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McCollough effect
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{{short description|Human visual perception phenomenon}} {{Multiple issues| {{More citations needed|date=October 2021}} {{Original research|date=October 2021}} }} The '''McCollough effect''' is a phenomenon of human [[visual perception]] in which colorless [[grating]]s appear colored [[Contingent perceptual aftereffect|contingent]] on the [[Orientation (geometry)|orientation]] of the gratings. It is an [[aftereffect]] requiring a period of [[Neural adaptation|induction]] to produce it. For example, if someone alternately looks at a red horizontal grating and a green vertical grating for a few minutes, a black-and-white horizontal grating will then look greenish and a black-and-white vertical grating will then look pinkish. The effect is remarkable because, although it diminishes rapidly with repeated testing, it has been reported to last up to 2.8 months when exposure to testing is limited. The effect was discovered by American psychologist [[Celeste McCollough]] in 1965.<ref name="mccol65">{{cite journal |last=McCollough |first=Celeste |author-link=Celeste McCollough |date=1965-09-03 |title=Color Adaptation of Edge-Detectors in the Human Visual System |journal=[[Science (journal)|Science]] |volume=149 |issue=3688 |pages=1115β1116 |pmid=17737844 |doi=10.1126/science.149.3688.1115 |bibcode=1965Sci...149.1115M |s2cid=29075991 |url=http://people.brandeis.edu/~sekuler/SensoryProcessesMaterial/McColloughArticle1965.pdf |access-date=2018-10-20}}</ref> ==Producing the effect== The effect is inducted by looking at a ''test'' image such as that below. It contains oppositely-oriented gratings of [[Line (mathematics)|lines]], horizontal and vertical. Next, the subject [[staring|stares]] alternately at two ''induction'' images similar to the ones directly beneath the top image. One image should show one orientation of grating (here horizontal) with a colored background (red) and the other should show the other orientation of grating (here vertical) with a different, preferably [[complementary color|oppositely colored]] background (green). Each image should be gazed at by the subject for several seconds at a time, and the two images should be gazed at for a total of several minutes for the effect to become visible. The subject should stare approximately at the center of each image, allowing the eyes to move around a little. After several minutes, the subject should look back to the test image; the gratings should appear tinted by the opposite color to that of the induction gratings (i.e., horizontal should appear greenish and vertical pinkish). {| class="wikitable mw-collapsible mw-collapsed" style="width: 800px;" ! colspan="3" | Test/Induction Images |- |[[File:Red grid for McCollough effect.svg.svg|250x250px]] |[[File:Green grid for McCollough effect.svg|250x250px]] |[[File:Grid for McCollough effect.svg|250x250px]] |- |One induction image for the McCollough effect. Stare at the center of this image for a few seconds, then at the center of the image to the right (with the green background) for a few seconds. Then return to this image. Keep looking between the two colored images for at least three minutes. |A second induction image for the McCollough effect. Stare at the center of this image for a few seconds, then at the center of the image to the left (with the red background) for a few seconds. Then return to this image. Keep looking between the two colored images for at least three minutes. |A test image for the McCollough effect. On first looking at this image, the vertical and horizontal lines should look black and white, colorless. After induction, the space between vertical lines should look red and the space between horizontal lines should look green. |} ==Properties of the McCollough effect== McCollough originally reported that these aftereffects may last for an hour or more.<ref name="mccol65"/> Jones and Holding (1975) found that with repeated testing of the effect, the effect itself diminishes; subjects inducted for 15 minutes and then tested several times over the course of a few days lost the effect within 5 days, but those inducted for the same time but not exposed to testing until 85 days (2.8 months) later retained the effect.