Talk:Contrast effect

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Untitled[edit]

6/17/2006 -- I'm the original poster of Contrast Effect. Thanks to those who corrected my spelling and other embarassments. However, the successive attempts to improve the definition of "normal" started to violate the basic structure of a proper abstract definition that separates the definition from specific examples and the examples given were compromising the generality of the original definition.

To wit: "(In this definition a "normal" perception is one free of immediate related context, greater or lesser, more appealing or less appealing.)"

First, there can never be a perception that is "free of immediate related context". All experience and performance have contexts and to suppose that a condition could be free of all immediate related context is confusing and supposes something extremely unlikely. Second, the basic definition carefully includes both perception and performance to cover the broad range of empirical observations in which contrast has been implicated, but the added supplemental definition of normal refers only to perception. Third, the insertion of "greater or lesser, more appealing or less appealing" is to insert examples into the abstract definition and confound that definition as I mentioned above. That's what the example paragraph does and it's unnecessary to redundantly insert them into the abstract definition.

My compromise with the urge to clarify is "(Here, normal perception or performance is that which would obtain in the absence of the comparison stimulus - i.e., one based on all previous experience.). I hope it scratches the itch without the messiness mentioned. Again, thanks for the corrections, but please study all implications of your suggested changes before posting.

Additionally, thanks for removing "Psychological theories" as a reference category. For others, a contrast effect is an empirical phenomenon that theories are designed to explain and is not, itself, a theory. There may be "theories of contrast" or "theories based on contrast", but this page is about the empirical phenomenon and it's ubiquity.

7/14/2007 -- I think this is a good article, but I have some trouble understanding the relevance of the second example (the one with the four circles). In my humble opinion, I do not see how it is an example of a cognitive bias, because the effect occurs in our eye, not in our brain. Our brain does not change its perception, the eye is making the illusion.

Maybe I am confused because I followed from the "list of cognitive biases" article.

Deersdrinkbeer 17:27, 14 July 2007 (UTC)

WikiProject class rating[edit]

This article was automatically assessed because at least one WikiProject had rated the article as stub, and the rating on other projects was brought up to Stub class. BetacommandBot 03:52, 10 November 2007 (UTC)

3/1/2008 -- Original poster here again... I did not insert the sections on simultaneous and successive contrasts at the bottom of the page. Those were added by another party and I recommend that someone more adept at Wikipedia editing than I - remove them from this page. I am uncomfortable with their presence on the same page for several reasons. They fall back into the habit that I warned against above in confusing definitions and examples. That is, by their titles, they imply that they are definitions of simultaneous contrast and successive contrast when they are not - they are only one example each of a very specific visual effect (and the second, while a successive effect to be sure, is not even a contrast effect in the sense defined here. It may be remotely related to "color contrast" by the hue of the illusion, but not the contrast effect being described on this page). Even if the second were a contrast effect and both were more properly labeled (e. g., "Simultaneous Visual Contrast Example" etc.), they would illustrate only one each (visual perceptions) of a wide range of simultaneous and successive effects and create the mis-perception that simultaneous and successive contrast effects have only to do with visual-perceptual effects. A long list of other sensory (e. g. tactile, auditory, olfactory etc), cognitive and performance examples of contrast effect would be required for a balanced presentation of examples. Again, the whole point of the page is to stress the ubiquity of the phenomenon of contrast effect and grasping on to a single narrow example - to give a false sense of understanding - defeats that purpose. Someone, please remove those examples to a more appropriate page.

Regarding the 7/14/2007 comment above about cognitive bias and the second visual example being an ocular/retinal (v. cognitive) effect: See my comment above about the second visual example. I agree that the visual examples don't belong on this page. However, in any case and as I discussed in my first post, the contrast effects being described on this page are empirical phenomena (i. e., without necessary reference to causal or theorized causal mechanism(s) be they eye, ear, muscular feedback, or brain). Digression: If we were discussing causal mechanisms regarding vision, I would say that the current conceptualization of seeing or vision (and thus, perception and perceptual "illusion") is that it is a function performed more actively by the brain than passively by the "eye" (older and wiser folk have always viewed the eye as only an outgrowth of the brain to provide fuzzy input, but that's a different thread). Further, contrary to older conceptualizations that limited vision to the eye, nuclei and occipital lobe, more recent brain studies indicate that substantially larger portions of the human brain - up to 1/3 - are directly involved in "creating" our vision. That is, our eyes and neural circuitry don't "see" passively, but instead, the brain actively creates most of the visual world we perceive from past impressions stored in and beyond the occipital lobe while the eyes provide relatively sparse cues which (with some processing) elicit a correct enough representation (hopefully) of the reality before us. From this POV, the objective of vision is to actively create and project a full and accurate representation or "visual understanding" of the world (dreams are the projection going on without guidance or tracking from the closed eyes, other senses, or conscious control) and "illusions" are not illusions or errors of visual judgment, but our brain interpreting the sparse input of the eye in a way that makes the most sense in the most number of cases. So, you may be right in asserting that the color illusion in the second example is wholly a function of the "eye" (cone-pigment bleaching or retinal neural fatigue? - I don't know but, likely, someone does}, but I would speculate that there is a "cognitive" component to it and, possibly, a substantial one.

