Posts tagged ‘eye’

Birth Control Makes Women Blink More

Blinking is a critical function for most animals. Few of us give it much thought, however, since blinking is a spontaneous action that we have little control over—similar to breathing. Although science has revealed many of the mechanisms behind blinking, there are still some mysteries and odd inconsistencies.

eyeball

The act of blinking, which is largely controlled by the central nervous system, keeps eyes moist and free of irritants such as dust and dirt. Blinking can also take the form of a reflex response to protect the eyes from an approaching object. Even though blinking technically results in a loss of vision for a few seconds, it’s not noticeable. This is because the brain fills in the gaps—it “remembers” the scene (this is also how the brain accounts for blind spots!). In a recent study, scientists found that the brain has a second trick for reducing visual disruptions. When you blink, your eyes reposition to maintain focus on what you were looking at. The brain does this by tracking the movements of both the person and any objects that were in view. In the experiment, participants stared at a dot that slowly moved. The movement wasn’t dramatic enough for the participants to notice but the brain took note, repositioning their eyeballs to follow the dot every time they blinked. The researchers explained that this function is necessary to stabilize our vision, preventing a shaky camera effect. (more…)

March 25, 2017 at 5:14 pm Leave a comment

Blue Eyes Are Not Actually Blue

By Chad Upton | Editor

The most common eye color is brown and the least common is green. Eye color is determined by a number of genes, the actual number of which is unknown. Using six known genes, scientists can predict eye color from brown to blue with 90% accuracy.

The darkness of brown eyes is determined by the amount of melanin (pigment) in them. Blue eyes have little or no melanin, making them translucent; they only appear blue because of an optical illusion known as the Tyndall effect.

The color we perceive something to be is usually due to their pigment, but somethings appear colored for other reasons. Structural colors are one classification of colors that occur not because of their pigment but because of the way light interacts with the matter.

Without getting too technical, different colors of light have different wavelengths. When those waves pass through matter, they can be filtered or scattered in different ways. The Tyndall effect occurs when a light scattering particulate is suspended in a light transmitting medium and the size of the individual particulate is slightly below or near that of the visible spectrum of light.

Some things that appear to be colored due to optical effects are: blue jay and peacock feathers, mother of pearl, butterfly wings, beetle shells, bubbles, oil slicks and one we see every day: the sky.

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Photo: Jennifer Durfey (cc)

Sources: Wikipedia (Eye Color, Tyndall Effect, Color)

March 7, 2011 at 2:00 am 19 comments

Trap Doors on Car Bumpers

From satellite navigation to chilled cup holders, modern cars are full of high-tech developments that get you from point A to point B without getting lost and with colder refreshments. Overall, car technology has improved the handling, efficiency, style, safety, comfort and entertainment of our cars.

There are even high-tech bumpers out there. If you see bumpers with three or four dimples aligned across the back bumper, those are likely sensors for the backup warning system.

If you see small rectangular patches, that’s what this secret is about. They’re actually pretty low-tech, but still cool.

Even if your car doesn’t have them, maybe you’ve noticed them on other cars while you’re sitting at a red light (they may be found on front and/or rear bumpers).

They look like trap doors that cartoon characters fall through long after the audience spots them and screams at their television to warn the carbon impaired being of the obvious hazard and their impending doom. In reality, they cover anchor points where you can insert a towing eye (aka “tow hook”).

Check your car out during the summer and if you need them in the winter, you’ll know if they’re there. The towing eye is usually stored with the spare tire and/or jack and it screws in behind these covers.

bumper patch open tow hook eye door

Like all of the secrets on this site, there will be somebody reading who already knows this one — that’s cool, you can brag (or complain) about it in the comments, or retweet it and say you knew this, “like 10 years ago.”

Broken Secrets | By: Chad Upton

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July 6, 2010 at 5:00 am 3 comments

Your Eyes Adapt to Darkness In 20-30 Minutes

If you’ve shopped for an HDTV, you’ve probably seen something on the spec sheet called “contrast ratio.” Contrast ratio is the difference between the darkest and brightest picture a TV can produce. Contrast is important to a good picture.

That’s because our eyes can recognize a contrast difference of 1,000,000,000:1. That means, the brightest thing our eyes can see is a billion times brighter than the darkest thing. Good contrast to your eyes is like a gourmet meal for your taste buds. Contrast adds a lot of detail to the picture and ultimately immerses you in the action.

Unfortunately, when shopping for TVs, contrast ratio is almost meaningless. It could be really useful, but all of the manufacturers measure this number differently and then call it the same thing — it’s really only useful when comparing two TVs from the same manufacturer.

Imagine you want to buy a new car: you are cross shopping three manufacturers who measure fuel economy in three different ways. The first one, measures fuel economy while driving down a hill, while the other two measure it on flat land and while driving up a hill. Obviously, you can’t compare the results of those tests. But, if you’re looking at two cars from the same manufacturer then there is some comparative value to those numbers, even though they may not be accurate in a typical situation.

Thankfully, our eyes are extremely sensitive to contrast. Turn both TVs on and look at a flat black image for a while. A flat black image makes it easy to spot variations in darkness (aka “banding”), no banding should be present in a good TV. If you still can’t tell the difference and they both look good, then the difference is too small to worry about. Trust your eyes, they are incredible instruments.

It takes 20-30 minutes for your eyes to adjust from one extreme to the other because the contrast ratio is so high. If you’re in bright sunlight and then walk into a very dark room, it will take 20-30 minutes before you can see your best in that room. If you are in a moderately bright room and go into a very dark room, it is often closer to 15 minutes.

The rods and cones in your eye are tested during dark adaptation. Rods are more sensitive to light and take longer to adjust. Cones are much faster to adjust, often in approximately 9 minutes. People over the age of 50 need twice as much light to see as well in the dark as a 30 year old. So, if you need more light, consider my CF light secret.

Frequent fliers will eventually notice that the aircrew dims the airplane’s interior lights on final approach during night landings . They want your eyes to be adjusted to the darkness outside in case the landing does not go as expected and you have to evacuate the plane.

Broken Secrets

Written By: Chad Upton

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Sources: Why Planes Dim Interior Lights, Adaptation (Eye), Contrast Ratio, Growing Older

January 22, 2010 at 1:10 am 1 comment


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