Perceptual Awareness of Optic Flows Paced Optimally and Non-optimally to Walking Speed

Perception ◽  
2021 ◽  
Vol 50 (9) ◽  
pp. 797-818
Author(s):  
Paweł Motyka ◽  
Zuzanna Kozłowska ◽  
Piotr Litwin
Keyword(s):  
Visual Processing ◽  
Walking Speed ◽  
Visual Awareness ◽  
Threshold Level ◽  
Perceptual Awareness ◽  
Flow Speeds ◽  
Motion Speed ◽  
Optic Flows ◽  
Walking Speeds ◽  
Self Motion

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.

scholarly journals Semantic and spatial congruency mould audiovisual integration depending on perceptual awareness

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Patrycja Delong ◽  
Uta Noppeney
Keyword(s):  
Information Integration ◽  
Visual Processing ◽  
Visual Awareness ◽  
Audiovisual Integration ◽  
Backward Masking ◽  
Perceptual Awareness ◽  
Semantic Congruency ◽  
Multisensory Interactions ◽  
The Impact ◽  
Ventriloquist Effect

AbstractInformation integration is considered a hallmark of human consciousness. Recent research has challenged this tenet by showing multisensory interactions in the absence of awareness. This psychophysics study assessed the impact of spatial and semantic correspondences on audiovisual binding in the presence and absence of visual awareness by combining forward–backward masking with spatial ventriloquism. Observers were presented with object pictures and synchronous sounds that were spatially and/or semantically congruent or incongruent. On each trial observers located the sound, identified the picture and rated the picture’s visibility. We observed a robust ventriloquist effect for subjectively visible and invisible pictures indicating that pictures that evade our perceptual awareness influence where we perceive sounds. Critically, semantic congruency enhanced these visual biases on perceived sound location only when the picture entered observers’ awareness. Our results demonstrate that crossmodal influences operating from vision to audition and vice versa are interactively controlled by spatial and semantic congruency in the presence of awareness. However, when visual processing is disrupted by masking procedures audiovisual interactions no longer depend on semantic correspondences.

scholarly journals Forward optic flow is prioritised in visual awareness independently of walking direction

2020 ◽  
Author(s):  
Paweł Motyka ◽  
Mert Akbal ◽  
Piotr Litwin
Keyword(s):  
Virtual Environment ◽  
Optic Flow ◽  
Visual Experience ◽  
Visual Awareness ◽  
Hand Movements ◽  
Perceptual Awareness ◽  
Forward Locomotion ◽  
Self Motion ◽  
Smooth Transitions ◽  
Source Of Information

When two different images are presented separately to each eye, one experiences smooth transitions between them. Previous studies have shown that exposure to signals from other senses can enhance perceptual awareness of stimulation-congruent images. Surprisingly, despite our ability to infer perceptual consequences from bodily movements, evidence that action can have an analogous influence on visual experience is scarce and mainly limited to local (hand) movements. Here, we investigated whether one’s direction of locomotion affects perceptual awareness of optic flow patterns. 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 results suggest that kinaesthetic-proprioceptive processing plays a limited role in shaping visual experience. This seems at odds with Bayesian accounts of perception but is in-line with Cancellation theories, which imply that crossmodal influences of self-generated signals are suppressed as a redundant source of information about the outside world.

Visual Perception and Awareness

2010 ◽  
Vol 24 (2) ◽  
pp. 62-67 ◽  
Author(s):  
Gastone G. Celesia
Keyword(s):  
Visual Perception ◽  
Visual Processing ◽  
Visual Awareness ◽  
Perceptual Awareness ◽  
Visual Agnosia ◽  
Clinical Observations ◽  
Psychophysical Testing ◽  
Visual Cortices ◽  
Cortical Regions ◽  
Visual Percept

The study of visual processing and abnormalities due to lesions of cortical structures sheds light on visual awareness/consciousness and may help us to better understand consciousness. We report on clinical observations and psychophysical testing of achromatopsia/prosopagnosia, visual agnosia, and blindsight. Achromatopsia and prosopagnosia reveal that visual cortices have functionally specialized processing systems for color, face perception, and their awareness, and that furthermore these systems operate independently. Dysfunction is limited to some aspects of visual perception; someone with achromatopsia, although not conscious of color, is aware of the objects’ form, motion, and their relationship with sound and other sensory percepts. Perceptual awareness is modular, with neuronal correlates represented by multiple separate specialized structures or modules. Visual agnosia shows that awareness of a complete visual percept is absent, though the subject is aware of single visual features such as edges, motion, etc., an indication that visual agnosia is a disruption of the binding process that unifies all information into a whole percept. Blindsight is characterized by the subject’s ability to localize a visual target while denying actually seeing the target. Blindsight is mediated by residual islands of the visual cortex, which suggests that sensory modules responsible for awareness can function only when structurally intact. We conclude (1) that perceptual awareness (consciousness?) is modular, and (2) that perceptual integration is also modular, which suggests that integration among distinct cortical regions is a parallel process with multiple communication pathways. Any hypothesis about consciousness must include these observations about the presence of multiple parallel, but spatially and temporally different, mechanisms.

