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"Microsaccades" Help To Refresh Your Field of View
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.'"
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.
The higher the technology, the sharper that two-edged sword.
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.
A learning experience is one of those things that say, 'You know that thing you just did? Don't do that.' - D. Adams
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!
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.
Faster! Faster! Faster would be better!
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.
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 is a miracle that curiosity survives formal education. - Einstein
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.
The higher the technology, the sharper that two-edged sword.