Which of the following is NOT a visual communication principle?

The principle of brightness is not typically classified as a visual communication principle in the same way that proximity, balance, and hierarchy are. Visual communication principles focus on how elements are arranged and interact with one another to effectively convey a message.

Proximity refers to the spatial relationship between elements, suggesting that items placed close together are perceived as related. Balance involves the distribution of visual weight in a design, which can be symmetrical or asymmetrical, affecting the overall harmony of the composition. Hierarchy organizes elements according to their importance, guiding the viewer's attention through the use of size, color, contrast, and placement.

Brightness, while important in terms of color and mood in a design, does not serve as a foundational principle for how visual information is structured and interpreted. Therefore, it stands out as not belonging to the core principles of visual communication like the other options presented.