What image do you see below?
For some, they immediately see a vase or a trophy (white), while for others, its two faces in profile (black). Switching between perceiving the two images is fairly easy for most.
What makes this illusion so interesting is that it proves that perceptions are not solely shaped by images. It is also critical that the brain be able to differentiate objects appearing in the background – which, as shown in the picture above, is not always obvious at first glance. Is it the vase or the two faces which are the central focus and what is the background? The instant switch between the central focus (object) and the background shows the shifting dynamics of perception.