DOCSLIB.ORG

The Effect of Three Levels of Duration and Intensity of Exercise Upon the Peripheral Vision and Depth Perception of Women." (1973)

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Effect of Three Levels of Duration and Intensity of Exercise Upon the Peripheral Vision and Depth Perception of Women. Louisiana State University LSU Digital Commons LSU Historical Dissertations and Theses Graduate School 1973 The ffecE t of Three Levels of Duration and Intensity of Exercise Upon the Peripheral Vision and Depth Perception of Women. Gracie J. Purvis Louisiana State University and Agricultural & Mechanical College Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_disstheses Recommended Citation Purvis, Gracie J., "The Effect of Three Levels of Duration and Intensity of Exercise Upon the Peripheral Vision and Depth Perception of Women." (1973). LSU Historical Dissertations and Theses. 2564. https://digitalcommons.lsu.edu/gradschool_disstheses/2564 This Dissertation is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Historical Dissertations and Theses by an authorized administrator of LSU Digital Commons. For more information, please contact [email protected]. INFORMATION TO USERS This material was produced from a microfilm copy of the original document. While the most advanced technological means to photograph and reproduce this document have been used, the quality is heavily dependent upon the quality of the original submitted. The following explanation of techniques is provided to help you understand markings or patterns which may appear on this reproduction. 1. The sign or "target" for pages apparently lacking from the document photographed is "Missing Page(s)". If it was possible to obtain the missing page{s) or section, they arc spliced into the film along with adjacent pages. This may have necessitated cutting thru an image and duplicating adjacent pages to insure you complete continuity. 2. When an image on the film is obliterated with a large round black mark, it is an indication that the photographer suspected that the copy may have moved during exposure and thus cause a blurred image. You will find a good image of the page in the adjacent frame. 3. When a map, drawing or chart, etc., was part of the material being photographed the photographer followed a definite method in "sectioning" the material. It is customary to begin photoing at the upper left hand corner of a large sheet and to continue photoing from left to right in equal sections with a small overlap. If necessary, sectioning is continued again — beginning below the first row and continuing on until complete. 4. The majority of users indicate that the textual content is of greatest value, however, a somewhat higher quality reproduction could be made from "photographs" if essential to the understanding of the dissertation. Silver prints of "photographs" may be ordered at additional charge by writing the Order Department, giving the catalog number, title, author and specific pages you wish reproduced. 5. PLEASE NOTE: Some pages may have indistinct print. Filmed as received. Xerox University Microfilms 300 North Zeeb Road Ann Arbor, Michigan 48106 74-18,360 PURVIS, Gracie J., 1946- THE EFFECT OF THREE LEVELS OF DURATION AND INTENSITY OF EXERCISE UPON THE PERIPHERAL VISION AND DEPTH PERCEPTION OF WOMEN. The Louisiana State University and Agricultural and Mechanical College, Ph.D., 1973 Education, physical University Microfilms,A XjEROXCompany, Ann Arbor, Michigan THIS DISSERTATION HAS BEEN MICROFILMED EXACTLY AS RECEIVED. THE EFFECT OF THREE LEVELS OF DURATION AND INTENSITY OF EXERCISE UPON THE PERIPHERAL VISION AND DEPTH PERCEPTION OF WOMEN A Dissertation Submitted to the Graduate Faculty of the Louisiana State University and Agricultural and Mechanical College in partial fulfillment of the requirements for the degree of Doctor of Philosophy in The Department of Health, Physical and Recreation Education by Gracie J. Purvis B.S., Winthrop College, 1967 M.S., University of Tennessee, 1968 December, 1973 DEDICATION Dedicated to my family ACKNOWLEDGEMENTS . The writer would like to express her gratitude to the members of the committee and to her major professor, Dr, Jack K. Nelson, for the assistance received during the completion of this study. The writer is also grateful to Dr. Barton R. Farthing for his guidance in the statistical preparation of this dissertation. ii TABLE OF CONTENTS Page ACKNOWLEDGEMENTS.................................................. ii LIST OF TABLES .................................................... vi LIST OF FIGURES.................. vii ABSTRACT ............................................................ viii Chapter 1. INTRODUCTION .............................................. 1 STATEMENT OF THE PROBLEM ................................ 3 PURPOSE OF THE STUDY . .................................. 4 DEFINITION OF TERMS...................................... 4 DELIMITATIONS OF THE STUDY ............................. 5 LIMITATIONS OF THE STUDY ........ ............... 5 SIGNIFICANCE OF THE STUDY................................ 6 2. REVIEW OF LITERATURE ..................................... 7 STUDIES IN PERIPHERAL VISION ........................... 7 STUDIES IN DEPTH PERCEPTION............................. 12 STUDIES RELATING VISION TO PERFORMANCE ................. 17 STUDIES MEASURING THE EFFECT OF PHYSICAL EXERCISE UPON VISION............................. 20 SUMMARY OF RELATED LITERATURE. ..................... 22 3. PROCEDURES................................................ 25 OVERVIEW ................................................ 25 SELECTION OF SUBJECTS.................................... 26 GROUPING OF S UBJECTS.................................... 27 iii lv Chapter ■ Page EQUIPMENT FOR TESTING AND MEASURING ........................ 27 PILOT STUDIES ................................................32 PERIPHERAL VISION TESTING PROCEDURE ..................... 33 DEPTH PERCEPTION.............................. 34 ORDER OF MEASUREMENT............... '.........................35 EXERCISE PROGRAM..............................................35 STATISTICAL PROCEDURE ............................ .... 37 4. PRESENTATION AND ANALYSIS OF D A T A ............................ 38 INTRODUCTION.................................................. 38 SIGNIFICANCE OF THE DIFFERENCES BETWEEN PRE-EXERCISE AND POST-EXERCISE PERIPHERAL VISION ................... 39 COMPARISON OF TOO ORDERS OF TEST ADMINISTRATION, THREE INTERVALS OF DURATION, THREE INTENSITIES OF EXERCISE, AND THE INTERACTION OF THE VARIABLES ON PERIPHERAL VISION................... 39 SIGNIFICANCE OF THE DIFFERENCE BETWEEN PRE-EXERICSE AND POST-EXERCISE DEPTH PERCEPTION........................ 42 COMPARISON OF TOO ORDERS OF TEST ADMINISTRATION, THREE INTERVALS OF DURATION, THREE INTENSITIES OF EXERCISE, AND THE INTERACTION OF THE VARIABLES ON DEPTH P E R C E P T I O N ....................................... 42 RELATIONSHIP OF PERIPHERAL VISION AND DEPTH PERCEPTION BEFORE AND AFTER EXERCISE .............................. 45 5. SUMMARY, FINDINGS, DISCUSSION OF FINDINGS AND CONCLUSION. 47 SUMMARY ...................................................... 47 FINDINGS...................................................... 49 DISCUSSION OF THE FINDINGS................................... 49 Peripheral Vision , ..................................... 49 Depth Perception. ..................................... 51 Relationship Between Peripheral Vision and Depth Perception......................................... 51 V Chapter Page CONCLUSIONS................ 52 RECOMMENDATIONS......................... 52 BIBLIOGRAPHY ..................................................... 54 APPENDIX ........................................................... 59 VITA ............ 63 LIST OF TABLES Table - Page 1. Heart Rate Progression for Each Minute of Work ...... 36 2. Significance of the Difference Between Pre and Post Exercise Measures of Peripheral Vision . ........... 40 3. Analysis of Covariance of Intensity and Duration of Exercise Effects on Peripheral Vision Scores of 180 Women................................................. 41 4. Significance of the Difference Between Pre and Post Exercise Measures of Depth Perception................... 43 5. Analysis of Covariance of Intensity and Duration of Exercise Effects on Depth Perception Scores of 180 Women........................................ 44 6. Relationships Between Peripheral Vision and Depth Perception Before and After Exercise ................... 46 vi LIST OF FIGURES Figure Page 1. Position for Pre- and Post-Exercise Measurements of Peripheral Vision and Depth Perception ............... 28 2. Position for Testing Peripheral Vision .................. 30 3. Howard-Dolman Apparatus................................... 