Talk:Saccade

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Comments
Changed rotational velocity based on http://www.cns.nyu.edu/~glimcher/PUBLICATIONS/abstracts/mitecs.html


 * Right now, article (and that ref above) suggests max velocity 1000 degrees/second. Brazis suggests that the maximal angular velocity achieved in long saccades is 700 degrees per second (see PPRF for complete reference).  Does anyone know which is correct?  I lean towards Brazis in most cases. -Ikkyu2 22:04, 28 January 2006 (UTC)

repetition error
"The duration of a saccade depends on its amplitude. The amplitude of a saccade is the angular distance that the eye needs to travel during the movement. For amplitudes up to about 60 degrees, the duration of a saccade linearly depends on the amplitude. In that range, the peak velocity of a saccade linearly depends on the amplitude." revphil 69.30.67.169 17:29, 25 July 2006 (UTC)

doesn't make sense
"The duration of a saccade depends on its amplitude. The amplitude of a saccade is the angular distance that the eye needs to travel during the movement. For amplitudes up to about 60 degrees, the duration of a saccade linearly depends on the amplitude. In that range, the peak velocity of a saccade linearly depends on the amplitude. In saccades larger than 60 degrees, the peak velocity remains constant at the maximum velocity attainable by the eye. Thus, the duration of these large saccades is no longer linearly dependent on the amplitude.

I'm confused about this section. If the peak velocity depends on the amplitude, then how is it that the duration of the saccade scales linearly with amplitude? For constant acceleration, one expects the duration to scale like the root of the amplitude. Also, if the peak velocity is constant (as it is for large amplitude excursions), one expects duration to scale linearly with amplitude. —The preceding unsigned comment was added by 205.175.123.22 (talk) 20:04, 10 April 2007 (UTC).

Amplitude to Peak-Velocity Relationship is Curvilinear
Bronstein and Kennard (1987) show data that supports a curvilinear relationship between saccade amplitude and saccade peak-velocity. Reference: Bronstein, A. M. & Kennard, C. (1987). Predictive eye saccades are different from visually triggered saccades. Vision Research, 27(4), 517-520. —Preceding unsigned comment added by David Hardwick (talk • contribs) 02:01, 17 August 2008 (UTC)

^^Agree with above^^
Amplitude vs Peak Velocity follows a logarithmic regression line. The relationship between Amplitude and Duration is linear.128.252.37.72 (talk) 22:34, 28 June 2010 (UTC)

Amplitude to Peak-Velocity Relationship is Curvilinear - true but...
Added the part on the main sequence. Also added the original references for main sequence computation. Bahill stated that it is in fact linear for amplitude up to 20° after which it saturates (due to reaching maximum possible angular peak velocity; see also Carpenters famous Book "Movements of the eyes"). Bahill stated the inverse power law function for computation of main sequence relationships over large amplitude ranges. Don't know if we should all fit that into the article... — Preceding unsigned comment added by InkassoSchroeder (talk • contribs) 16:42, 21 January 2015 (UTC)

Police use of saccades for roadside sobriety tests
(I hope someone will "wikify" this comment for me!) I wonder if anyone knows more about this than I do - I once read that the "follow the light with your eyes" test performed (at least in the US) in roadside sobriety tests is actually to observe the changes brought about in saccade increments (ie, how many degrees in each jump) by the drying of bodily tissues due to alcohol consumption? If they do, it would be a great addition to this article, I think. human 23:32, 10 October 2005 (UTC)
 * They're looking for ocular dysmetria and nystagmus, effects of alcohol on the flocconodular lobe of the cerebellum. Ocular dysmetria is obviously saccade-related.  -Ikkyu2 22:04, 28 January 2006 (UTC)

Maybe we should add some...
I don't know anything about wikifying the subject or anything about saccade, but I noticed in the first paragraph they say that saccades can be in the eyes, head, or other part of the body or of device, but in the article they only talk about a saccade of the eye. It is all very interesting, but needs some more about the other kinds.

