scholarly journals The photometric matching field. — II. The effect of peripheral stimulation of the retina on the contrast sensibility of the fovea

1925 ◽  
Vol 108 (747) ◽  
pp. 483-500 ◽  
Keyword(s):  
White Light ◽  
Focal Plane ◽  
Wave Length ◽  
Monochromatic Light ◽  
Peripheral Stimulation ◽  
Brass Plate ◽  
Contrast Perception ◽  
Matching Field ◽  
Different Parts ◽  
Stimulation Of

A paper by one of us has shown that peripheral stimulation of the retina with white light is capable of causing a considerable reduction in the limen of contrast perception at the fovea when the brightness of the central matching field is approximately equal to that of the surround. The present paper describes the extension of the work to include investigations of the effects when the wave-length of approximately monochromatic light illuminating the fields was varied throughout the spectrum, and also when the intensity of the surround was varied while that of the centre remained constant. In all cases the wave-length was the same in the centre as in the surround. The Apparatus. A plan of the apparatus employed is shown in fig. 1. A Nutting photometer was used in conjunction with a Hilger wave-length spectrometer to provide the central tripartite matching field. The shutter eyepiece of the spectrometer was replaced by a thin brass plate F, about 5 cm. square, with a small rect­angular aperture in the centre. This was placed in the focal plane of the lens L 3 , the position of the plate being such that the wave-length of the light from the centre of the hole was indicated by the wave-length drum of the spectrometer. The height and width of the aperture were 2.25 mms. and 1.25 mms. respectively. Fig. 2 shows the range of wave-lengths transmitted in different parts of the spectrum.

scholarly journals The photometric matching field. —II. The effect of peripheral stimulation of the retina on the contrast sensibility of the fovea

1925 ◽  
Vol 98 (690) ◽  
pp. 353-353 ◽  
Keyword(s):  
White Light ◽  
Wave Length ◽  
Peripheral Stimulation ◽  
Retinal Rods ◽  
Contrast Perception ◽  
Matching Field ◽  
Stimulation Of

A previous paper showed that peripheral stimulation of the retina with white light may cause a reduction in the limen of contrast perception at the fovea. The present paper extends the investigation to monochromatic lights, using the same wave-length in centre and surround. Initial reductions followed by a rise in the limen are found with increasing brightness of surround at all wave-lengths, but the reductions are small in the red as compared with the blue end of the spectrum. The effects may be partly due to reflex actions associated with the retinal rods.

scholarly journals On the luminosity curves of persons having normal and abnormal colour vision

1913 ◽  
Vol 88 (604) ◽  
pp. 404-428 ◽  
Keyword(s):  
White Light ◽  
Wave Length ◽  
Monochromatic Light ◽  
Absolute Intensity ◽  
White Patch ◽  
The Press ◽  
Colour Sense ◽  
Intimate Relation ◽  
Series Of Experiments ◽  
Pass Through

1. When reading a recent paper before the Royal Society, and also in the Press, Dr. Edridge Green has stated that he can find no connection between the luminosity and the colour sense of persons having either normal or abnormal colour sensations. Since I feel that to allow such a statement to go unchallenged might be interpreted as meaning that no such connection could be shown to exist, I propose in the following paper to place before the Society some of the evidence which indicated that there is in reality a very intimate relation between luminosity and colour sense. The results given include a small part of those which have been obtained in a series of experiments which have occupied the last two years and form part of investigation which is still in progress. The term “luminosity” as used in this paper has the following meaning: Suppose that light from some source, such as the electric arc, is admitted to a spectroscope by means of which a real pure spectrum is produced, and that a slide in the plane in which the spectrum is formed carries a slit of fixed width. Light of sensibly one wave-length, i. e. monochromatic light, will pass through this slit, and by means of a lens placed in the beam of this light an image of the first face of the prism which is used to from the spectrum can be formed on a screen. In this way a monochromatic patch of light is obtained, the brightness of which depends on the nature of the source of light, the width of the collimator slit, the width of the slit placed in the spectrum, which for short will be called the movable slit, and the dimensions of the lenses employed. Further, if alongside this coloured patch is formed a white patch of light produced by light which proceeds from the same source but has not undergone dispersion, and that by some means or other the intensity of this white light is altered till the coloured and white light, measured in any arbitrary units, measure the luminosity of the light of that colour which is passing through the movable slit. Since the unit in which the white light is measured is arbitrary, we are not concerned with the absolute intensity of illumination of the white patch, and may use any device we like to alter the quantity of white light which falls on the screen so long as we are able to measure the ratio of the quantity of light employed in different experiments. It will further be observed that for any given person the measurement of the luminosity of a given coloured light in the spectrum involves the comparsion of the brightness of the coloured patch as it appears to him with the brightness of the white patch as it appears to him.

