Biomedical subjects

A Bulatov

Publications and source records attributed to A Bulatov.

13 recordsLinked to original sources

PubMed2005

Distortions in length perception: visual field anisotropy and geometrical illusions.

Psychometric experiments were performed to study the effects of visual field anisotropy and geometrical illusions on the accuracy of comparison of objects in terms of length. Stimuli consisting of V-shaped symbols were used, made up of three light spots or one spot plus components of illusory figures, which were pairs of Müller-Layer wings or an interval of the Oppel-Kundt figure filled with spots of light. Relationships between the length comparison errors and the orientations of the reference and test parts of the stimulus were obtained. The experimental data showed that the simultaneous appearance of illusions and visual field anisotropy can be summed algebraically.

Anisotropy↗

PubMed2003

[Effect of striate visual cortex topography on the parameters of image filtering].

A model of spatial-frequency filtering at the level of 4C layer of the striate visual cortex is proposed and based on the well-known literature data. The evidence on conformable character of representation of the visual field on the primary visual cortex and the suggestions concerning uniformity of horizontal connections of cortical neurones serve as the ground of the model. A correspondence between predictions of the model and results of the experiments with shape perception and size discrimination has been obtained.

Animals↗

PubMed2003

[Distortions of length perception: anisotropy of the visual field and geometric illusions].

A combined influence of stimulus orientation and structure on the judgement of length was tested in psychophysical experiments. The subjects adjusted the test part of a stimulus to be equal in length to the reference part. The V-shaped stimuli (three dots, or the Oppel-Kundt figure, or one dot and two Müller-Layer wings) were generated on the monitor. In the Oppel-Kundt and Müller-Layer figures, the filled part was considered as a reference and the empty part as a test. In session of the experiments, values of errors measured as functions of orientation of the parts of the stimuli. We assume that experiments with the three-dot stimuli yielded pure characteristics of visual field anisotropy, while those with the Oppel-Kundt and Müller-Layer figures showed a combined effect of both anisotropy and illusions. The data demonstrated that illusions and anisotropy are to be interpreted as independent factors, which converge to an algebraic summation in a simultaneous manifestation.

Anisotropy↗

PubMed2001

Phase mixing, induced relaxation, and chaos in one-dimensional dynamical systems.

This paper investigates the mechanism of induced phase mixing, which leads to effective dissipation in classical nonlinear dynamical systems with a fast modulation of the potential. The suggested model can be applied to a classical dynamical description of cold atomic clouds in optical traps. We show that the parametric nonadiabatic modulation of the laser intensity can provide a tool for dynamical control of the effective relaxation in such systems.

Journal Article↗

PubMed1999

Distortions of length perception.

A combined influence of stimulus orientation and structure on the judgment of length was tested in psychophysiological experiments. The subjects adjusted the test part of a stimulus to be equal in length to the reference part. The orientation of the parts of the stimulus varied in the experiments. The stimuli (three dots or the Oppel-Kundt figure, which had ten dots within the filled part) were generated on the monitor. In the Oppel-Kundt figure, the filled part was considered as a reference and the empty part as a test. In sessions of the experiments, values of errors were measured as functions of the size and orientation of the stimulus. The reference part length varied within 14-150 min are range, and the orientation was fixed in 0 degree, 90 degrees, 180 degrees or 270 degrees positions. The orientation of the test part varied from 0 degree to 360 degrees in 7 degrees steps. We assume, that the experiments with the three-dot stimuli yielded pure characteristics of visual field anisotropy, while those with the Oppel-Kundt figure showed the combined effect of both the components (anisotropy and spatial filtering). The data demonstrated independence of the two factors from each other in a simultaneous manifestation. The characteristics of a pure Oppel-Kundt illusion have been found to be in close correspondence with the predictions of the model of spatial filtering.

Cybernetics↗

PubMed1997

Geometrical illusions: study and modelling.

The phenomena of geometrical illusions of extent suggest that the metric of a perceived field is different from the metric of a physical stimulus. The present study investigated the Müller-Lyer and Oppel-Kundt illusions as functions of spatial parameters of the figures, and constructed a neurophysiological model. The main idea of the modelling is based on the uncertainty principle, according to which distortions of size relations of certain parts of the stimulus, so-called geometrical illusions, are determined by processes of spatial filtering in the visual system. Qualitative and quantitative agreement was obtained between psychophysical measurement of the strength value of the illusions and the predictions of our model.

Female↗

PubMed1996