Archive for 07/01/2009 - 08/01/2009
The Poggendorff Illusion is an optical illusion that involves the brain’s perception of the interaction between diagonal lines and horizontal and vertical edges.
It is named after Johann Poggendorff (1796-1877), a German physicist who first described it in 1860. In the image above, a straight black and red line is obscured by a grey rectangle. The blue line appears, instead of the red line, to be the same as the black one, which is clearly shown not to be the case in the second picture.
Stare at the center black dot. Do all of the black dots seem to bet bigger?
OR! Look at the center black dot again for 20 seconds.
Then look away from it quickly and you should see the same image just opposite. The Black dots will be white and the white bigger circles will be black, try it!
The following are common tests used to detect colour blindness.
Can you read the numbers hidden in each square?
You should see 58 (upper left), 18 (upper right), E (lower left) and 17 (lower right).
If you cannot see any of the above numbers/letters, you may suffer from colour blindness.
You are likely to see that the top row of circles appear as "bumps" followed by "holes" and so on in an alternating pattern.
Can you try and see the opposite? Have a good hard look and try to see the first row as holes and the second as bumps. Difficult?
Now hide the bottom row of circles from your field of vision (either with your hand, or scrolling your browser window appropriatly). Is it easier to see the first row as holes now?
An investigation of an English university discovered that it doesn't matter in which order the letter are written in a word. The only importance is that the first and the last letter are standing at the right location.
The letters between the first and the last letter in a word may be located at random. Because we don't read each letter at a time, we read the word as a whole.