In the eye of the beholder: where cognitive neuroscience & data visualization intersect

I'm currently taking two (seemingly) very different classes: Cognitive Neuroscience (required course in my graduate program) and Infographics & Data Visualization (an elective in the School of Communication). We're about halfway through the semester and I hadn't noticed a connection between the classes (beyond planning to make an infographic for my Cog Neuro final project). So I was surprised to get to Part II (Chapters 5-7) of The Functional Art, which is on Cognition. I got excited while reading this section while thinking of how presenting data visualization through this perspective could help get buy-in from scientific disciplines. I also thought about useful the recommendations in these chapters would be for my Cog Neuro classmates for both their own personal research and for our class projects. So I present, in the words of Dr. Cairo, a brief overview of: "How to translate a perceptual principle into a design principle."

Our brains process and interpret sensory stimuli—often through interactions between two or more sensory inputs. I would say that that we need to assume that our brains are trying to be as efficient as possible—determining what matters and what doesn't when processing stimuli. We make automatic interpretations based on our prior experiences. So here is how we can use this information to help us design graphics:

When we first look at something, we look for the most obvious visual clues:

• Difference between background/foreground: If we want to highlight a particular difference within a set, illustrations/graphics with high contrast can make it easier to identify differences.

• Don't provide too much at once, especially when showing things that are unfamiliar to the viewer. If explaining something with both text and an animated graphic: "Don't show the moving object and piece of text on opposite sides of the screen... instead, when the action stops, then let the text appear"

• We tend to notice/be better at identifying differences in color than in shapes. So if you want to highlight the difference between certain things, using different color hues or shades may be better than using different shapes.

• Make sure your graphics "do not include distracting or irrelevant aspects that may actually take away from [the goal of the graphic]" - Sometimes less is more!

Antoine de Saint-Exupéry—"Perfection is achieved, not when there is nothing more to add, but when there is nothing left to take away."

Next, here are very useful (but not perfect) guidelines by Cleveland & McGill (1984) for graphical perception.

The following are ranked by how accurately we can detect differences/make comparisons using the following methods (from most accurate to least):

1. Position along a common scale

2. Position along nonaligned scales

3. Length, direction, angle

4. Area

5. Volume, curvature

6. Shading, color saturation

As illustrated by the following figure from The Functional Art (Figure 6.12, pg. 120).

"If the goal is to facilitate precise comparisons, then ... a bar chart is always superior to a bubble chart or a heat map"

However, sometimes our goal is not to provide the viewer with a precise number, the number itself may not be most important, but instead, we're looking for demonstrate a larger pattern or how a particular variable differs across geographic locations, then if the goal isn’t precision, but larger patterns or relationship of a variable with a geographic location..." then it may be more effective to use something like color hue (like the use of a map showing geographic concentrations of republicans vs democrats results using shades of red and blue).

Finally, Dr. Cairo (in The Truthful Art) states that "vision is the most developed sense in the human species" - I cannot verify or deny that statement. I honestly don't know. However, from my Cog Neuro class, I do know that when presented with conflicting visual and auditory stimuli, the visual system is dominant. This is illustrated in the McGurk effect, which is described in the following video. It is fascinating and I highly recommend you watch!

https://www.youtube.com/watch?v=G-lN8vWm3m0