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https://www.readbyqxmd.com/read/29450832/perceptual-modification-of-the-built-environment-to-influence-behavior-associated-with-physical-activity-quasi-experimental-field-studies-of-a-stair-banister-illusion
#1
Rich Masters, Catherine Capio, Jamie Poolton, Liis Uiga
BACKGROUND: Re-engineering the built environment to influence behaviors associated with physical activity potentially provides an opportunity to promote healthier lifestyles at a population level. Here we present evidence from two quasi-experimental field studies in which we tested a novel, yet deceptively simple, intervention designed to alter perception of, and walking behavior associated with, stairs in an urban area. OBJECTIVES: Our objectives were to examine whether adjusting a stair banister has an influence on perceptions of stair steepness or on walking behavior when approaching the stairs...
February 15, 2018: Sports Medicine
https://www.readbyqxmd.com/read/29447183/a-mass-density-model-can-account-for-the-size-weight-illusion
#2
Christian Wolf, Wouter M Bergmann Tiest, Knut Drewing
When judging the heaviness of two objects with equal mass, people perceive the smaller and denser of the two as being heavier. Despite the large number of theories, covering bottom-up and top-down approaches, none of them can fully account for all aspects of this size-weight illusion and thus for human heaviness perception. Here we propose a new maximum-likelihood estimation model which describes the illusion as the weighted average of two heaviness estimates with correlated noise: One estimate derived from the object's mass, and the other from the object's density, with estimates' weights based on their relative reliabilities...
2018: PloS One
https://www.readbyqxmd.com/read/29428805/more-far-is-more-right-manual-and-ocular-line-bisections-but-not-the-judd-illusion-depend-on-radial-space
#3
Luca Rinaldi, Giovanni Bertolini, Christopher J Bockisch, Angelo Maravita, Luisa Girelli, Peter Brugger
Line bisection studies generally find a left-to-right shift in bisection bias with increasing distance between the observer and the target line, which may be explained by hemispheric differences in the processing of proximo-distal information. In the present study, the segregation between near and far space was further characterized across the motor system and contextual cues. To this aim, 20 right-handed participants were required to perform a manual bisection task of simple lines presented at three different distances (60, 90, 120 cm)...
February 8, 2018: Brain and Cognition
https://www.readbyqxmd.com/read/29422883/detecting-cortical-spreading-depolarization-with-full-band-scalp-electroencephalography-an-illusion
#4
Jeannette Hofmeijer, C R van Kaam, Babette van de Werff, Sarah E Vermeer, Marleen C Tjepkema-Cloostermans, Michel J A M van Putten
Introduction: There is strong evidence suggesting detrimental effects of cortical spreading depolarization (CSD) in patients with acute ischemic stroke and severe traumatic brain injury. Previous studies implicated scalp electroencephalography (EEG) features to be correlates of CSD based on retrospective analysis of EEG epochs after having detected "CSD" in time aligned electrocorticography. We studied the feasibility of CSD detection in a prospective cohort study with continuous EEG in 18 patients with acute ischemic stroke and 18 with acute severe traumatic brain injury...
2018: Frontiers in Neurology
https://www.readbyqxmd.com/read/29416065/judging-the-position-of-the-artificial-hand-induces-a-visual-drift-towards-the-real-one-during-the-rubber-hand-illusion
#5
Roberto Erro, Angela Marotta, Michele Tinazzi, Elena Frera, Mirta Fiorio
When subjects look at a rubber hand being brush-stroked synchronously with their own hidden hand, they might feel a sense of ownership over the rubber hand. The perceived mislocalization of the own hand towards the rubber hand (proprioceptive drift) would reflect an implicit marker of this illusion occurring through the dominance of vision over proprioception. This account, however, contrasts with principles of multisensory integration whereby percepts result from a "statistical sum" of different sensory afferents...
February 7, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29407592/spontaneous-imitative-movements-induced-by-an-illusory-embodied-fake-hand
#6
Satoshi Shibuya, Satoshi Unenaka, Takuro Zama, Sotaro Shimada, Yukari Ohki
In the rubber hand illusion (RHI), individuals perceive a fake hand as their own when the hidden real hand and visible fake hand are synchronously stroked. Several RHI studies have reported that visual manipulation of the embodied fake hand inversely affects the perceptual processing of the observer's own hand (e.g., thermal or pain sensitivity). In this study, we examined whether motor manipulation of the fake hand similarly affects the observer's motor system. Our study employed a novel RHI paradigm wherein stroking was interrupted by unexpected movement of the fake hand (i...
