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At least 37 records · Page 2Linked to original sources
PubMed2002

[Space perception: the history and its significance for art].

Some aspects of the opthalmologic history of Denmark are briefly mentioned. Lens extraction in 1667 in Copenhagen, Edmund Hansen Gruts stereoophtalmoscopy in 1857, Ludvig Panums area in 1858 (single vision) space perception and outside this area double vision), squint treatment, Marius Tschernings periscopic spectacle lenses, Henning Rønnes stereoortograph and keiroscope and Gerhard Rønnes stereoscope. Space perception depends mostly on binocular function (convergens), but in fact some space perception occurs in vision due to perspective, accommodation, parallaxe, blurring, colours and shadows. The Danisk Poet, Hans Christian Andersen, has in his novels mentioned latent squint. The German poet Rainer Maria Rilke was much interested in perspective in connection with the development of impressionism, especially Paul Cézanne. Rilke in his later period developed the view that concentration on perspective removed those essential aspects from the world, in which he found God or a fourth dimension, as exemplified in the presence of ghosts.

Denmark↗
PubMed1980

Visual stability and space perception in monocular vision: mathematical model.

A deterministic model for monocular space perception is presented. According to the model, retinal luminance changes due to involuntary eye movements are detected and locally analyzed to yield the angular velocity of each image point. The stable three-dimensional spatial coordinates of viewed objects are then reconstructed using a method of infinitesimal transformations. The extraction of the movement (parallax) field from the optical flow is represented by a set of differential equations, the derivation of which is based on the conservation of energy principle. The relation of the model to retinal neurophysiology and to various aspects of visual space perception is discussed.

Depth Perception↗
PubMed2004

Influence of age, sex, and education on the Visual Object and Space Perception Battery (VOSP) in a healthy normal elderly population.

The assessment of visual perception and cognition forms an important part of any general cognitive evaluation. We have studied the possible influence of age, sex, and education on a normal elderly Spanish population (90 healthy subjects) in performance in visual perception tasks. To evaluate visual perception and cognition, we have used the subjects performance with The Visual Object and Space Perception Battery (VOSP). The test consists of 8 subtests: 4 measure visual object perception (Incomplete Letters, Silhouettes, Object Decision, and Progressive Silhouettes) while the other 4 measure visual space perception (Dot Counting, Position Discrimination, Number Location, and Cube Analysis). The statistical procedures employed were either simple or multiple linear regression analyses (subtests with normal distribution) and Mann-Whitney tests, followed by ANOVA with Scheffe correction (subtests without normal distribution). Age and sex were found to be significant modifying factors in the Silhouettes, Object Decision, Progressive Silhouettes, Position Discrimination, and Cube Analysis subtests. Educational level was found to be a significant predictor of function for the Silhouettes and Object Decision subtests. The results of the sample were adjusted in line with the differences observed. Our study also offers preliminary normative data for the administration of the VOSP to an elderly Spanish population. The results are discussed and compared with similar studies performed in different cultural backgrounds.

Age Factors↗
PubMed1989

Helmholtz and Zoellner: nineteenth-century empiricism, spiritism, and the theory of space perception.

J. K. F. Zoellner began writing on "experimental proofs" of a fourth spatial dimension, and of the existence of spirits, in 1878. His arguments caused strong controversy, with rebuttal essays by Wilhelm Wundt and others. The author argues that Zoellner's case that these matters are experimental questions rested on arguments which Hermann von Helmholtz, inveighing against rationalist views of space and space perception, had recently published. Zoellner's use of Helmholtz's arguments to advance and defend his spiritist views occasioned strong criticism of Helmholtz, affected careers and reputations of scholars in Berlin and Leipzig, and caused enduring controversy over the credibility of Helmholtz's empiricist theory of space perception.

Germany↗
PubMed1998

Texture information in tactual space perception.

The significance of texture as a source of information in tactual space perception was studied using a linear positioning task. A spatial texture gradient, whose elements changed with position and distance, a homogeneous raised-element pattern and a smooth surface were used. Participants had to reproduce locations and distances on these surfaces under various conditions. In active conditions, participants moved their indexfinger across the surface. In passive conditions, the texture was moved beneath the indexfinger of the participant. In conditions with equal movement speed, movement speeds' of criterion and reproduction phase were matched, in conditions with unequal movement speed, they did not match. The largest errors were obtained for the combined passive movement-unequal movement speed conditions. In these conditions, differences between textures were visible for signed and unsigned errors, indicating that textures may differ in the cutaneous specification of distance and location.

Adult↗
PubMed2003

Sonification of range information for 3-D space perception.

We present a device that allows three-dimensional (3-D) space perception by sonification of range information obtained via a point laser range sensor. The laser range sensor is worn by a blindfolded user, who scans space by pointing the laser beam in different directions. The resulting stream of range measurements is then converted to an auditory signal whose frequency or amplitude varies with the range. Our device differs from existing navigation aids for the visually impaired. Such devices use sonar ranging whose primary purpose is to detect obstacles for navigation, a task to which sonar is well suited due to its wide beam width. In contrast, the purpose of our device is to allow users to perceive the details of 3-D space that surrounds them, a task to which sonar is ill suited, due to artifacts generated by multiple reflections and due to its limited range. Preliminary trials demonstrate that the user is able to easily and accurately detect corners and depth discontinuities and to perceive the size of the surrounding space.