Merge Saccadic movement into this article?
Since the article Saccade specifically mentions saccadic eye movements I think that article Saccadic movement should be merged into this, with a redirect for Saccadic movement. Shenme 20:41, 30 December 2005 (UTC)
 * This is the entire text of Saccadic movement. I'd've merged it, but I'm not sure how best to incorporate it, or if it's necessary.  I'm just redirecting it now.
 * Saccadic movement is the act of quickly placing an object within view on the fovea, the central part of the retina.
 * NickelShoe 18:34, 10 January 2006 (UTC)

Comparative physiology
I thought I'd add a note on the following, which made the front cover of Nature 15 years ago: Nature. 1990 Jan 25;343(6256):362-3. Needs formatting.

Saccadic oscillations facilitate ocular perfusion from the avian pecten.

Pettigrew JD, Wallman J, Wildsoet CF.

THE evolution of the eye is constrained by two conflicting requirements--good vascular perfusion of the retina, and an optical path through the retina that is unobstructed by blood vessels. Birds are interesting in that they have higher metabolic rates and thicker retinas than mammals, but have no retinal blood vessels. Nutrients and oxygen must thus reach the neurons of the inner retina either from the choroid through 300 micron of metabolically very active retina, or from the pecten, a pleated vascular structure protruding from the head of the optic nerve into the vitreous chamber, and more than a centimetre away from some retinal neurons. Despite the diffusional distance involved, several lines of evidence indicate that the pecten is the primary source of nutrients for the inner retina: the presence of an oxygen gradient from pecten to retina, the large surface area produced by macroscopic folds and by microscopic infoldings of the luminal and external surfaces of the capillary endothelium, extrusion of circulating fluorescein, high content of carbonic anhydrase and alkaline phosphatase, and retinal impairments after pecten ablation. Another peculiarity of birds, their saccadic oscillations, occur with a large cyclotor-sional component during every saccadic eye movement. In different species, saccades, which occur at intervals of 0.5-40 s, have up to 13 oscillations with frequencies of 15-30 Hz and amplia-tudes of about 10 degrees. Therefore, as much as 12% of some birds' total viewing time may be subject to the image instability caused by the oscillations. Using fluorescein angiography, we show here that during every saccade, the pecten acts as an agitator which propels perfusate towards the central retina much more effectively than is observed during intersaccadic intervals. Jellytussle 03:49, 5 January 2006 (UTC)

Shift in frequency definition
I've never heard, nor have a handful of dictionaries, of saccade meaning a shift in frequency -- could it be sourced? -- Metahacker 18:10, 11 July 2006 (UTC)

Purpose of microsaccades?
This article mentions microsaccades (and links to the microsaccades article). This article states that without microsaccades, the image would fade quickly. However, the microsaccade article says that their purpose is still "highly debated", and the article presents a couple of different possibilities. Should the wording in this article be toned down? - netjeff 00:23, 9 September 2006 (UTC)

Functions of fixational saccades, also called microsaccades, are indeed under intense investigation and highly debated. However, I believe that "microsaccades" mentioned in this article are in fact referring to ocular microtremor (see Ocular_microtremor) and thus have to be renamed accordingly.

- Mucioh 02:24, 9 July 2007 (UTC)

How to relate to the average Wikipedian?
I agree that this is an interesting article that deserves more explanation. I'm wondering what happens / how long it takes for my eye to "jump" from the last word of one line to the first word on the following line, and if someone can quantify this in everyday terms that we average mortals can understand. This could make the Saccadasiacal experience easier for the average person to relate to. --Torchpratt 16:13, 10 April 2007 (UTC)

