To be honest, it seems like such an arbitrary principle, but having tried it, it makes your styling less subject to being checked for balance.
When styling, arrange objects in groups of 3 or 5
The more general principle is that it is more satisfying to the human eye for elements to come in groups of odd numbers than that of even numbers. What this means, is that when you are deciding to put and arrange objects on a wall or on surface, you want to go for odd numbers.
- Place 3 pieces of artwork on one wall instead of 2
- Arrange 5 objects on a shelf instead of 4 or 6
- Have 3 plants instead of 2 or 4
Obviously, this principle will apply when the number of objects or elements is up for choice, and balance is not a big consideration. For example, the number of night tables in a bedroom is for the most part, always 2, because you are putting one on either side of the bed. You can’t have 2 chairs on one side of a table and only one on the other side. These cases just feel unbalanced. But, when you are considering one nook, or one wall, this is where the rule of 3 applies.
This principle forces you to think of design in groups rather than in individual objects or elements. You want to be “telling a story” about 3 objects instead of a story of object 1 and another story about object 2.
Why it works
Like a lot of principles of design, the rule of 3 comes from a guttural and instinctive part of how we examine a scene visually. I believe it has something to do with capturing what we see in front of us and translating it as a picture in our heads. We of course capture the most notable things. Consider for example, looking out your window and seeing 2 mountains, the biggest thing in the horizon. This is the first thing we put in our heads, two triangles that are the mountains. Then, as we try to put in more detail, we start noting things, like, are the two mountains similar? Is one bigger? Are they the same color? This is the instinctive way that we deal with two objects, and we will often note and focus on what is different between the two. When we take in a design centered around two objects, our last impression is focused on whether it is balance, and if we see that it isn’t, that’s what we are left with. This can work if this is intentional, but if you mean something to be symmetrical, but you don’t achieve it because you place an object too much to the left or right, it becomes bad implementation of a design.
In contrast, a group of 3 has two advantages. First, it does not lend itself to being compared. You don’t have to be worrying of 2 objects are balanced or similar. In this regard, our response to a group of 3 or 5 is less strict. Second, what’s interesting about a group of 3 is that you can start to form a pattern, think an increasing or decreasing one. Again, this is something that we do when we take in something visually: we will try to look for a pattern. It helps us digest the visual information. Both of these make it easier to make a group of 3 elements visually pleasing.
A group of the same object in 2’s or 3’s
Let’s take this example, where we are arranging the same exact bottle. In the group of 2, we automatically look for symmetry, and we are trying to determine if the bottles spaced the same way in the left and right sides? The group of 3 in contrast feels like a single group, comprising one bottle in the middle, and 2 on either of its side.
A group of similarly colored objects in 2’s or 3’s
Now let’s examine this design of objects that are different but are of the same color. The group of 2 is clearly unbalanced. One is bigger than the other, and this leaves us with an incomplete feeling. The group of 3 lends itself to a pattern, and we can jump from the smallest to the middle to the biggest. It’s a story that completes itself.
Summary
The advantage of being aware of the principles of design is that you can put a logic to why a vignette works or doesn’t work. Without this knowledge, you will usually be left with a weird it-doesn’t-seem-quite-right feeling, but are unable to pinpoint what it is exactly that is wrong. Moreover, you wouldn’t be able to solve it. Being aware of this principle helps us design scenes in our houses better, helping us appreciate them more.