31 vii ABSTRACT The purpose of this study was to compare the effects of three durations of time and three intensities of exercise upon peripheral vision and depth perception of women. A secondary purpose was to determine the correlation between peripheral vision and depth per­ ception prior to and after participation in exercise. One-hundred eighty women between the ages of 18 and 35 served as subjects. Each subject was assigned to one of nine work-time groups and within each work-time group each subject was randomly assigned to an order of measurement. Subjects designated as order 1 were tested first on peripheral vision and then on depth perception prior to and after exercise. Subjects designated as order 2 were tested first oh depth perception and then on peripheral vision prior to and after exercise. A Light Work load was defined as a heart rate range between 125-130 beats per minute. A Moderate Work load was defined as a heart rate range
Load more

Recommended publications
  • Specific Eye Conditions with Corresponding Adaptations/Considerations
    Specific Eye Conditions with Corresponding Adaptations/Considerations # Eye Condition Effect on Vision Adaptations/Considerations 1 Achromotopsia colors are seen as shades of grey, tinted lenses, reduced lighting, alternative nystagmus and photophobia improve techniques for teaching colors will be with age required 2 Albinism decreased visual acuity, photophobia, sunglasses, visor or cap with a brim, nystagmus, central scotomas, strabismus reduced depth perception, moving close to objects 3 Aniridia photophobia, field loss, vision may tinted lenses, sunglasses, visor or cap with fluctuate depending on lighting brim, dim lighting, extra time required to conditions and glare adapt to lighting changes 4 Aphakia reduced depth perception, inability to sunglasses, visor or cap with a brim may accommodate to lighting changes be worn indoors, extra time required to adapt to lighting changes 5 Cataracts poor color vision, photophobia, visual bright lighting may be a problem, low acuity fluctuates according to light lighting may be preferred, extra time required to adapt to lighting changes 6 Colobomas photophobia, nystagmus, field loss, sunglasses, visor or cap with a brim, reduced depth perception reduced depth perception, good contrast required 7 Color Blindness difficulty or inability to see colors and sunglasses, visor or cap with a brim, detail, photophobia, central field reduced depth perception, good contrast scotomas (spotty vision), normal required, low lighting may be preferred, peripheral fields alternative techniques for teaching colors
    [Show full text]
  • 3D Computational Modeling and Perceptual Analysis of Kinetic Depth Effects
    Computational Visual Media DOI 10.1007/s41095-xxx-xxxx-x Vol. x, No. x, month year, xx–xx Research Article 3D Computational Modeling and Perceptual Analysis of Kinetic Depth Effects Meng-Yao Cui1, Shao-Ping Lu1( ), Miao Wang2, Yong-Liang Yang3, Yu-Kun Lai4, and Paul L. Rosin4 c The Author(s) 2020. This article is published with open access at Springerlink.com Abstract Humans have the ability to perceive 3D shapes from 2D projections of rotating 3D objects, which is called Kinetic Depth Effects. This process is based on a variety of visual cues such as lighting and shading effects. However, when such cues are weakened or missing, perception can become faulty, as demonstrated by the famous silhouette illusion example – the Spinning Dancer. Inspired by this, we establish objective and subjective evaluation models of rotated 3D objects by taking their projected 2D images as input. We investigate five different cues: ambient Fig. 1 The Spinning Dancer. Due to the lack of visual cues, it confuses humans luminance, shading, rotation speed, perspective, and color as to whether rotation is clockwise or counterclockwise. Here we show 3 of 34 difference between the objects and background. In the frames from the original animation [21]. Image courtesy of Nobuyuki Kayahara. objective evaluation model, we first apply 3D reconstruction algorithms to obtain an objective reconstruction quality 1 Introduction metric, and then use a quadratic stepwise regression analysis method to determine the weights among depth cues to The human perception mechanism of the 3D world has represent the reconstruction quality. In the subjective long been studied.
