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Horrocks EAB, Mareschal I, Saleem AB. Walking humans and running mice: perception and neural encoding of optic flow during self-motion. Philos Trans R Soc Lond B Biol Sci 2023; 378:20210450. [PMID: 36511417 PMCID: PMC9745880 DOI: 10.1098/rstb.2021.0450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 08/30/2022] [Indexed: 12/15/2022] Open
Abstract
Locomotion produces full-field optic flow that often dominates the visual motion inputs to an observer. The perception of optic flow is in turn important for animals to guide their heading and interact with moving objects. Understanding how locomotion influences optic flow processing and perception is therefore essential to understand how animals successfully interact with their environment. Here, we review research investigating how perception and neural encoding of optic flow are altered during self-motion, focusing on locomotion. Self-motion has been found to influence estimation and sensitivity for optic flow speed and direction. Nonvisual self-motion signals also increase compensation for self-driven optic flow when parsing the visual motion of moving objects. The integration of visual and nonvisual self-motion signals largely follows principles of Bayesian inference and can improve the precision and accuracy of self-motion perception. The calibration of visual and nonvisual self-motion signals is dynamic, reflecting the changing visuomotor contingencies across different environmental contexts. Throughout this review, we consider experimental research using humans, non-human primates and mice. We highlight experimental challenges and opportunities afforded by each of these species and draw parallels between experimental findings. These findings reveal a profound influence of locomotion on optic flow processing and perception across species. This article is part of a discussion meeting issue 'New approaches to 3D vision'.
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Affiliation(s)
- Edward A. B. Horrocks
- Institute of Behavioural Neuroscience, Department of Experimental Psychology, University College London, London WC1H 0AP, UK
| | - Isabelle Mareschal
- School of Biological and Behavioural Sciences, Queen Mary, University of London, London E1 4NS, UK
| | - Aman B. Saleem
- Institute of Behavioural Neuroscience, Department of Experimental Psychology, University College London, London WC1H 0AP, UK
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2
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Raffi M, Trofè A, Meoni A, Gallelli L, Piras A. Optic Flow Speed and Retinal Stimulation Influence Microsaccades. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19116765. [PMID: 35682346 PMCID: PMC9180672 DOI: 10.3390/ijerph19116765] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 05/28/2022] [Accepted: 05/29/2022] [Indexed: 02/04/2023]
Abstract
Microsaccades are linked with extraretinal mechanisms that significantly alter spatial perception before the onset of eye movements. We sought to investigate whether microsaccadic activity is modulated by the speed of radial optic flow stimuli. Experiments were performed in the dark on 19 subjects who stood in front of a screen covering 135 × 107° of the visual field. Subjects were instructed to fixate on a central fixation point while optic flow stimuli were presented in full field, in the foveal, and in the peripheral visual field at different dot speeds (8, 11, 14, 17, and 20°/s). Fixation in the dark was used as a control stimulus. For almost all tested speeds, the stimulation of the peripheral retina evoked the highest microsaccade rate. We also found combined effects of optic flow speed and the stimulated retinal region (foveal, peripheral, and full field) for microsaccade latency. These results show that optic flow speed modulates microsaccadic activity when presented in specific retinal portions, suggesting that eye movement generation is strictly dependent on the stimulated retinal regions.
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Affiliation(s)
- Milena Raffi
- Department of Biomedical and Neuromotor Sciences, University of Bologna, 40126 Bologna, Italy; (A.M.); (A.P.)
- Correspondence:
| | - Aurelio Trofè
- Department of Quality of Life, University of Bologna, 47921 Rimini, Italy;
| | - Andrea Meoni
- Department of Biomedical and Neuromotor Sciences, University of Bologna, 40126 Bologna, Italy; (A.M.); (A.P.)
| | - Luca Gallelli
- Department of Health Science, School of Medicine, University of Catanzaro, 88100 Catanzaro, Italy;
- Clinical Pharmacology and Pharmacovigilance Unit, Mater Domini Hospital Catanzaro, 88100 Catanzaro, Italy
| | - Alessandro Piras
- Department of Biomedical and Neuromotor Sciences, University of Bologna, 40126 Bologna, Italy; (A.M.); (A.P.)
