Use of Foreground and Background Information in Visually Guided Locomotion

Perception ◽  
1981 ◽  
Vol 10 (2) ◽  
pp. 191-198 ◽  
Author(s):  
Edward R Strelow ◽  
John A Brabyn
Keyword(s):  
Spatial Perception ◽  
Motion Parallax ◽  
Background Information ◽  
Visually Guided ◽  
Locomotor Control

The effects of reducing the range of spatial perception on the accuracy of visually guided locomotion were studied in two experiments. Limiting the range of perception to only near objects produces changes in the flow of stimulus detail and reduces opportunities for the appearance of an aiming point and for motion parallax. Such conditions were found to produce inferior performance compared to full vision, or to minimal background information. A defined aiming point was also found to assist control when no other background was present. The results are discussed with reference to theories of locomotor control and the design of artificial spatial sensing aids for the blind.

Reaching beyond spatial perception: Effects of intended future actions on visually guided prehension

2004 ◽  
Vol 11 (2-3) ◽  
pp. 371-399 ◽  
Author(s):  
Scott Johnson‐Frey ◽  
Michael McCarty ◽  
Rachel Keen
Keyword(s):  
Spatial Perception ◽  
Visually Guided

The Importance of Stereo and Eye-Coupled Perspective for Eye-Hand Coordination in Fish Tank VR

2004 ◽  
Vol 13 (5) ◽  
pp. 549-559 ◽  
Author(s):  
Roland Arsenault ◽  
Colin Ware
Keyword(s):  
Force Feedback ◽  
Motion Parallax ◽  
Visual Display ◽  
Head Tracking ◽  
Visually Guided ◽  
High Quality ◽  
Depth Cues ◽  
Hand Coordination ◽  
Fish Tank ◽  
Sense Of Touch

It is possible to simulate a high-quality virtual environment with viewpoint-controlled perspective, high-quality stereo, and a sense of touch obtained with the PHANToM force feedback device using existing “fish tank VR” technologies. This enables us to investigate the importance of different depth cues and touch using higher quality visual display than is possible with more immersive technologies. Prior work on depth perception suggests that different depth cues are important depending on the task performed. A number of studies have shown that motion parallax is more important than stereopsis in perceiving 3D patterns, but other studies suggest that stereopsis should be critically important for visually guided reaching. A Fitts' Law tapping task was used to investigate the relative importance of stereo and head tracking in visually guided hand movements. It allowed us to examine the intertap intervals following a head movement in order to look for evidence of rapid adaptation to a misplaced head position. The results show that stereo is considerably more important than eye-coupled perspective for this task, and that the benefits increase as task difficulty increases. Disabling stereo increased mean intertap intervals by 33%, while disabling head tracking produced only an 11% time increase. However, we failed to find the expected evidence for adaptation during the series of taps. We conclude by discussing the theoretical and practical implications of the results.

scholarly journals Center of Pressure Feedback Modulates the Entrainment of Voluntary Sway to the Motion of a Visual Target

2019 ◽  
Vol 9 (19) ◽  
pp. 3952 ◽  
Author(s):  
Haralampos Sotirakis ◽  
Vassilia Hatzitaki ◽  
Victor Munoz-Martel ◽  
Lida Mademli ◽  
Adamantios Arampatzis
Keyword(s):  
Dynamic Stability ◽  
Visual Target ◽  
Center Of Pressure ◽  
Spatial Perception ◽  
Target Motion ◽  
Phase Lag ◽  
Visually Guided ◽  
Pressure Feedback ◽  
Cost Of Time ◽  
Voluntary Sway

Visually guided weight shifting is widely employed in balance rehabilitation, but the underlying visuo-motor integration process leading to balance improvement is still unclear. In this study, we investigated the role of center of pressure (CoP) feedback on the entrainment of active voluntary sway to a moving visual target and on sway’s dynamic stability as a function of target predictability. Fifteen young and healthy adult volunteers (height 175 ± 7 cm, body mass 69 ± 12 kg, age 32 ± 5 years) tracked a vertically moving visual target by shifting their body weight antero-posteriorly under two target motion and feedback conditions, namely, predictable and less predictable target motion, with or without visual CoP feedback. Results revealed lower coherence, less gain, and longer phase lag when tracking the less predictable compared to the predictable target motion. Feedback did not affect CoP-target coherence, but feedback removal resulted in greater target overshooting and a shorter phase lag when tracking the less predictable target. These adaptations did not affect the dynamic stability of voluntary sway. It was concluded that CoP feedback improves spatial perception at the cost of time delays, particularly when tracking a less predictable moving target.