    [Show full text]
  • Interacting with Autostereograms
    See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/336204498 Interacting with Autostereograms Conference Paper · October 2019 DOI: 10.1145/3338286.3340141 CITATIONS READS 0 39 5 authors, including: William Delamare Pourang Irani Kochi University of Technology University of Manitoba 14 PUBLICATIONS 55 CITATIONS 184 PUBLICATIONS 2,641 CITATIONS SEE PROFILE SEE PROFILE Xiangshi Ren Kochi University of Technology 182 PUBLICATIONS 1,280 CITATIONS SEE PROFILE Some of the authors of this publication are also working on these related projects: Color Perception in Augmented Reality HMDs View project Collaboration Meets Interactive Spaces: A Springer Book View project All content following this page was uploaded by William Delamare on 21 October 2019. The user has requested enhancement of the downloaded file. Interacting with Autostereograms William Delamare∗ Junhyeok Kim Kochi University of Technology University of Waterloo Kochi, Japan Ontario, Canada University of Manitoba University of Manitoba Winnipeg, Canada Winnipeg, Canada [email protected] [email protected] Daichi Harada Pourang Irani Xiangshi Ren Kochi University of Technology University of Manitoba Kochi University of Technology Kochi, Japan Winnipeg, Canada Kochi, Japan [email protected] [email protected] [email protected] Figure 1: Illustrative examples using autostereograms. a) Password input. b) Wearable e-mail notification. c) Private space in collaborative conditions. d) 3D video game. e) Bar gamified special menu. Black elements represent the hidden 3D scene content. ABSTRACT practice. This learning effect transfers across display devices Autostereograms are 2D images that can reveal 3D content (smartphone to desktop screen). when viewed with a specific eye convergence, without using CCS CONCEPTS extra-apparatus.
    [Show full text]
  • Stereopsis and Stereoblindness
    Exp. Brain Res. 10, 380-388 (1970) Stereopsis and Stereoblindness WHITMAN RICHARDS Department of Psychology, Massachusetts Institute of Technology, Cambridge (USA) Received December 20, 1969 Summary. Psychophysical tests reveal three classes of wide-field disparity detectors in man, responding respectively to crossed (near), uncrossed (far), and zero disparities. The probability of lacking one of these classes of detectors is about 30% which means that 2.7% of the population possess no wide-field stereopsis in one hemisphere. This small percentage corresponds to the probability of squint among adults, suggesting that fusional mechanisms might be disrupted when stereopsis is absent in one hemisphere. Key Words: Stereopsis -- Squint -- Depth perception -- Visual perception Stereopsis was discovered in 1838, when Wheatstone invented the stereoscope. By presenting separate images to each eye, a three dimensional impression could be obtained from two pictures that differed only in the relative horizontal disparities of the components of the picture. Because the impression of depth from the two combined disparate images is unique and clearly not present when viewing each picture alone, the disparity cue to distance is presumably processed and interpreted by the visual system (Ogle, 1962). This conjecture by the psychophysicists has received recent support from microelectrode recordings, which show that a sizeable portion of the binocular units in the visual cortex of the cat are sensitive to horizontal disparities (Barlow et al., 1967; Pettigrew et al., 1968a). Thus, as expected, there in fact appears to be a physiological basis for stereopsis that involves the analysis of spatially disparate retinal signals from each eye. Without such an analysing mechanism, man would be unable to detect horizontal binocular disparities and would be "stereoblind".