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3
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Steinmetz ST, Layton OW, Powell NV, Fajen BR. A Dynamic Efficient Sensory Encoding Approach to Adaptive Tuning in Neural Models of Optic Flow Processing. Front Comput Neurosci 2022; 16:844289. [PMID: 35431848 PMCID: PMC9011806 DOI: 10.3389/fncom.2022.844289] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Accepted: 02/10/2022] [Indexed: 11/13/2022] Open
Abstract
This paper introduces a self-tuning mechanism for capturing rapid adaptation to changing visual stimuli by a population of neurons. Building upon the principles of efficient sensory encoding, we show how neural tuning curve parameters can be continually updated to optimally encode a time-varying distribution of recently detected stimulus values. We implemented this mechanism in a neural model that produces human-like estimates of self-motion direction (i.e., heading) based on optic flow. The parameters of speed-sensitive units were dynamically tuned in accordance with efficient sensory encoding such that the network remained sensitive as the distribution of optic flow speeds varied. In two simulation experiments, we found that model performance with dynamic tuning yielded more accurate, shorter latency heading estimates compared to the model with static tuning. We conclude that dynamic efficient sensory encoding offers a plausible approach for capturing adaptation to varying visual environments in biological visual systems and neural models alike.
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Affiliation(s)
- Scott T. Steinmetz
- Cognitive Science Department, Rensselaer Polytechnic Institute, Troy, NY, United States
- *Correspondence: Scott T. Steinmetz,
| | - Oliver W. Layton
- Computer Science Department, Colby College, Waterville, ME, United States
| | - Nathaniel V. Powell
- Cognitive Science Department, Rensselaer Polytechnic Institute, Troy, NY, United States
| | - Brett R. Fajen
- Cognitive Science Department, Rensselaer Polytechnic Institute, Troy, NY, United States
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Motyka P, Kozłowska Z, Litwin P. Perceptual Awareness of Optic Flows Paced Optimally and Non-optimally to Walking Speed. Perception 2021; 50:797-818. [PMID: 34459288 DOI: 10.1177/03010066211034368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Previous research suggests that visual processing depends strongly on locomotor activity and is tuned to optic flows consistent with self-motion speed. Here, we used a binocular rivalry paradigm to investigate whether perceptual access to optic flows depends on their optimality in relation to walking velocity. Participants walked at two different speeds on a treadmill while viewing discrepant visualizations of a virtual tunnel in each eye. We hypothesized that visualizations paced appropriately to the walking speeds will be perceived longer than non optimal (too fast/slow) ones. The presented optic flow speeds were predetermined individually in a task based on matching visual speed to both walking velocities. In addition, perceptual preference for optimal optic flows was expected to increase with proprioceptive ability to detect threshold-level changes in walking speed. Whereas faster (more familiar) optic flows showed enhanced access to awareness during faster compared with slower walking conditions, for slower visual flows, only a nonsignificant tendency for the analogous effect was observed. These effects were not dependent on individual proprioceptive sensitivity. Our findings concur with the emerging view that the velocity of one's locomotion is used to calibrate visual perception of self-motion and extend the scope of reported action effects on visual awareness.
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Affiliation(s)
- Paweł Motyka
- Faculty of Psychology, University of Warsaw, Poland
| | | | - Piotr Litwin
- Faculty of Psychology, University of Warsaw, Poland
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5
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Motyka P, Akbal M, Litwin P. Forward optic flow is prioritised in visual awareness independently of walking direction. PLoS One 2021; 16:e0250905. [PMID: 33945563 PMCID: PMC8096117 DOI: 10.1371/journal.pone.0250905] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 04/15/2021] [Indexed: 12/31/2022] Open
Abstract
When two different images are presented separately to each eye, one experiences smooth transitions between them-a phenomenon called binocular rivalry. Previous studies have shown that exposure to signals from other senses can enhance the access of stimulation-congruent images to conscious perception. However, despite our ability to infer perceptual consequences from bodily movements, evidence that action can have an analogous influence on visual awareness is scarce and mainly limited to hand movements. Here, we investigated whether one's direction of locomotion affects perceptual access to optic flow patterns during binocular rivalry. Participants walked forwards and backwards on a treadmill while viewing highly-realistic visualisations of self-motion in a virtual environment. We hypothesised that visualisations congruent with walking direction would predominate in visual awareness over incongruent ones, and that this effect would increase with the precision of one's active proprioception. These predictions were not confirmed: optic flow consistent with forward locomotion was prioritised in visual awareness independently of walking direction and proprioceptive abilities. Our findings suggest the limited role of kinaesthetic-proprioceptive information in disambiguating visually perceived direction of self-motion and indicate that vision might be tuned to the (expanding) optic flow patterns prevalent in everyday life.
