Skip to content

Light and Dark Adaptation by Michael Kalloniatis and Charles Luu

 

Michael Kalloniatis and Charles Luu

Dark Adaptation.

 

The eye operates over a large range of light levels. The sensitivity of our eye can be measured by determining the absolute intensity threshold, that is, the minimum luminance of a test spot required to produce a visual sensation. This can be measured by placing a subject in a dark room, and increasing the luminance of the test spot until the subject reports its presence. Consequently, dark adaptation refers to how the eye recovers its sensitivity in the dark following exposure to bright lights. Aubert (1865) was the first to estimate the threshold stimulus of the eye in the dark by measuring the electrical current required to render the glow on a platinum wire just visible. He found that the sensitivity had increased 35 times after time in the dark, and also introduce for the term “adaptation”.

Dark adaptation forms the basis of the Duplicity Theory which states that above a certain luminance level (about 0.03 cd/m2), the cone mechanism is involved in mediating vision; photopic vision. Below this level, the rod mechanism comes into play providing scotopic (night) vision. The range where two mechanisms are working together is called the mesopic range, as there is not an abrupt transition between the two mechanism.

The dark adaptation curve shown below depicts this duplex nature of our visual system (figure 1). The first curve reflects the cone mechanism. The sensitivity of the rod pathway improves considerably after 5-10 minutes in the dark and is reflected by the second part of the dark adaptation curve. One way to demonstrate that the rod mechanism takes over at low luminance level, is to observe the colour of the stimuli. When the rod mechanism takes over, coloured test spots appear colourless, as only the cone pathways encode colour. This duplex nature of vision will affect the dark adaptation curve in different ways and is discussed below.

To produce a dark adaptation curve, subjects gaze at a pre-adapting light for about five minutes, then absolute threshold is measured over time (figure 1). Pre-adaptation is important for normalisation and to ensure a bi-phasic curve is obtained.

Figure 1. Dark adaptation curve. The shaded area represents 80% of the group of subjects. Hecht and Mandelbaum’s data from From Pirenne M. H., Dark Adaptation and Night Vision. Chapter 5. In: Davson, H. (ed), The Eye, vol 2. London, Academic Press, 1962

 

From the above curve, it can be seen that initially there is a rapid decrease in threshold, then it declines slowly. After 5 to 8 minutes, a second mechanism of vision comes into play, where there is another rapid decrease in threshold, then an even slower decline. The curve asymptotes to a minimum (absolute threshold) at about 10-5 cd/m2 after about forty minutes in the dark.

Factors Affecting Dark Adaptation.

 

 

Intensity and duration of pre-adapting light:


Different intensities and duration of the pre-adapting light will affect dark adaptation curve in a number of areas. With increasing levels of pre-adapting luminances, the cone branch becomes longer while the rod branch becomes more delayed. Absolute threshold also takes longer to reach. At low levels of pre-adapting luminances, rod threshold drops quickly to reach absolute threshold (figure 2).

Figure 2. Dark adaptation curves following different levels of pre-adapting luminances. Hecht, Haig and Chase’s data from Bartlett N. R., Dark and Light Adaptation. Chapter 8. In: Graham, C. H. (ed), Vision and Visual Perception. New York: John Wiley and Sons, Inc., 1965

 

 

The shorter the duration of the pre-adapting light, the more rapid the decrease in dark adaptation (figure 3). For extremely short pre-adaptation periods, a single rod curve is obtained. It is only after long pre-adaptation that a bi-phasic, cone and rod branches are obtained.

Figure 3. Dark adaptation curves following different duration of a pre-adapting luminance. Wald and Clark’s data from Bartlett N. R., Dark and Light Adaptation. Chapter 8. In: Graham, C. H. (ed), Vision and Visual Perception. New York: John Wiley and Sons, Inc., 1965

 

 

Size and location of the retina used:
The retinal location used to register the test spot during dark adaptation will affect the dark adaptation curve due to the distribution of the rod and cones in the retinal (figure 4).