    [Show full text]
  • Relative Importance of Binocular Disparity and Motion Parallax for Depth Estimation: a Computer Vision Approach
    remote sensing Article Relative Importance of Binocular Disparity and Motion Parallax for Depth Estimation: A Computer Vision Approach Mostafa Mansour 1,2 , Pavel Davidson 1,* , Oleg Stepanov 2 and Robert Piché 1 1 Faculty of Information Technology and Communication Sciences, Tampere University, 33720 Tampere, Finland 2 Department of Information and Navigation Systems, ITMO University, 197101 St. Petersburg, Russia * Correspondence: pavel.davidson@tuni.fi Received: 4 July 2019; Accepted: 20 August 2019; Published: 23 August 2019 Abstract: Binocular disparity and motion parallax are the most important cues for depth estimation in human and computer vision. Here, we present an experimental study to evaluate the accuracy of these two cues in depth estimation to stationary objects in a static environment. Depth estimation via binocular disparity is most commonly implemented using stereo vision, which uses images from two or more cameras to triangulate and estimate distances. We use a commercial stereo camera mounted on a wheeled robot to create a depth map of the environment. The sequence of images obtained by one of these two cameras as well as the camera motion parameters serve as the input to our motion parallax-based depth estimation algorithm. The measured camera motion parameters include translational and angular velocities. Reference distance to the tracked features is provided by a LiDAR. Overall, our results show that at short distances stereo vision is more accurate, but at large distances the combination of parallax and camera motion provide better depth estimation. Therefore, by combining the two cues, one obtains depth estimation with greater range than is possible using either cue individually.
    [Show full text]
  • Chromostereo.Pdf
    ChromoStereoscopic Rendering for Trichromatic Displays Le¨ıla Schemali1;2 Elmar Eisemann3 1Telecom ParisTech CNRS LTCI 2XtremViz 3Delft University of Technology Figure 1: ChromaDepth R glasses act like a prism that disperses incoming light and induces a differing depth perception for different light wavelengths. As most displays are limited to mixing three primaries (RGB), the depth effect can be significantly reduced, when using the usual mapping of depth to hue. Our red to white to blue mapping and shading cues achieve a significant improvement. Abstract The chromostereopsis phenomenom leads to a differing depth per- ception of different color hues, e.g., red is perceived slightly in front of blue. In chromostereoscopic rendering 2D images are produced that encode depth in color. While the natural chromostereopsis of our human visual system is rather low, it can be enhanced via ChromaDepth R glasses, which induce chromatic aberrations in one Figure 2: Chromostereopsis can be due to: (a) longitunal chro- eye by refracting light of different wavelengths differently, hereby matic aberration, focus of blue shifts forward with respect to red, offsetting the projected position slightly in one eye. Although, it or (b) transverse chromatic aberration, blue shifts further toward might seem natural to map depth linearly to hue, which was also the the nasal part of the retina than red. (c) Shift in position leads to a basis of previous solutions, we demonstrate that such a mapping re- depth impression. duces the stereoscopic effect when using standard trichromatic dis- plays or printing systems. We propose an algorithm, which enables an improved stereoscopic experience with reduced artifacts.
    [Show full text]
  • Two Eyes See More Than One Human Beings Have Two Eyes Located About 6 Cm (About 2.4 In.) Apart
    ivi act ty 2 TTwowo EyesEyes SeeSee MoreMore ThanThan OneOne OBJECTIVES 1 straw 1 card, index (cut in half widthwise) Students discover how having two eyes helps us see in three dimensions and 3 pennies* increases our field of vision. 1 ruler, metric* The students For the class discover that each eye sees objects from a 1 roll string slightly different viewpoint to give us depth 1 roll tape, masking perception 1 pair scissors* observe that depth perception decreases *provided by the teacher with the use of just one eye measure their field of vision observe that their field of vision decreases PREPARATION with the use of just one eye Session I 1 Make a copy of Activity Sheet 2, Part A, for each student. SCHEDULE 2 Each team of two will need a metric ruler, Session I About 30 minutes three paper cups, and three pennies. Session II About 40 minutes Students will either close or cover their eyes, or you may use blindfolds. (Students should use their own blindfold—a bandanna or long strip VOCABULARY of cloth brought from home and stored in their science journals for use—in this depth perception and other activities.) field of vision peripheral vision Session II 1 Make a copy of Activity Sheet 2, Part B, for each student. MATERIALS 2 For each team, cut a length of string 50 cm (about 20 in.) long. Cut enough index For each student cards in half (widthwise) to give each team 1 Activity Sheet 2, Parts A and B half a card. Snip the corners of the cards to eliminate sharp edges.
