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Medicine Science

"Microsaccades" Help To Refresh Your Field of View 96

Posted by Soulskill
from the adding-a-new-word-to-the-spellchecker dept.
Ponca City, We love you writes with news of research from the Salk Institute into small, unconscious eye movements called "microsaccades," the purpose of which has been in question for many years. A recent study showed that those movements were essentially responsible for maintaining a coherent image for interpretation by the brain. They are also the cause of a famous optical illusion in which a still image appears to move. '"Because images on the retina fade from view if they are perfectly stabilized, the active generation of fixational eye movements by the central nervous system allows these movements to constantly shift the scene ever so slightly, thus refreshing the images on our retina and preventing us from going 'blind,'" explains Hafed. "When images begin to fade, the uncertainty about where to look increases the fluctuations in superior colliculus activity, triggering a microsaccade," adds Krauzlis.'"
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"Microsaccades" Help To Refresh Your Field of View

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  • how is this new? (Score:1, Interesting)

    by Anonymous Coward

    I remember reading about this back in the 90s...so what is new here?

    • Re:how is this new? (Score:5, Interesting)

      by ScrewMaster (602015) on Sunday February 15, 2009 @02:26PM (#26864577)

      I remember reading about this back in the 90s...so what is new here?

      Nothing that I can tell. I was working as a software developer back in 1982 or so for a group of neuroscientists at a local university. One of the projects I worked on used a pair of glasses with infrared motion sensors on them to continuously track pupil movements. The idea was to monitor saccades for diagnostic purposes (they become exaggerated in, for example, people who habitually work in near-darkness ... like miners.) It was explained to me that it had been known since the sixties (if not earlier) that saccades were, at least in part, needed to avoid retinal fatigue. Early experiments were performed using a grain-of-wheat bulb literally glued to the eyeball. It was shown that when the image didn't move relative to the retina, it quickly became invisible.

      It sounds like what these guys are doing is relating these involuntary eye movements to brain activity. That's interesting if not particularly novel: some of the people I worked for were doing this twenty-five years ago using EEGs. What's more interesting to me is that we're generally completely unaware of these eye movements, just as we're generally unaware of our blind spots. It's an impressive bit of (ahem) abstraction layering that the brain does for us.

      • Re: (Score:3, Insightful)

        by causality (777677)

        Early experiments were performed using a grain-of-wheat bulb literally glued to the eyeball.

        Am I the only one who shuddered a bit when I read this and thought about how it would feel to have a small object glued to the eyeball? I'm sure it was benign and performed by competent people who knew what they were doing ... but damn, that just sounds like a form of torture.

        • by JustOK (667959)

          It wasn't torture, just part of the search for Wobbles of Microsaccades, Duh!

        • Re: (Score:3, Interesting)

          by kylben (1008989)

          Am I the only one who shuddered a bit when I read this and thought about how it would feel to have a small object glued to the eyeball?

          Anybody who wore contact lenses back in the 80's knows just how it feels. Especially if you were lazy, in college, and/or drank alot...

        • Early experiments were performed using a grain-of-wheat bulb literally glued to the eyeball.

          I first saw this in a Life Magazine article published in the late 1940s or early 1950s. That experiment used a mirror glued to a contact lens, not to the eyeball.

          The mirror shifted an image on a screen to negate the retinal image's movement caused by microsaccades. The mirror was better for detecting the eye's angular movement than a light bulb would have been.

          • Re: (Score:3, Interesting)

            by ScrewMaster (602015)

            Early experiments were performed using a grain-of-wheat bulb literally glued to the eyeball.

            I first saw this in a Life Magazine article published in the late 1940s or early 1950s. That experiment used a mirror glued to a contact lens, not to the eyeball.

            The mirror shifted an image on a screen to negate the retinal image's movement caused by microsaccades. The mirror was better for detecting the eye's angular movement than a light bulb would have been.

