SEARCH · PubMed Health

Results for “Space Perception”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8Linked to original sources

PubMed1999

Functional Equations in Binocular Space Perception.

A general theory of the relationship of binocular visual space to physical space is formulated within a conjoint measurement framework. Psychophysically motivated invariance relations induce various functional equations. Another class of functional equations arises if we additionally assume the validity of a different psychophysical theory that is based on a formula suggested by A. A. Blank. We solve and interpret most of these equations and point out an unsolved problem. The obtained results lead to a measurement-theoretic foundation of the psychophysical assumptions underlying the Luneburg theory of binocular vision. They also contribute to clarifying the relationship between the presented general theory and Blank's approach. Copyright 1999 Academic Press.

Journal Article↗

PubMed1999

[Concept formation and space perception in the blind--a summary of behavioral psychological studies].

Blindness entails an altered situation in the areas of information intake and processing concerning the aspects of perception, inter alia spatial, and concept formation. Numerous individual factors, such as life age, age at blindness onset, and occupational biography, constitute additional influences on the above cognitive faculties. A range of different study modules were used in seeking to obtain generally valid evidence relative to spatial perception and concept formation. The study overall had been directed at devising didactic and learning tools towards specific programme components. To illustrate potential applications of the study findings, the article briefly outlines a music programme guide intended for parents of blind, and possibly multi-handicapped, pre-school children.

Adolescent↗

PubMed1983

Normal and abnormal space perception.

The mononuclear spatial judgments made by normal adults are quite accurate and precise. Although relatively little is known about how the spatial sense develops, it is likely that it can be compromised by abnormal visual experience as provided, for example, by strabismus. Previously, we reported that the spatial sense of strabismic amblyopic eyes is distorted, having quantified these distortions as marked inaccuracies in equating spatial extents in the nasal and temporal field and specifying when one target is vertically aligned with another. Distortions--localized "expansions" and "compressions" of spatial values and "bending" of direction lines--characterize the amblyopic eyes of strabismics but not non-squinting anisometropes. Thus, according to our previously published hypothesis, spatial distortions can account for the reduced acuity and abnormal oculomotor behavior of strabismic (but not anisometropic) amblyopic eyes. In the present paper, we provide quantification of another spatial measures--spatial precision--and show that extensive imprecision characterizes the space sense of the strabismic amblyopic eye. We now add spatial imprecision to our original hypothesis as a significant element in accounting for the abnormal sensory and motor behaviors of strabismic amblyopic eyes.

Adolescent↗

PubMed1990

[Psychotropic effects of captopril? Effect of a short-term treatment on reaction and concentration capabilities and space perception ability].

In a randomized, placebo-controlled double-blind trial 22 healthy normotensive young men (mean age 25 +/- 1.7 years) were given a single oral dose of 50 mg captopril or a placebo (11 subjects each). To test their concentration and proficiency, as well as spatial perception and reaction capacity four tests were administered: attention, concentration, hose-pattern perception and "Bonn Determination Device". Captopril had no negative effects on any test performances either one or five hours after its administration, or after a single daily dose for seven days. There was only a small, statistically not significant, difference in the effect on blood pressure between captopril and the placebo.

Adult↗

PubMed1977

Laboratory apparatus for studying visual space perception of the pilot in simulated night approaches to landing.

The device provides a relatively inexpensive means of assessing a number of perceptual and human factors parameters in the night approach to landing situation. A technique for modeling airport runway lighting is described along with electromechanical and optical systems for precise control of simulated approach speed, model slant, and direction in the visual field of the simulated radial approach axis. The realism of this display is enhanced by preservation of the natural relations of size and brightness of simulated runway lights to distance.

Aerospace Medicine↗

PubMed2001

Modelling space perception in human early vision: a computational approach.

A computational approach in studying vision is important for understanding the biological mechanisms, as well as for integrating the known cortical architecture of primary visual area (V1) and the physiological functions (some of them experimentally proved, some only presumed). We present, in parallel, two models for early vision mechanisms: one for obtaining the disparity map in stereo vision, and the other for edges enhancement in contour integration, both of them seen from such a computational perspective. We implemented the two models and the results of the simulation were consistent with the biological data. They also account for the importance of interactions between parallel channels of visual information processing.