February 2, 2018: Neuropsychologia
https://www.readbyqxmd.com/read/29391505/body-ownership-and-the-four-hand-illusion
#7
Wen-Yeo Chen, Hsu-Chia Huang, Yen-Tung Lee, Caleb Liang
Recent studies of the rubber hand illusion (RHI) have shown that the sense of body ownership is constrained by several factors and yet is still very flexible. However, exactly how flexible is our sense of body ownership? In this study, we address this issue by investigating the following question: is it possible that one may have the illusory experience of owning four hands? Under visual manipulation, the participant adopted the experimenter's first-person perspective (1PP) as if it was his/her own. Sitting face to face, the participant saw four hands-the experimenter's two hands from the adopted 1PP together with the subject's own two hands from the adopted third-person perspective (3PP)...
February 1, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29375754/effect-of-grouping-segmentation-and-vestibular-stimulation-on-the-autokinetic-effect
#8
Vilayanur S Ramachandran, Chaipat Chunharas, Rachel Croft, Nader Batal
We report some new observations on what could be regarded as the world's simplest visual illusion-the autokinetic effect. When a single dim spot of light is viewed in a completely dark room, it moves vividly in random directions. During steady fixation, perhaps subtle eye movements cause the image to move and a failure to correct for this using eye movement command signals leads to motion perception. This is especially true because eye muscle fatigue can lead to miscalibration. However, if two dots are shown, they often move independently in different directions, which negate the eye movement theory...
January 2018: I-Perception
https://www.readbyqxmd.com/read/29367629/lighting-from-above-prior-in-biological-motion-perception
#9
Leonid A Fedorov, Tjeerd M H Dijkstra, Martin A Giese
The visual system is able to recognize body motion from impoverished stimuli. This requires combining stimulus information with visual priors. We present a new visual illusion showing that one of these priors is the assumption that bodies are typically illuminated from above. A change of illumination direction from above to below flips the perceived locomotion direction of a biological motion stimulus. Control experiments show that the underlying mechanism is different from shape-from-shading and directly combines information about body motion with a lighting-from-above prior...
January 24, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29358090/integrating-multisensory-information-across-external-and-motor-based-frames-of-reference
#10
Yuqi Liu, Jared Medina
In the mirror box illusion, participants often report that their hand is located where they see it, even when the position of the reflected hand differs from the actual position of their hand. This illusory shift (an index of multisensory integration) is stronger when the two hands engage in synchronous bimanual movement, in which visual and proprioceptive information is congruent in both motor-based (i.e. coordinate centered on the effector) and external (i.e. coordinates centered on elements external to the effector) frames of reference...
January 19, 2018: Cognition
https://www.readbyqxmd.com/read/29354875/a-parsimonious-model-of-brightness-induction
#11
Ashish Bakshi, Kuntal Ghosh
We present a parsimonious model of brightness induction which can account for various brightness illusions of both brightness-contrast and brightness-assimilation types. Our model is based on a difference of difference-of-Gaussian filter and a two-pass model of attentive vision based on the parallel channels in the central visual pathway. It overcomes some of the problems that could not be addressed by the well-known oriented difference of Gaussian model like those associated with Mach band and checkerboard illusions...
January 22, 2018: Biological Cybernetics
https://www.readbyqxmd.com/read/29353311/effects-of-wrist-tendon-vibration-and-eye-movements-on-manual-aiming
#12
Ann Lavrysen, Oron Levin, Matthieu P Boisgontier, Digby Elliott, Werner F Helsen
In the present study, we investigated whether visual information mediates a proprioceptive illusion effect induced by muscle tendon vibration in manual aiming. Visual information was gradually degraded from a situation in which the targets were present and participants (n = 20; 22.3 ± 2.7 years) were permitted to make saccadic eye movements to designated target positions, to a condition in which the targets were not visible and participants were required to perform cyclical aiming while fixating a point between the two target positions...
January 20, 2018: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
https://www.readbyqxmd.com/read/29348911/reduction-of-flicker-in-four-stroke-motion-of-color-images
#13
Takahiro Kawabe, Shin'ya Nishida
When two sequential video frames extracted from a single video clip are followed by the negative of the two frames, a viewer often experiences a visual illusion whereby a scene in the frames continuously moves in a single direction (four-stroke apparent motion). To create a four-stroke apparent motion display, the image intensities of the whole of the second pair of images are reversed. However, this intensity reversal creates a strong impression of flicker that can be undesirable for comfortable viewing. This study reports that four-stroke apparent motion can be induced by only reversing the luminance intensities in those spatial areas which contain motion signals in high-pass filtered images...
January 2018: I-Perception
https://www.readbyqxmd.com/read/29344909/flash-induced-forward-and-reverse-illusory-line-motion-in-offset-bars
#14
Sihang Han, Jeff P Hamm
Illusory line motion (ILM) refers to perception of motion in a bar that onsets or offsets all at once. When the bar onsets or offsets between two boxes after one of the boxes flashes, the bar appears to shoot out of the flashed box (flashILM). If the bar offsets during the flash, it appears to contract into the flashed box (reverse ILM; rILM). Onset bars do not show rILM. Moreover, rILM and flashILM are not correlated, indicating they are two different illusions. To date, rILM has only been studied using a 50-ms flash where the bar offsets 16...
