[visionlist] [cvnet] Third-eye rivalry?
liul7788 at uab.edu
Fri Sep 20 02:42:51 -04 2019
The Third-eye rivalry is yet another demonstration of the set of laws (propositions) about monocular and binocular visual directions, first proposed by William Charles Wells in 1792 and later publicized by Ewald Hering (1879, 1942). Hiroshi Ono had a very nice review of these laws (Ono, H. Perception & Psychophysics, 1981, 30(4) 403-406). In the center of these laws is the proposition that normal binocular visual directions are originated from neither the left nor the right eye, but from an imaginary Cyclopian eye.
"Let us imagine instead of two eyes, one eye lying in the middle between the two real eyes, and the images of both retinas so transferred to the retina of this single eye that the images will bear the same relation to the vertical and horizontal mid sections of this retina, .... Then the direction lines of this imaginary single eye would be approximately the visual directions (when both eyes are open). This imaginary single eye is known as the Cyclopian eye" (Hering, E. Spatial sense and movement of the eye, The American Academy of Optometry, Baltimore, 1942, pp 43).
One of the laws directly related to the third eye rivalry states that "Objects situated in the Optic Axis (should be the fovea) do not appear to be in that Line (visual direction in that eye), but in the Common Axis (the fovea of the Cyclopian eye)". Ono's review showed a popular demonstration of this law. One makes a mark on a pane of glass, lines up the left eye with this mark and a distant object, for example, a house then lines up the right eye with the same mark and another distance object, for example, a tree. The mark on the glass serves to cross the eyes in front of the house and the tree. The percept is one tree on the left, one house on the right and a tree AND a house straight ahead, occupying the same visual direction and alternating (rivalry). Because the house and the tree fall on the foveas of the left and right eyes, they should appear in the common axis of the Cyclopian eye, according to Wells' proposition (Hering's law), and they do. There are several simple demonstrations of cardboard and strings that we use to teach these laws to our professional students. The third eye rivalry can be a new addition to our class demos. :)
A note. In Nepal, where the majority of the population is Buddhist, one can find everywhere illustrations of two eyes with a curly symbol in between (Google "Buddha's all seeing eye"). This symbol is the Nepali character for the number 1, symbolizing the all-seeing eye of the Buddha. The saying goes that ordinary people only use their two physical eyes to see the physical world but the Buddha can see through the third, wisdom eye, all the truth behind the physical world. I guess the truth consists of harmony (stereopsis) and dissonance (rivalry).
Lei Liu, PhD
School of Optometry
University of Alabama at Birmingham
From: visionlist <visionlist-bounces at visionscience.com> On Behalf Of Prof. Dr. Wolfgang Fink
Sent: Thursday, September 19, 2019 3:13 AM
To: Regan Gallagher <regan.gallagher at monash.edu>; Nao Tsuchiya <naotsugu.tsuchiya at monash.edu>
Cc: Ishan Singhal <ishan.s at cbcs.ac.in>; cvnet at mail.ewind.com; visionlist at visionscience.com
Subject: Re: [visionlist] [cvnet] Third-eye rivalry?
For the phenomenon of the "third eye" please see, for example:
"imaginäres Deckauge" after Hering ~1861 or 1879
"Zyklopenauge" after Helmholtz
For both of the above, see for example pages 892 and 893:
or even much earlier:
"Horopter" after Franciscus Aguilonius, 1613:
Aguilonii, F.: e Societate Iesv Opticorvm libri sex. Plantin, Antverpiae 1613, page 111
Here is a link to Aguilonius' book: https://archive.org/stream/opticorumlibrise00agui#page/110/mode/2up
See the diagram in the upper right corner on page 111.
Prof. Dr. Wolfgang Fink, Fellow AIMBE, PHM, daVinci (UA), ACABI (UA)
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On Sep 18, 2019, at 11:05, Andrew Parker wrote:
Dear Ishan Singhal
Thank you so much for these very significant and insightful comments. I am sure it is not helpful to link a simple perceptual phenomenon with the complex structure of thought that surrounds the mythological aspects of the third eye in diverse cultures.