Figure 4. Distribution of rod and cones in the retina. Plot from Osterberg’s data

When a small test spot is located at the fovea (eccentricity of 0o), only one branch is seen with a higher threshold compared to the rod branch. When the same size test spot is used in the peripheral retina during dark adaptation, the typical break appears in the curve representing the cone branch and the rod branch (figure 5).

Figure 5. Dark adaptation measured with a 2o test spot at different angular distances from fixation. Subject was pre-adapted for 2 minutes to 300 mL. Hecht, Haig and Wald’s data from Bartlett N. R., Dark and Light Adaptation. Chapter 8. In: Graham, C. H. (ed), Vision and Visual Perception. New York: John Wiley and Sons, Inc., 1965

 

A similar principle applies when different size of the test spot is used. When a small test spot is used during dark adaptation, a single branch is found as only cones are present at the fovea. When a larger test spot is used during dark adaptation, a rod-cone break would be present since the test spot stimulates both cones and rods. As the test spot becomes even larger, incorporating more rods, the sensitivity of the eye in the dark is even greater (figure 6), reflecting the larger spatial summation characteristics of the rod pathway.

 

 

 

Figure 6. Dark adaptation measured using different size test spots. Hecht, Haig and Wald’s data from Bartlett N. R., Dark and Light Adaptation. Chapter 8. In: Graham, C. H. (ed), Vision and Visual Perception. New York: John Wiley and Sons, Inc., 1965

 

Wavelength of the threshold light:
When stimuli of different wavelengths are used, the dark adaptation curve is affected. From figure 7 below, a rod-cone break is not seen when using light of long wavelengths such as extreme red. This occurs due to rods and cones having similar sensitivities to light of long wavelengths (figure 8). Figure 8 depicts the photopic and scotopic spectral sensitivity functions to illustrate the point that the rod and cone sensitivity difference is dependent upon test wavelength (although normalization of spatial, temporal and equivalent adaptation level for the rod and cones is not present in this figure). On the other hand, when light of short wavelength is used, the rod-cone break is most prominent as the rods are much more sensitive than the cones to short wavelengths once the rods have dark adapted.

Figure 7. Dark adaptation curve using different test stimuli of different wavelengths. Subjects were pre-adapted to 2000mL for 5 minutes. A 3 degree test stimuli was presented 7 degrees on the nasal retina. The colours were: RI (extreme red)=680 nm; RII (red)=635 nm; Y (yellow)=573 nm; G (green)=520 nm; V (violet)=485nm and W (white). Chapanis’ data from Bartlett N. R., Dark and Light Adaptation. (Chapter 8. In: Graham, C. H. (ed), Vision and Visual Perception. New York: John Wiley and Sons, Inc., 1965)

 

Figure 8. Scotopic (rods) and photopic (cones) spectral sensitivity functions. Wald’s data from Davson, H., Physiology of the Eye, 5th ed. London: Macmillan Academic and Professional Ltd, 1990


Rhodopsin regeneration

Dark adaptation also depends upon photopigment bleaching. Retinal (or reflection) densitometry, which is a procedure based on measuring the light reflected from the fundus of the eye, can be used to determine the amount of photopigment bleached. Using retinal densitometry, it was found that the time course for dark adaptation and rhodopsin regeneration was the same. However, this does not fully explain the large increase in sensitivity with time. Bleaching rhodopsin by 1% raises threshold by 10 (decreases sensitivity by 10). In figure 9, it can be seen that, bleaching 50% of rhodopsin in rods raises threshold by 10 log units while the bleaching 50% of cone photopigment raises threshold by about one and a half log units. Therefore, rod sensitivity is not fully accounted for at the receptor level and may be explained by further retinal processing. The important thing to note is that bleaching of cone photopigment has a smaller effect on cone thresholds.

Figure 9. Log relative threshold as a function of the percentage of photopigment bleached. From Cornsweet, T.N., Visual Perception. New York: Academic Press, 1970

 

Light Adaptation.

