”, i.e. the relation between vertical and horizontal dot distances). Further, with equal horizontal and vertical dot distances (AR = 1) perception is biased towards vertical motion. In a series of five experiments, we presented tactile SAM versions and studied the role of AR and of different reference frames for the perception of tactile apparent motion. Methods We presented tactile SAM stimuli and varied the ARs, while participants reported the perceived motion directions. Pairs of vibration stimulators were attached to the participants’ forearms and stimulator distances were varied within and between forearms. We compared straight and rotated forearm conditions with each other in order to disentangle the roles of exogenous and endogenous reference frames. Results Increasing the tactile SAM’s AR biased perception towards vertical motion, but the effect was weak compared to the visual modality. We found no horizontal disambiguation, even for very small tactile ARs. A forearm rotation by 90° kept the vertical bias, even though it was now coupled with small ARs. A 45° rotation condition with crossed forearms, however, evoked a strong horizontal motion bias. Discussion Existing approaches to explain the visual SAM bias fail to explain the current tactile results. Particularly puzzling is the strong horizontal bias in the crossed-forearm conditions. In the case of tactile apparent motion, there seem to be no fixed priority rule for perceptual disambiguation. Rather the weighting of available evidence seems to depend on the degree of stimulus ambiguity, the current situation and on the perceptual strategy of the individual observer.
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Affiliation(s)
- Emanuela Liaci
- Institute for Frontier Areas of Psychology and Mental Health, Freiburg, Germany
- Eye Center, Medical Center, University of Freiburg, Freiburg, Germany
- Clinic for Psychiatry and Psychotherapy, Medical Center, University of Freiburg, Freiburg, Germany
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Michael Bach
- Eye Center, Medical Center, University of Freiburg, Freiburg, Germany
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Ludger Tebartz van Elst
- Clinic for Psychiatry and Psychotherapy, Medical Center, University of Freiburg, Freiburg, Germany
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Sven P. Heinrich
- Eye Center, Medical Center, University of Freiburg, Freiburg, Germany
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Jürgen Kornmeier
- Institute for Frontier Areas of Psychology and Mental Health, Freiburg, Germany
- Eye Center, Medical Center, University of Freiburg, Freiburg, Germany
- Faculty of Medicine, University of Freiburg, Freiburg, Germany
- * E-mail:
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