<ref name="jones75">{{cite journal |last1=Jones |first1=Paul D. |last2=Holding |first2=Dennis H. |date=1975-12-20 |title=Extremely long-term persistence of the McCollough effect |journal=[[Journal of Experimental Psychology: Human Perception and Performance]] |volume=1 |issue=4 |pages=323β327 |pmid=1185119 |doi=10.1037/0096-1523.1.4.323}}</ref> The effect is different from colored [[afterimage]]s, which appear superimposed on whatever is seen and which are quite brief. It depends on retinal orientation (tilting the head to the side by 45 degrees makes the colors in the above example disappear; tilting the head by 90 degrees makes the colors reappear such that the gravitationally vertical grating now looks green). Multiple effects can be stacked by inducting with multiple sets of grids. A set of horizontal and vertical induction grids and a separate set of opposing diagonal induction grids will produce two distinct afterimages when a black and white grid is held normally, and at 45 degrees. The number of different orientations that can be stacked is unknown. As well, inducing the effect with one eye leads to no effect being seen with the other eye. However, there is some evidence of binocular interactions.<ref name="white78">{{cite journal |last1=White |first1=K. D. |last2=Petry |first2=H. M. |last3=Riggs |first3=L. A. |last4=Miller |first4=J. |date=1978-10-20 |title=Binocular interactions during establishment of McCollough effects |journal=[[Vision Research]] |volume=18 |issue=9 |pages=1201β1215 |doi=10.1016/0042-6989(78)90105-0 |pmid=716240|s2cid=40072550 }}</ref> Any aftereffect requires a period of induction (or [[Neural adaptation|adaptation]]) with an ''induction stimulus'' (or, in the case of the McCollough effect, ''induction stimuli''). It then requires a ''test stimulus'' on which the aftereffect can be seen. In the McCollough effect as described above, the induction stimuli are the red horizontal grating and the green vertical grating. A typical test stimulus might show adjacent patches of black-and-white vertical and horizontal gratings (as above). The McCollough-effect colors are less [[saturation (color theory)|saturated]] than the induction colors. The induction stimuli can have any different colors. The effect is strongest, however, when the colors are [[complementary color|complementary]], such as red and green, or blue and orange. A related version of the McCollough effect also occurs with a single color and orientation. For example, induction with only a red horizontal grating makes a black-and-white horizontal test grating appear greenish whereas a black-and-white vertical test grating appears colorless (although there is some argument about that). Stromeyer (1978) called these ''non-redundant'' effects. According to him, the classic effect with induction from two different orientations and colors simply makes the illusory colors more noticeable via [[contrast effect|contrast]]. The effect is specific to the region of the retina that is exposed to the induction stimuli. This has been shown by inducing opposite effects in adjacent regions of the retina (i.e., from one region of the retina verticals appear pink and horizontals appear greenish; from an adjacent region of the retina, verticals appear greenish and horizontals appear pink). Nevertheless, if a small region of the retina is exposed to the induction stimuli, and the test contours run through this region, the effect spreads along those test contours. Of course, if the induced area is in the [[Fovea centralis|fovea]] (central vision) and the eyes are allowed to move, then the effect will appear everywhere in the visual scene visited by the fovea. The effect is also optimal when the thickness of the bars in the induction stimulus matches that of those in the test stimulus (i.e., the effect is tuned, albeit broadly, to [[spatial frequency]]). This property led to non-redundant effects being reported by people who had used [[computer monitor]]s with uniformly colored [[phosphor]]s to do [[word processing]]. These monitors were popular in the 1980s, and commonly showed text as green on black. People noticed later when reading text of the same spatial frequency, such as in a book, that it looked pink. Also, a horizontal grating of the same spatial frequency as the horizontal lines of the induction text (such as the horizontal stripes on the letters "IBM" on the envelope for early [[floppy disk]]s) looked pink. A variety of similar aftereffects have been discovered not only between pattern and color contingencies, but between movement/color, spatial frequency/color and other relationships. All such effects may be referred to as McCollough Effects or MEs.