The Influence of Light-Dark Adaptation and Lateral Inhibition on Phototaxic Foraging: A Hypothetical Animal Study

1997 ◽  
Vol 5 (2) ◽  
pp. 141-167 ◽  
Author(s):  
René J. V Bertin ◽  
Wim A. van de Grind
Keyword(s):  
Lateral Inhibition ◽  
Light Adaptation ◽  
Background Information ◽  
Visually Guided ◽  
Neural Firing ◽  
Dark Light ◽  
Visual Background ◽  
Foraging Performance ◽  
Two Stages ◽  
Parameter Values

Vision did not arise and evolve merely so that individuals might "see" things but rather so that they might act on and interact with their habitat. Thus it might be misleading to study vision without looking also at its natural coupling to vital action. Here we investigate this problem in a simulation study of the simplest kind of visually guided foraging by a species of two-dimensional hypothetical animal called the (diurnal) paddler. In a previous study, we developed a hypothetical animal called the archaepaddler, which used positive phototaxis to forage for autoluminescent prey in a totally dark environment (the deep sea). Here we discuss possible visual mechanisms that allow (diurnal) paddlers to live in shallower water, foraging for light-reflecting prey in ambient light. The modification consists of two stages. In the first stage, Weber adaptation compresses the retinal illumination into an acceptable range of neural firing frequencies. In the second stage, high-pass filtering with lateral inhibition separates background responses from foreground responses. We report on a number of parameter studies conducted with the foraging diurnal paddler, in which the influence of dark-light adaptation and lateral inhibition on foreground-background segregation and foraging performance ("fitness") are quantified. It is shown that the paddler can survive adequately for a substantial range of parameters that compromises between discarding as much unwanted visual (background) information as possible and retaining as much information on potential prey as possible. Parameter values that optimize purely visual performance, such as foreground-background segregation, are not always optimal for foraging performance, and vice versa. This article shows that studies of vision might indeed require more serious consideration of the goals of vision and the ethogram of the studied organisms than has been customary.

Passy-Muir Speaking Valve Use in a Children's Hospital: An Interdisciplinary Approach

2008 ◽  
Vol 18 (2) ◽  
pp. 76-86 ◽  
Author(s):  
Lauren Hofmann ◽  
Joseph Bolton ◽  
Susan Ferry
Keyword(s):  
Tracheostomy Tube ◽  
Pediatric Population ◽  
Interdisciplinary Approach ◽  
Extended Period ◽  
Speech Development ◽  
Tube Placement ◽  
Background Information ◽  
Speaking Valve ◽  
Children's Hospital ◽  
Children’S Hospital

Abstract At The Children's Hospital of Philadelphia (CHOP) we treat many children requiring tracheostomy tube placement. With potential for a tracheostomy tube to be in place for an extended period of time, these children may be at risk for long-term disruption to normal speech development. As such, speaking valves that restore more normal phonation are often key tools in the effort to restore speech and promote more typical language development in this population. However, successful use of speaking valves is frequently more challenging with infant and pediatric patients than with adult patients. The purpose of this article is to review background information related to speaking valves, the indications for one-way valve use, criteria for candidacy, and the benefits of using speaking valves in the pediatric population. This review will emphasize the importance of interdisciplinary collaboration from the perspectives of speech-language pathology and respiratory therapy. Along with the background information, we will present current practices and a case study to illustrate a safe and systematic approach to speaking valve implementation based upon our experiences.

Searching Online for Methods of Suicide

Crisis ◽  
2020 ◽  
pp. 1-8
Author(s):  
Christian Ulrich Eriksen ◽  
Flemming Konradsen ◽  
Thilde Vildekilde
Keyword(s):  
Content Analysis ◽  
English Language ◽  
Significant Proportion ◽  
Background Information ◽  
Access To Information ◽  
Online Content ◽  
Negative Effects ◽  
Search Terms ◽  
Methods Of Suicide

Abstract. Background: Information on methods of suicide is available online, and access to information on methods of suicide appears to contribute to a small but significant proportion of suicides. There is limited documentation of how methods of suicide are being profiled, as well as what content exists in other languages than English. Aim: We aimed to analyze and compare how methods of suicide are profiled on Danish and English-language websites. Method: We applied a categorization and content analysis of websites describing methods of suicide. Sites were retrieved by applying widely used Danish and English-language search terms. Results: A total of 136 English-language websites and 106 Danish-language websites were included for analysis. Websites were more often categorized as prevention or support sites, academic or policy sites, and against suicide sites than dedicated suicide sites (i.e., pro-suicide sites), or information sites. However, information on methods of suicide was available, and 20.1% and 8.9% of the English and Danish-language sites, respectively, suggested that a particular method of suicide was quick, easy, painless, or certain to result in death. Limitations: Only one author coded and analyzed all websites. A further operationalization of the content analysis checklist is warranted to increase reliability. Conclusion: The websites primarily had a prevention or anti-suicide focus, but information on methods of suicide was available, requiring an increased focus on how to diminish the negative effects of harmful online content.

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