Examples created in class:
As you can see in the above example on the right, these are not complete shapes, but our mind can and will perceive them as wholes. Very similar to the Red Wedge logo designed by Neville Brody. Note: I was unable to find the Red Wedge logo on the web.
When we observe an object moving towards us, such as a friend we know, we do not tend to notice components of the object at first. Very few people would say “here comes a pair of hands”. It is more likely that they would say “here comes John or Jill”. This is because we tend to firstly see the object in full rather than individual elements of the object. The phenomena of seeing an object as a whole, is referred to as the Gestalt principle. This principle can be applied in countless ways in design.
More reading: Closure, Common fate, Figure-ground relationship, Good continuation, Law of Pragnanz, Proximity, Similarity, Uniform connectedness
Also see my post entitled Gestalt (Psychology).