Perception of Self-Motion and Regulation of Walking Speed in Young-Old Adults

Motor Control ◽  
2015 ◽  
Vol 19 (3) ◽  
pp. 191-206 ◽  
Author(s):  
Marie-Jasmine Lalonde-Parsi ◽  
Anouk Lamontagne
Keyword(s):  
Visual Motion ◽  
Walking Speed ◽  
Perceptual Task ◽  
Old Adults ◽  
Motion Speed ◽  
Perception Of Self ◽  
Speed Discrimination ◽  
Self Motion ◽  
The Relationship ◽  
Young Old

Whether a reduced perception of self-motion contributes to poor walking speed adaptations in older adults is unknown. In this study, speed discrimination thresholds (perceptual task) and walking speed adaptations (walking task) were compared between young (19–27 years) and young-old individuals (63–74 years), and the relationship between the performance on the two tasks was examined. Participants were evaluated while viewing a virtual corridor in a helmet-mounted display. Speed discrimination thresholds were determined using a staircase procedure. Walking speed modulation was assessed on a self-paced treadmill while exposed to different self-motion speeds ranging from 0.25 to 2 times the participants’ comfortable speed. For each speed, participants were instructed to match the self-motion speed described by the moving corridor. On the walking task, participants displayed smaller walking speed errors at comfortable walking speeds compared with slower of faster speeds. The young-old adults presented larger speed discrimination thresholds (perceptual experiment) and larger walking speed errors (walking experiment) compared with young adults. Larger walking speed errors were associated with higher discrimination thresholds. The enhanced performance on the walking task at comfortable speed suggests that intersensory calibration processes are influenced by experience, hence optimized for frequently encountered conditions. The altered performance of the young-old adults on the perceptual and walking tasks, as well as the relationship observed between the two tasks, suggest that a poor perception of visual motion information may contribute to the poor walking speed adaptations that arise with aging.

scholarly journals Myofascial Release of the Hamstrings Improves Physical Performance—A Study of Young Adults

Healthcare ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 674
Author(s):  
Keisuke Itotani ◽  
Kanta Kawahata ◽  
Wakana Takashima ◽  
Wakana Mita ◽  
Hitomi Minematsu ◽  
...  
Keyword(s):  
Young Adults ◽  
Physical Performance ◽  
Walking Speed ◽  
Quadriceps Muscle ◽  
Lower Limbs ◽  
Joint Movement ◽  
Myofascial Release ◽  
Functional Reach Test ◽  
Hamstring Flexibility ◽  
Walking Speeds

Physical performance is mainly assessed in terms of gait speed, chair rise capacity, and balance skills, and assessments are often carried out on the lower limbs. Such physical performance is largely influenced by the strength of the quadriceps and hamstrings muscles. Flexibility of the hamstrings is important because quadriceps muscle activity influences the hip flexion angle. Therefore, hamstring flexibility is essential to improve physical performance. In this study, Myofascial Release (MFR) was applied to the hamstrings to evaluate its effects. MFR on the hamstrings was performed on 17 young adults. Physical function and physical performance were measured before, immediately after, and 5 days after the MFR intervention: finger floor distance (FFD), range of motion (ROM) of the straight leg raising test (SLR), standing long jump (SLJ), squat jump (SJ), functional reach test (FRT), comfortable walking speeds (C-walking speed), and maximum walking speeds (M-walking speed). The results of the analysis show a significant increase in FFD (−2.6 ± 8.9 vs. 0.4 ± 9.4 vs. 2.4 ± 8.9, p < 0.01), SLJ (185.6 ± 44.5 vs. 185.0 ± 41.8 vs. 196.6 ± 40.1, p < 0.01), and M-walking speed (2.9 ± 0.6 vs. 3.0 ± 0.6 vs. 3.3 ± 0.6, p < 0.01). This study has shown that MFR for hamstrings not only improves flexibility but also increases M-walking speed and physical performance of the SLJ. As MFR is safe and does not involve joint movement, it may be useful for maintaining and improving performance and flexibility during inactivity and for stretching before exercise.

