He called this illusion “Young- Girl Old-Woman” as it depicts a younger girl looking away and an older woman looking down. This image was the first of its kind and has stood the test of time whilst competing amongst newer photos. His image has been seen by millions of people, probably even billions at this point!
Take a look at the image below and see if you can see the double image! As mentioned above, you should see a young woman looking away and a young woman looking down and somewhat discouraged. Can you spot both ladies? If you need assistance, check out the tutorial below- for a simplified version of the original illusion.
From: http://www.allcuteallthetime.com/no_one_can_see_the_double_image_in_this_portrait_can_you