Computer Simulation↗

PubMed1982

[Value of the space perception test for evaluation of the aptitude for precision work in geodesy].

The visual spatial localization ability of geodesy and cartography - employers and of the pupils trained for the mentioned profession has been examined. The examination has been based on work duration and the time of its performance. A correlation between the localization ability and the precision of the hand - movements required in everyday work has been proven. The better the movement precision, the more efficient the visual spatial localization. The length of work has not been significant. The test concerned appeared to be highly useful in geodesy for qualifying workers for the posts requiring good hands efficiency.

Adult↗

PubMed1994

Mirror symmetry and parallelism: two opposite rules for the identity transform in space perception and their unified treatment by the Great Circle Model.

Two opposite rules control the contributions of individual lines to the perceptual processing of two different spatial dimensions of egocentric localization and orientation. For lines restricted to the frontal plane, a tilted line on one side of the median plane induces a rotation of the orientation visually perceived as vertical (VPV) identical to that induced by the same tilt on the other side of the median plane, but the influences exerted on the elevation of visually perceived eye level (VPEL) are mirror symmetric. The rule for VPV fits our intuitions; the rule for VPEL does not. However, the reverse peculiarity holds when the inducing lines are rotated within sagittal planes (pitched): Two parallel, pitched-from-vertical lines on opposite sides of the median plane generate identical effects on VPEL but mirror symmetric effects on VPV. These counterintuitive symmetry reversals are reconciled by the Great Circle Model of spatial orientation (GCM), in which line orientations are represented by the great circle coordinates of their images on a sphere centered at the nodal point of the eye via central projection.

Humans↗

PubMed1975

Marked accommodation, retinal stretch, monocular space perception and retinal receptor orientation.

In recent years we have come to recognize that retinal receptors are probably aligned with the center of the exit pupil of the eye. It becomes crucial to define those factors influencing and determining photoreceptor alignment. Here, the effect of retinal stretch associated with marked accommodation has been considered. Assuming that a sense of direction is associated with a given retinal locus, we have used a classical monocular bisection test technique in order to see if marked accommodation altered bisection settings. Substantial changes in bisection settings were found when testing in the region of the posterior pole. These could be localized most probably in the retina and choroid. In separate studies, the effect of anterior retinal stretch upon cone receptor orientation in the region of the fovea was evaluated. Marked accommodation caused a transient nasal displacement of the peak of the Stiles-Crawford directional sensitivity function. These studies suggest that the posterior pole of the eye is routinely subject to stresses and strains. This point is of clinical significance. Our studies suggest that the presence of the blind spot influences the magnitude of change of measured parameters. We have only begun the important task of evaluating the nature of recovery processes following marked accommodation. Lastly, in order to obtain the necessary responses, we have had to train our young observers to voluntarily utilize nearly their entire accommodative capability.

Accommodation, Ocular↗

PubMed2005

Nature of the transition between two modes of external space perception in tilted subjects.

A striking feature of visual verticality estimates in the dark is undercompensation for lateral body tilt. Earlier studies and models suggest that this so-called Aubert (A) effect increases gradually to around 130 degrees tilt and then decays smoothly on approaching the inverted position. By contrast, we recently found an abrupt transition toward errors of opposite sign (E effect) when body tilt exceeded 135 degrees . The present study was undertaken to clarify the nature of this transition. We tested the subjective visual vertical in stationary roll-tilted human subjects using various rotation paradigms and testing methods. Cluster analysis identified two clearly separate response modes (A or E effect), present in all conditions, which dominated in different but overlapping tilt ranges. Within the overlap zone, the subjective vertical appeared bistable on repeated testing with responses in both categories. The tilt range where bistability occurred depended on the direction of the preceding rotation (hysteresis). The overlap zone shifted to a smaller tilt angle when testing was preceded by a rotation through the inverted position, compared with short opposite rotations from upright. We discuss the possibility that the A-E transition reflects a reference shift from compensating line settings for the head deviation from upright to basing them on the tilt deviation of the feet from upright. In this scenario, both the A and the E effect reflect tilt undercompensation. To explain the hysteresis and the bistability, we propose that the transition is triggered when perceived body tilt, a signal with known noise and hysteresis properties, crosses a fixed threshold.