Acoustics↗
PubMed2000

Disruption of space perception due to cortical lesions.

Space control has for a long time been considered a unitary function. The structure associated with this function was the right parietal lobe. Hemispheric specialization for space appeared to make it automatically a human-specific function. However, recent primate research shows different regions of the parietal lobes to be differently involved with space control. A review of the literature, together with own cases shows that there is ample evidence of a modular organization of space control in humans on the basis of specific deficits subsequent to circumscribed cerebral lesions. Lesions influence differentially retinotopic, spatiotopic, egocentric, and allocentric frames of references. They also influence differentially the attention to far or near space, or to global or local features of space. Moreover, preattentive processes can be studied in the neglected hemispace of humans and prove to be sensible to the meaning of visual stimuli. Space representation and attentional mechanisms that seem to operate on these representations are organized in our brain in a very modular fashion, similar to the modularity of visual submodalities. There is probably not a unified space representation in the parietal lobes, but distributed functional modules. Thus, the study of visual optic recognition, either by the brain or by machines, is inconceivable without considering space, attention and awareness.

Brain Neoplasms↗
PubMed1982

[Neurobiological principles of binocular space perception. Historical review on the development of the concept and knowledge].

Binocular vision and space perception are not readily explained on the basis of direct anatomical evidence on the visual system. Galen (2nd century A.D.) localized the mechanism underlying binocular vision into the optic chiasm. Nearly 2000 years later the famous physicist Newton (1704), undoubtedly stimulated by clinical reports on hemianopia and Descartes' (1686) hypothesis on the retinal image projections on the brain, came up with a new hypothesis on the optic chiasm which could explain how information from homonymous visual hemifields could converge from the two eyes to one and the same area in the brain. He predicted that the temporal retinal fibers of both eyes fail to cross. Irrefutable proof of the special arrangement of the optic chiasm was provided by Ramon y Cajal (1899) with the aid of the Golgi method. It took more than 50 years before binocularly oriented cells were discovered in the visual cortex by Baumgartner and colleagues (1958), and before neurons were found in that area by Hubel and Wiesel (1959) which responded to stimulation from corresponding retinal sites of the two eyes. These electrophysiological studies profited by the localization of the cortical visual center in the occipital lobe by Panizza (1856), the identification of the corpus geniculatum laterale as a relais station of the retino-cortical pathway by Monakow (1883, 1885) and the discovery of the projection of homonymous retinal halves upon alternating layers of this structure by Minkowski (1920). Wheatstone opened the road to the understanding of stereoscopic vision by inventing the stereoscope in 1838. He based his research largely upon the the investigation of Aguilonius (1613), Vieth (1818) and Müller (1926) on the horopter. The most elegant evidence on the significance of visual disparity for depth perception came recently from Julesz and his demonstration of "random-dot-stereograms" (1971). Binocular neurons which are sensitive to minimal stimulus disparities within Panum's area (1858) have only recently been observed in the striate cortex by electrophysiological recordings (Barlow et al., 1967; Poggio and Fischer, 1977). These cells were designated as "disparity or depth detectors". They displace the "cyclopean eye" of Helmholtz (1867) and Hering (1879) from its Homeric seat in the forehead to the cortical field whose striations were already noted by Gennari (1782) near the posterior end of the cranium.

Animals↗
PubMed2000

Neurophysiological evaluation of tactile space perception deficits through transcranial magnetic stimulation.

We describe a procedure useful to investigate the contralateral space perception deficits frequently encountered in patients with unilateral right brain damage. In particular, we focused on the phenomenon of extinction, i.e., the failure to perceive a contralesional stimulus only when a symmetrical contralateral stimulus is simultaneously applied. Fifteen right brain- and 15 left brain-damaged patients were examined. Somatosensory perception was evaluated by using a dedicated electronic device able to provide electrical stimuli of variable intensity to digits of one or both hands. The electrical stimulator was able to trigger a magnetic brain stimulator connected with a focal figure of eight coil. Threshold electrical stimuli were delivered to one or both hands of the patients, who were asked to indicate whether they perceived the stimulus (i) and to localise it (them). The electrical stimulator was connected with a magnetic stimulator with an interstimulus interval (ISI) of 40 msec (electrical stimulation preceding the transcranial one). Focal threshold transcranial magnetic stimulation (TMS) was applied to frontal and parietal scalp sites of the unaffected hemisphere. At each interpulse interval we found that TMS of the unaffected hemisphere was associated to a decrease in the level of contralesional extinction. Our method demonstrates that a basic deficit underlying neglect and extinction of contralateral space in unilaterally brain damaged patients is the interhemispheric imbalance between the two hemispheres in directing contralateral attention. A transient interference with the function of the unaffected hemisphere can improve these deficits, suggesting a possible application of TMS in the daily clinical practice for speeding up recovery from neglect.

Cognition↗