            Well, the experiment I read did indeed have a small lamp assembly glued to an eyeball. It's been a long time, but as I recall the experiment wasn't about monitoring eye motion, but to determine what happens when the retina is exposed to an unchanging image. The article mentioned the fact that rabbits are pretty much unable to see anything unless it's moving (something about a lot of the visual preprocessing being done in the rabbit's eye, not in the brain.)

        • I shuddered a bit when I realized that these people discovered a way to make ordinary object invisible - a cloaking device. They just abandoned it when all it needed was a few small changes to make it practical.

          • Re: (Score:2, Interesting)

            by socha23 (1137849)

            Peter Watts explores this subject (among many other interesting topics - including existence of free will, the chinese room, and the nature of empathy and sentience) in his newest book, 'Blindsight'. It's a pretty good read.

            The book is available online here: http://www.rifters.com/real/Blindsight.htm [rifters.com]. It's published under Creative Commons license.

      • by ColdWetDog (752185) * on Sunday February 15, 2009 @02:58PM (#26864765) Homepage

        It sounds like what these guys are doing is relating these involuntary eye movements to brain activity. That's interesting if not particularly novel: some of the people I worked for were doing this twenty-five years ago using EEGs.

        Yes, however this research points to a particular part of the brain, the superior colliculus. That's interesting in a mapping sense. Perhaps not earth shattering, mind boggling interesting like a picture of the FSM, but interesting. Perhaps with better techniques, somebody will be able to tease the movements apart a bit better. As you alluded to in your post, sacchades are interesting from a clinical point of view. How about being able to manipulate microsacchades on a monitor and insert (evil-commercial-concept-or-product)? Your garden variety tinfoil goggles would be useless!

        What's more interesting to me is that we're generally completely unaware of these eye movements, just as we're generally unaware of our blind spots. It's an impressive bit of (ahem) abstraction layering that the brain does for us.

        Well and again, yes. Do you want to have to will your heart to beat faster when you go up a flight of stairs? What happens if you forget that detail. The automaticity of our bodies allows us to concentrate on important things.

        Like Slashdot.

        • by BronsCon (927697)

          What's funny is, as I was concentrating on reading the last paragraph of your post, I was focusing on each word as I read it. Something seemed strange as I read, so I read it again, this time pausing for several seconds before moving to the next word.

          Having already read the paragraph, I knew what it said. There was no sense of urgency in my mind, nothing to influence whatever part of my brain causes saccades to refresh my field of view so I could read the next word.

          I could see each word very clearly when I

          • by ScrewMaster (602015) on Monday February 16, 2009 @12:11AM (#26868751)

            What's funny is, as I was concentrating on reading the last paragraph of your post, I was focusing on each word as I read it. Something seemed strange as I read, so I read it again, this time pausing for several seconds before moving to the next word.

            Having already read the paragraph, I knew what it said. There was no sense of urgency in my mind, nothing to influence whatever part of my brain causes saccades to refresh my field of view so I could read the next word.

            I could see each word very clearly when I first focused on it. By the time I moved my focus the the next word, I saw mostly gray.

            Try it. Read this post a couple times, comprehend it, then focus on each word, individually, for several seconds.

            Funny, for an instant I thought your post had some actual content, but for some reason all I can see now is the word "fnord" repeated over and over.

      • Re:how is this new? (Score:4, Informative)

        by jellie (949898) on Sunday February 15, 2009 @04:20PM (#26865225)

        That's interesting if not particularly novel: some of the people I worked for were doing this twenty-five years ago using EEGs.

        The superior colliculus is fairly deep within the brain, so my guess is that they're using single-unit recording, which has been around for at least 30 years, to record from neurons. EEGs don't give readings at the neuronal level, anyway.

    • Re: (Score:3, Funny)

      by tomhudson (43916)

      Ditto - but back in the 70's. What next - wide ties and lapels, bell-bottoms and flood pants, nehru jackets and peasant skirts, platform shoes and disco?

      Well, what the heck, if you can't get bail-out money, at least get research grant money.

      • by causality (777677)

        Ditto - but back in the 70's. What next - wide ties and lapels, bell-bottoms and flood pants, nehru jackets and peasant skirts, platform shoes and disco?