scholarly journals The luminous efficiency of monochromatic rays entering the eye pupil at different points and a new colour effect

1937 ◽  
Vol 123 (830) ◽  
pp. 90-118 ◽  
Keyword(s):  
White Light ◽  
Wave Length ◽  
Monochromatic Light ◽  
Luminous Efficiency ◽  
Visual Sensitivity ◽  
Angle Of Incidence ◽  
Apparent Brightness ◽  
Point Of Entry ◽  
In Transit ◽  
Considerable Range

It has been found by the writer, in collaboration with B. H. Crawford (1933), that light rays entering the eye pupil near its periphery are less efficient in producing the impression of brightness than rays entering centrally, the patch of retina stimulated (the fovea) being the same in both cases. Reasons were put forward in the paper cited for thinking the effect to be retinal in origin, i. e. due to a variation of visual sensitivity with angle of incidence of the light on the retina, rather than the result of a greater absorption of the peripheral rays in transit through the optic media of the eye. Most of the observations were made with white light and, although the absence of any pronounced coloration of the field illuminated by the peripheral ray indicated that the reduction of apparent brightness could not be very different for different colours, it was considered desirable to test this point directly by observations with monochromatic light throughout the spectrum. In Part I of this paper an investigation on these lines is described from which it appears that for the writer’s eye the ratio of the luminous efficiencies of rays entering centrally and peripherally varies systematically to a limited extent in passing through the spectrum. It was also found that within a considerable range of intensity the value of the ratio for a given wave-length is independent of intensity. Since the publication of the original paper, Dziobek (1934) and Wright and Nelson (1936) have both made measurements confirming the existence of a marked variation of luminous efficiency with point of entry. The latter workers employed white light and coloured lights obtained with the aid of filters. Goodeve (1936) has also measured the effect, in the extreme red.

scholarly journals Note on the sensibility of the eye to variations of wave-length

1911 ◽  
Vol 84 (569) ◽  
pp. 118-121 ◽  
Keyword(s):  
Fixed Point ◽  
White Light ◽  
Royal Society ◽  
Wave Length ◽  
Monochromatic Light ◽  
Magnesium Carbonate ◽  
Micrometer Screw ◽  
The Difference ◽  
Second Spectrum

In a recent communication to the Royal Society, Dr. Edridge-Green has suggested that the reason Lord Rayleigh found he was able to distinguish a difference in hue between two monochromatic patches of yellow (D) light, when they differ in wave-length by about the distance between the sodium lines (0.6 μμ ), is that ( a ) the spectrum used was not pure, and hence the patches were not monochromatic; and ( b ) that the difference in wave-length was apparent because of admixture with white light. Some experiments made by the author seem so conclusively to show that at any rate the second of the above reasons cannot be correct that it seems worth while to put them on record. By means of Sir William Abney’s double spectrum apparatus, two patches of monochromatic light were thrown side by on a magnesium carbonate screen, and matters were so arranged that no line of separation was observable when the patches were of the same colour. Each patch was 9 mm. by 18 mm., and the observer was at a distance of 60 cm. The intensity of the illumination on the screen was throughout 3.5 candle-metres. The silt in the second spectrum apparatus was kept at a fixed point in the spectrum, while that in the first spectrum was moved by means of a micrometer screw, the movement being read on a scale on which a millimetre represents in the yellow a difference in wave-length of 3.7 μμ .

scholarly journals The liminal brightness increment for white light for different conditions of the foveal and parafoveal retina

1934 ◽  
Vol 116 (796) ◽  
pp. 55-102 ◽  
Keyword(s):  
White Light ◽  
Wave Length ◽  
Monochromatic Light ◽  
Black Body ◽  
Conditioning Stimulation ◽  
Test Spot ◽  
Uniform Background ◽  
The Subject ◽  
Additional Stimulation ◽  
Background Brightness