With dark adaptation, we noticed that there is progressive decrease in threshold (increase in sensitivity) with time in the dark. With light adaptation, the eye has to quickly adapt to the background illumination to be able to distinguish objects in this background. Light adaptation can be explored by determining increment thresholds. In an increment threshold experiment, a test stimulus is presented on a background of a certain luminance. The stimulus is increased in luminance until detection threshold is reached against the background (figure 10) Therefore, the independent variable is the luminance of the background and the dependent variable is the threshold intensity or luminance of the incremental test required for detection. Such an approach is used when visual fields are measured in clinical practice.

Figure 10. Light adaptation using an increment threshold experiment. (a) example of the stimulus used (b) luminance profile of the stimulus

 

The experimental conditions shown in figure 10, can be repeated by changing the background field luminance. Depending upon the choice of test and background wavelength, the test size and retinal eccentricity, a monophasic or biphasic threshold versus intensity (tvi) curve is obtained. Figure 11 illustrates such a curve for parafoveal presentation of a yellow test field on a green background. This stimulus choice leads to two branches. A lower branch belonging to the rod system. As the background light level increases, visual function shifts from the rod system to the cone system. A dual-branched curve reflects the duplex nature of vision, similar to the bi-phasic response in the dark adaptation curve.

 

Figure 11. Light adaptation curve plotted as increment threshold versus background luminance (or a threshold-versus-intensity: tvi curve). The above plot shows increment threshold (Nl ) and background luminance (Mm ). Light of two different wavelengths are used in this case (580 nm for the test and 500 nm for the background). Stiles’ data from Davson (Davson’s Physiology of the Eye, 5th ed. London: Macmillan Academic and Professional Ltd, 1990)

 

When a single system (eg. the rod system) is isolated under certain experimental conditions, four sections of the curve is apparent. These experiment conditions involve using a red background to suppress the cone photoreceptors and a green test spot to stimulate the rod photoreceptors (Aguilar and Stiles, 1954). The curve in figure 12 can also be obtained by performing increment threshold experiments on rod monochromats who lack cone photoreceptors. When the rod system is isolated using the conditions of Aguilar and Stiles, four sections are obtained:

  1. Dark light
  2. Square Root Law (de Vries-Rose Law)
  3. Weber’s Law
  4. Saturation

 

The threshold in the linear portion of the tvi curve is determined by the dark light level. As background luminance is increased, the curve remains constant (and equal to the absolute threshold). Sensitivity in this section is limited by neural (internal) noise, the so called “dark light”. The background field is relatively low and does not significantly affect threshold. This neural noise is internal to the retina and examples of these include thermal isomerisations of photopigment, spontaneous opening of photoreceptor membrane channels and spontaneous neurotransmitter release.

Figure 12. Schematic of the increment threshold curve of the rod system. Aguilar and Stiles’ data from Davson (Davson’s Physiology of the Eye, 5th ed. London: Macmillan Academic and Professional Ltd, 1990).

The second part of the tvi curve is called the square root law or (de Vries-Rose Law) region. This part of the curve is limited by quantal fluctuation in the background. Rose (1948) proposed that visual threshold would be quantal limited. The visual system is usually compared to a theoretical construct, an ideal light detector. An ideal detector can detect and encode each absorbed quantum of light and is limited only by the noise due to quantal fluctuations in the source. To detect the stimulus, the stimulus must be sufficiently exceed the fluctuations of the background (noise).

Because the variability in quanta increases with the number of quanta absorbed, threshold would increase with background luminance. In fact, the increase in threshold should be proportional to the square root of the background luminance; hence the slope of one half in a log-log plot. For the rod pathway a slope of 0.6 is often found (Hallett, 1969). Barlow (1958) explored the conditions which influenced the transition from the square root law to Weber’s law (see below). He concluded that for brief, small test spots, increment thresholds rise as the square root of the background over the entire photopic range. Spots of large areas and long durations have slopes close to Weber’s law. Other spatio-temporal configurations result in different proportions of each region.

