scholarly journals THEORY AND MEASUREMENT OF VISUAL MECHANISMS

1944 ◽  
Vol 27 (6) ◽  
pp. 513-528 ◽  
Author(s):  
W. J. Crozier ◽  
Ernst Wolf
Keyword(s):  
White Light ◽  
Wave Length ◽  
Visual Image ◽  
Slope Parameter ◽  
Probability Summation ◽  
Present Evidence ◽  
High Slope ◽  
Anolis Lizard ◽  
Slope Class

Flicker contours from vertebrates (fishes to man) show that the slope parameter σ'log I in the efficiently descriptive probability summation 100 F/Fmax. = ∫–inf;log I e–(log I/Ii)–(log I/Ii)2/2(σ')/2(σ')2 ·d log I is distributed bimodally (simple fields, "white" light), from 0.60 to 2.3, with well defined peaks at 0.80 and 1.75. This parameter is independent of Fmax., log Ii, temperature, light-time fraction, and in general not greatly influenced by λ. "Rod" components of known visually duplex contours, without exception, and some "cone" contours, are in the first group; an equal number of "cone" curves are in the second group, together with one simplex "rod" contour; purely cone contours are in each group, as well as cone segments of duplex curves. No firm zoological grouping of the "cone" curves can be made, on present evidence,—although the 5 fishes used give high-slope curves, 2 amphibians low slopes, reptiles (5) either high or low, birds (2) and anthropoids (2) low-slope "cone" curves. By subdivision of the visual image and by change of wave-length, under certain conditions, in man, and by use of the "pecten effect" in birds (and man), cone contours of the low-slope class can be transformed into curves of the high-slope group. These procedures do not fundamentally change the "rod" slopes. Consequently, although under simple conditions they are specifically determined, the forms of the F - log I contour cannot be used as diagnostic for rod or cone functioning. It is reinforced, by new data on Anolis (lizard) and Trionyx (turtle), that an obviously duplex retina is specifically correlated with a duplex performance contour, a simplex retina with a simplex one. But no support is given to the view that the shapes of these curves are diagnostic of differences in rod or cone fundamental excitabilities, or that they describe properties of these units. In visual duplexity we have to do simply with the fact that two groups of neural effects are available; it is with their properties that we deal in measurements of duplex visual excitability.

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 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 COUNTERACTING THE RETARDING AND INHIBITORY EFFECTS OF STRONG ULTRAVIOLET ON FUCUS EGGS BY WHITE LIGHT

1942 ◽  
Vol 25 (3) ◽  
pp. 391-397 ◽  
Author(s):  
D. M. Whitaker
Keyword(s):  
Ultraviolet Light ◽  
White Light ◽  
Ultraviolet Irradiation ◽  
Wave Length ◽  
Considerable Degree ◽  
Inhibitory Effects ◽  
Degree Of Recovery ◽  
Damaging Effects

1. Strong dosages (20,000–50,000 ergs per mm.2) of ultraviolet light, predominantly of the wave-length 2537 Å, greatly retard and inhibit the development of rhizoids in Fucus eggs irradiated at about 8 hours after fertilization. 2. If white light shines on the eggs after the irradiation by ultraviolet is terminated, the white light causes a considerable degree of recovery from the retarding and inhibiting effects. 3. If strong white light shines on the eggs during the ultraviolet irradiation, its effect is even more marked in protecting the cells from the damaging effects of the ultraviolet.

scholarly journals Emission and absorption in the infra-red spectra of mercury, zinc, and cadmium

1919 ◽  
Vol 95 (669) ◽  
pp. 280-299 ◽  
Keyword(s):  
White Light ◽  
Vapour Pressure ◽  
Wave Length ◽  
Mercury Vapour ◽  
Stimulate Emission ◽  
First Line ◽  
Absorption Bands ◽  
Infra Red ◽  
Partial Parallelism ◽  
Lower Voltage

In a previous paper the writer pointed out that well-marked absorption bands exist in the infra-red region of the spectrum caused by passing white light through non-luminous mercury vapour. These bands occur at λ 1·014, λ 1·129. and λ 1·205, the first and third of these being especially strong. This investigation has since been extended further into the infra-red with mercury vapour, and it has also been repeated with the vapours of zinc and cadmium in place of that of mercury. The results serve to establish at least a partial parallelism in the behaviour of the three metals, the resemblance being most marked in the region of the first line of the series represented by v = (2·5, S)—( m , P), at which wave-length absorption takes place in the case of all three metals with extremely small vapour-pressure. On account of the ease with which the wave-length corresponding to v = (2·5, S)—( m , P) was absorbed, it was suspected that it should be emitted under electronic bombardment. At the suggestion of Prof. McLennan an investigation was undertaken with mercury vapour, in order to determine the speed which electrons must be given in order to stimulate emission of the wave-length λ 1·014. If we apply the quantum relation ve = hv to the frequency of this wave-length, we get V = 1·26 volts. In the experiments which will be described herein, the wave-length λ 1·014 was actually emitted with a voltage as low as 5 volts. There were strong indications that even a lower voltage would suffice to stimulate emission of the wave-length, but under the conditions of the experiment the radiations of this wave-length when emitted were reabsorbed by the intervening layers of mercury vapour.

scholarly journals Emission and absorption in the infra-red spectrum of mercury

1916 ◽  
Vol 92 (645) ◽  
pp. 608-620 ◽  
Keyword(s):  
Absorption Spectrum ◽  
Emission Spectrum ◽  
White Light ◽  
Wave Length ◽  
Mercury Vapour ◽  
Red Emission ◽  
Characteristic Absorption ◽  
Additional Work ◽  
Infra Red ◽  
The Way

In a previous paper by McLennan and Dearle, it was pointed out that hands had been found in the absorption spectrum of non-luminous mercury vapour at λ = 1849 Å. U., λ = 2536·72 Å.U., and λ = 2338 Å.U., but that nothing had been done up to the present in the way of investigating the infra-red region of this spectrum for characteristic absorption hands. In the same paper an account was given of some measurements made on the infra-red emission spectrum of the mercury are for the purpose of establishing the wave-length and intensities of the lines in that region. The Present paper deals first with some additional work on the relative intensities of these lines, and, secondly, with the absorption hands produced by passing white light through non-luminous mercury vapour.

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 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 WAVE LENGTH OF LIGHT AND PHOTIC INHIBITION OF STEREOTROPISM IN TENEBRIO LARVÆ

1924 ◽  
Vol 6 (6) ◽  
pp. 647-652 ◽  
Author(s):  
W. J. Crozier
Keyword(s):  
White Light ◽  
Glass Surface ◽  
Wave Length ◽  
Minimal Energy ◽  
Photosensitive Material ◽  
Effective Absorption ◽  
Vertical Glass

A definite intensity of white light is required (about 136 m.c.) to produce negative phototropic orientation of creeping Tenebrio larvæ away from contact with a vertical glass surface. This gives a measure of stereotropism in terms of phototropism, or reciprocally. The effectiveness of light for the suppression of stereotropism varies with wave length. It is therefore simple to obtain a measure of the relation between wave length and stimulating efficiency in this case of phototropic orientation. By determinations of the minimal energy required to inhibit stereotropism with different regions of the spectrum, it is found that the maximum effectiveness is sharply localized in the neighborhood of 535µµ. The curve connecting stimulating efficiency with wave length, while giving a picture of the effective absorption by the photosensory receptors, probably does not permit accurate characterization of the essential photosensitive material.

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 .

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