2 faced woman

All that I know is that it first appeared on a postcard in Germany in 1888.

This is my all-time favourite optical illusion sketch:



The author: Maurits Cornelis Escher, compiled it in 1953 - it was entitled "Relativity."

You can see the author's lightly disguised autograph in the top left hand corner of the sketch.

Here are the famous Zoellner Lines:



Believe it or not, those thick, black, diagonal lines are all PARALLEL!

Biblio

Craven's ilusion is signed " 99 " (I have some doubts that it was created in 1799!)

I believe that CDK's illustration was probably created in 1999 - because the original does not show the two possible female images below the main image.

Would anyone like to try and build this crate?:

What animal do you see here?:

Could you manufacture this Triangle?:

Hee heee - are those your elucidatory squiggles underneath, Craven? I have never seen that picture presented with them before.

What beasties do I see, heehee? Well, one of then is me!!!

Bib, That's a rabbit...... isn't it? ha, ha.... c.i.

optical illusions
Seems this is a good place to post optical illusions.

Here are a few:

Count the black dots:



Spiral



big or small circle?


dot



elephant



lines



Another

Hi Craven, Was that a rhetorical question? ha, ha..... That skull-woman looking in the mirror picture is a good one! c.i.

CDK: nice selection. Did you have those over at your old place?

Yup. I have some other ones on a hard drive somewhere that I'll post eventually.

This image appears to BULGE, although it's only made from squares:

The knotted triangles:

http://psylux.psych.tu-dresden.de/i1/kaw/diverses%20Material/www.illusionworks.com/html/perceptual_ambiguity.html

This web site gives the history of the OLD/YOUNG picture.

Subsequent posting illustrate different forms of "illusion".

(1)The OLD/YOUNG etc, and the Escher type impossible figures are examples of central processing imposing a "Gestalt" or attempted interpretation on the stimulus. Such illusions have a correlation to culture as does the Muller-Lyer (arrowheads) one which is explainable by the way 2 dimensions are used to display 3 dimensional corners.

(2) The apparent bulges and fluctuating shadings in Mach type black and white pictures are often caused by automatic periphereral visual processing involving lateral inhibition in contour enhancing detectors. Such visual enhancement is thought to have arisen as a survival mechanism in humans.

The importance of illusions is to underscore the fact that perception is active not passive and that "truth" like beauty may always lie in the eye of the beholder.

Spectacular post.

My thanks to everyone for starting my day off with so much enjoyment.

Frank: you are welcome...glad that you liked the images.