When plotted using log DL versus log L coordinates, the Weber law section ideally has a slope 1. For the rod pathway, a slope 0.8 or less is found, implying that the rod pathway does operate under true Weber conditions. This section of the curve demonstrates an important aspect of our visual system. Our visual system is designed to distinguish objects from its background. In the real world, objects have contrast, which is constant and independent of ambient luminance. Therefore, the principle of Weber’s law can be applied to contrast which remains constant regardless of illumination changes. This is called contrast constancy or contrast invariance, with this contrast level defined as Webers constant. Contrast constancy can be mathematically expressed as DL /L = constant. DL is the increment threshold on a background L. The constant is also known as the Weber constant or Weber fraction. The Weber constant for the rod and cone is 0.14 (Cornsweet, 1970) and 0.02 to 0.03 (Davson, 1990) respectively. Within the cone pathways, the S-cone pathway, again has a different characteristics to those of the longer-wavelength pathway with a Weber constant of around 0.09 (Stiles, 1959).

Section 4 of the curve (figure 12) shows rod saturation at high background luminance. The slope begins to increase rapidly and the rod system starts to become unable to detect the stimulus. This section of the curve occurs for cone mechanism under high background light levels.

References.

Aguilar M, Stiles WS. Saturation of the rod mechanism of the reina at high levels of stimulation. Opt Acta (Lond). 1954;1:59–65.

Aubert H. Physiologie der Netzhaut. Breslau: E. Morgenstern. 1865

Barlow HB. Increment thresholds at low intensities considered as signal noise discriminations. J Physiol. 1958;141:337–350. [PubMed]

Barlow HB. The physical limits of visual discrimination. In: Giese A. C. (ed), Photophysiology. Chapter 16. New York: Academic Press 1964.

Bartlett NR. Dark and light adaptation. In: Graham CH, editor. Vision and visual perception. New York: John Wiley and Sons, Inc.; 1965.

Cornsweet TN. . Visual perception. New York: Academic Press. 19707.Davson H. . Physiology of the eye. 5th ed. London: Macmillan Academic and Professional Ltd. 1990

Davson H (1990) Physiology of the Eye, 5th ed. London: Macmillan Academic and Professional Ltd.

Hallett PE. The variations in visual threshold measurement. J Physiol. 1969;202:403–419. [PubMed] [Free Full text in PMC]

Osterberg G. Topography of the layer of rods and cones in the human retina. Acta Ophthalmol Suppl. 1935;6:1–103.

Pirenne MH (1962) Dark Adaptation and Night Vision. Chapter 5. In: Davson, H. (ed), The Eye, vol 2. London, Academic Press.

Pirenne MH (1962) Rods and Cones. Chapter 2. In: Davson, H. (ed), The Eye, vol 2. London, Academic Press.

Rose A. The sensitivity performance of the human eye on a absolute scale. J Opt Soc Am. 1948;38:196–208. [PubMed]

Stiles WS. Colour vision: the approach through increment threshold sensitivity. Proc Natl Acad Sci U S A. 1959;75:100–114.

Last Update: July 9, 2007.

The author

Michael Kalloniatis was born in Athens Greece in 1958. He received his optometry degree and Master’s degree from the University of Melbourne. His PhD was awarded from the University of Houston, College of Optometry, for studies investigating colour vision processing in the monkey visual system. Post-doctoral training continued at the University of Texas in Houston with Dr Robert Marc. It was during this period that he developed a keen interest in retinal neurochemistry, but he also maintains an active research laboratory in visual psychophysics focussing on colour vision and visual adaptation. He was a faculty member of the Department of Optometry and Vision Sciences at the University of Melbourne until his recent move to New Zealand. Dr. Kalloniatis is now the Robert G. Leitl Professor of Optometry, Department of Optometry and Vision Science, University of Auckland. e-mail: m.kalloniatis@unsw.edu.au

 

The author

Charles Luu was born in Can Tho, Vietnam in 1974. He was educated in Melbourne and received his optometry degree from the University of Melbourne in 1996 and proceeded to undertake a clinical residency within the Victorian College of Optometry. During this period, he completed post-graduate training and was awarded the post-graduate diploma in clinical optometry. His areas of expertise include low vision and contact lenses. During his tenure as a staff optometrist, he undertook teaching of optometry students as well as putting together the “Cyclopean Eye”, in collaboration with Dr Michael Kalloniatis. The Cyclopean Eye is a Web based interactive unit used in undergraduate teaching of vision science to optometry students. He is currently in private optometric practice as well as a visiting clinician within the Department of Optometry and Vision Science, University of Melbourne.