<ref name="dodwell90">{{cite journal |last1=Dodwell |first1=Peter C. |last2=Humphrey |first2=G. Keith |date=1990-10-20 |title=A functional theory of the McCollough effect |journal=[[Psychological Review]] |volume=97 |issue=1 |pages=78β79 |pmid=2408090 |doi=10.1037/0033-295X.97.1.78}}</ref> ==Explanations== McCollough's paper has sparked hundreds of other scientific papers.<ref name="mccol00">{{cite journal |last=McCollough |first=C. |year=2000 |title=Do McCollough effects provide evidence for global pattern processing? |journal=Perception & Psychophysics |volume=62 |issue=2 |pages=350β362 |doi=10.3758/bf03205555|pmid=10723214 |doi-access=free }}</ref><ref name="strom78">{{cite journal |last=Stromeyer |first=C.F. |year=1978 |title=Color aftereffects dependent on form |editor1-first=R. |editor1-last=Held |editor2-first=H.W. |editor2-last=Leibowitz |editor3-first=H.L. |editor3-last=Teuber |journal=Handbook of Sensory Physiology: Perception |location=Berlin |publisher=Springer-Verlag|doi=10.1007/978-3-642-46354-9_4 }}</ref> Explanations appear to fall into three camps.<ref name="mccol65"/><ref name="dodwell90"/><ref name="allan98">{{cite journal |last1=Allan |first1=Lorraine G. |last2=Siegel |first2=Shepard |year=1998 |title=Learning and Homeostasis: Drug Addiction and the McCollough Effect |journal=[[Psychological Bulletin]] |volume=124 |issue=2 |pages=230β239 |url=https://sites.oxy.edu/clint/learn/articles/learningandhomeostasisdrugaddiction.pdf |access-date=2018-10-20 |doi=10.1037/0033-2909.124.2.230 |pmid=9747187 |archive-date=2021-09-14 |archive-url=https://web.archive.org/web/20210914212444/https://sites.oxy.edu/clint/learn/articles/learningandhomeostasisdrugaddiction.pdf |url-status=dead }}</ref> * McCollough indicated color adaptation of edge sensitive neurons in lower, [[monocular]] regions of the [[visual cortex]].<ref name="mccol65"/> * A [[wikt:functional|functional]] explanation of MEs has been posited in the form of an error-correcting device (ECD) whose purpose is to maintain an accurate internal representation of the external world. Consistent pairings of color and oriented lines are not found frequently in natural environments, thus consistent pairing may indicate pathology of the eye. An ECD might compensate for such [[pathology]] by adjusting the appropriate [[neurons]] to a neutral point in adaptation to orientation contingent color.<ref name="dodwell90"/> * A third explanation points to the contribution of [[classical conditioning]] to normal homeostatic regulation. MEs are explained by the same mechanisms as pharmacological [[withdrawal symptoms]], thus the "pharmacological CR is expressed as pharmacological adaptation (tolerance) in the presence of the drug, and withdrawal symptoms in the absence of the drug" and the "chromatic CR is expressed as chromatic adaptation in the presence of colour, and the ME in the absence of colour".<ref name="allan98"/> By this account MEs are of no adaptive value, but have been selected for as a domain-general ability to anticipate events.<ref name="allan98"/> This is related to [[opponent-process theory]]. These theories are not targeted toward the anti-McCollough effect.<ref name="sheth08">{{cite journal |last1=Sheth |first1=B. |last2=Shimojo |first2=S. |year=2008 |title=Adapting to an aftereffect |journal=[[Journal of Vision]] |volume=29 |issue=3 |pages=1β10|pmid=18484835 |doi=10.1167/8.3.29 |doi-access=free }}</ref> Neurophysiological explanations of the effect have variously pointed to the adaptation of cells in the [[lateral geniculate nucleus]] designed to correct for [[chromatic aberration]] of the eye, to adaptation of cells in the [[visual cortex]] jointly responsive to color and orientation (this was McCollough's explanation) such as monocular areas of cortical hypercolumns, to processing within higher centers of the brain (including the frontal lobes<ref name="barnes99">{{cite journal |first1=J. |last1=Barnes |first2=R.J. |last2=Howard |first3=C. |last3=Senior |first4=M.J. |last4=Brammer |first5=E.T. |last5=Bullmore |author5-link=Edward Bullmore |first6=A. |last6=Simmons |first7=A.S. |last7=David |year=1999 |title=Brain imaging: The functional anatomy of the McCollough contingent color after-effect |journal=[[NeuroReport]] |volume=10 |issue=1 |pages=195β199 |doi=10.1097/00001756-199901180-00037|pmid=10094161 }}</ref>), and to [[learning]] and [[memory]]. In 2006, the explanation of the effect was still the subject of debate, although there was a consensus in favor of McCollough's original explanation. MEs do not transfer interocularly<ref name="mccol65"/><ref name="allan91">{{cite journal |last1=Allan |first1=Lorraine G. |last2=Siegel |first2=Shepard |last3=Toppan |first3=P. |year=1991 |title=Assessment of the McCollough effect by a shift in the psychometric function |journal=[[Psychonomic Society|Bulletin of the Psychonomic Society]] |volume=29 |pages=21β24 |doi=10.3758/bf03334757|doi-access=free }}</ref> and from this it seems reasonable to deduce that the effect occurs in an area of the visual system prior to V1-4B, where binocular cells first occur. == The anti-McCollough effect{{anchor|The Anti-McCollough Effect}} == In 2008, a similar effect with different results was discovered, and has been termed the "anti-McCollough effect".<ref name="sheth08"/> This effect may be induced by alternating pairings of gratings in parallel alignment, one achromatic (black and white) and the other black and a single color (say black and red). If the color used was red, then after the induction phase the achromatic grating appeared slightly red. This effect is distinct from the classical effect in three important regards: the perceived color of the aftereffect is the same as the inducer's color, the perceived color of the aftereffect is weaker than the classical effect, and the aftereffect shows complete [[interocular transfer]]. Like the classic effect, the anti-McCollough effect (AME) is long lasting. {| class="wikitable mw-collapsible mw-collapsed" style="width: 800px;" ! colspan="3" | Test/Induction Images |- |[[File:Red grid for McCollough effect.svg.svg|250x250px]] |[[File:Gray grid for anti-McCollough effect.svg|250x250px]] |[[File:Grid for McCollough effect.svg|250x250px]] |- |One induction image for the anti-McCollough effect. Stare at the center of this image for 10 seconds, then at the center of the image to the right for 10 seconds. Then return to this image. Keep looking between the two colored images for 20 minutes. |One induction image for the anti-McCollough effect. Stare at the center of this image for 10 seconds, then at the center of the image to the left for 10 seconds. Then return to this image. Keep looking between the two colored images for 20 minutes. |A test image for the anti-McCollough effect. On first looking at this image, the vertical and horizontal lines should look black and white, colorless. After induction, the space between vertical lines should look '''green''' and the space between horizontal lines should look '''red'''. |} Given that AMEs do transfer interocularly,<ref name="sheth08"/> it is reasonable to suppose that they must occur in higher, binocular regions of the brain. Despite producing a less saturated illusory color, the induction of an AME may override a previously induced ME, providing additional weight to the argument that AMEs occur in the higher visual areas than MEs.<ref name="sheth08"/> Explanations of the effect by adaptation of edge-detectors,<ref name="mccol65"/> functional ECDs,<ref name="dodwell90"/> and classical conditioning<ref name="allan98"/> are compelling but may have to be adjusted for the inclusion of AMEs, if the AME can be shown to replicate by independent labs.<ref name="robinson11">{{cite journal |last1=Robinson |first1=A.E. |last2=Weiss |first2=E. |last3=de Sa |first3=V.R. |year=2011 |title=Temporal sequence and contingent adaptation: A failure to replicate the anti-McCollough effect}} -- Poster presented at the Temporal Dynamics of Learning All Hands Meeting, San Diego, CA.</ref> ==See also== * [[Optical illusion]] * [[Visual perception]] * [[Color vision]] ==References== {{reflist}} ==External links== * [http://lite.bu.edu/vision-flash10/applets/Color/McCollough/McCollough.html The McCollough Effect at Project LITE] {{Webarchive|url=https://web.archive.org/web/20150515195250/http://lite.bu.edu/vision-flash10/applets/Color/McCollough/McCollough.html |date=2015-05-15 }} * [http://www.cheswick.com/ches/projects/me/index.html The McCollough Effect β An On-line Science Exhibit] {{Optical illusions}} [[Category:Optical illusions]] [[Category:1965 introductions]]
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