Invariance is the belief that any recognizable object will still be recognizable no matter how much it is altered or moved, with some limit of course. Take typography for example. Their are thousands of different fonts and yet people still recognize them instantly.
The idea of multistability is an object that is neither one thing or another. There is no way of determining one from another. The Necker cube cane be viewed in two different ways and the vase/face illusion is the same.
In this conceptual drawing, we again mentally create images of triangle, spheres, and curved lines with the use of Gestalt. Using this principle, there are many possibilities for creating images without creating them. It relates to positive and negative space as well.
Source Image, Artist unknown
The idea of this drawing is that the Gestalt Principle of emergence lets us see the Dalmatian in all the black spots even the whole dog is not outlined. We mentally connect the dots and create the image.