The next law is the law of connection. This law says that if objects are connected by a line or some other elongated objects then they are perceived as belonging to the same group. Let me give you a few examples. Here we have four squares and two squares of the same color and the other two squares on the right of the same color. Because of that, according to the guess law of similarity you perceive the object with the same color as belonging to the same group. But now, notice what happens when I draw a line that connects these objects. Now you perceive this grouping differently. You see the squares on top as belonging to the same group, in the squares on the bottom as belonging to the same group despite the fact that these breaks the law of similarity. So objects that are connected by a line or anything similar are perceived as being grouped together. Let me give you another example. Here once again we have four squares and some squares are smaller than the other and because of that, we doubt the presence of a line that connects them, you perceive them as two groups. The groups of small ones and the groups of big ones. But when I draw a line that connects them, now you perceive the squares on top as belonging to the same group, and the squares on the bottom as belonging to the same group, same thi. Exactly the same thing with shape. So we have circles and squares and when I connect them with lines, they are perceived as belonging to a group of objects that are connected through a line. Let me give you a practical example of how these translates into real world visualizations. A very very common example is what happens in line charts. So if we draw a line chart without lines but only using the dots, we don't really perceive these elements as being connected and being part of one single object. Right. Look at these graphics. You actually perceive these as individual data points, individual dots. But when I connect them with the line, now I have the perception that this is one single object. Why is it one single object? Because all of these dots are connected through lines. The next law is the law of enclosure. Somehow similar to the law of connection. These laws says that if a group of object is enclosed in an area then they are perceived as being part of the same group. Once again, let me give you a few examples. First, here we have the same set of foursquare's as before, but if I create, if I circled them and I enclose them in this circle in this area, I perceive these objects belonging to the same group. Now, a really nice practical example of existing visualizations that use these property is a technique called Bubble Sets. What is Bubble Sets? Bubble Sets is the idea of connecting dots that spread out in different locations of a visualization through areas that convey the idea that all of these objects belong to the same group to the same category. Notice in the specific example. So this is applied to a map visualization, but it can be applied to any other visualization that uses individual dots or individual graphical elements to depict something. What is interesting here? The main thing that you should notice, is that despite the fact that these elements are spread out in the map, those that are enclosed by the same object, they are all perceived as belonging to the same group despite the fact that they are in very different locations. So that's the main idea here. So in summary the main laws that we have seen so far are: the law of proximity, the law of similarity, the law of enclosure and the law of connection. All of them play a role in the perception of how objects are grouped together to form a unit to form a group. And as we will see in the next video, there is a hierarchy of these graphical methods. What do I mean by a hierarchy? I mean that some are stronger than others and when they compete there are some that supersede the others. So we would see that in the next video.