We have given in a previous paper (1933) the results of measurements of the liminal brightness increment (l. b. i.) for monochromatic light of different wave-length throughout the spectrum, for various conditions of adaptation of the eye, and for foveal and 5°-parafoveal vision. In the present paper measurements of the l. b. i. will be reported, in which the additional stimulation representing the test spot whose presence or absence is adjudged by the subject, consists of white light or more precisely of radiation with a continuous spectrum corresponding to that of a black body at approximately 2800°K. Conditioning stimulations of the following types have been studied ( a ) uniform background brightness (white), ( b ) uniform surround brightness (white or coloured) with a dark centre field, ( c ) an isolated bright patch or glare source (white or coloured). The test spot was observed either by direct (foveal) or slightly indirect (5°-parafoveal) vision. In Paper 1, attention was directed to the effect of wave-length on the value of the l. b. i., expressed in energy units, when the eye was subjected to one of a few widely different conditioning stimulations. In the present work, the test stimulus colour is fixed and the interest shifts to the effect on the l. b. i. of progressive changes in the conditioning stimulation, either in regard to brightness or colour. White backgrounds and surrounds of brightnesses ranging from zero to 500 c./sq. ft. and white glare sources producing an eye illumination up to 50 ft. c. have been used. In addition the effect of colour of surround or glare source has been studied. Although the colour of the test spot is fixed, its size and flash period have been varied and the data obtained throw light on the operation of these factors under different conditioning stimulations.

scholarly journals A case of abnormal trichromatic colour vision due to a shift in the spectrum of the green-sensation curve

1913 ◽  
Vol 89 (610) ◽  
pp. 232-245 ◽  
Keyword(s):  
White Light ◽  
Royal Society ◽  
Colour Vision ◽  
Wave Length ◽  
Electric Arc ◽  
Simple Spectrum ◽  
Normal Vision ◽  
Yellow Light ◽  
Colour Perception ◽  
Stimulation Of

The authors have each separately dealt with the question of complete and incomplete colour-blindness caused by the absence of, or decrease in, the response to stimulation of the red or green perceiving apparatus which is functional in the case of vision. We have shown that a large number of cases of defective perception of colour are simply explained on this hypothesis. Abnormality of colour vision may also be due to a shift in, or an alteration in form of, one of the sensation curves. In the present paper we discuss the effect of one type of shift on the colour perception and give the results of a series of measurements which show that such a shift, without any alteration of form, does sometimes occur. In a paper which appeared in the ‘Proceedings of the Royal Society,’ one of us indicated how a shift, that is a displacement of the whole curve so that the maximum is displaced to a different wave-length, of one of the sensation curves could be detected by a simple spectrum test, which is as follows. When yellow light of wave-length 5760 Å. U. is mixed with blue light of wave-length 4610 in suitable proportions the mixed light looks to the normal eye exactly the same as the white light from the crater of the electric arc both in hue and brightness. If a person who has a shift in one of the sensation curves is shown this match it will not appear correct to him nor can it be made correct by any alteration in the proportions of the yellow and blue lights. There will, however, in every case be found a position of the slit through which the yellow light is obtained with which a satisfactory match can be obtained. In other words the wave-length of the light which is complementary to the blue will be different to that of normal vision.

scholarly journals Peripheral Stimulation of the Saphenous and Superior Lateral Genicular Nerves for Chronic Knee Pain

Cureus ◽  
2021 ◽  
Author(s):  
Jamal Hasoon ◽  
Ahish Chitneni ◽  
Ivan Urits ◽  
Omar Viswanath ◽  
Alan D Kaye
Keyword(s):  
Knee Pain ◽  
Peripheral Stimulation ◽  
Chronic Knee Pain ◽  
Stimulation Of

THE REACTIONS OF THE HOUSEFLY, MUSCA DOMESTICA LINN., TO LIGHT OF DIFFERENT WAVE-LENGTHS

1938 ◽  
Vol 16d (11) ◽  
pp. 307-342 ◽  
Author(s):  
J. W. MacBain Cameron
Keyword(s):  
White Light ◽  
Copper Sulphate ◽  
Wave Length ◽  
Short Wave ◽  
Quantitative Relation ◽  
Copper Sulphate Solution ◽  
Quartz Mercury ◽  
Intensity Changes ◽  
Constant Quality ◽  
Colored Lights

