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Journal ArticleDOI

A Vertical Horopter

01 Apr 1974-Journal of Modern Optics (Taylor & Francis Group)-Vol. 21, Iss: 4, pp 277-292
TL;DR: It is shown that when a perpendicularly stretched thread is fixated at its centre with the eyes in symmetrical convergence, the thread has to be tilted around the fixated point with its top away from the observer towards the observer.
Abstract: When a perpendicularly stretched thread is fixated at its centre with the eyes in symmetrical convergence, the thread has to be tilted around the fixated point with its top away from the observer for it to appear perpendicular. This fact was recognized by a number of investigators as early as the 1850's. For this reason both Hering and Helmholtz described the horopter as an ‘upside-down’ cone. The present investigation employs a twin point-light source apparatus to estimate the orientation and the shape of a subjective equidistant line that lies in the median plane of the observer. Since the method of measurement depends on retinal disparity clues, this locus corresponds to the stereoscopic frame of reference in the median plane. The results are in qualitative agreement with previous findings. Quantitatively, however, they show a much smaller tilt of the reference plane than the ones reported by Helmholtz and others. The stereoscopic sensitivities of the retinal regions at the various elevations above and...
Citations
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Journal ArticleDOI
TL;DR: This model can help explain the 3-D imbalances in prominant neuropsychological disorders and regulated neurochemically with dopaminergic and cholinergic excitation associated with extrapersonal activation and noradrenergic and serotonergic excite associated with peripersonalactivation.
Abstract: The neuropsychological literature on 3-D spatial interactions is integrated using a model of 4 major behavioral realms: (a) peripersonal (visuomotor operations in near-body space), (b) focal extrapersonal (visual search and object recognition), (c) action extrapersonal (orienting in topographically defined space), and (d) ambient extrapersonal (orienting in earth-fixed space). Each is associated with a distinct cortical network: dorsolateral peripersonal, predominantly ventrolateral focal-extrapersonal, predominantly ventromedial action-extrapersonal, and predominantly dorsomedial ambient-extrapersonal systems. Interactions in 3-D space are also regulated neurochemically with dopaminergic and cholinergic excitation associated with extrapersonal activation and noradrenergic and serotonergic excitation associated with peripersonal activation. This model can help explain the 3-D imbalances in prominant neuropsychological disorders.

507 citations

Journal ArticleDOI
TL;DR: The Helmholtzian declination of the main vertical retinal meridians is confirmed and a new scaling effect is postulated to account for veridicality of the stereoscopic vertical.

58 citations

Journal ArticleDOI
TL;DR: The up‐down asymmetry of intrasaccadic vergence changes arises when targets require both a vergence change and a vertical shift of gaze, thereby accelerating refixation for the typical natural spatial configuration, in which nearer objects are lower in the visual field.
Abstract: 1. When a downward saccade is made between equidistant targets, convergence consistently occurs during the saccade: about 1 deg overconvergence after an 8 deg saccade, with either binocular or monocular viewing, with either far (3 m) or near (30 cm) viewing distance. 2. During binocular viewing, this unnecessary convergence is corrected by divergence movement with a half-time of about 200 ms. During monocular viewing of far targets, similar post-saccadic divergence occurs, but for monocularly-seen near targets, recovery is considerably slower. 3. Vergence changes associated with upward saccades are much smaller and typically more variable among subjects. 4. The up-down asymmetry of intrasaccadic vergence changes can be accounted for by superposition of two plausible adventitious processes: co-contraction of the vertical recti, and tension increase (upward saccades) or tension release (downward saccades) in the superior oblique muscles. 5. During the 1000 ms after an upward saccade, constriction of the pupil consistently occurs; it apparently represents a near-triad response, for which concurrent convergence is masked. Such near-triad activation during upward gaze would presumably be necessary to counterbalance residual steady-state torques from the superior oblique muscles. 6. The up-down asymmetry of intrasaccadic vergence changes also arises when targets require both a vergence change and a vertical shift of gaze, thereby accelerating refixation for the typical natural spatial configuration, in which nearer objects are lower in the visual field. 7. During binocular viewing of equidistant targets, the convergence resulting from downward saccades produces large transient disparities, which can be expected to lead to biased evaluations of relative distances to targets. Several up-down illusions involving apparent distance may well be due to these disparities, including (a) backward tilt of the apparent vertical and of the vertical horopter, (b) the 'soup-bowl sky' illusion, and (c) the 'diverging sunbeams' illusion.