Comment Feed

38 Responses

  1. Is there any data on whether either light or dark adaptation change on repeated exposure to large changes in luminance? That is, if a person moves from a light to a dark envioronment many times, will they be quicker to adapt to the change?

    Tom Brashers-KrugJune 24, 2011 @ 9:38 amReply
    • Hey Tom,

      I seem to remember a *huge* body of literature on this starting back in the 1950s, going through to the 1960s and 1970s. Lots of that literature was done in the limulus but a tremendous amount of psychophysics done in avians, primate and humans as well. Look for work by P Gouras, J. Dowling back in 1960 and others. Other than that, since adaptation is not my area of expertise, I’ll defer to wiser minds on your question.

      Bryan William JonesJune 24, 2011 @ 3:32 pmReply
  2. http://www.birding.com/twilight.asp
    http://consumer.usa.canon.com/app/pdf/binocular/Binoculars-BC.pdf

    How could you explain that ? Does it mean, that detail resolution (and perhaps contrast sensitivity) depends on viewing distance in low light conditions ? Or this is only about magnification of details ? At larger magnification they are simply bigger ?

    And how to derive this equation:
    Twilight Factor = √(binocular entrance pupil × magnification)
    Or maybe it is based only on the intuition ?

    Because this one:
    Relative Brightness Index = (binocular entrance pupil / magnification) ^ 2
    is obvious.

    Thank you in advance.

    P.S.
    And why Square Root Law portion in Fig 12 is not linear ?
    deVries-Rose Law
    delta L / sqrt(L) = K
    Log deltaL = 0.5 Log L + Log K
    Weber’s Law
    delta L / L = K
    Log deltaL = (1) Log L + Log K
    Both plots should be linear in logarithmic scale. But maybe these laws overlap there partially ?

  3. http://www.birding.com/twilight.asp
    http://consumer.usa.canon.com/app/pdf/binocular/Binoculars-BC.pdf

    How could you explain that ? Does it mean, that detail resolution (and perhaps contrast sensitivity) depends on viewing distance in low light conditions ? Or this is only about magnification of details ? At larger magnification they are simply bigger ?

    http://books.google.pl/books?id=7wAAAAAAMBAJ&pg=PA79&lpg=PA79&dq=%22Twilight+Factor%22+backyard+wife&source=bl&ots=1j3SUR_9sA&sig=WfkINtanl9wR2uOYPFgI4f5u-jo&hl=en&ei=eNPPTqKRJsvQ4QSH4Zgy&sa=X&oi=book_result&ct=result&resnum=4&ved=0CDEQ6AEwAw#v=onepage&q=%22Twilight%20Factor%22%20backyard%20wife&f=false
    Popular Science Dec 1976, p 79
    The only explanation I vave found so far is:
    “If you are standing in the backyard at night with your wife and she’s few feet from you (…) you have no difficulty seeing her. But if you move 30 feet away it becomes difficult”
    But this is not proffessional point of view.

    And how to derive this equation:
    Twilight Factor = √(binocular entrance pupil × magnification)
    Or maybe it is based only on the intuition ?

    Because this one:
    Relative Brightness Index = (binocular entrance pupil / magnification) ^ 2
    is obvious.

    Thank you in advance.

    P.S.
    And why Square Root Law portion in Fig 12 is not linear ?
    deVries-Rose Law
    delta L / sqrt(L) = K
    Log deltaL = 0.5 Log L + Log K
    Weber’s Law
    delta L / L = K
    Log deltaL = (1) Log L + Log K
    Both plots should be linear in logarithmic scale. But maybe these laws overlap there partially ?

  4. http://www.birding.com/twilight.asp
    http://consumer.usa.canon.com/app/pdf/binocular/Binoculars-BC.pdf

    How could you explain that ? Does it mean, that detail resolution (and perhaps contrast sensitivity) depends on viewing distance in low light conditions ? Or this is only about magnification of details ? At larger magnification they are simply bigger ?