Houseflies were reared on an artificial medium and tested with different wave-lengths of spectral light obtained from a quartz-mercury arc. The spectrum tested extended from λ3022 Å to λ5780 Å, and the lines were made of approximately equal intensity throughout. In addition, λ5461 Å and λ4078 Å were tested at several other intensities. The comparison standard in all cases was white light, obtained from a tungsten-filament, inside-frosted bulb, and filtered through copper sulphate solution. It was of constant quality, and the intensity was varied by changing the size of the bulb and by varying the distance from the bulb to the copper sulphate filter. The lighted areas to which the flies reacted were 5 by 10 mm. On one of these fell a total intensity of colored light of approximately 10.3 microwatts, on the other a range of intensity of white light of from 0.34 to 36.1 μw.Flies to be tested were removed from the breeding cage ten hours before tests began and were kept in darkness until used. Each fly whose record was used in compiling the final results was caused to make ten trips towards the two test lights, and a record was kept of the choice on each trip.A description and discussion of the four different methods found in the literature for conducting experiments of this type, and for analyzing the results, are included. In the first method, the intensity of the test light of a given wave-length is kept constant, while that of the standard light, usually white, is varied until both are equally attractive.The second method involves testing the colored light against a fixed intensity of white and finding the ratio of insects attracted to color. The intensity of white that will give the same ratio of attractiveness when tested against the standard is then determined.In the third method, the two test lights are made equal in intensity, and their relative efficiency is considered to be directly proportional to the number of insects attracted to each.In the last method, the standard is kept fixed in both quality and intensity, and the intensity of the test color is varied until the two are equal in attractiveness.Application of the first three methods to the same data shows that they give results that vary greatly as the intensity changes. Some show that efficiency increases as the intensity increases, while others show a decrease in efficiency with increasing intensity.If the intensities of all colored lights are equal, the three methods give practically the same qualitative results when applied to the same data. That is, a curve of efficiency is found which has its peak at the same wave-length, whatever method is used. Quantitatively, the results given by the three methods differ, so that no definite ratio of attractiveness can be determined between colors.The data obtained were not amenable to analysis by the fourth method, but published results indicate that this is perhaps the best method for determining the quantitative relation between the stimulative efficiencies of light of different colors.The housefly, M. domestica, is much more strongly stimulated by ultraviolet light of wave-length 3656 Å than by any other part of the spectrum examined. The effect decreases, at first rapidly and then more slowly, as the longer wave-lengths are reached; it also decreases on the short-wave side of the peak. The spectrum available extended only as far as λ3022 Å in the ultraviolet, at which point there was still an appreciable attractiveness, apparently greater than that of either yellow or green.Several problems are suggested that require further investigation.

scholarly journals Spectral Tuning of White Light Allows for Strong Reduction in Melatonin Suppression without Changing Illumination Level or Color Temperature

2018 ◽  
Vol 33 (4) ◽  
pp. 420-431 ◽  
Author(s):  
Jan L. Souman ◽  
Tobias Borra ◽  
Iris de Goijer ◽  
Luc J. M. Schlangen ◽  
Björn N. S. Vlaskamp ◽  
...  
Keyword(s):  
White Light ◽  
High Power ◽  
Spectral Power ◽  
Monochromatic Light ◽  
Action Spectrum ◽  
Color Temperature ◽  
Light Spectrum ◽  
Melatonin Suppression ◽  
Dim Light ◽  
Melatonin Production

Studies with monochromatic light stimuli have shown that the action spectrum for melatonin suppression exhibits its highest sensitivity at short wavelengths, around 460 to 480 nm. Other studies have demonstrated that filtering out the short wavelengths from white light reduces melatonin suppression. However, this filtering of short wavelengths was generally confounded with reduced light intensity and/or changes in color temperature. Moreover, it changed the appearance from white light to yellow/orange, rendering it unusable for many practical applications. Here, we show that selectively tuning a polychromatic white light spectrum, compensating for the reduction in spectral power between 450 and 500 nm by enhancing power at even shorter wavelengths, can produce greatly different effects on melatonin production, without changes in illuminance or color temperature. On different evenings, 15 participants were exposed to 3 h of white light with either low or high power between 450 and 500 nm, and the effects on salivary melatonin levels and alertness were compared with those during a dim light baseline. Exposure to the spectrum with low power between 450 and 500 nm, but high power at even shorter wavelengths, did not suppress melatonin compared with dim light, despite a large difference in illuminance (175 vs. <5 lux). In contrast, exposure to the spectrum with high power between 450 and 500 nm (also 175 lux) resulted in almost 50% melatonin suppression. For alertness, no significant differences between the 3 conditions were observed. These results open up new opportunities for lighting applications that allow for the use of electrical lighting without disturbance of melatonin production.

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