Today’s interesting fact has to do with lenses.
The purpose of a lens is to focus light.
Children often learn about this is science classes, but before that many children learn to burn holes in cardboard, leaves and wood.
The average lens children play with to burn things focus light up to 1000 times.
The lens of your eye is better at focusing light, and is 2.5 times more effective.
Because the lens of the eye focuses mainly on the fovea, this is why they tell you to not look at the sun.
Showing posts with label Fovea. Show all posts
Showing posts with label Fovea. Show all posts
Thursday, June 09, 2011
Tuesday, June 07, 2011
Today's interesting fact again has to do with sight.
Our visual cortex processes the information our eyes send to us.
While everyone knows the eye contains rods and cones which allow us to see, most people think that these are evenly distributed throughout the eye.
The Fovea is the small section of the eye that the lense of the eye primarily focuses on, and it contains the majority of cones found in the eye.
You can see how small the Fovea is by extending your arm completely out and lift your thumb.
The area the Fovea sees is about the size of your thumbnail.
You continue to see colour in your perferial vision because your visual cortex fills in the information for you.
If you don't see something in your Fovea, you might not notice it at all.
There is an experiment that involves videoing four or five individuals playing basket ball, and a man in a gorilla suit walks through the play.
When this video has been shown to subjects, and they were told to keep an eye on who has the ball, most watchers miss the gorrilla suit completely.
Our visual cortex processes the information our eyes send to us.
While everyone knows the eye contains rods and cones which allow us to see, most people think that these are evenly distributed throughout the eye.
The Fovea is the small section of the eye that the lense of the eye primarily focuses on, and it contains the majority of cones found in the eye.
You can see how small the Fovea is by extending your arm completely out and lift your thumb.
The area the Fovea sees is about the size of your thumbnail.
You continue to see colour in your perferial vision because your visual cortex fills in the information for you.
If you don't see something in your Fovea, you might not notice it at all.
There is an experiment that involves videoing four or five individuals playing basket ball, and a man in a gorilla suit walks through the play.
When this video has been shown to subjects, and they were told to keep an eye on who has the ball, most watchers miss the gorrilla suit completely.
Monday, June 06, 2011
Today's interesting fact has to do with sight.
While those of us who have sight, take it for granted, we don't see as much as we think we do.
We blink about every 5 seconds, which takes about 150 milliseconds.
Studies have shown that when we blink, we don't see, but the visual cortex edits out these blackouts so we never notice them.
About three times a second and lasting up to 200 milliseconds our eyes make jerky moves which are called saccades.
These movements allow the Fovea, to focus on different parts of our environment and to provide the information to the brain that then fills what we see.
During each of these saccades, while the eyes keep transmitting data to the brain, the brain doesn't process about 100 milliseconds of the information.
The average individual will perform up to 15,000 saccades a day and even if we don't include the blinking, this means that while awake and having our eyes open, our visual system is offline for up to four hours every day.
Tomorrow I'll try cover why we still think we see during these four hours.
While those of us who have sight, take it for granted, we don't see as much as we think we do.
We blink about every 5 seconds, which takes about 150 milliseconds.
Studies have shown that when we blink, we don't see, but the visual cortex edits out these blackouts so we never notice them.
About three times a second and lasting up to 200 milliseconds our eyes make jerky moves which are called saccades.
These movements allow the Fovea, to focus on different parts of our environment and to provide the information to the brain that then fills what we see.
During each of these saccades, while the eyes keep transmitting data to the brain, the brain doesn't process about 100 milliseconds of the information.
The average individual will perform up to 15,000 saccades a day and even if we don't include the blinking, this means that while awake and having our eyes open, our visual system is offline for up to four hours every day.
Tomorrow I'll try cover why we still think we see during these four hours.
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