Well, can you? ~ Page 2

Are these actually squares?

Sander Paralelogram ~ 1926
Measure the diagonals - you'll be surprised

Life ~ The Fraser Illusion
Are the letters really crooked?

Are you looking at the inside or the outside of this card?

Look at this picture for a couple of seconds and bring your face closer to the screen.
The woman will seem to join herself back together.
Alternatively you can bring the monitor closer to your face, if you like)

Sausage Fingers
The above picture reminded me of a childish amusement.

Hey presto ! Sausage fingers.

Are these rows really parallel?

Thanks to Peter Shearn for reminding me of this building at the bottom of St Michaels Hill, Bristol

Please scroll down for some more pictures of the tiles

This really is an optical illusion, the tiles are perfectly rectangular!

Even when damaged and dirty the illusion shows through !

How can a two dimensional image show bumps and hollows?

This isn't really an optical illusion but it is an interesting problem.
Although the large triangles are made up of the same smaller triangles,
why is there a space left over in the lower one?

It's because that although the hypotenuse of the large composite triangle looks as if it's a straight line, it's not.
From my school days and SOH CAH TOA (Sine = Opposite / Hypotenuse, Cosine = Adjacent / Hypotenuse and Tan = Opposite / Adjacent, we find that for the smaller blue triangle the bottom angle is 21.8, whilst for the bigger red triangle it is 20.56, This small difference (1.24 degrees) is enough so that in the first composite triangle the "hypotenuse" is actually concave and in the second convex, giving the extra unit of space.

Try saying the colour you're seeing not the word

What's happening is that the right hand side of your brain is trying to say the colour,
but the left hand side insists on reading the words

Focus on the dot in the centre of this picture, then move your head backwards and forwards