Adaptation, Physiological↗

PubMedDate not supplied

Distortions in two-dimensional visual space perception in strabismic observers.

Amblyopic subjects were asked to memorize circles of different radii (2, 4 and 6 degrees), and then to reconstruct them monocularly with each eye, point by point (12 points per circle). The resulting two-dimensional maps of visual space showed considerable distortions, including expansion, shrinkage and torsion of specific regions of the visual field of the amblyopic eye, but not the normal eye. Based on the differences between the two eyes, we computed complex two-dimensional patterns (gratings, checkerboards, optotypes, written text, natural scenes) as "seen" monocularly with the amblyopic eye. These reconstructed patterns were then compared with drawings of the same patterns observed through the amblyopic eyes of the same subjects. The reconstructed patterns only partially reflected the actual perception for the amblyopic eyes. The compensation of complex, globally-extended scenes in comparison to the distortions obtained by local, punctate settings probably reflects cooperative interactions occurring at higher brain levels.

Adult↗

PubMedDate not supplied

[Work of the human visual system. III. Color perception space].

In the previous parts of this work the author presented thet expression for percieved colour: Ei=k1n(ai/ao) where k -- is the coefficient of proportionality which have dimension of sensation and ai, ao -- are the light actions in some retinal point and in the extreme periphery correspondingly. Here the author describes some consequences from this expression and gives a new conception about the space of colour sensations.

Color Perception↗

PubMed1992

Visual space perception and visually directed action.

The results of two types of experiments are reported. In 1 type, Ss matched depth intervals on the ground plane that appeared equal to frontal intervals at the same distance. The depth intervals had to be made considerably larger than the frontal intervals to appear equal in length, with this physical inequality of equal-appearing intervals increasing with egocentric distance of the intervals (4 m-12 m). In the other type of experiment, Ss viewed targets lying on the ground plane and then, with eyes closed, attempted either to walk directly to their locations or to point continuously toward them while walking along paths that passed off to the side. Performance was quite accurate in both motoric tasks, indicating that the distortion in the mapping from physical to visual space evident in the visual matching task does not manifest itself in the visually open-loop motoric tasks.

Adult↗

PubMed2000

Vestibular influence on human auditory space perception.

We investigated the effect of vestibular stimulation on the lateralization of dichotic sound by cold-water irrigation of the external auditory canal in human subjects. Subjects adjusted the interaural level difference of the auditory stimulus to the subjective median plane of the head. In those subjects in whom dizziness and nystagmus indicated sufficient vestibular stimulation, these adjustments were significantly shifted toward the cooled ear compared with the control condition (irrigation with water at body temperature); i.e., vestibular stimulation induced a shift of the sound image toward the nonstimulated side. The mean magnitude of the shift was 7.3 dB immediately after vestibular stimulation and decreased to 2.5 dB after 5 min. As shown by an additional control experiment, this effect cannot be attributed to a unilateral hearing loss induced by cooling of the auditory periphery. The results indicate the involvement of vestibular afferent information in the perception of sound location during movements of the head and/or the whole body. We thus hypothesize that vestibular information is used by central-nervous mechanisms generating a world-centered representation of auditory space.

Acoustic Stimulation↗

PubMedDate not supplied

[The characteristics of the color perceptive space in protanomals].