    The only explanation I vave found so far is:
    http://books.google.pl/books?id=7wAAAAAAMBAJ&pg=PA79&lpg=PA79&dq=%22Twilight+Factor%22+backyard+wife&source=bl&ots=1j3SUR_9sA&sig=WfkINtanl9wR2uOYPFgI4f5u-jo&hl=en&ei=eNPPTqKRJsvQ4QSH4Zgy&sa=X&oi=book_result&ct=result&resnum=4&ved=0CDEQ6AEwAw#v=onepage&q=%22Twilight%20Factor%22%20backyard%20wife&f=false
    Popular Science Dec 1976, p 79
    “If you are standing in the backyard at night with your wife and she’s few feet from you (…) you have no difficulty seeing her. But if you move 30 feet away it becomes difficult”
    But this is not proffessional point of view.

    And how to derive this equation:
    Twilight Factor = √(binocular entrance pupil × magnification)
    Or maybe it is based only on the intuition ?

    Because this one:
    Relative Brightness Index = (binocular entrance pupil / magnification) ^ 2
    is obvious.

    Thank you in advance.

    P.S.
    And why Square Root Law portion in Fig 12 is not linear ?
    deVries-Rose Law
    delta L / sqrt(L) = K
    Log deltaL = 0.5 Log L + Log K
    Weber’s Law
    delta L / L = K
    Log deltaL = (1) Log L + Log K
    Both plots should be linear in logarithmic scale. But maybe these laws overlap there partially ?

  5. One more question. If
    delta L / L were 1 for Weber – Fechner law, what would be corresponding value of K for deVries-Rose Law (causing the same subjective impression of brightness difference in an observers brains, consciousness, soul or however to call it).
    Thank you.

  6. What are the available treatment approaches for a person with problem in adaption especially light adaption?
    (sorry this is a personal question related to problem i face)

    • Hey Shraddha,

      We are testing night vision adaptation in our lab. Are you someone who’s eyes do not adapt in the dark, even after long periods of time? Would be interested to here more..if it is a medical anomaly, we could pay you to come to our lab.

  7. I meant adaptation

  8. The practical solution to light>dark adaptation problem is to minimize the change by wearing sunglasses and to also provide time for the visual system to adapt.

    In the same way, dark>light difficulties can be minimized using sunglasses. Depending upon the cause (often blue-light scatter), sunglasses with short-wavelength cutoff around 500nm are quite useful (they look dark orange/red in colour). Noir have a range of sunglasses prescribed by many clinicians.

    Michael KalloniatisJanuary 20, 2013 @ 9:59 pmReply
  9. Hi, I’d like to ask a perhaps amateur question about the light adaptation. It seems that such an incident often happens in novels: if a person spent too much time in total darkness (like trapped in an underground cave or something), when he finally came out, if he didn’t protect his eyes from the strong sunlight, he might become blind permanently. Is this true in reality?

    • If it were a normal adult, there may be some discomfort for a time, but they would not be blind because they stayed in a cave for a prolonged period of time. They’d also have circadian rhythm issues, but those would resolve within a few days of normal exposure to sunlight as well.

  10. We are conducting electrophysiology studies using harvested fresh mice retina samples on a multi-electrode array. On MEA system, we submerge the retina sample in a perfusion saline solution, which is similar to the artificial CSF solution. Would there be any advantage of the dark adaptation of the animal before sacrifice with regard to the luminal sensitivity of the harvested retina sample on MEA?

    Francis SuhMarch 14, 2013 @ 11:13 pmReply
    • It would depend upon what you are trying to record and how sensitive you need the results to be…

      • We are recording spike signals from the retina sample using multi-electrode array. The MEA is usually used to record the electrical signals mostly coming from RGCs, but can also detect the ERG signals from the entire retina sample. I am wondering whether the luminal sensitivity of the retina sample in vitro would be dependent on the level of dark adaptation of the retina sample.