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Affiliation(s)
- Paweł Motyka
- Faculty of Psychology, University of Warsaw, Warsaw, Poland
| | - Mert Akbal
- Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
- Academy of Fine Arts Saar, Saarbrücken, Germany
| | - Piotr Litwin
- Faculty of Psychology, University of Warsaw, Warsaw, Poland
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6
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Caramenti M, Pretto P, Lafortuna CL, Bresciani JP, Dubois A. Influence of the Size of the Field of View on Visual Perception While Running in a Treadmill-Mediated Virtual Environment. Front Psychol 2019; 10:2344. [PMID: 31681123 PMCID: PMC6812648 DOI: 10.3389/fpsyg.2019.02344] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 10/01/2019] [Indexed: 11/13/2022] Open
Abstract
We investigated how the size of the horizontal field of view (FoV) affects visual speed perception with individuals running on a treadmill. Twelve moderately trained to trained participants ran on a treadmill at two different speeds (8 and 12 km/h) in front of a moving virtual scene. Different masks were used to manipulate the visible visual field, masking either the central or the peripheral area of the virtual scene or showing the full visual field. We asked participants to match the visual speed of the scene to their actual running speed. For each trial, participants indicated whether the scene was moving faster or slower than they were running. Visual speed was adjusted according to the responses using a staircase method until the Point of Subjective Equality was reached, that is until visual and running speed were perceived as matching. For both speeds and all FoV conditions, participants underestimated visual speed relative to the actual running speed. However, this underestimation was significant only when the peripheral FoV was masked. These results confirm that the size of the FoV should absolutely be taken into account for the design of treadmill-mediated virtual environments (VEs).
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Affiliation(s)
- Martina Caramenti
- Department of Neurosciences and Movement Sciences, University of Fribourg, Fribourg, Switzerland.,Istituto di Bioimmagini e Fisiologia Molecolare, Consiglio Nazionale delle Ricerche, Segrate, Italy.,HumanTech Institute, University of Applied Sciences and Arts Western Switzerland, Fribourg, Switzerland
| | | | - Claudio L Lafortuna
- Istituto di Fisiologia Clinica, Consiglio Nazionale delle Ricerche, Milan, Italy
| | - Jean-Pierre Bresciani
- Department of Neurosciences and Movement Sciences, University of Fribourg, Fribourg, Switzerland.,LPNC, University Grenoble Alpes, Grenoble, France
| | - Amandine Dubois
- Department of Neurosciences and Movement Sciences, University of Fribourg, Fribourg, Switzerland.,Université de Lorraine, 2LPN-CEMA Group (Cognition-EMotion-Action), EA 7489, Metz, France
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7
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Distance perception during self-movement. Hum Mov Sci 2019; 67:102496. [PMID: 31301557 DOI: 10.1016/j.humov.2019.102496] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 07/03/2019] [Accepted: 07/04/2019] [Indexed: 11/20/2022]
Abstract
The perception of distance in open fields was widely studied with static observers. However, it is a fact that we and the world around us are in continuous relative movement, and that our perceptual experience is shaped by the complex interactions between our senses and the perception of our self-motion. This poses interesting questions about how our nervous system integrates this multisensory information to resolve specific tasks of our daily life, for example, distance estimation. This study provides new evidence about how visual and motor self-motion information affects our perception of distance and a hypothesis about how these two sources of information can be integrated to calibrate the estimation of distance. This model accounts for the biases found when visual and proprioceptive information is inconsistent.
