Unit 5 Reading

In chapter 6, Cairo explores the hierarchy of human perceptions, and what types of perceptual distinctions make the most difference in cognitive awareness of surroundings and visual calculation. This has great implications for infographics: differences in lightness and color make more of a distinctual impression than differences in shape, for instance. The former create more of an instinctual, automatic sense of distinction ("preattentively"), before focus and reason begin to come into the equation.

 Our visual brains have evolved to recognize patterns as a means of survival. Elements such as differentiation in size, orientation, or color and shade that stick out from the environment consequently are perceived as striking and noteworthy. We also tend to aggregate similar elements together into groups (as per Gestalt theory), which enables us to differentiate separately moving entities in our environment.  Proximity is another factor that informs our sense of grouping and pattern recognition, which becomes very important in visual hierarchy. Both similarity and proximity can be combined to overlay two different dimensions to a visual graphic to communicate more dynamic information (as in separate sets of bars in a bar chart being grouped together, with each group having one of each symbolic color). Closure is yet another important element (either borders or areas differentiated by different background colors/shades, etc).

The Cleveland-McGill study (conducted for AT&T Bell Labs) ranks the elements of visual design in this order, from that which lends to the most accurate perceptions to the least:

• Position along a common scale
• Position along nonaligned scales
• Length/Direction/Angle
• Area
• Volume/Curvature
• Shading/Color saturation

Cairo then goes on to speak of visual depth and the overlaying of elements over each other to create the sense of 3Dimensional reality.

But one of the most important takeaways of this whole chapter, in my opinion, is the difference between creating graphics to represent technical data points vs. visual representations of relationships and comparisons. This can create a huge difference in representation and bring to the forefront dynamic, complex relationships that would otherwise likely not be seen.