51 citations

Journal ArticleDOI
TL;DR: The results suggest that cyclovergence is designed to correct for small, slow drifts in the stereoscopic alignment of the images in the two eyes.
Abstract: By the use of scleral search coils a continuous record of human cyclovergence was obtained while two identical 80° textured patterns, presented dichoptically, oscillated in the frontal plane in counterphase through 1, 3 and 6° of cyclorotation at frequencies between 0.05 and 2 Hz. The amplitude and gain of the response decreased exponentially with increasing stimulus frequency. As stimulus amplitude increased, response amplitude also increased but gain was highest for low-amplitude cyclorotations. For an amplitude of 1° and a frequency of 0.05 Hz the gain reached 0.87 for two subjects. The phase lag increased from a few degrees at a frequency of 0.05 Hz to over 100° at a frequency of 2 Hz. These results suggest that cyclovergence is designed to correct for small, slow drifts in the stereoscopic alignment of the images in the two eyes. Although the disparity in the textured display was not interpreted as slant, it provided a strong stimulus for cyclovergence. The cyclovergence caused a transfer of cyclodisparity into a superimposed vertical line, which was then perceived as slanting in depth.

41 citations


Cites background from "A Vertical Horopter"

  • ...The inclination of the vertical horopter may also be affected by cyclovergence which accompanies a change in horizontal vergence (Amigo 1974)....

    [...]

Journal ArticleDOI
TL;DR: It is showed that the horopter is not adaptive for long viewing distances because at such distances uncrossed disparities between corresponding points cannot be stimulated, and the vertical horopter seems to be adaptive for perceiving convex, slanted surfaces at short distances.
Abstract: Depth estimates from disparity are most precise when the visual input stimulates corresponding retinal points or points close to them. Corresponding points have uncrossed disparities in the upper visual field and crossed disparities in the lower visual field. Due to these disparities, the vertical part of the horopter--the positions in space that stimulate corresponding points--is pitched top-back. Many have suggested that this pitch is advantageous for discriminating depth in the natural environment, particularly relative to the ground. We asked whether the vertical horopter is adaptive (suited for perception of the ground) and adaptable (changeable by experience). Experiment 1 measured the disparities between corresponding points in 28 observers. We confirmed that the horopter is pitched. However, it is also typically convex making it ill-suited for depth perception relative to the ground. Experiment 2 tracked locations of corresponding points while observers wore lenses for 7 days that distorted binocular disparities. We observed no change in the horopter, suggesting that it is not adaptable. We also showed that the horopter is not adaptive for long viewing distances because at such distances uncrossed disparities between corresponding points cannot be stimulated. The vertical horopter seems to be adaptive for perceiving convex, slanted surfaces at short distances.

41 citations


Cites background from "A Vertical Horopter"

  • ...With the exception of Amigo (1974), all previous papers on the vertical horopter have described the deviation of empirical corresponding points from geometric points as a horizontal shear, i.e., horizontal offsets proportional to elevation....

    [...]

  • ...However, the measured angle could be a consequence of cyclovergence, the disconjugate rotation of the eyes around the visual axes (Amigo, 1974)....

    [...]