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9
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Kim AJ, Fenk LM, Lyu C, Maimon G. Quantitative Predictions Orchestrate Visual Signaling in Drosophila. Cell 2017; 168:280-294.e12. [PMID: 28065412 DOI: 10.1016/j.cell.2016.12.005] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Revised: 10/18/2016] [Accepted: 12/01/2016] [Indexed: 11/18/2022]
Abstract
Vision influences behavior, but ongoing behavior also modulates vision in animals ranging from insects to primates. The function and biophysical mechanisms of most such modulations remain unresolved. Here, we combine behavioral genetics, electrophysiology, and high-speed videography to advance a function for behavioral modulations of visual processing in Drosophila. We argue that a set of motion-sensitive visual neurons regulate gaze-stabilizing head movements. We describe how, during flight turns, Drosophila perform a set of head movements that require silencing their gaze-stability reflexes along the primary rotation axis of the turn. Consistent with this behavioral requirement, we find pervasive motor-related inputs to the visual neurons, which quantitatively silence their predicted visual responses to rotations around the relevant axis while preserving sensitivity around other axes. This work proposes a function for a behavioral modulation of visual processing and illustrates how the brain can remove one sensory signal from a circuit carrying multiple related signals.
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Affiliation(s)
- Anmo J Kim
- Laboratory of Integrative Brain Function, The Rockefeller University, New York, NY 10065, USA
| | - Lisa M Fenk
- Laboratory of Integrative Brain Function, The Rockefeller University, New York, NY 10065, USA
| | - Cheng Lyu
- Laboratory of Integrative Brain Function, The Rockefeller University, New York, NY 10065, USA
| | - Gaby Maimon
- Laboratory of Integrative Brain Function, The Rockefeller University, New York, NY 10065, USA.
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10
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Cuturi L, MacNeilage P. Optic Flow Induces Nonvisual Self-Motion Aftereffects. Curr Biol 2014; 24:2817-21. [DOI: 10.1016/j.cub.2014.10.015] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Revised: 08/26/2014] [Accepted: 10/07/2014] [Indexed: 11/30/2022]
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11
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Palmisano S, Allison RS, Ash A, Nakamura S, Apthorp D. Evidence against an ecological explanation of the jitter advantage for vection. Front Psychol 2014; 5:1297. [PMID: 25426096 PMCID: PMC4227477 DOI: 10.3389/fpsyg.2014.01297] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Accepted: 10/25/2014] [Indexed: 11/13/2022] Open
Abstract
Visual-vestibular conflicts have been traditionally used to explain both perceptions of self-motion and experiences of motion sickness. However, sensory conflict theories have been challenged by findings that adding simulated viewpoint jitter to inducing displays enhances (rather than reduces or destroys) visual illusions of self-motion experienced by stationary observers. One possible explanation of this jitter advantage for vection is that jittering optic flows are more ecological than smooth displays. Despite the intuitive appeal of this idea, it has proven difficult to test. Here we compared subjective experiences generated by jittering and smooth radial flows when observers were exposed to either visual-only or multisensory self-motion stimulations. The display jitter (if present) was generated in real-time by updating the virtual computer-graphics camera position to match the observer’s tracked head motions when treadmill walking or walking in place, or was a playback of these head motions when standing still. As expected, the (more naturalistic) treadmill walking and the (less naturalistic) walking in place were found to generate very different physical head jitters. However, contrary to the ecological account of the phenomenon, playbacks of treadmill walking and walking in place display jitter both enhanced visually induced illusions of self-motion to a similar degree (compared to smooth displays).