January 17, 2018: Attention, Perception & Psychophysics
https://www.readbyqxmd.com/read/29344331/the-peripheral-flicker-illusion
#15
Hiroyuki Ito, Tomomi Koizumi
A new illusion is reported. A visual object suddenly appearing on a red background sometimes causes an impression of flicker or double flash. In Experiment 1, a red, green, or blue object was presented on a red, green, blue, or gray background. Participants evaluated the illusion strength in reference to the physical flicker of a gray object presented in central vision. The results show that the green or blue object presented on the red background caused the illusion. In Experiment 2, the effect of retinal eccentricity on the illusion was tested...
November 2017: I-Perception
https://www.readbyqxmd.com/read/29332124/optimal-audiovisual-integration-in-the-ventriloquism-effect-but-pervasive-deficits-in-unisensory-spatial-localization-in-amblyopia
#16
Michael D Richards, Herbert C Goltz, Agnes M F Wong
Purpose: Classically understood as a deficit in spatial vision, amblyopia is increasingly recognized to also impair audiovisual multisensory processing. Studies to date, however, have not determined whether the audiovisual abnormalities reflect a failure of multisensory integration, or an optimal strategy in the face of unisensory impairment. We use the ventriloquism effect and the maximum-likelihood estimation (MLE) model of optimal integration to investigate integration of audiovisual spatial information in amblyopia...
January 1, 2018: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/29330457/spatially-selective-responses-to-kanizsa-and-occlusion-stimuli-in-human-visual-cortex
#17
Benjamin de Haas, Dietrich Samuel Schwarzkopf
Early visual cortex responds to illusory contours in which abutting lines or collinear edges imply the presence of an occluding surface, as well as to occluded parts of an object. Here we used functional magnetic resonance imaging (fMRI) and population receptive field (pRF) analysis to map retinotopic responses in early visual cortex using bar stimuli defined by illusory contours, occluded parts of a bar, or subtle luminance contrast. All conditions produced retinotopic responses in early visual field maps even though signal-to-noise ratios were very low...
January 12, 2018: Scientific Reports
https://www.readbyqxmd.com/read/29282487/temporal-ventriloquism-along-the-path-of-apparent-motion-speed-perception-under-different-spatial-grouping-principles
#18
Cansu Ogulmus, Merve Karacaoglu, Hulusi Kafaligonul
The coordination of intramodal perceptual grouping and crossmodal interactions plays a critical role in constructing coherent multisensory percepts. However, the basic principles underlying such coordinating mechanisms still remain unclear. By taking advantage of an illusion called temporal ventriloquism and its influences on perceived speed, we investigated how audiovisual interactions in time are modulated by the spatial grouping principles of vision. In our experiments, we manipulated the spatial grouping principles of proximity, uniform connectedness, and similarity/common fate in apparent motion displays...
December 28, 2017: Experimental Brain Research. Experimentelle Hirnforschung. Expérimentation Cérébrale
https://www.readbyqxmd.com/read/29272995/primary-care-challenges-of-an-obscure-case-of-alice-in-wonderland-syndrome-in-a-patient-with-severe-malaria-in-a-resource-constrained-setting-a-case-report
#19
Benjamin Momo Kadia, Cyril Jabea Ekabe, Ettamba Agborndip
BACKGROUND: "Alice in Wonderland" syndrome (AIWS) is a rare neurological abnormality characterized by distortions of visual perceptions, body schema and experience of time. AIWS has been reported in patients with various infections such as infectious mononucleosis, H1N1 influenza, Cytomegalovirus encephalitis, and typhoid encephalopathy. However, AIWS occurring in a patient with severe malaria is less familiar and could pose serious primary care challenges in a low-income context. CASE PRESENTATION: A 9-year-old male of black African ethnicity was brought by his parents to our primary care hospital because for 2 days he had been experiencing intermittent sudden perceptions of his parents' heads and objects around him either "shrinking" or "expanding"...
December 22, 2017: BMC Infectious Diseases
https://www.readbyqxmd.com/read/29261684/neural-mechanisms-underlying-sensitivity-to-reverse-phi-motion-in-the-fly
#20
Aljoscha Leonhardt, Matthias Meier, Etienne Serbe, Hubert Eichner, Alexander Borst
Optical illusions provide powerful tools for mapping the algorithms and circuits that underlie visual processing, revealing structure through atypical function. Of particular note in the study of motion detection has been the reverse-phi illusion. When contrast reversals accompany discrete movement, detected direction tends to invert. This occurs across a wide range of organisms, spanning humans and invertebrates. Here, we map an algorithmic account of the phenomenon onto neural circuitry in the fruit fly Drosophila melanogaster...
2017: PloS One
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