Color vision of three protanomal subjects was studied by means of direct paired comparison technique using 25 colors with different brightness. It was shown that the characteristics of their color vision could be completely and adequately described in the frames of the four-dimensional spherical model of color perception. The spatial axes could be identified as the two color-opponent mechanisms (red-green and blue-yellow) and the two achromatic mechanisms (brightness and darkness). Deformation of the color axes in protanomals (as compared with the normal trichromatics) was demonstrated in the "red" and "yellow" spectral region. The visual disturbance in protanomal subjects involves not only color but also achromatic mechanisms. This is manifested in the a deformation of perceptual brightness scale. In comparison with normal trichromatic subjects, the protanomals perceive the red and adjacent colors as achromatic while green, yellow-green, and orange as more bright but low-saturated colors.

Adolescent↗

PubMed2001

Deficit of auditory space perception in patients with visuospatial neglect.

There have been many studies of visuospatial neglect, but fewer studies of neglect in relation with other sensory modalities. In the present study we investigate the performance of six right brain damaged (RBD) patients with left visual neglect and six RBD patients without neglect in an auditory spatial task. Previous work on sound localisation in neglect patients adopted measure of sound localisation based on directional motor responses (e.g., pointing to sounds) or judgement of sound position with respect to the body midline (auditory midline task). However, these measures might be influenced by non-auditory biases related with motor and egocentric components. Here we adopted a perceptual measure of sound localisation, consisting in a verbal judgement of the relative position (same or different) of two sequentially presented sounds. This task was performed in a visual and in a blindfolded condition. The results revealed that sound localisation performance of visuospatial neglect patients was severely impaired with respect to that of RBD controls, especially when sounds originated in contralesional hemispace. In such condition, neglect patients were always unable to discriminate the relative position of the two sounds. No difference in performance emerged as a function of the visual condition in either group. These results demonstrate a perceptual deficit of sound localisation in patients with visuospatial neglect, suggesting that the spatial deficits of these patients can arise multimodally for the same portion of external space.

Adult↗

PubMed2004

Gender-specific hemispheric asymmetry in auditory space perception.

This study aimed to investigate gender-related functional asymmetries in monaural sound localization in the vertical plane. In a simple pointing task, right-handed subjects localized vertical positions of sound sources using only one ear. Results show that females were more precise when listening with the left ear, while males did better with the right. However, significant differences in monaural localization performance as a function of gender occurred exclusively when listening with the right ear, with males performing substantially more precisely than females. These findings suggest gender-related differences in the intrahemispheric functional organization of the left hemisphere for the processing of monaural spatial cues. It is proposed that the results may be related to the sexual dimorphism of the posterior parietal cortex, or planum temporale, both areas known to be involved in spatial auditory functions.

Acoustic Stimulation↗

PubMed2001

Systematic distortions of auditory space perception following prolonged exposure to broadband noise.

Perceptual distortions referred to as aftereffects may arise following exposure to an adapting sensory stimulus. The study of aftereffects has a long and distinguished history [Kohler and Wallach, Proc. Am. Philos. Soc. 88, 269-359 (1944)] and a range of aftereffects have been well described in sensory modalities such as the visual system [Barlow, in Vision: Coding and Efficiency (Cambridge University Press, Cambridge, 1990)]. In the visual system these effects have been interpreted as evidence for a population of cells or channels specific for certain features of a stimulus. However there has been relatively little work examining auditory aftereffects, particularly in respect of spatial location. In this study we have examined the effects of a stationary adapting noise stimulus on the subsequent auditory localization in the vicinity of the adapting stimulus. All human subjects in this study were trained to localize short bursts of noise in a darkened anechoic environment. Adaptation was achieved by presenting 4 min of continuous noise at the start of each block of trials and was maintained by a further 15-s noise burst between each trial. The adapting stimulus was located either directly in front of the subject or 30 degrees to the right of the midline. Subjects were required to determine the location of noise burst stimuli (150 ms) in the proximity of the adapting stimulus following each interstimulus period of adaptation. Results demonstrated that following adaptation there was a general radial displacement of perceived sound sources away from the location of the adapting stimulus. These data are more consistent with a channel-based or place-based process of sound localization rather than a simple level-based adaptation model. A simple "distribution shift" model that assumes an array of overlapping spatial channels is advanced to explain the psychophysical data.

Adult↗