What to see?
At first when you look at this picture you will probably see just spots, dots, a mixture between black and white. Even if your brain will see that it will try to search a meaningful image, it will try to make sense of these meaningless spots. Even if the answer doesn’t come to you its ok… look for a silhouette of a dog, a Dalmatian dog to be more accurate. Now do you see it? If you do, then the image will remain in your mind and every time you’ll try to look at the picture you’ll see the dog in a moment.
How it works?
This “illusion” is meant to show that past experience can interfere with your perception. Basically in this case form and depth are affected. Now let’s explain from the top!
When you started watching the illustration you probably couldn’t see what this picture shows. All you could see were spots and dots… now! When you started to explore it, to find something, you know you noticed that the fragments suddenly started to reorganize and to be recognized, in this case the fragments shown a Dalmatian dog. Our neurons store all kind of knowledge, of images that will be reactivated when we will encounter that object in the real life. Our brain functions with images, with memories. So in this case we tried to access the correspondent of the image in our brain and we stopped in the moment we found the corresponded. At the end the figure looks like the object it was supposed to represent – it now has the shape and depth relations of a Dalmatian dog.
This type of experiment is a case in which a high-level brain area underlying language comprehension tells a lower-level area, in this case the cortical areas dedicated to visual scene analysis, what is happening. So if the picture would be sustained by a verbal material or by a motion we would be able to see the dog easily because our visual system connects with other cortical areas.
What happened different in this case? During all the time you looked at the picture, the image remained the same on your retina but in the same time your brain worked to construct a correct interpretation of the image. This shows us that perception is an active process of constructing a description.
For an animal it’s important to be able to recognize the environment or else he might not spot easily a predator, prey or other type of food. It’s important for them to be able to separate the figure form the ground. The attempt to deceive these processes it’s called “camouflage”. For example: a stalking cat moves slowly and freezes from time to time to avoid giving motion clues to its prey.