Express Saccades
I've struck upon the mentioning of "express saccades", but couldn't understand them yet. Are they too belong to the "Saccade" article? If yes, please include the description and explanation. Best regards, CopperKettle 16:29, 21 April 2007 (UTC) PubMed has 154 articles on express saccades, many are of recent dates; see also free fulltext 1993 article: [http://www.bbsonline.org/Preprints/OldArchive/bbs.fischer.html Fischer, B. & Weber, H. (1993). Express saccades and visual attention. Behavioral and Brain Sciences 16 (3): 553-610.] CopperKettle 16:58, 21 April 2007 (UTC)

Microsaccade amplitudes
The Wikipedia entry on "Microsaccade" claims that "Microsaccade amplitudes vary from 2 to 120 arcminutes". This is very different from "... microsaccades are tiny movements, roughly 20 arcseconds in excursion ..." presented in this entry. What are the correct values? JL1971 20:23, 20 August 2007 (UTC)

Inaccuracies deleted
It was claimed that only the fovea ...has a high concentration of color sensitive photoreceptor cells called cone cells." This is true, but is a partial truth. The fovea has a high concentration of M and L cones in particular, which is key for resolving objects.  The foveola, consisting of the central area in the eye, contains half of all M and L cones--and no S cones (and no rods).  S cones only appear outside the foveola, and increase in frequency the further away you go (there's a very good reason for this, having to do with the sensitivity curves, and how it relates to chromatic abberation). "The rest of the retina is mainly made up of monochrome photoreceptor cells called rod cells," Since there are about 100 million rods in the eye, but only 6 million cones, this is technically true.  However, for the same reason, it's highly misleading.  Again, the S cones, which play a key role in the blue-yellow opponent process for color vision, appear mainly in these areas of the eye. "which are especially good for motion detection." ...and this is just a plane mistake. Rods play no role in vision in any moderately lighted scene. Rods are easily saturated, and once saturated, they are completely useless. So unless you are in low light conditions, they play no role in vision.

The rest was snipped just to make the edit read a bit better.

Animation/Video
Would it be informative to find a video or animation of saccadic eye movement? Would anyone be able to find such a resource? Ged3000 (talk) 19:06, 19 May 2008 (UTC)

Added a video of saccades. Could also provide a video of one single saccade in slow-mo... Usefull? InkassoSchroeder (talk) 16:48, 21 January 2015 (UTC)InkassoSchroeder

how are they fastest?
this article says "Saccades are the fastest movements produced by the human body." what does that mean? do the muscles contract faster than other ones?

elsewhere it mentions the peak angular speed in primates to be about 1000 deg / sec. that's about 17.45 radians. human eyes are 24 mm in diameter, so that's a radius of 12 mm, so the part of the eye moving fastest in a rotation is going 12 * 17.24 mm / s or .21 m / s. It seems to me humans can do other things faster than that. I.e. throw a ball 100 mph (45 m /s) (which means the hand would have to be moving about that fast).

Cibumamo (talk) 00:13, 7 January 2009 (UTC)

Indeed eye blinks are faster. Added a small reference to that (although the blink article is not very informative about that topic).InkassoSchroeder (talk) 16:50, 21 January 2015 (UTC)

Types
This doesn't look right so I moved it off the page. If this is a legitimate type of saccade the text needs work. Hbrackett (talk) 15:41, 29 December 2009 (UTC)
 * In an involuntary saccade, the eyes are pulled toward a stimulus by a hook. This is typically followed by a savage beating.

Comparative physiology
"Thus, in birds, saccadic eye movements appear to be important in retinal nutrition and respiration.[9]"

I dont think the above information is correct when it says its important to "respiration" and the link that it goes to is not relevent. --61.68.143.26 (talk) 12:45, 15 July 2010 (UTC)

Control
I deleted this line (perhaps a translation from a different language?) as incomprehensible: Since there is little inertia in the eyeball, one muscle, upon relaxing, does it on its own rather than by force of the antagonist, stop the motion is not ballistic. If someone knows what it means, feel free to re-enter it with better wording. Joule36e5 (talk) 07:04, 6 April 2011 (UTC)

Saccade vs. Microsaccade
the Spanish article on the side should be linked to this: http://en.wikipedia.org/wiki/Microsaccade and not the current article.