Sent from my iPhone
On 18 Sep 2019, at 19:10, Ishan Singhal <ishan.s at cbcs.ac.in<mailto:ishan.s at cbcs.ac.in>> wrote:
Greetings Dr. Gallagher,
Let me first congratulate you on your discovery. Not only is it easily reproducible by your instructions, but it is also immediately visible. Such strong illusions will grant the future readers of your paper great ease of relating phenomenologically.
However, I don't quite see any relation of it to Eastern spiritual mythology (specifically Hinduism and or Buddhism). While yes, on the surface there is talk of a third eye in both these spiritual/philosophical schools, however the relation to this illusion I feel might be overstated and spurious. First of all, the third eye of Shiva is depicted as rotated 90 degrees and situated "vertically" between the two eyes. A common custom in Hinduism involves putting a "tilaka<https://en.wikipedia.org/wiki/Tilaka>" to symbolize one's third eye, this too is shaped like an eye rotated 90 degrees. See here<https://www.google.co.in/search?biw=1536&bih=702&tbm=isch&sa=1&ei=mVeCXYjjOofOvgTG1JWIAg&q=shiva+third+eye&oq=shiva+third+eye&gs_l=img.3...98632.100769..100990...0.0..0.0.0.......0....1..gws-wiz-img.oj73OeiK8Lk&ved=0ahUKEwjIk8Tp4drkAhUHp48KHUZqBSEQ4dUDCAY&uact=5> and here.<https://en.wikipedia.org/wiki/Third_eye#/media/File:Shiva_Mus%C3%A9e_Guimet_22971.jpg>
In Buddhism the depictions of the third eye are usually by a circular dot. Debates about it's origins are two-fold. One, that they adopted the Yoga schools' ideas of a "third eye chakra" (many depictions show a spiraling circle, another word for such a figure in Sanskirt is "chakra") or the second more likely origin story of the dot depicting the focal location of meditation. Usually, a point is chosen to focus attention during closed eye mindfulness meditation. Buddhist practices include focusing on either breath, the touch of the breath as it leaves the nostrils or on the gap (near the forehead) between the eyes.
Finally, both Shiva and Buddha, in their respective stories, get enlightened with eyes closed meditation. And there are a lot of metaphorical claims about third eyes in both these spiritual practices, none of which seem perceptual or phenomenological.
As novel and wonderfully strong your discovery is, any claims of relating it to Eastern thought are unwarranted. To summarize this view 1) The way in which the third eye is depicted in historical texts, statues, idols and paintings are not how we see the "third eye" in your illusion. 2) This is further shown by how Hindus put tilaka. 3) Buddhists depict third eyes with a dot, specifying location of focus. 4) "Opening third eye" in both these cultures is a focused meditation and mindfulness based practice, almost always done with eyes closed. 5) Both these Gods (Shiva and Buddha) achieved access to third eye through eyes closed meditation. Even in the figures of your pre-print, Shiva's eye is shown rotated 90 degrees, while the one of Buddha seems like a contemporary artistic rendition and not based on original depictions.
I write to you with an urgent request to avoid unnecessarily evoking Eastern thought, because this dilutes the impact of attempts which necessitate reference to Eastern thought.
Centre of Behavioural and Cognitive Sciences
University of Allahabad
On Wed, Sep 18, 2019 at 8:23 PM Regan Gallagher <regan.gallagher at monash.edu<mailto:regan.gallagher at monash.edu>> wrote:
Thank you to those who made contact with us and pointed us to relevant literature and demonstrations. It appears that the Third-eye rivalry effect hasn't been reported so far in the scientific literature. For those interested, we have uploaded a quick summary and pre-print detailing our discovery.
See a lay description here: https://link.growkudos.com/1kacuq5pqm8
For the pre-print see here: https://psyarxiv.com/9p6da/
As before, any comments, critiques, or relevant literature are very welcome.
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