        Well, what the heck, if you can't get bail-out money, at least get research grant money.

        You forgot the leisure suit. No grant money for you!

    • Re:how is this new? (Score:5, Informative)

      by splodus (655932) on Sunday February 15, 2009 @03:07PM (#26864815)

      Saccadic movements have been understood for a very long time, and it has pretty much always been assumed that part of their 'function' was to prevent the Ganzfeld effect and to facilitate in the construction of a representation in the mind of a wider field of view. It has also been known for a long time that the superior colliculus and brain stem are involved in those movements.

      This work has begun to identify highly specialised structures in the superior colliculus that seem to control the saccades, and that *has* furthered our understanding of this aspect of perception.

      I'd be surprised if the researchers themselves believe that most people thought saccades were 'mere 'motor noise''. I think when Krauzlis says 'scientists have debated the function, if any, of these fixational eye movements' he's being a good scientist and making a statement that does not have to be qualified to be true.

      • Saccadic movements have been understood for a very long time, and it has pretty much always been assumed that part of their 'function' was to prevent the Ganzfeld effect and to facilitate in the construction of a representation in the mind of a wider field of view. It has also been known for a long time that the superior colliculus and brain stem are involved in those movements.

        Yes but the real reason for microsaccades is that almost all the photoreceptors in the retina are designed to detect changes, such

      • Re: (Score:1, Interesting)

        by Anonymous Coward

        Saccades also provide oversampling, which increases resolution in the exact same manner an electrical A/D converter does.

  • by HEbGb (6544)

    There is nothing new here; this has been well known for decades. People with vision difficulties also move their eyes more than those with perfect vision, for the same reasons. This isn't news.

    • by oloron (1092167)

      of course this is pertinent, Slashdot is losing its vision, and has to look at stories over and over again to keep from forgetting them, or is this just your first day here.... no wait UID too low... what is your excuse ;)

      hmm
        captcha = speech
      how ironic

      • ... no wait UID too low... what is your excuse ;)

        hmm captcha = speech how ironic

        No kidding ... I wonder what happens if your UID goes negative. Do you simply cease to exist?

    • Some people reading this now were not actually functionally living in the '90s
      • Some people reading this now were not actually functionally living in the '90s

        Well, if they were not functioning when they were alive in the 90's, what decade were they functioning in, then?

      • by Anonymous Coward

        News for nerds, stuff that matters, replacement for a failing school system.

        Slashdot, just like a good video streaming protocol, must send a background stream of image updates about science and knowledge, filling in all the missing pieces of static, known stuff for the lossy observers, while also trying to selectively send some content that is actually new and different.

    • by osu-neko (2604)

      Um, if the research was about the existence of or the reasons for these movements, you'd be right, it wouldn't be news. Those are things that have been known for decades.

      If you actually read the article, you'd see what's new here. It's not anything that's been well known for decades, or even strongly suspected for decades.

  • I tested both illusions on the link provided in the summary and neither one had the effect on me that was claimed. What would that imply?

    I tried them multiple times shifting my focus to different aspects of the image than directed just to see if it had any effect and it was no different.

    • Re: (Score:3, Interesting)

      by More_Cowbell (957742) *
      Perhaps your eyes aren't perfectly in sync? My brother had this as a child (one eye would wander around while the other was looking straight ahead. The doctors 'cured' it by having him wear an eye patch for a while to strengthen the weak eye. He looks fine but he's never been able to see 3D images or movies.
    • by thermian (1267986) on Sunday February 15, 2009 @02:41PM (#26864673)

      I tested both illusions on the link provided in the summary and neither one had the effect on me that was claimed. What would that imply?

      I tried them multiple times shifting my focus to different aspects of the image than directed just to see if it had any effect and it was no different.

      Optical illusions don't work for everyone.

      As an undergrad I had to sit through tests involving optical illusions for the psychology students, and in my case lots of the illusions didn't work. That got me excused from further tests, because they didn't want to make their precious stats go funny by including cases like mine (and about three other people in the class I recall).

      Its not that unusual.

