All that seems to be optical illusion may not always be. For example, a large number of atmospheric phenomenons produce optical effects that are troubling but not inducing brain errors and deceptions.
This is exactly what the English ATOptics.co.uk web site is dedicated to. You will find a large number of photos of many visual effects from our good old planet. Including very curious things.
I love the list of the subjects:
Typical example of an “Hering” optical illusion.
Just to change a little, here is an auditory illusion that is known as the Shepard scale. Listen to the video, you’ll think that the tone has a continuously ascending pitch while it’s only a superposition of sine waves that never progress.
Thanks to Dave Munger on ScienceBlogs, it is now possible to understand why and how a cube can be seen in two different ways.
The first cube (A) is ambiguous because it can be recognized in two different ways (either cube B or cube C) and this perception can change from time to time if you keep looking at it. It’s not a perceptual illusion per se, but a visual reconstruction by our brain. And this same process is often used by optical illusions.
Now, “Seeing shapes in two different ways: how and when it happens” is a good paper trying to give us a better understanding of this phenomenon and even showing a video to support the explanations.
“Hering” optical illusion.
Bridget Riley, whose work was exposed in Paris a few months ago, is an artist who is worth mentionning to all optical illusions lovers since many of her works are based upon these phenomenons.
The research of some neuro-physiologists allowed to study the cerebral mechanisms inside those paintings and to determine that our brain needs some time to be tricked by optical illusions (the effect merely disappears if the painting is disclosed only shortly -during a split second- by an electronic flash light).
Source: ScienceBlogs
If you show a picture of a rotating grid, the brain will try to group things and it will ook like some parts are rotating together. This is temporal aliasing.
Source: David O’Reilly.
We know that all human beings are able to detect what we usually call an optical illusion (it’s a feature of our brains trying to reconcile illogical forms with what the brain is wired for). However, there was a good question left open: Can a baby see an optical illusion?
A team led by Sarah Shuwairi showed images of optical illusions similar to the one here. By hiding parts critical to the understanding of the illusion in some images and showing the full optical illusion in some other images, they determined that 10-month old babies (and 4-month toddlers) are able to distinguish the illusion from the “normal” image.
Source: ScienceBlogs.
This optical illusion is perfectly classical, but it would be a mess to try and draw it by yourself, no?