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Affiliation(s)
- Stephen Palmisano
- School of Psychology, University of Wollongong Wollongong, NSW, Australia
| | - Robert S Allison
- Department of Electrical Engineering and Computer Science, York University Toronto, ON, Canada
| | - April Ash
- School of Psychology, University of Wollongong Wollongong, NSW, Australia
| | - Shinji Nakamura
- Division of Clinical Psychology, Faculty of Child Development, Nihon Fukushi University Nagoya, Japan
| | - Deborah Apthorp
- School of Psychology, University of Wollongong Wollongong, NSW, Australia ; Research School of Psychology, Australian National University Canberra, ACT, Australia
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12
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Nilsson NC, Serafin S, Nordahl R. Establishing the range of perceptually natural visual walking speeds for virtual walking-in-place locomotion. IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS 2014; 20:569-578. [PMID: 24650984 DOI: 10.1109/tvcg.2014.21] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Walking-In-Place (WIP) techniques make it possible to facilitate relatively natural locomotion within immersive virtual environments that are larger than the physical interaction space. However, in order to facilitate natural walking experiences one needs to know how to map steps in place to virtual motion. This paper describes two within-subjects studies performed with the intention of establishing the range of perceptually natural walking speeds for WIP locomotion. In both studies, subjects performed a series of virtual walks while exposed to visual gains (optic flow multipliers) ranging from 1.0 to 3.0. Thus, the slowest speed was equal to an estimate of the subjects normal walking speed, while the highest speed was three times greater. The perceived naturalness of the visual speed was assessed using self-reports. The first study compared four different types of movement, namely, no leg movement, walking on a treadmill, and two forms of gestural input for WIP locomotion. The results suggest that WIP locomotion is accompanied by a perceptual distortion of the speed of optic flow. The second study was performed using a 4×2 factorial design and compared four different display field-of-views (FOVs) and two types of movement, walking on a treadmill and WIP locomotion. The results revealed significant main effects of both movement type and field of view, but no significant interaction between the two variables. Particularly, they suggest that the size of the display FOV is inversely proportional to the degree of underestimation of the virtual speeds for both treadmill-mediated virtual walking and WIP locomotion. Combined, the results constitute a first attempt at establishing a set of guidelines specifying what virtual walking speeds WIP gestures should produce in order to facilitate a natural walking experience.
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13
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Apthorp D, Palmisano S. The role of perceived speed in vection: does perceived speed modulate the jitter and oscillation advantages? PLoS One 2014; 9:e92260. [PMID: 24651861 PMCID: PMC3961335 DOI: 10.1371/journal.pone.0092260] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Accepted: 02/19/2014] [Indexed: 11/30/2022] Open
Abstract
Illusory self-motion (‘vection’) in depth is strongly enhanced when horizontal/vertical simulated viewpoint oscillation is added to optic flow inducing displays; a similar effect is found for simulated viewpoint jitter. The underlying cause of these oscillation and jitter advantages for vection is still unknown. Here we investigate the possibility that perceived speed of motion in depth (MID) plays a role. First, in a 2AFC procedure, we obtained MID speed PSEs for briefly presented (vertically oscillating and smooth) radial flow displays. Then we examined the strength, duration and onset latency of vection induced by oscillating and smooth radial flow displays matched either for simulated or perceived MID speed. The oscillation advantage was eliminated when displays were matched for perceived MID speed. However, when we tested the jitter advantage in the same manner, jittering displays were found to produce greater vection in depth than speed-matched controls. In summary, jitter and oscillation advantages were the same across experiments, but slower MID speed was required to match jittering than oscillating stimuli. Thus, to the extent that vection is driven by perceived speed of MID, this effect is greater for oscillating than for jittering stimuli, which suggests that the two effects may arise from separate mechanisms.
