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PubMedDate not supplied

[Contancy of color perception in the grey toad].

Under the conditions of behavioural experiment capacity of grey toads for constant perception of an object colour was studied. It is shown that irrespective of the spectral composition of light source toad males are able to recomgnize blue colorations among the other ones (green and grey of various gradations).

Animals↗
PubMed1987

[Visual evoked potentials following double-pattern stimulation with pseudo-color perception].

We examined in which form an additional structural stimulus in the white checks influenced the visual evoked potential of a checkerboard reversal induced response. A pattern of vertical bars was introduced with a short delay to the checkerboard reversal. The purpose of these experiments was to find out about the discrimination threshold of the occipital cortex for timely spaced stimuli. The double stimulus was separated from the next change minimally for 800 ms. With this arrangement we avoided "steady states", which are shown by repetitive interstimulus intervals of less than 200 ms. Nine normal volunteers between 22 to 28 years of age were measured. We found a typical waveform after the P 100 potential consisting of a positive peak followed by a negative long-lasting baseline elevation. Only separations of more than 60 ms yielded this configuration. Interstimulus times of less than 60 ms resulted in refractory effects on the visual evoked response. All the subjects reported colour or brightness changes of the additional bars. These pseudo colours were very probably due to the Prevost-Fechner-Benham-Effect which is common with repetitive white and black pattern changes. Our pseudo colours showed remarkable differences to the classical designs which has led us to the conclusion that colour perception on TV monitors is influenced so far by unpredictable flicker factors.

Adult↗
PubMed1991

Two carriers for motion perception: color and luminance.

Starting with the experiments of Ramachandran and Gregory (Nature, 275, 55-56, 1978), several psychophysical studies in apparent motion (AM) have established that the perception of motion is significantly impaired at equiluminance. Still debated, however, is whether color alone can resolve ambiguities in AM. We report here on several psychophysical experiments, the quantitative results of which indicate that color does play a substantial role in AM. These findings seem to support recently proposed neurophysiological frameworks according to which there exist significant interactions among the neuronal pathways mediating the perception of basic visual attributes such as color, motion, form and depth.

Color Perception↗
PubMed1974

Infant color perception.

Human infants 4 to 6 months of age devoted more visual fixation to checkerboards composed of two Munsell hues equated for brightness and saturation than to unpatterned targets of either hue. Strength of pattern preference was positively related to degree of hue difference in the checkerboards.

Age Factors↗
PubMedDate not supplied

[Constancy of color perception in the gray toad (Bufo bufo L.)].

Colour vision and constancy of colour perception in Bufo bufo L, were examined by means of unconditioned reaction of choosing moving and stationary models of females by males during breeding season. The males chose blue and dark blue models. Control of the choice of blue models presented in pairs with models of different shades of grey proves the existence of colour vision in Bufo bufo L. The choice of blue models has been observed under significantly varying conditions: both with artificial illumination and in sunlight. This attests the capacity of toads for constant colour perception. When a model was presented against a saturated red background, colour contrast was observed: under such conditions the toads chose the grey models which evoked no reactions when presented against white background.

Animals↗
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↗
PubMed1990

[Changes in color perception during the use of the Vacumcolor 50% tinted glasses in normal trichromatic individuals].

The authors assessed the spectral absorption of coloured glasses Vacumcolor 50% and found differences between different pairs of glasses which attained in the red areas as much as 17%. They also examined changes of the colour sense in a group of normal trichromats when using these coloured glasses. They found that these glasses alter the colour sense in the direction of deuteranomaly and cause deterioration of colour asthenopia.

Adult↗
PubMedDate not supplied

[A model of constant color perception for continuous spectral functions].

A trichromatic model is proposed of constant pattern of colour perception (MCCP) for scenes with a single illumination source. In MCCP functions of the source emission, surface reflection, photoacceptor sensitivity are approximated by the normal distribution curves. MCCP characteristics "colour tone", "cleanness", and "lightness" organize its output colour metric by the human's pattern, and in a wide range of spectral composition of illumination they are invariant under these changes. Special colorimetric regime of MCCP work which estimates the colour of visual stimulus permits a comparison between the efficiencies of two proposed algorithms of visual information processing for MCCP.

Color Perception↗
PubMed1977

[Importance, especially in aeronautics, of color perception tests under dynamic conditions. Study of a suitable experimental apparatus].

Following a review of the most recent opinion on the physiology of colour vision, a device for examining it in dynamic, i.e. real-life conditions is described. The apparatus consist of two projectors which flash two absolutely identical pictures on to the screen, one of them is upside down. It appears at fixed but adjustable intervals so that the exposure time of the intelligible image can be varied. Subjects were also controlled with Ishihara charts and Nägel anomaloscope. The results are compared and point to the higher sensitivity of the dynamic test to even slight degrees of dyschromatopsia.

Color Perception Tests↗
PubMedDate not supplied

[The spherical theory of color perception: its verification by the methods of psychophysics and neurophysiology].

In the paper data of experimental verification of "spherical theory of perception" (E. N. Sokolov) are summed on the material of colour perception study. The results of psychophysical experiments with subjects having different forms of colour perception (normal trichromats, colour anomalies) and neurophysiological experiments on animals (carp) are considered within single psychophysiological system--spherical model of colour discrimination. Neuron-like elements of the model reflect the activity of light-sensitive cells of the visual system and at the same time reproduce some rules of subjective colours discrimination at the psychophysical level. Advantages of spherical model are considered allowing to analyze human individual colour functions in norm and pathology and giving the opportunity of strictly quantitative approach to description of neuronal mechanisms of colour vision. From the position of spherical model of colour discrimination neuronal structure of colour analyzer is discussed, which includes layers of photoreceptors, ++predetectors (colour-opponent and achromatic cells) and colour-selective detectors.

Animals↗