      • by qw0ntum (831414)
        To be fair some are harder to see than others; I had to try a couple times for this one. I was showing the circle and dot one to a friend and I had to coach him through part of it; he saw it eventually but I don't think he got how intently he needed to stare at the red dot. I don't doubt some illusions don't affect some people though.

        Anyway, my contribution to this thread: http://allpsych.com/opticalillusions/images/jesus.jpg [allpsych.com]

        Stare at that for thirty seconds or so then look at a blank wall and blink a
        • Re: (Score:3, Funny)

          by SGDarkKnight (253157)

          Stare at that for thirty seconds or so then look at a blank wall and blink a couple times.

          Damn you! why couldn't you have provided a link like that to a sweedish swimsuit model instead... now i got this bearded freak who looks somewhat familiar to me, i think his name is Buddy... something....

          • Re: (Score:1, Funny)

            by Anonymous Coward

            Are you dumb or what?
            It is RMS!!

      • by causality (777677) on Sunday February 15, 2009 @03:23PM (#26864911)

        As an undergrad I had to sit through tests involving optical illusions for the psychology students, and in my case lots of the illusions didn't work. That got me excused from further tests, because they didn't want to make their precious stats go funny by including cases like mine (and about three other people in the class I recall).

        That sounds like they are not very concerned about the accuracy of their stats. You mentioned that this was a type of test. What's the point of running a test if you have pre-determined the outcome? That is more properly called (by them, not you) a demonstration.

        While the optical illusion tests you describe are probably not terribly important in the scheme of things, I mention this because it's surprising how many important things are handled this way. It's to the point that whenever I see a purportedly scientific study, my first question is "who funded it?"

    • It just looks like one

    • by kylben (1008989) on Sunday February 15, 2009 @04:19PM (#26865213) Homepage

      I tested both illusions on the link provided in the summary and neither one had the effect on me that was claimed.

      If at first you don't saccade...

    • by Verteiron (224042)

      They only work for me with my glasses on. With them off, even when I move into the range where I can focus on them (4 inches from the screen or so) the illusions don't work. Only with my glasses on can I see the effects.

  • You think that's the world, you're seeing? No, you're seeing a representation of it constructed by your mind. The only time you need to see something is when it's moving (or when you're moving in relation to it.) Otherwise it still looks pretty much like it did the last time you looked at it. On the other hand, if something is moving and your eye is damaged, or your brain wants more information about it, then it should need the information. Not that I know more about what this guy is talking about than he d

    • You think that's the world, you're seeing? No, you're seeing a representation of it constructed by your mind.

      That's how all your senses work. The sensory signals are nothing until interpreted by the brain. Your brain literally does not know the difference between what it perceives through the senses vs. what is playing back in your 'minds eye' through memory. Remembering what an apple looks like and seeing an apple produces the exact same synaptic patterns in the brain.

      As far as your postulation about needing to see only movement, I can kind of see your point, though not totally. Evolutionarily speaking, we t

      • by drinkypoo (153816)

        That's how all your senses work.

        Granted. I was just being snarky. In fact, all your senses are just input for your current world-representation. And... so is memory. But then, memory is little-understood anyway. But it's interesting how some half-forgotten memory can manifest itself in your waking life and interfere with your perceptions.

    • You think that's the world, you're seeing?

      No, you're seeing a representation of it constructed by your mind.

      So, you think that's the representation of the world you're seeing?

    • by causality (777677)

      You think that's the world, you're seeing? No, you're seeing a representation of it constructed by your mind.

      This reminds me of a section from The Book of Lies by Aleister Crowley (of all people):

      A red rose absorbs all colours but red; red is therefore
      the one colour that it is not.
      This Law, Reason, Time, Space, all Limitation blinds
      us to the Truth.
      All that we know of Man, Nature, God, is just that
      which they are not; it is that which they throw off
      as repungnant.

