This is a very famous optical illusion which may be seen in two ways: as a duck or as a rabbit.
Which one do you see first? It doesn’t really matter…
And, when you see one can you see the other?
And now the most important question – how fast can you switch between the two images?
Many people at first see the duck and they may switch between the two versions, but the question is: how fast you can switch from one to other version?
Do you need some mental effort or you can do it very easily?