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Affiliation(s)
- Deborah Apthorp
- Research School of Psychology, Australian National University, Canberra, Australian Capital Territory, Australia
- School of Psychology, University of Wollongong, Wollongong, New South Wales, Australia
- * E-mail:
| | - Stephen Palmisano
- School of Psychology, University of Wollongong, Wollongong, New South Wales, Australia
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14
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Ash A, Palmisano S, Apthorp D, Allison RS. Vection in depth during treadmill walking. Perception 2013; 42:562-76. [PMID: 23964381 DOI: 10.1068/p7449] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Vection has typically been induced in stationary observers (ie conditions providing visual-only information about self-motion). Two recent studies have examined vection during active treadmill walking--one reported that treadmill walking in the same direction as the visually simulated self-motion impaired vection (Onimaru et al, 2010 Journal of Vision 10(7):860), the other reported that it enhanced vection (Seno et al, 2011 Perception 40 747-750; Seno et al, 2011 Attention, Perception, & Psychophysics 73 1467-1476). Our study expands on these earlier investigations of vection during observer active movement. In experiment 1 we presented radially expanding optic flow and compared the vection produced in stationary observers with that produced during walking forward on a treadmill at a 'matched' speed. Experiment 2 compared the vection induced by forward treadmill walking while viewing expanding or contracting optic flow with that induced by viewing playbacks of these same displays while stationary. In both experiments subjects' tracked head movements were either incorporated into the self-motion displays (as simulated viewpoint jitter) or simply ignored. We found that treadmill walking always reduced vection (compared with stationary viewing conditions) and that simulated viewpoint jitter always increased vection (compared with constant velocity displays). These findings suggest that while consistent visual-vestibular information about self-acceleration increases vection, biomechanical self-motion information reduces this experience (irrespective of whether it is consistent or not with the visual input).
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Affiliation(s)
- April Ash
- School of Psychology, University of Wollongong, Wollongong, Northfields Avenue, NSW 2522, Australia.
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15
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Manipulation of visual information does not change the accuracy of distance estimation during a blindfolded walking task. Hum Mov Sci 2013; 32:794-807. [DOI: 10.1016/j.humov.2013.04.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Revised: 04/15/2013] [Accepted: 04/23/2013] [Indexed: 11/17/2022]
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16
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Fajen BR, Matthis JS. Direct perception of action-scaled affordances: the shrinking gap problem. J Exp Psychol Hum Percept Perform 2012; 37:1442-57. [PMID: 21500936 DOI: 10.1037/a0023510] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The aim of this study was to investigate the perception of possibilities for action (i.e., affordances) that depend on one's movement capabilities, and more specifically, the passability of a shrinking gap between converging obstacles. We introduce a new optical invariant that specifies in intrinsic units the minimum locomotor speed needed to safely pass through a shrinking gap. Detecting this information during self-motion requires recovering the component of the obstacles' local optical expansion attributable to obstacle motion, independent of self-motion. In principle, recovering the obstacle motion component could involve either visual or non-visual self-motion information. We investigated the visual and non-visual contributions in two experiments in which subjects walked through a virtual environment and made judgments about whether it was possible to pass through a shrinking gap. On a small percentage of trials, visual and non-visual self-motion information were independently manipulated by varying the speed with which subjects moved through the virtual environment. Comparisons of judgments on such catch trials with judgments on normal trials revealed both visual and non-visual contributions to the detection of information about minimum walking speed.
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Affiliation(s)
- Brett R Fajen
- Department of Cognitive Science, Rensselaer Polytechnic Institute, Troy, NY 12180, USA.
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17
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Treadmill experience alters treadmill effects on perceived visual motion. PLoS One 2011; 6:e21642. [PMID: 21799740 PMCID: PMC3143122 DOI: 10.1371/journal.pone.0021642] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2011] [Accepted: 06/04/2011] [Indexed: 11/24/2022] Open
Abstract
Information on ongoing body movements can affect the perception of ambiguous visual motion. Previous studies on “treadmill capture” have shown that treadmill walking biases the perception of ambiguous apparent motion in backward direction in accordance with the optic flow during normal walking, and that long-term treadmill experience changes the effect of treadmill capture. To understand the underlying mechanisms for these phenomena, we conducted Experiment 1 with non-treadmill runners and Experiment 2 with treadmill runners. The participants judged the motion direction of the apparent motion stimuli of horizontal gratings in front of their feet under three conditions: walking on a treadmill, standing on a treadmill, and standing on the floor. The non-treadmill runners showed the presence of downward bias only under the walking condition, indicating that ongoing treadmill walking but not the awareness of being on a treadmill biased the visual directional discrimination. In contrast, the treadmill runners showed no downward bias under any of the conditions, indicating that neither ongoing activity nor the awareness of spatial context produced perception bias. This suggests that the long-term repetitive experience of treadmill walking without optic flow induced the formation of a treadmill-specific locomotor-visual linkage to perceive the complex relationship between self and the environment.
