Amazing Brain and Eye Fixation

Seriously, I have spent a very long time writing something special just for you. You see, I have given your brain and eyes a hard time over the last w

Seriously, I have spent a very long time writing something special just for you. You see, I have given your brain and eyes a hard time over the last week. I apologise as they are in fact amazing and I want to celebrate them with you. So I am going to give them both (your brain and your eyes) a little treat, a present if you will, with some real secrets about the universe and your body combined with some of my favourite Op Art.

But first look into my eyes. Deep into my eyes.

You can’t for very long. Not because I am particularly ugly (I am average apparently) but because your eyes are in fact always moving in a fast tremor, dancing around in little micro saccades. Saccades are quick, simultaneous movements of both eyes in the same direction. Initiated by the frontal eye fields or sub-cortically by the superior colliculus, saccades serve as a mechanism for fixation, rapid eye movement, and the fast phase of optokinetic nystagmus. Sorry back to the fun…

Try this little experiment on someone in the office or home. Tell them to look into your eyes and say they can’t stop looking. Then ask them what they had for lunch three days ago and chances are they won’t be able to answer. It’s very hard to remember something without moving your eyes.

We are as humans are extremely visual creatures. Many of us are guilty of taking some of the most wondrous and spectacular things about how our bodies work for granted. Ben Franklin once remarked how people marvel at beautiful vistas, but forget about the miracle of the human body. For example, how often do you consider the sheer number of individual cells working in unison to sustain life inside your body? It is hard to grasp just how small the atoms that make up your body are until you take a look at the massive number of them.

An adult male (me) is made up of around 7,000,000,000,000,000,000,000,000,000 (7 octillion) atoms. Maybe a few more for me after the skiing and eating last week. The retina in the back of your eyes are made up of at least 120 million cells that are extremely sensitive to light. Of those cells, between 6 and 7 million of them are colour sensitive cones, and details of the world surrounding you in HD. The other more than 110 million cells are called rods, which help you to see better in the dark and distinguish between black and white. So surprisingly, less than a tenth of your visual receptors actually detect colour or indeed see much beyond the latest 4K Ultra High Definition screens.

Here is a fact for your (unlimited) hard drive memory to encode ( i.e. remember then recall): on average, you blink around 17 times per minute, 28,800 times per day, and 5.2 million times per year. The old saying, in a blink of an eyecame about because the muscle which allows you to blink is the fastest muscle in the body. A blink typically lasts 100-150 milliseconds, and this action plays a vital role in keeping your eyes moist and debris-free.

Now this is truly amazing: your eyes are unbelievably sensitive, able to detect just a few photons of light. A photon is the smallest elementary particle, the smallest quantum of light and indeed of all other forms of electromagnetic radiation. It is the force carrier for the electromagnetic force, even when static via virtual photons.

To demonstrate this amazing fact, if you take a look on a very clear night at the constellation of Andromeda, a little fuzzy patch of light is just visible with the naked eye. It was one of the 48 constellations listed by the 2nd-century astronomer Ptolemy and remains one of the 88 modern constellations. Located north of the celestial equator, it is named for Andromeda, daughter of Cassiopeia, who was chained to a rock to be eaten by the sea monster Cetus. Nice. Now if your eyes are good enough and you can make out that tiny blob, you are seeing as far as is humanly possible without technology.

Andromeda is the nearest large galaxy to our own Milky Way. But near is a relative term in intergalactic space, the Andromeda galaxy is 2.5 million light years away. When the photons of light that hit your eye began their journey, there were no human beings on earth and we were yet to evolve. You are seeing an almost inconceivable distance and looking back in time through 2.5 million years. Tell your friends how good your eyes (well rods) are and spread that fact around from me!

The picture of the world we see (or think we see) as I have already mentioned in previous articles, is in fact an artificial construct. Our brains don’t produce an image the way a GO-Pro camera works. Instead, the brain constructs a model of the world from the information provided by modules that measure light and shade, edges, curvature and so on. This makes it simple for the brain to paint out the blind spot, the area of your retina where the optic nerve joins, which has no sensors. It also compensates for the rapid jerky movements of our eyes called saccades, giving a false picture of steady vision.

But the downside of this process is that it makes our eyes easy to fool. TV, films and optical illusions work by misleading the brain about what the eye is seeing. This is also why the moon appears much larger than it is and seems to vary in size. To look at something seems a simple act; just hold your eyes steadily on the target.This is called fixation.Although we spend about 80 % of our time in fixation, less is known about this important skill than different types of eye movements. You are about to fixate on a problem. However, fixation presents a real paradox.

If you look at something without ever moving your eyes and retina, the target fades away. You can see this with Troxler’s effect. Make sure the circle above is 4 inches (you can’t do this on a phone very well I have tried) or more in diameter. Then, stare steadily at the centre dot and, with time, the peripheral grey circle should fade away, then return, only to fade again. Your visual system, indeed our sensory systems in general, do not like sameness; they get bored (sort of). They respond only when something changes, so, as you stare at the central dot without intentionally moving your eyes, the large circle fails to keep activating your low resolution peripheral visual system. The circle disappears, but you see it again when you make a subtle eye movement, thus changing the visual stimuli that move across your retinal cells.

You eyes are always moving.

My favourite op art pieces, like Enigma (above) by Isia Leviant or The Fall by Bridget Riley (below) may have their bizarre effects in large part because of these subtle fixational eye movements. When you look at Enigma for several seconds to a minute, you may start to see a streaming movement in the coloured circles. Your eyes are flicking around and these movements are very subtle, small jerks (microsaccades) that cover less than 2 degrees of visual space, slow drifts, and high frequency tremor. Microsaccades brought the grey circle back after it disappeared in Troxler’s illusion.

A relatively recent study has shown that this effect is a result of your own micro saccades. Fixational eye movements may also be involved in the undulations and shimmering you see in The Fall. The repeating nature of these lines in the painting may create, via subtle eye movements, illusions of motion. These illusions excite the motion sensitive areas of your brain which may, in turn, stimulate even more eye movements so that the illusions build over time. People who experience eyestrain when reading experience more of these illusions than people who read comfortably. Which mY explain the head aches if you stare at a flickering screen for too long.

So my gift to you today was,

Art, Science, Cosmology, Space, Troxler, Ben Franklin, The Fall, Constellations, Greek Mythology, Ptolemy, Physiology, Anatomy, Physics, History, Movement, The Matrix, Hypnosis, Photons, Evolution, Neuroscience, 3 New Facts, 2 Strange Illusions, some Chemistry and a little Humour, all in one blink of a blog.

Oh and one more brain secret for you: by whispering something to someone almost guarantees that they’ll whisper back. Try whispering Be Amazing Every Day and ‘this was the best blog you have read’ and see what happens. If you enjoyed it, click like and share it with the world. I thank you in advance and be amazing and kind on those eyes.

Categories: : blog