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Results for “Space Perception”

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At least 451 records · Page 25Linked to original sources
PubMed1997

Comparison of line and space bisection in evaluation of normal and amblyopic spatial vision.

BACKGROUND: Partitioning experiments have been used historically and in the recent past to evaluate space perception in visually normal and disturbed individuals. Specifically, amblyopic patients display notably distorted and/or uncertain spatial localization when assessed by either line or space bisection. METHODS: This investigation was concerned with the comparison of line bisection with space bisection. Normal and amblyopic subjects bisected horizontal lines and spaces extending 1, 2, 3 and 15 deg arc monocularly on a computer screen. Results of the two procedures were compared. RESULTS: Visually normal subjects bisected both lines and spaces without reproducible distortion, within uncertainties approximating 1-3% of their length. No differences were observed between the two procedures. Strabismic amblyopes bisected without constant distortion to either side of the geometrical mean, irrespective of direction or extent of the deviation; their uncertainty at bisecting ranged from 2% to 12%. Again, no distinction between line and space bisection could be made. CONCLUSION: We conclude that the two procedures yield comparable results.

Adolescent↗
PubMedDate not supplied

[A model of color vision in trichromats and protans].

A model which explains the human vision protanopic deficiency and its biologic prototype with the absence of red-absorbing pigment (rabbit) was constructed from neuron-like elements. In behavioral experiments and by means of evoked potential technique it was shown that the rabbit's color space is characterized by a spherical four-dimensional with a reduction of red-coding area. Similar spherical four-dimensional structure of color space is characteristic for a group of protanopic human subjects. The perceptive space of another group of protanopic subjects (protanomals) is characterized by a reduction of both parts of the red-green opponent axis. These disorders are reproduced in the model either by a loss of some color-coding elements (the absence of the red-absorbing pigment as in protanops) or a shift of the spectral characteristics of the red pigment towards those of the green one (protanomals).

Animals↗
PubMed1982

[Results of visual perception tests in prematurely born children of pre-school age (author's transl)].

Taking into account the criterions "birth weight", "small for date" (birth weight in relation to gestational age), "perinatal complications", "normal delivery" and "oxygen post partum" 32 children of pre-school age, who had been prematurely born tested with the following variables of the FROSTIG developmental tests of visual perception: visuo-motor coordination, figure-ground discrimination, perceptual constancy, space perception and perception of spacial relations. There were not significant differences between the premature-groups. No relations could be found between the quantity of O2 post partum and the tested abilities. After comparing the test subjects and a group of full-term born controls significant differences could be established. The different abilities were not related to the birth weight. Extensive deficits were observed in the "small for date" born prematures. The results are discussed with regard to their therapeutic relevance.

Birth Weight↗
PubMedDate not supplied

[The retention of a color image in short-term memory].

The article deals with the study of the dynamics of retention of a colour image in the short-term memory by a technique of multidimensional scaling under conditions of delayed administration of a second stimulus in a pair. Comparison of colour spaces of the short-term memory (delays of 4, 15, and 60 sec) with the perceptive space without any delay showed that the four-dimensional spherical structure of the colour space remained stable, but the accuracy of assessments decreased with increase of the delay time. This led to a deterioration of the metrical determinacy of the space and an increase in the thickness of the spherical layer.

Adult↗
PubMed1997

Parietal cortex: from sight to action.

Recent findings have altered radically our thinking about the functional role of the parietal cortex. According to this view, the parietal lobe consists of a multiplicity of areas with specific connections to the frontal lobe. These areas, together with the frontal areas to which they are connected, mediate distinct sensorimotor transformations related to the control of hand, arm, eye or head movements. Space perception is not unitary, but derives from the joint activity of the fronto-parietal circuits that control actions requiring space computation.

Animals↗
PubMed2006

Three-dimensional spatial skill training in a simulated space station: random vs. blocked designs.

BACKGROUND: Astronauts floating inside a spacecraft must be able to recall the direction to surrounding visual landmarks, regardless of their viewing perspective. If 3D orientation skills are taught preflight, should perspective sequences be blocked or randomized? Can standard spatial skill tests predict performance? METHODS: Undergraduates (40 men and 40 women; ages 19-24) learned 3D spatial relationships among landmark pictures in a cubic chamber simulating a space station node. Subjects learned to predict picture directions when told one picture's direction (the one behind them) and the subject's simulated roll orientation, which was changed between trials by rotating pictures. The dependent variable was the proportion of correct predictions. A between group (n=40 per group) independent variable was training type (random vs. blocked sequencing of perspectives). Experiment phase (familiarization, training, transfer, and 2 retention phases) was a within group variable. Subjects also took three standard spatial skill tests: Card Rotation, Cube Comparison, and Group Imbedded Figures. RESULTS: As hypothesized, during training, performance for the random group (0.56) was worse than the blocked group (0.83); during transfer, the random group (0.75) was better than the blocked group (0.56); during retention-i, the random group (0.70) was better than the blocked group (0.55); and during retention-2, the random group (0.76) was better than the blocked group (0.65). Spatial skill tests correlated differently across the two groups, indicating that random sequencing elicits different skills. CONCLUSION: Random presentation enhances 3D spatial skill transfer and retention. Standard spatial tests can predict performance and have the potential to customize training.

Adult↗
PubMed2002

The neuroscience of Helmholtz and the theories of Johannes Müller. Part 2: Sensation and perception.

In this, our continuation paper on Helmholtz and Müller, we examine Helmholtz's contributions to sensation and perception, with emphasis on his extension and modification of Müller's theory of specific nerve energies. The material is again presented in biographical-chronological context. We also examine Helmholtz's views on depth and space perception, and his empirical theory of knowledge, which are also compared to Müller's views. It will be shown that Helmholtz remained stimulated by the thoughts and doctrines of Johannes Müller in the sensory-perceptual part of his career, which began early in the 1850s and ended with his death. Nevertheless, Helmholtz's own experiments and new discoveries by others sometimes led him to quite different conclusions.

Germany↗