arrowGuide Dogs website 
 
 
  healthyEyes - your sight is precious to us  
  Browser default text sizeBrowser large text sizeBrowser largest text size

How we see  |  Looking after your sight  |  Problems & solutions
 

Text only  |  Accessibility

Home  |  Free updates  |  Help  |  Site map  |  Legal  |  Detailed search

 
 
 

Up arrowOptical illusion

Answer

  

Impossible trident

How many prongs are there?

Cover the one end of the trident and count how many there are, then cover the other end and count again.

spacer
The shape that is shown cannot exist. It appears to be a three-pronged object, with each prong being of the same length, pointing in the same direction and with a circular end – here the ends are black with centres of red, blue and yellow. However, although anyone of these two-dimensional prongs can be traced back by the eye to the rectangular shaped base, which supports them all, there is no sensible three-dimensional link between them. This image is exposed as simply being a collection of drawn lines which give the illusion of three-dimensions until one tries to view the whole three-pronged object as a whole.

For a description of the image place your cursor over it (certain browsers only), or click here for an audio transcript.

Answer


Jump to top of page

  
spacer
What's your EyeQ? Take part in the biggest eye care poll ever!

Did you know?

Eating brocoli, spinach and other similar vegetables regularly can help prevent eye disease. Find out more

    

 
HealthSure logo: This web site is supported by HealthSure - "Be sure of your sight with HealthSure healthcare." Guide Dogs logo