Posts Tagged ‘optical illusion’
“Reality is merely an illusion, albeit a very persistent one”*…
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The Dynamic Ebbinghaus takes a classic, static size illusion and transforms it into a dynamic, moving display. A central circle, which stays the same size, appears to change size when it is surrounded by a set of circles that grow and shrink over time. Interestingly, this effect is relatively weak when looking directly at a stationary central circle. But if you look away from the central circle or move your eyes, or if the entire stimulus move across the screen, then the illusory effect is surprisingly strong – at least twice as large as the classic, static Ebbinghaus illusion.
Each year the visual illusion research community gathers in Naples, Florida for a meeting that culminates in a contest that names the Best Illusion of the Year. This year’s grand prize winner is captured in the video above.
See all of the finalists here, read more about the contest (e.g., below) here— and check out the cool trophies here.
This is an anamorphic illusion. It begins as a normal photograph and then is tilted backwards and forwards to create opposite vanishing points. The tilting distorts the shape of the head and facial features to create the illusion of an actual age progression and regression. For the age progression the top half of the head narrows, and the bottom half expands creating a more mature look. For the age regression, the opposite happens. The head and ears enlarge and the lower face narrows giving them a smaller nose, chin and neck, which results in a realistic childlike appearance.
* Albert Einstein
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As we uncross our eyes, we might recall that it was on this date in 1758 that John Dollond filed for a patent (which he ultimately received) on achromatic lenses, and reported this to the Royal Society. Isaac Newton had described the blurring effect due to chromatic aberration (the fact that different colored light wave have different focal lengths), which was important in the preparation of lenses for telescopes and microscopes; but could not solve the problem in simple lenses. Indeed, the answer lay in compounding two lens. In the event, Dollond had not invented the answer, but had learned it from another lens maker, George Bass, who prepared the first achromatic lens at the instruction of Chester Moore Hall, who actually deserves credit for the creation.
![](https://i0.wp.com/farm6.staticflickr.com/5533/14136693558_b4fc12e494.jpg?resize=415%2C250&ssl=1)
Chromatic aberration of a single lens causes different wavelengths of light to have differing focal lengths.
![](https://i0.wp.com/farm6.staticflickr.com/5116/14300215096_2784706299.jpg?resize=415%2C250&ssl=1)
An achromatic doublet, like the one patented by Dollond, brings red and blue light to the same focus, and is the earliest example of an achromatic lens.
Seeing is… well, seeing…
Via Discover‘s Bad Astronomy blog, one of the more amazing optical illusions that your correspondent has ever seen:
Alternating red and green spirals, right? Actually, they are exactly the same color. As Bad Astronomy explains,
The reason they look different colors is because our brain judges the color of an object by comparing it to surrounding colors. In this case, the stripes are not continuous as they appear at first glance. The orange stripes don’t go through the “blue” spiral, and the magenta ones don’t go through the “green” one. Here’s a zoom to make this more clear:
The orange stripes go through the “green” spiral but not the “blue” one. So without us even knowing it, our brains compare that spiral to the orange stripes, forcing it to think the spiral is green. The magenta stripes make the other part of the spiral look blue, even though they are exactly the same color.
Read the full story in Bad Astronomy here. And for a treat, visit the site of the originator of the illusion, Japanese psychologist Akiyoshi Kitaoka here.
As we reconsider the evidence of our eyes, we might recall that it ’twas on this date in 1852 (according to the stories) that Sherlock Holmes’ sidekick, Dr. John H. Watson, was born… while Holmes did occasionally say “Elementary!” (e.g., in “The Crooked Man”), he never actually said “Elementary, my dear Watson” to Dr. Watson in any of the stories/novels by Sir Arthur Conan Doyle. The phrase was actually a kind of homage, offered by P.G. Wodehouse, who first used it in Psmith Journalist in 1915; it found more common currency as it made it’s way into the scripts of the Sherlock Holmes films, perhaps most notably on the pursed lips of Basil Rathbone… Ironically, it was on this date in 1930 that Arthur Conan Doyle, Holmes’ creator, died.
Watson (left) as Holmes, as drawn by Doyle’s original illustrator, Sidney Padget
Sir Arthur Conan Doyle (never actually seen in the room at the same time as Dr. Watson)
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