        Francis SuhMarch 18, 2013 @ 8:44 pmReply
        • Oh, I understand now. Dark adaptation will most certainly play a role in your in vitro recording. The signals that you will record, photopic/scotopic will vary depending upon state or any pharmacological intervention. That research goes back to the late 60’s and early 70’s I believe. Look at Normann or Kaneko in the early 1970’s

  11. A tourism operator here (NZ) is proposing a monorail through a large native forest
    – the train will be moving through dark and light patches of forest at approx 50kmh (14 metres per second).
    – dark patches are around 5% of full sunlight
    – all patches probably have a mean diameter of 200metres, so a patch takes 14 seconds to traverse.

    Surely adaptation time would mean folk will be functionally blind much of the time. No one has raised it in objections to the project (yet). I was hoping to find valid objections to the development (I’m a landscape architect), and then remembered bicycling in Germany, where I was on a very long down-hill with many tunnels (each a 100m long or more) – the overwhelming impression was of being nearly sightless for the whole time (I was probably doing 60-80kmh).

    nigel cowburnSeptember 9, 2013 @ 12:25 pmReply
    • Hey Nigel,

      You have a valid point on this. Full adaptation will take time, particularly if one is going from full light to darkness and the result is that much of the detail in the dark will be missed.

  12. To ilustrate light adaptation, you uses the tvi curve of the rod system, fig 12. I must say that I have
    seen this curve more times in several books. However, as human use the photopic system most of the time,
    I would consider more interesting a photopic tvi curve. Can you provide some reference with a photopic
    tvi curve?, or this topic has no been studied.

  13. The biphasic curve (Fig. 11) shows typical tvi curve extending from the scotopic to the photopic range. WS Stiles is the person who investigated tvi curves and cone only tvi curves have been measured by him try [W. S. Stiles, "Color vision: the approach through increment threshold sensitivity," Proc. Natl. Acad. Sci. USA 45, 100-114 (1959)]; if not cone only curves will likely be found in G. Wyszecki and W. S. Stiles, Color Science text.

    Michael KalloniatisJanuary 27, 2014 @ 1:29 pmReply
  14. I have now gone up the comments and realise that tvi (or increment thresholds) are not what are relevant here. Light adaptation (moving from dark to light) is predominantly neuronal and relatively fast and will not be a major problem. Easily dealt with by putting on a pair of sunglasses. Dark adaptation (moving from bright to dark) is more of concern as the change from light to dark is dependent upon both neural and photochemical changes in the retina. Under most conditions where the visual system still operates within the photopic range, removing a pair of sunglasses will deal with the adaptation problem. The time course of recovery is available for light to dark (as part of dark adaptation curves); the recovery of visual function after a light increment has not attracted much interest as it is so fast to make it practically instantaneous. It is however quite detrimental to people with corneal opacities or cataract who will have major glare issues when going from dark to light.

    Michael KalloniatisJanuary 27, 2014 @ 1:39 pmReply
  15. Thanks very much for your kindly and quick answer, but also for the whole wonderful website.

    Se MonchoJanuary 30, 2014 @ 6:23 amReply
  16. I am researching a completely different subject (in equitation science) but there is a link! Do you know if any research has been carried out looking at whether people percieve broken (i.e. black and white) better or quicker than solid colours?

    Rose ScofieldMarch 28, 2014 @ 10:14 amReply
    • Rose,

      There is a rich field of psychophysics that looks at black and white vs. color. What specifically are you looking for?

      • What I am after is a reference for a peer reviewed paper on visual speed of perception for humans for a black and white object (in my case a black and white horse) versus a solid coloured object.
        Cheers.

        Rose ScofieldMarch 28, 2014 @ 10:50 amReply
  17. You need to look at the suprathreshold reaction time literature: if you use the terms ‘reaction time Harwerth’ you will come up with a number of publications that should guide your search. Ron Harwerth has done a lot of work on reaction time using different size gratings; I am not sure about colour, but someone would have looked at suprathreshold reaction times of coloured spots vs achromatic spots.

    Michael

    Michael KalloniatisMarch 31, 2014 @ 4:52 pmReply
  18. Here are two key references that may also be useful to speed of detection of colored objects:

    1. Hawken, M.J., Gegenfurtner, K.R., and Tang, C. (1994). Contrast dependence of colour and luminance motion mechanisms in human vision. Nature 367, 268–270.

