The last two laws of grouping are the Law of Closure and the Law of Continuing. So what are these laws about? The Law of Closure says that if there are gaps in open structures, these structures are perceived as being closed, despite the presence of these gaps. Let me give you an example. Look at these two objects. These are two separate objects. But once they are arranged in the specific configuration, since they give the impression of creating a square. Despite the fact that there are lots of gaps, we perceive this as a square. So this is an example of the Law of Closure. The Law of Continuity, somewhat related to that, says that if a set of objects are aligned along a specific direction or line, or curve, they are perceived as being connected, despite having gaps between them. Or even despite any intersections with other objects. So here is a practical example. We have two lines, right? And some of the objects that belong to these lines are colored with one color, or colored with another. So when we look at these little dots, we actually perceive two intersecting lines, despite the fact that individual objects have different colors. So in a way, having the objects aligned around a specific curve or direction, produces the effect of having these objects grouped together in one single line. How does this relate to visualization? Let me give you a couple of practical examples. The first one is the old idea that alignment is a very powerful tool in this utilization. Every time you align objects together, despite adding gaps between them and no lines or other objects connecting them, you will perceive them as being one unit. Classic example is bar charts. If you align bars together, even though you don't have a reference line or anything else, you only draw the bar. You still perceive them as being one single unit. Another example is when you have node link diagrams in networks like this one that you have in front of you. Despite the fact that the lines intersect many other lines, most of the time you can perceive the direction of every single line if you focus on them. Despite the fact that there may be a lot of intersection between them.