    [Show full text]
  • Binocular Vision
    BINOCULAR VISION Rahul Bhola, MD Pediatric Ophthalmology Fellow The University of Iowa Department of Ophthalmology & Visual Sciences posted Jan. 18, 2006, updated Jan. 23, 2006 Binocular vision is one of the hallmarks of the human race that has bestowed on it the supremacy in the hierarchy of the animal kingdom. It is an asset with normal alignment of the two eyes, but becomes a liability when the alignment is lost. Binocular Single Vision may be defined as the state of simultaneous vision, which is achieved by the coordinated use of both eyes, so that separate and slightly dissimilar images arising in each eye are appreciated as a single image by the process of fusion. Thus binocular vision implies fusion, the blending of sight from the two eyes to form a single percept. Binocular Single Vision can be: 1. Normal – Binocular Single vision can be classified as normal when it is bifoveal and there is no manifest deviation. 2. Anomalous - Binocular Single vision is anomalous when the images of the fixated object are projected from the fovea of one eye and an extrafoveal area of the other eye i.e. when the visual direction of the retinal elements has changed. A small manifest strabismus is therefore always present in anomalous Binocular Single vision. Normal Binocular Single vision requires: 1. Clear Visual Axis leading to a reasonably clear vision in both eyes 2. The ability of the retino-cortical elements to function in association with each other to promote the fusion of two slightly dissimilar images i.e. Sensory fusion. 3. The precise co-ordination of the two eyes for all direction of gazes, so that corresponding retino-cortical element are placed in a position to deal with two images i.e.
    [Show full text]
  • Collaborative Treatment for Vision After TBI
    Collaborative Treatment for Vision After TBI Tom Wilson, OD, COVD Terri Cassidy, OTR, CDRS Vision is Primary • Human vision is a complex process that involves the coordinated efforts of both the eyes and the brain. • We use central vision (focal) to see detail. • We use peripheral vision (ambient) to inform us of movement or a direction we should point our eyes. • Even if we feel like our eyes (and brain) are not giving us accurate information – we believe our eyes. 2 Case Study 1 56 y/o woman involved in a motor vehicle crash. She was able to walk and talk. MRI was negative. Not long after she notices symptoms of not being able to read correctly, headaches, motion sickness is much worse than normal, she can’t go back to work on the computer, she is very tentative about driving. Her eye doctor tells her that her eyes are fine, it must be her medications. Finally she is referred to Dr. Wilson who does an evaluation and refers her to vision rehab with OT. Presentation Title – Date (month #, ####) 3 Evaluation Neuro-optometric Assessment • Eye health • Binocular Vision • Prism evaluation • Function Occupational Therapy Vision Assessment • Goal of OT is to improve the client’s level of performance in a needed ADL. • Deficiencies in visual processing are significant to the OT Process if they interfere with occupational performance – doing the tasks that she wants and needs to do. Presentation Title – Date (month #, ####) 4 Evaluation Results OD Finds: OT Finds: Characteristics of Post Trauma Pt is not able to work more than 2 Vision Syndrome
    [Show full text]
  • Motion-In-Depth Perception and Prey Capture in the Praying Mantis Sphodromantis Lineola
    © 2019. Published by The Company of Biologists Ltd | Journal of Experimental Biology (2019) 222, jeb198614. doi:10.1242/jeb.198614 RESEARCH ARTICLE Motion-in-depth perception and prey capture in the praying mantis Sphodromantis lineola Vivek Nityananda1,*, Coline Joubier1,2, Jerry Tan1, Ghaith Tarawneh1 and Jenny C. A. Read1 ABSTRACT prey as they come near. Just as with depth perception, several cues Perceiving motion-in-depth is essential to detecting approaching could contribute to the perception of motion-in-depth. or receding objects, predators and prey. This can be achieved Two of the motion-in-depth cues that have received the most using several cues, including binocular stereoscopic cues such attention in humans are binocular: changing disparity and as changing disparity and interocular velocity differences, and interocular velocity differences (IOVDs) (Cormack et al., 2017). monocular cues such as looming. Although these have been Stereoscopic disparity refers to the difference in the position of an studied in detail in humans, only looming responses have been well object as seen by the two eyes. This disparity reflects the distance to characterized in insects and we know nothing about the role of an object. Thus as an object approaches, the disparity between the stereoscopic cues and how they might interact with looming cues. We two views changes. This changing disparity cue suffices to create a used our 3D insect cinema in a series of experiments to investigate perception of motion-in-depth for human observers, even in the the role of the stereoscopic cues mentioned above, as well as absence of other cues (Cumming and Parker, 1994).
