Do you know what makes a design good?

Design is powerful because of the way our brain processes visuals. We might think of vision working by our eyes pulling in images and projecting them in the back of our mind. If this were the case then there would no be design or art. There are in fact 30 areas in the back of your brain that process different aspects of the image. The various vision processing areas of the brain are individually recreating the design. So, in a way, the viewer is also an artist. In reality, design and art stimulate the mind more than a realistic image would do. Which is why it affects us differently. Randomly placing objects on a screen do not create the same reaction. There must be purpose to the visual distortion/arrangement for the mind to pick up.

It would be nearly impossible to lock down all the various styles of design that are out there. Sure, we can categorize them into bigger buckets and generalize with words like “clean,” or “grunge,” and designers certainly understand what kind of design to expect from those words. Although at the surface there is a difference between them, at their very core the brain is being stimulated by them in the same way.
The principles below are based on studies of the brain and neurological research that have been presented a variety of ways online. In this article I have attempted to present them in a way that best relates them to design.

The Principles of Aesthetic Experience

Grouping

When you look at a design layout and notice subtle touches — like the links of a specific color — this is not just a nice design touch, or good usability. It is tapping into the way your mind groups together things like shapes or colors. This technique is used heavily in design and plays off the mind’s natural tendency to try and find connections in elements. For example, in logos like FedEx, the arrow is created in the mind by grouping the negative space between the “E” and the “X.”
The neural mechanisms that we are tapping into are the same as those that evolved as a survival trait in the brain to protect us from predators and defeat their camouflage. Consider an early human seeing a golden color behind some foliage. The mind grouped those together as one whole so we can tell that there is a lion waiting behind the leaves. There are a set of design principles known as Gestalt Theory which breakdown the various types of grouping into specific categories. These can be explored for further understanding of grouping.

Symmetry and Balance

A symmetrical object taps into the same neural machinery made to help the mind detect other people or predators. The more symmetrical and balanced something like a human face is, the more perceived beauty that is interpreted by the mind. No human face is perfectly symmetrical, however when the two sides are nearly equal, they are seen at a metacognitive level as more beautiful. Some scientists have argued this is because asymmetrical organisms are suffering from disease and the mind has evolved to recognize that.
So, when we create symmetry and balance in a design through the use of guides like the grid and specific sizing of elements, we are creating something that is more perfect (almost hyperreal) compared to what is found in naturally created objects or organisms. It can be argued that most design is asymmetrical, however there must be a balance in the design. If that balance is not there, the mind will see the layout as asymmetrical and potentially awkward or wrong.

Peak Shift

Peak shift is how the mind reacts to differences between elements. The more you exaggerate those differences the more you are drawn to them. For example, If you were to present a lab rat with a square and a rectangle and teach it that the rectangle will get them food, and the square will not, it will obviously go for the rectangle. If you add a third element, a longer, skinny rectangle, the rat will be drawn to that more than the other one because the form has been exaggerated.
This same principle is applied to viewing a realistic drawing and a caricature of a person. To the mind the caricature looks almost closer to the person than the realistic drawing. The mind picks up on the differences that have been accentuated.
We notice this done in many designs with lighting for example. The shadows and reflections, or soft spotlights behind elements is an exaggerated version of what occurs with natural lighting. By pumping up these effects we are creating a more aesthetically appealing lighting in our compositions.

Isolation

As designers we learn to create focus on the essential elements of a layout and simplify the message that we are trying to communicate. In art, a drawing that is merely a minimal outline of the subject can be much more powerful than a 3D rendition of the same thing. This is why a sketch is more effective as art than a full color photo.
The principle of isolation is removing the gratuitous visual information that might clutter the design and concentrating on the essentials. It directs attention to what matters. By extracting what is critical and only showing that, the mind reacts strongly to this.

Perceptual Problem Solving

When watching a horror movie the directors have setup the scenes to play off of this principle. The longer the monster or killer in the film remain in the shadows or only revealed in small pieces, the more frightening the film is. The fear is created in your mind and imagination. If during the entire film you saw the killer or creature in daylight, there would be nothing that scary about it.
Perceptual Problem Solving is forcing the mind to try and figure out, or imagine, what the object looks like. The struggle almost introduces pleasure and forces the mind to figure out the image. This stimulates the mind more than just being literal with something, but rather teasing the mind with pieces of it and building up to a big reveal.

Contrast

We know contrast well as a graphic design principle in relation to light versus dark, curves versus angles, and dynamic versus static. This contrast is in how the human retina and brain respond more to the edges and sharp stepped changes in color or gradation. The visual information mainly is in the area of change like the outline/edge of a person and the color wash background. Therefore, this becomes a more interesting and attention grabbing area for the eye and brain to focus.
So, by adding other dimensions of contrast to the design, like texture or color, the design attracts the cells and holds their attention. Contrast can also exist as repetitive elements like black and white lines that create a sort of visual rhythm for the eye to follow. Creating areas of that contrast each other is vital to a dynamic and well-composed design.

Generic Viewpoint

When given an object to view the mind prefers a less complex vantage point. Take for example the cubes in the image to the right. The one on the left looks to us like what a cube should look like, because it is from a generic viewpoint. The cube on the right appears to be a flat hexagon to most people because it is from a very specific viewpoint. With the sides filled in with color we can finally see the cube. So although there are exceptions to this rule, this more generic viewpoint is usually more aesthetically pleasing.

Metaphor

Designers understand the use of metaphor very well. It is used in creating a familiar user experience by tapping into real objects that people already understand. In this case the understanding of metaphor is a bit different. The metaphor is a sort of mental tunnel between two objects that at first seem unrelated. On an unconscious level though, the mind has already made the association.
Some examples of this are Shakespeare saying, “Juliet is the sun.” In this case he is relating Juliet to being warm and nurturing, not that she is an object in our solar system. Good metaphors are easy to grasp and universal. Some design or imagery is compelling — because of the use of metaphor — the moment we see it. That is because before we even understand why, our mind has already deciphered it.