    2. Dougherty RF, Press WA, Wandell BA. Perceived speed of colored stimuli. Neuron. 1999 Dec;24(4):893-9.

    Michael

    Michael KalloniatisMarch 31, 2014 @ 6:25 pmReply
  19. I am curious on how this relates to my own experiences and how to measure it. I’ve camped in parts where I couldn’t see my hand in front of my face (tree canopy blocking moonless star night) but want to equate this to darkness of rooms in my house and figure out a scale.

    Most scales I see are based on spotting stars in the night sky, but I haven’t seen anything with respect to background illumination or human potential.

    Most of my home (open floor plan) is impossible to darken to below my limits of night vision and no adaptation is needed to navigate with lights off.

    However I did an experiment in my bedroom where I covered light sources with foil tape and my vision went from the dim snow you see on old B&W tvs, e.g. able to see room objects, to zero. It was the first time I experienced dark where I saw no noise in years. I was able, after about 30 minutes, to see the shape of the ceiling fan while staring at the ceiling. The only source of light was northern facing windows with pulled shades. I woke later in the night and could make out most room objects. I understand this may be because of Rhodopsin regeneration.

    How do I measure the light level am seeing? I know of no light meter that can read down to these levels. Is there a standardized test?

  20. Hi Scott,

    Our visual system can detect a single quantum of light and reliably detect a light source when about 10 quanta are present (from the classic Hecht et al experiment). I am not sure of any light meter that can do this and infact, Hecht estimated the number of quanta.

    I did some consulting for the police in relation to prosecuting an individual who lasered an aircraft. I had three light meters with me in the flight deck coming into an airport: none gave me a reading yet we could see the city lights in the distance and pilots (and I) could read the instrument panels.

    There may be some more sensitive instruments to the commercial light meters I had but I suspect they are laboratory based and not portable.

    Michael

    Michael KalloniatisAugust 25, 2014 @ 11:23 pmReply



Some HTML is OK

or, reply to this post via trackback.

Continuing the Discussion

  1. [...] Vaikka ihmissilmässä ei ole heijastavaa pintaa, sauvasolumme kehittävät pimeässä näköpurppuraa, joka parantaa pimeänäköä. Näköpurppuran kehittymisessä tosin voi kestää jopa 45 minuuttia, ja yksikin vilkaisu kirkasta valoa kohti riittää hajottamaan jo kertyneen aineen täysin, ja avot: taas ollaan sokeita. -> Eli ei kännykän vilkuilua reitillä tai lähestyvien ajovalojen jäätynyttä tuijottelua (http://webvision.med.utah.edu/book/part-viii-gabac-receptors/light-and-dark-adaptation/). [...]

  2. [...] reading @ Light and Dark Adaptation – Webvision. Light and Dark Adaptation – [...]

  3. [...] in the outer retina. Compared to term infants, preterm infants at term-corrected age have reduced dark-adapted retinal sensitivity, which could be due to reduced availability of [...]

  4. [...] eyes take around 30 minutes to fully adjust to darkness (the reverse process – dark to bright – only takes around 5 minutes). Blocking your [...]

  5. […] vaikutusta pimeäadaptaatioon. Löysin kahden Australiassa vaikuttavan silmämiehen kirjoittaman kirjoituksen, jossa mainitaan niin sanotun esitottumisvalon voimakkuuden ja altistumisajan vaikuttavan pimeään […]

  6. […] what ‘eye adaption to darkness’ is for basic information. Reference : Website – http://webvision.med.utah.edu/book/part-viii-gabac-receptors/light-and-dark-adaptation/ , Youtube video – http://www.youtube.com/watch?v=6lky4H  2. Make a survey to ask people […]

  7. […] what ‘eye adaption to darkness’ is for basic information. Reference : Website – http://webvision.med.utah.edu/book/part-viii-gabac-receptors/light-and-dark-adaptation/ , Youtube video – http://www.youtube.com/watch?v=6lky4H7.Go to the senior library and search […]