    [Show full text]
  • From Stereogram to Surface: How the Brain Sees the World in Depth
    Spatial Vision, Vol. 22, No. 1, pp. 45–82 (2009) © Koninklijke Brill NV, Leiden, 2009. Also available online - www.brill.nl/sv From stereogram to surface: how the brain sees the world in depth LIANG FANG and STEPHEN GROSSBERG ∗ Department of Cognitive and Neural Systems, Center for Adaptive Systems and Center of Excellence for Learning in Education, Science, and Technology, Boston University, 677 Beacon St., Boston, MA 02215, USA Received 19 April 2007; accepted 31 August 2007 Abstract—When we look at a scene, how do we consciously see surfaces infused with lightness and color at the correct depths? Random-Dot Stereograms (RDS) probe how binocular disparity between the two eyes can generate such conscious surface percepts. Dense RDS do so despite the fact that they include multiple false binocular matches. Sparse stereograms do so even across large contrast-free regions with no binocular matches. Stereograms that define occluding and occluded surfaces lead to surface percepts wherein partially occluded textured surfaces are completed behind occluding textured surfaces at a spatial scale much larger than that of the texture elements themselves. Earlier models suggest how the brain detects binocular disparity, but not how RDS generate conscious percepts of 3D surfaces. This article proposes a neural network model that predicts how the layered circuits of visual cortex generate these 3D surface percepts using interactions between visual boundary and surface representations that obey complementary computational rules. The model clarifies how interactions between layers 4, 3B and 2/3A in V1 and V2 contribute to stereopsis, and proposes how 3D perceptual grouping laws in V2 interact with 3D surface filling-in operations in V1, V2 and V4 to generate 3D surface percepts in which figures are separated from their backgrounds.
    [Show full text]
  • 20/20 VISION Part I: Eyesight, Perception and Vision
    20/20 VISION Part I: Eyesight, perception and vision In this first part of our three-part exploration of 20/20 vision, we are going to look at our physical eyes and how they work. Then we will explore perception and how the brain actually converts all that sensory information into images. Finally, we will look at some of the techniques for improving our vision naturally and ask if these really work. 20/20 vision is a term used to express normal visual acuity (the clarity or sharpness of vision) measured at a distance of 20 feet. ... If you have 20/100 vision, it means that you must be as close as 20 feet to see what a person with normal vision can see at 100 feet. Having 20/20 vision does not necessarily mean you have perfect vision. 20/20 vision only indicates the sharpness or clarity of vision at a distance. Other important vision skills, including peripheral awareness or side vision, eye coordination, depth perception, focusing ability and colour vision, contribute to your overall visual ability. Some people can see well at a distance but are unable to bring nearer objects into focus. This condition can be caused by hyperopia (far-sightedness) or presbyopia (loss of focusing ability). Others can see items that are close but cannot see those far away. This condition may be caused by myopia (near-sightedness). Is it possible to see better than 20/20? Yes, it's indeed possible to have sharper than 20/20 vision. In fact, most people with young, healthy eyes are capable of identifying at least some of the letters on the 20/15 line or even smaller letters on the Snellen chart.
    [Show full text]