References
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Book
23 Aug 2011
TL;DR: The missing plates are on a CD held in the Pamphlet and ephemera filing cabinet under Catalogue number 2924 together with print-outs of the images.
Abstract: Dark brown calf leather cover, 240 x 160 mm, gold stamped on the front and back with the heraldic crest of Pembroke College, Oxford, and gold stamped with the book title on the spine, 874 pages and one page addendum A pocket formed by the back paste down contains five of originally eight folding plates There are pencil notes in English in a few margins The book is volume 9 in the series Allgemeine Encylopaedie der Physik edited by Gustav Karsten (see page facing the title page) Digital images of the missing plates are on a CD held in the Pamphlet and Ephemera filing cabinet under Catalogue number 2924 together with print-outs of the images They were copied courtesy of the BOA Museum Curator, Neil Handley, from a copy of this book in the Library of the the College of Optometrists, London Images of this missing plates are on the Museum iPhoto

2,068 citations

Journal ArticleDOI
18 Mar 1950-BMJ

1,005 citations

Book
01 Jan 1950
TL;DR: This is an original printing in 1950, and the Nathan Library holds a copy of the 1964 reprint (cat No 509) which was published in 1964.
Abstract: Original orange cloth cover, 345 pages, 182 figures in text. This is an original printing in 1950. The Nathan Library holds a copy of the 1964 reprint (cat No 509).

558 citations

BookDOI
01 Jan 1930
TL;DR: An important chapter deals with workmen's compensation, a subject that is rapidly becoming of practical importance in all countries, and a best exponent than Thiel could not have been found, as his researches have covered many parts of this field.
Abstract: One of the outstanding features of this remarkable "Handbuch" is the promptness with which its volumes are appearing. The new volume is the fourth and contains : "The Diseases of the Conjunctiva, Cornea and Sclera," which are described by Professor Schieck, of W\l=u"\rzburg Dr. Cramer, of Kottbus, contributes the part on the "Injuries and Occupational Diseases of the Eye," including the subject of "Compensation." "Sympathetic Diseases of the Eye" are treated by Professor Reis, of Bonn. "The Physiology and Pathology of Intra-Ocular Pressure and Glaucoma" are discussed by Professor Thiel, of Berlin. The part on the conjunctiva, cornea and sclera occupies one half of the volume. Professor Schieck has treated this important part in a masterly way, presenting the essentials and omitting nothing of importance, with many new and excellent illustrations, often in colors, pertinent slit-lamp findings and a brief bibliography. The second part on injuries and occupational diseases as they pertain to the eye was written by Dr. E. Cramer, of Kottbus, who unfortunately died in 1929; his nearly completed manuscript had to be revised and brought up to date by Dr. O. Thies, of Dessau. The subject is systematically treated and adequately illustrated, and a useful bibliography is appended. Burns and injuries by caustics are particularly well described and are evidence of the large experience gained by Dr. Thies in Dessau. An important chapter deals with workmen's compensation, a subject that is rapidly becoming of practical importance in all countries. That important and still obscure condition, sympathetic disease, is handled by Prof. W. Reis, of Bonn. After a description of sympathetic irritation, sympathetic ophthalmia is considered under the following headings : the conditions that lead to sympathetic inflammation, the clinical picture of sympathetic uveitis, sympathetic serous iritis, sympathetic papilloretinitis, retinal periphlebitis, retrobulbar neuritis, sympathetic chorioretinitis, detachment of the retina and secondary glaucoma. Pathology, etiology, diagnosis and treatment complete this unusually well written chapter. Professor Thiel, writing on the physiology and pathology of ocular pressure, first speaks of the normal height and variations of intra\x=req-\ ocular pressure; then he takes up the relation of ocular pressure to intracranial pressure, local blood pressure, general blood pressure, the constitution of the blood, internal secretion and the vegetative nervous system. This is a most timely exposition of a subject that at present is arousing a great deal of interest, and a better exponent than Thiel could not have been found, as his researches have covered many parts of this field. An excellent bibliography will be of great use to those working in this subject.

235 citations

Book
17 Jul 2009

166 citations