There should also be more internal links to the microsaccade article, in my opinion — Preceding unsigned comment added by 88.1.32.55 (talk) 10:31, 5 June 2012 (UTC)

Image
It would be nice to have an image on the page to illustrate the concept. I'd suggest one of the images at Eye movements in reading. -- SpareSimian (talk) 14:58, 29 July 2012 (UTC)

Saccades in platypus
the term "saccades" has been used to describe the behaviour of platypus when using elelctroreception to hunt for prey. Should this be included in this article? I am prepared to do this, but it will involve some considerable re-writing as I think the article at the moment is exclsively about eye movements/vision. Related refs include "platypus make short-latency head saccades that are highly directional to electrical sources (Manger and Pettigrew, 1995)." and Pettigrew, J. D. (1999). "Electroreception in Monotremes" (pdf). The Journal of Experimental Biology 202 (Pt 10): 1447–1454. .__DrChrissy (talk) 17:54, 16 August 2014 (UTC)

The Javal Myth
According to

Wade et al. "Dodge-ing the issue: Dodge, Javal, Hering, and the measurement of saccades in eye-movement research". Perception, 2003, 32, 793-804

and also to his chapter in The Oxford Handbook of Eye Movements (from which I will quote):

"[...] Javal said virtually nothing about eye movements in his eight essays on the physiology of reading, and saccades were only mentioned in passing in the final article. Moreover, he was not referring to his own work [but to the work of Lamare]" p. 24

Thus, the introductory part of the article should be correctly identify Herring and Lamare as the founders of saccades (during reading).

Quoting for the Wade Paper:

"Hering and Lamare deserve the credit for demonstrating the pattern of eye movements during reading. The descriptions of Lamare's experiments by Javal, and the account of Javal's writing by Huey, seem to have resulted in the discovery being associated with Javal rather than Lamare."

With best regards, DJM — Preceding unsigned comment added by 134.2.114.21 (talk) 11:04, 21 January 2015 (UTC)

Ballistic nature vs. Main Sequence
I'm quite sure, that the ballistic nature is something different then the relationship mentioned ("their top velocity is proportional to their length" which is just a description of the main sequence). For me, ballistic means, that there is no online correction possible after the start of the event which is not obviously related to the main sequence in my opinion. Nevertheless, the main sequence can be used to distinguish saccade from other eye movements (although that does work pretty well on pure velocity for normal saccades). So should that be changed?InkassoSchroeder (talk) 16:58, 21 January 2015 (UTC)

Clear separation of saccades from other eye movements
Although OKN and REM sleep may have saccadic eye movements components, they are not generally subsumed under the term saccades. We should try to clearly separate this in the article. InkassoSchroeder (talk) 21:16, 21 January 2015 (UTC)

Don't start a paragraph with a false belief?
Right under "Saccadic Masking" it opens with a "common, yet false" belief, but it isn't clarified what part of the statement exactly is false, nor clarify when the article switches back to accurate statements. I think it could just be formatted a bit better. FinetalPies (talk) 11:23, 7 January 2020 (UTC)


 * Here's what I got out of that paragraph. The misconception that no information is being transmitted to the brain during saccades is false because the brain goes to great lengths to make the image clear... if saccades didn't convey new information to the eye these movements would be fuzzy, but aren't. The brain alters its image processing to eliminate the fuzziness: in other words, it masks the saccade.


 * I agree with you this section is confusing. Who holds this common, yet false belief? Laymen? Scientists? I've certainly never held this belief before; I imagine saccadic masking is too esoteric a topic for the average joe to hold misconceptions about. Some clarification would be nice.


 * I'm also unsure about the second paragraph's purpose. It sounds like it's merely describing the stopped-clock illusion, instead of showing how it relates to the false belief in the previous paragraph. Maybe it should have its own subheading under "Saccades and Vision?" -- ⁂ (talk) 17:23, 14 January 2020 (UTC)