I think that the first picture listed, which should illustrate that close elements are perceived as a group, doesn’t really obtain its intended result: (to me a

I think that the first picture listed, which should illustrate that close elements are perceived as a group, doesn’t really obtain its intended result: (to me at least) the pink elements are the ones that stand out and tend to form a group. Tint/saturation is stronger than shape and/or proximity in this case.