The red and blue lines below span the diameter of two spinning helicopter rotors. When you first look at this image, which line appears to be the longest? Try measuring the two lines to see if you were right. This illustration was drawn by the talented Gianni Sarcone.
If you stare at the center of this pattern designed by Ramiro Chavez Tovar, you should see a series of nonexistent black radial lines coming from the center of the image to the outer edge. Some people have also reported seeing colors and peripheral rotation.
This is an excellent example of the way in which our eyes deceive us. In the street view shown below, the line AB looks to be much longer than line CD. If you measure them, however, you will find that they are exactly the same length.
Are the horizontal lines on the following figure parallel? They are indeed parallel but appear to run at angles. This illusion is commonly known as the cafe wall illusion.
Do the red lines below appear to bow outward? Or are they parallel? The red lines are straight and parallel and do not bow outward despite their appearance. This illusion, known as the Hering illusion, was discovered in 1861 by a German physiologist named Ewald Hering. The Hering illusion produces the opposite effect of the [...]
Do the red bars appear perfectly straight and parallel? The lines are straight and parallel. Some viewers will perceive the lines to bow inwards due to the angles of the blue lines. This illusion was first observed by German psychologist Wilhelm Wundt during the 19th century. The Wundt illusion produces the opposite effect of the [...]
These three horizontal lines are all the same length. Does the middle line appear to be longer than the top line? The arrows on the end of the lines give the impression that the lines are different lengths. The red horizontal lines help to show that they are all equal. This is known as the [...]