Visual Processing without Awareness: Evidence from Unilateral Neglect

1992 ◽  
Vol 4 (4) ◽  
pp. 345-351 ◽  
Author(s):  
Anna Berti ◽  
Giacomo Rizzolatti
Keyword(s):  
Visual Processing ◽  
Visual Awareness ◽  
Visual Cognition ◽  
Congruent Condition ◽  
Experimental Conditions ◽  
Unilateral Neglect ◽  
Normal Field ◽  
The Third ◽  
Physically Identical ◽  
Physiological Theory

Can visual processing be carried out without visual awareness of the presented objects? In the present study we addressed this problem in patients with severe unilateral neglect. The patients were required to respond as fast as possible to target stimuli (pictures of animals and fruits) presented to the normal field by pressing one of the two keys according to the category of the targets. We then studied the influence of priming stimuli, again pictures of animals or fruits, presented to the neglected field on the responses to targets. By combining different pairs of primes and targets, three different experimental conditions were obtained. In the first condition, "Highly congruent," the target and prime stimuli belonged to the same category and were physically identical; in the second condition, "Congruent," the stimuli represented two elements of the same category but were physically dissimilar; in the third condition, "Noncongruent," the stimuli represented one exemplar from each of the two categories of stimuli. The results showed that the responses were facilitated not only in the Highly congruent condition, but also in the Congruent one. This finding suggests that patients with neglect are able to process stimuli presented to the neglected field to a categorical level of representation even when they deny the stimulus presence in the affected field. The implications of this finding for psychological and physiological theory of neglect and visual cognition are discussed.

Pedestrian Behavior at Signalized Intersection Crosswalks: Observational Study of Factors Associated with Distracted Walking, Pedestrian Violations, and Walking Speed

2018 ◽  
Vol 2672 (35) ◽  
pp. 1-12 ◽  
Author(s):  
Brendan J. Russo ◽  
Emmanuel James ◽  
Cristopher Y. Aguilar ◽  
Edward J. Smaglik
Keyword(s):  
Traffic Safety ◽  
Walking Speed ◽  
The United States ◽  
Ordinary Least Squares ◽  
Signalized Intersections ◽  
Video Data ◽  
High Definition ◽  
Pedestrian Behavior ◽  
Factors Associated ◽  
Walking Speeds

In the past two decades, cell phone and smartphone use in the United States has increased substantially. Although mobile phones provide a convenient way for people to communicate, the distraction caused by the use of these devices has led to unintended traffic safety and operational consequences. Although it is well recognized that distracted driving is extremely dangerous for all road users (including pedestrians), the potential impacts of distracted walking have not been as comprehensively studied. Although practitioners should design facilities with the safety, efficiency, and comfort of pedestrians in mind, it is still important to investigate certain pedestrian behaviors at existing facilities to minimize the risk of pedestrian–vehicle crashes, and to reduce behaviors that may unnecessarily increase delay at signalized intersections. To gain new insights into factors associated with distracted walking, pedestrian violations, and walking speed, 3,038 pedestrians were observed across four signalized intersections in New York and Arizona using high-definition video cameras. The video data were reduced and summarized, and an ordinary least squares (OLS) regression model was estimated to analyze factors affecting walking speeds. In addition, binary logit models were estimated to analyze both pedestrian distraction and pedestrian violations. Ultimately, several site- and pedestrian-specific variables were found to be significantly associated with pedestrian distraction, violation behavior, and walking speeds. The results provide important information for researchers, practitioners, and legislators, and may be useful in planning strategies to reduce or mitigate the impacts of pedestrian behavior that may be considered unsafe or potentially inefficient.

scholarly journals Awareness and Integration: Understanding the Challenges of Inferring Multisensory Integration Outside of Awareness

2021 ◽  
Author(s):  
◽  
Daniel Jenkins
Keyword(s):  
Spatial Attention ◽  
Multisensory Integration ◽  
Subjective Experience ◽  
Visual Masking ◽  
Target Location ◽  
Visual Awareness ◽  
Visual Speech ◽  
Emotional Prosody ◽  
Perceptual Awareness ◽  
Spatial Cueing

<p>Multisensory integration describes the cognitive processes by which information from various perceptual domains is combined to create coherent percepts. For consciously aware perception, multisensory integration can be inferred when information in one perceptual domain influences subjective experience in another. Yet the relationship between integration and awareness is not well understood. One current question is whether multisensory integration can occur in the absence of perceptual awareness. Because there is subjective experience for unconscious perception, researchers have had to develop novel tasks to infer integration indirectly. For instance, Palmer and Ramsey (2012) presented auditory recordings of spoken syllables alongside videos of faces speaking either the same or different syllables, while masking the videos to prevent visual awareness. The conjunction of matching voices and faces predicted the location of a subsequent Gabor grating (target) on each trial. Participants indicated the location/orientation of the target more accurately when it appeared in the cued location (80% chance), thus the authors inferred that auditory and visual speech events were integrated in the absence of visual awareness. In this thesis, I investigated whether these findings generalise to the integration of auditory and visual expressions of emotion. In Experiment 1, I presented spatially informative cues in which congruent facial and vocal emotional expressions predicted the target location, with and without visual masking. I found no evidence of spatial cueing in either awareness condition. To investigate the lack of spatial cueing, in Experiment 2, I repeated the task with aware participants only, and had half of those participants explicitly report the emotional prosody. A significant spatial-cueing effect was found only when participants reported emotional prosody, suggesting that audiovisual congruence can cue spatial attention during aware perception. It remains unclear whether audiovisual congruence can cue spatial attention without awareness, and whether such effects genuinely imply multisensory integration.</p>

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