Type2: illusions about size, length and angle

Have you ever seen illusions about size, length and angle?

 I think this topic is the most familiar to many people because many books relatively carry about it.

 Look at the left picture. You may think the left table is longer than the right one. But the depth of the left one is as long as the breadth of right one. If you doubt me, measure it actually. This illusion is caused by human's instinct.





 There is a very interesting experiment to show the instinct. First of all, write "T" on paper, provided that the horizontal line and the vertical line are same length. Next, measure the lines. So you will notice that the horizontal line is longer than vertical one in spite of you tried to write same length lines! In other words, if "T" is made from same length lines, vertical line is seemed to be seen longer than horizontal one. This is called "Fick illusion". Well, in the picture of "T", the figure B looks long even if leans this figure 90 degrees. So the detailed mechanism has not been solved yet.

 Next, look at the right picture. There are two figures written in bold line. The left one is seemed to be seen longer than right one. But both lines are same length. It called "Muller-Lyer optical illusion".
 Below picture is application of Muller-Lyer optical illusion. Of course, A and B are same length.

















 Next, look at the left picture. It is called "Cafe wall illusion". In fact, all the gray lines are parallel!



 The theory of Cafe wall illusion is like following.
(A) If there is a black line at the tip of corner of a black square, the square is seemed to tilt opposite corner side.
(B) If there is a white line at the tip of corner of a white square, the square is seemed to tilt opposite corner side.
(C) If there is a white line at the tip of corner of a black square, the square is seemed to tilt opposite corner side.
(D) If there is a black line at the tip of corner of a white square, the square is seemed to tilt opposite corner side.

　Because of this theory, when the horizontal lines are gray (the color between black and white), the illusion effects the best. Well, if the lines are white or black, what happens? The answer is below picture.














Next illusion is easy for you to make. Just type "杏マナー" again and again on a word processor. So you will notice the illusion. This is called "Popple illusion".

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杏マナー杏マナー杏マナー杏マナー杏マナー杏マナー杏マナー杏マナー杏マナー
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ーナマ杏ーナマ杏ーナマ杏ーナマ杏ーナマ杏ーナマ杏ーナマ杏ーナマ杏ーナマ杏
杏マナー杏マナー杏マナー杏マナー杏マナー杏マナー杏マナー杏マナー杏マナー
杏マナー杏マナー杏マナー杏マナー杏マナー杏マナー杏マナー杏マナー杏マナー
杏マナー杏マナー杏マナー杏マナー杏マナー杏マナー杏マナー杏マナー杏マナー

　"Zollner illusion" is very popular, so you should have seen it at least once. In Zollner illusion, all lines are mutually parallel. I will explain the reason.
 In Zollner illusion, the angle on the crossing point is seemed to be seen bigger than actual angle. Such effect occurs on whole of long lines and the illusion appears.

 Last illusion is "Ebbinghaus illusion". In this picture, both orange balls are same size. It happens because of comparative effect. To make it clear, influence of surrounding environment.









 There are more and more illusions in this world.  So I will introduce little more.

They are same tall.

They are same tall.

Green lines are same length

 Did you enjoy illusions about size, length and angle? This topic has too many illustrations to put on this blog. If you want to know more, please research by all means. Next week is objects that change the form by the difference of the point of view (for example Edger Rubin). Don't miss it!