      I can't say I subscribe to much of any

  • Can we finally get some specs on life, such as Refresh rate and resolution?
  • by Mprx (82435) on Sunday February 15, 2009 @03:06PM (#26864805)
    If you can perfectly relax your eyes you can watch the image fade. Color fades before lightness, and eventually the whole image is just noisy gray. It's easiest if there's nothing visually interesting in your field of vision so you don't accidentally look at something and move your eyes.
    • Re: (Score:2, Interesting)

      As a long-time meditator I can absolutely attest to this. It does not always happen, but there are certain states of relaxation in which my eyes stop doing this and whatever is in my field of vision becomes gray/green blurry outlines or eventually nothing at all until I move.
    • by finity (535067)
      I've never experienced it to that extreme, but definitely know what you're talking about. Standing at "attention" is really boring, and it gets slightly more interesting if you can make everything turn kinda gray. I can always still see whatever is directly in front of my eyes, but everything else fades out.
    • by ehud42 (314607)

      Cool! I have been able to do this for many years - especially when I'm tired. I remember in an intro-psych course many years ago the professor showing some kind of image and discussing how people see. I believe it was either the 'count the dots in a grid' illusion or the test your eyes for some disease simple grid image (if the lines are not straight you have a visual problem). Anyway, I asked what it meant when the image faded - as I was tired that day in class, I was able to hold still enough to have the

  • I noticed that rapid eye movement already years ago.

    Until now I couldn't quite explain it, say there was this tall blond passing by my eyes would continuesly wander.
    Was it some large brunette it wouldn't happen but once only, even though I've always liked dark haired women best.

    But this study finally explains it, the big broad doesn't get lost from vision as easily as the slim blonde!
    Thanks for nature!

  • by Anonymous Coward

    Finally, a viable excuse...
    "Yes, I keep glancing at your tits. Nope, sorry, I'm afraid I can't stop unconscious eye movements"

  • All I can think of is DRAM. You need to keep refreshing the memory by re-addressing it and recharging the cells. By moving the eye, you are just refreshing the pixels.

    I am also reminded by the probably nonsensical warning to "hold still" because the T-REX's vision was based on movement. It seems our vision is also based on movement, except we supply the movement with our eyes.

    • by Dahamma (304068)

      If you are going to use an electronics analogy, I think a better one would be anti-burn in technology in modern plasma TVs. They can periodically shift the image on screen by tiny incremental amounts not detectable to the eye, which lessens the amount of time any one pixel will be fixed on one color.

  • might this be the cause of those people who lose their sight after having especially traumatic experiences?
  • Martinez-Conde still doesn't know exactly how microsaccades create the false perception of motion.

    Aliasing at the retinal level ??

  • What I find amazing is that no-one seems to have figured out that it also increases effectives resolution too. And is probably involved in focusing.

    • Michele Rucci's lab figured out a while back that microsaccades improve our perception of high spatial frequency stimuli.. here's the article. [nature.com]

      • by spectecjr (31235)

        Michele Rucci's lab figured out a while back that microsaccades improve our perception of high spatial frequency stimuli..

        Thanks for the link :)

        The thing that gets me is, surely this is obvious? The receptors on the retina are arranged in a poisson distribution (random, no receptors closer to each other than a certain limit). As long as the microsaccades are roughly 1/2 the poisson distance in any direction, this should at least lead to a doubling of the resolution of the signal achieved, averaged over time

        • by wanax (46819)

          I think the main reason that it's not obvious is that the structure of the retina is quite a bit more complex than you make it out to be. First of all, there is essentially an exponential fall-off of receptor density as we move away from the fovea. Secondly, there are several horizontal channels in the lamina of the retina that aggregate receptor inputs in an center-surround manner (eg. on-center, off surround, off center, on surround)- and these horizontal channels are of differing lengths.

          So it's not such

          • by spectecjr (31235)

            I think the main reason that it's not obvious is that the structure of the retina is quite a bit more complex than you make it out to be. First of all, there is essentially an exponential fall-off of receptor density as we move away from the fovea. Secondly, there are several horizontal channels in the lamina of the retina that aggregate receptor inputs in an center-surround manner (eg. on-center, off surround, off center, on surround)- and these horizontal channels are of differing lengths.