I don't know anything about this phenomenon: I restored the text because the above IP deleted it without giving a reason. It doesn't matter who adds or deletes text: it stands or falls on its merits. Someone please source this, or let's have discussion between people who know what this page is talking about. Nyttend (talk) 23:17, 5 April 2008 (UTC)

Original poster again - regarding immediately preceding post. If you don't know anything about this phenomenon, then don't go restoring text that I have deleted. I explained clearly in my posts above why it didn't fit and why it should be removed. As no one did that, I went ahead and did the deletion with the above rationale for that removal. If you don't understand the phenomenon and the rationale for removing the text, then you are incapable of "judging it on its merits" and you wouldn't understand "a discussion between people who know what's this page is talking about" (I have advanced degrees in this area of science and 35 years research experience - I know what I'm talking about). So quit insisting on having the rationale for removal in exactly the right spot. Remove the text and relocate it to some other page without a confusing name - or I will remove it again, and I won't relocate the deleted text. —Preceding unsigned comment added by 76.88.6.7 (talk) 07:51, 10 August 2008 (UTC)

Text in Wikipedia should be able to stand on its own feet. If someone with no knowledge of a topic cannot understand an article then it is the article that should be changed. Perhaps some of the elaboration in these discussion pages could be added to the article. And if an editor is going to use his or her credentials to justify certain edits, then I think readers should know who that editor is, so they can assess these credentials. That means signing posts and using a Wikipedia name that allows readers to find out who the editor really is. Robert P. O'Shea (talk) 05:53, 13 September 2008 (UTC)

Original author again... "If someone with no knowledge of a topic cannot understand an article then it is the article that should be changed." What? People should come here to learn, not inflict their ignorance on the enterprise. The lack of action on my previous discussion entries (for many months now) are what is wrong with Wikipedia. Please read my arguments there (that stand on their own feet, btw) for removing all after the first two paragraphs - the specific visual "examples" - to a different page entitled "VISUAL CONTRAST EFFECTS" as they undermine the definition of the general effect which goes far beyond narrowly conceived exemplars of that effect - e. g. to behavioral contrast effect, tactile contrast effect, etc. As the page stands now, "Simultaneous Contrast" and "Successive Contrast" are ERRONEOUSLY identified as visual contrast effects when, in fact, simultaneous and successive contrast are generic descriptors of experimental manipulations and resultant effects in not only the other senses in addition to vision but in general behavior as well. THAT IS THE WHOLE POINT OF THE CONCEPT - I. E., TO EMPHASIZE AN IMPORTANT AND GENERAL FEATURE OF NERVOUS SYSTEMS AND NOT TO BE SIDETRACKED WITH SPECIFIC EXAMPLES OF SAME AND LED TO BELIEVE THAT THOSE ARE ALL THERE IS TO IT. It's called "science". To be edited and talked down by people who can only cut-and-paste without broader knowledge of the subject dampens any motivation to contribute to Wikipedia in the future or to refer to it for any authoritative information.

I'll make it easier still. Delete my first two paragraphs, relabel the topic any way you see fit (or don't), and then, visitors to Wikipedia can get a nice friendly lamed-down definition of this topic too. Happy now? —Preceding unsigned comment added by 76.88.4.187 (talk) 19:01, 30 May 2009 (UTC)

Successive contrast[edit]

I too, did not experience the demonstration as it was originally worded. When I looked at upper disks then shifted my attention, without moving my eyes, to the lower disks, I experienced the lower disks as the same colour. What I did see was that occasionally one of the lower disks disappeared, an example of the Troxler effect. I reworded the instructions to yield a perceptual experience that accords with that claimed, but I suspect this is not what the original editor had in mind. There is certainly a simple explanation of the perceptual effect involving afterimages. Robert P. O'Shea (talk) 06:00, 13 September 2008 (UTC)

Contrast effect, neural adaptation, and hot/cold/lukewarm water experiment.[edit]

How is the contrast effect related to neural adaptation? Consider this experiment:

Have three buckets of water, one hot, one cold, and one lukewarm. Place one hand in the hot water and one in the cold water, and wait for three minutes. Then place both hands in the lukewarm water. The hand previously in hot water will feel cold, and the hand previously in cold water will feel hot, even though they are both in the same temperature water.

Is this the contrast effect, neural adaptation, or both? —Preceding unsigned comment added by 192.171.3.126 (talk) 12:31, 5 January 2011 (UTC)

It's both. Contrast effect is the effect on perception. Neural adaption is the mechanism by which it occurs. MartinPoulter (talk) 23:22, 4 September 2013 (UTC)


I had a similar question, since the images presented reminded me of what happens when one takes off amber sunglasses and the world looks blue. After some Googling, it seems like that's due to the afterimage effect. Is there a major difference here, or are they all part of the same phenomenon? Daemon328 (talk) 00:16, 30 October 2015 (UTC)

Assessment comment[edit]

The comment(s) below were originally left at Talk:Contrast effect/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.

merge to Contrast (vision)

Substituted at 00:58, 12 June 2016 (UTC)