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18
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Souman JL, Freeman TCA, Eikmeier V, Ernst MO. Humans do not have direct access to retinal flow during walking. J Vis 2010; 10:14. [PMID: 20884509 DOI: 10.1167/10.11.14] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Perceived visual speed has been reported to be reduced during walking. This reduction has been attributed to a partial subtraction of walking speed from visual speed (F. H. Durgin & K. Gigone, 2007; F. H. Durgin, K. Gigone, & R. Scott, 2005). We tested whether observers still have access to the retinal flow before subtraction takes place. Observers performed a 2IFC visual speed discrimination task while walking on a treadmill. In one condition, walking speed was identical in the two intervals, while in a second condition walking speed differed between intervals. If observers have access to the retinal flow before subtraction, any changes in walking speed across intervals should not affect their ability to discriminate retinal flow speed. Contrary to this "direct access hypothesis," we found that observers were worse at discrimination when walking speed differed between intervals. The results therefore suggest that observers do not have access to retinal flow before subtraction. We also found that the amount of subtraction depended on the visual speed presented, suggesting that the interaction between the processing of visual input and of self-motion is more complex than previously proposed.
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Affiliation(s)
- Jan L Souman
- Multisensory Perception and Action Group, Max Planck Institute for Biological Cybernetics, Tübingen, Germany.
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Durgin FH, Hajnal A, Li Z, Tonge N, Stigliani A. Palm boards are not action measures: an alternative to the two-systems theory of geographical slant perception. Acta Psychol (Amst) 2010; 134:182-97. [PMID: 20176342 DOI: 10.1016/j.actpsy.2010.01.009] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2009] [Revised: 01/25/2010] [Accepted: 01/27/2010] [Indexed: 11/17/2022] Open
Abstract
Whereas most reports of the perception of outdoor hills demonstrate dramatic overestimation, estimates made by adjusting a palm board are much closer to the true hill orientation. We test the dominant hypothesis that palm board accuracy is related to the need for motor action to be accurately guided and conclude instead that the perceptual experience of palm-board orientation is biased and variable due to poorly calibrated proprioception of wrist flexion. Experiments 1 and 3 show that wrist-flexion palm boards grossly underestimate the orientations of near, reachable surfaces whereas gesturing with a free hand is fairly accurate. Experiment 2 shows that palm board estimates are much lower than free hand estimates for an outdoor hill as well. Experiments 4 shows that wrist flexion is biased and noisy compared to elbow flexion, while Experiment 5 shows that small changes in palm board height produce large changes in palm board estimates. Together, these studies suggest that palm boards are biased and insensitive measures. The existing literature arguing that there are two systems in the perception of geographical slant is re-evaluated, and a new theoretical framework is proposed in which a single exaggerated representation of ground-surface orientation guides both action and perception.
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Affiliation(s)
- Frank H Durgin
- Department of Psychology, Swarthmore College, Swarthmore, PA 19081, United States.
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Controlled interaction: Strategies for using virtual reality to study perception. Behav Res Methods 2010; 42:414-20. [DOI: 10.3758/brm.42.2.414] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Abstract
When we move, the visual world moves toward us. That is, self-motion normally produces visual signals (flow) that tell us about our own motion. But these signals are distorted by our motion: Visual flow actually appears slower while we are moving than it does when we are stationary and our surroundings move past us. Although for many years these kinds of distortions have been interpreted as a suppression of flow to promote the perception of a stable world, current research has shown that these shifts in perceived visual speed may have an important function in measuring our own self-motion. Specifically, by slowing down the apparent rate of visual flow during self-motion, our visual system is able to perceive differences between actual and expected flow more precisely. This is useful in the control of action.
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The precision of locomotor odometry in humans. Exp Brain Res 2008; 193:429-36. [DOI: 10.1007/s00221-008-1640-1] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2008] [Accepted: 10/29/2008] [Indexed: 12/01/2022]
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