            So it's not such

  • I kept seeing the phantom of the white background when I looked off the screen. It's like a watermark. Is that the illusion?
  • by dpbsmith (263124) on Sunday February 15, 2009 @06:52PM (#26866153) Homepage

    Stabilized images on the retina fade. Microsaccades prevent it from happening. I actually think I read an article about this in Scientific American in the 1960s. Certainly I encountered it in a perceptual psychology course I took in the 1970s.

    As for illusions like the Enigma illusion, we were told that caused by small eye movements, amplified by a moire effect between the image and the afterimage. Maybe that was only the professor's guess, and the new study did something to pin it down, but it's not a very new idea.

  • I read that as "microcascades" and was expecting to see headcrabs in TFA. I was sorely disappointed. :(
  • I was 13, in the 7th grade at my school back in 1983 and I can clearly remember, as if it had happend today, the way our teacher described this phenomenon in biology and how the scientists examining it discovered the effects the prevention of these micromovements of the eye have on the visual perception of things. He also specifically described the blinding of the retina once an eyeball is held fix by small suction-cups.

    Ever so often I encounter this, that things people have discovered decades or even a cen

    • by osu-neko (2604)

      Actually, all that means is you read the inaccurate summary too well and didn't read the actual article carefully enough. (What's new here has nothing to do with anything you just said, and is not something anyone knew about back in 1983.)

      What's new here has absolutely nothing to do with the fact that these movements occur, nor anything to do with their purpose, which has also been well understood for decades. What's new here is the pinpointing (or at least narrowing down) of the mechanism (or at least th

  • The article in Wired seems to be a 'dumbed down for public consumption' version of an article that appeared in Scientific American in August 2007. The original was authored by Dr Susana Martinez-Conde and Dr Stephen L Macknik, and referred to a study they had completed in 2006. There is a preview available here:

    http://www.sciam.com/article.cfm?id=windows-on-the-mind [sciam.com]

    unfortunately one would have to pay for the whole article as they are a subscription magazine. But the proof is in the preview, and if anyone sh

  • ... at least in my field.

    It's been awhile since it's come up but it takes 7 of those little vibrations (if memory serves- I can ask the expert) to register the j-curve for the minimum contrast detection in the standard observer.

    Useful for image refresh calculations :)

  • into a negative term or is it still positive?

    'Damn, whatever that guy gave me last week seems to be sponge-worthy, better go to the clinic'

    'course, it'd go for guys too now...

    'Damn girl, you're so hot you're Sponge-Worthy!'

  • Blindness can be induced by paralyzing the ocular muscles and immobilizing the head. This was done decades ago using curare. If the visual field remains constant, there is a loss of visual contrast until everything greys out. With practice this can be done by forcing the eyes to remain focused on a point. The visual system detects edges via saccades, movement or both, and fills in the remainder via a combination of detection and heuristic recognition. The process description and references are in Karl Pribr

  • I focused on the dot without issue, but when the blue circle disappeared I found it harder to focus on the dot. Does anybody else experience this?
  • I had assumed that type of eye movement allowed the brain to apply a super-resolution filter. Since the eye has a limited number of rods and cones and the eyes lens isn't perfect, it would allow the brain take multiple images and average to get a more detailed image. http://en.wikipedia.org/wiki/Super-resolution [wikipedia.org]
  • Though knowing what part of the brain is responsible for this feat is a great revelation, it has been known that eye movement helps us to filter the noise and false images generated by our all too imperfect visual system.

    With movement our brain tests repeatedly our rods and cones to verify that what they see is actually in front of us and not due to various things like the blood flowing through our retina, or the attenuation of a single or group of rods or cones with respect to others. After such eye moveme

  • Without looking at the paper in detail (things to do today, I'm afraid) I'd have to agree that this doesn't sound like anything new. I worked in video compression about, oh, ten years ago, and I remember it being explained to me as already fairly well established that:

    1. The eye makes tiny, constant movements referred to as "tremor".

    2. While the iris reacts to total constant light levels over time, the rods, cones, and optic nerve work to transfer transition data, primarily, to the visual cortex-- like

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