Designing Interpretive Visuals -- Building the Mental Model
There are plenty of books available on creating graphics -- few, however, tie the epistemology of seeing to the creation of graphics that promote understanding. If there were just one book that I could recommend (besides Ruth Clark’s and my own Graphics for Learning), it would be Stephen Kosslyn’s Graph Design for the Eye and Mind
Kosslyn, chair of Harvard’s Department of psychology, has been --for over three decades – on the forefront research and understanding the cognitive, psychological and biological processes of how we “see” visual images.
In his earlier 2002 landmark but dense work, Image and Brain, he painstakingly constructs a theory of visualization in the various brain regions, relying on the latest research in neurology. Kosslyn’s diagrams evolve as he elucidates how an image – whether “seen” through the eyes or “imagined” -- takes shape and color and dimension, and travels through various neurological processing centers within the brain. Throughout, readers learn fascinating details such as why mental images are fleeting and ephemeral, difficult to “hold” in our mind’s eye (so that new “moving” data is immediately observed, a mechanism helping our hunter/gatherer forbearers from becoming the lunch of predators). Kosslyn shows why we are suddenly shocked by the aging evidenced in a photograph of a person we’ve looked at every day, but missed registering the physical changes in his or her appearance. We even learn why a simple blurred outline can be more recognizable and comprehensible than an exact photographic version of the actual item.
Yet, even for energized reader, Image and Brain was daunting, reading it was a task best undertaken with a dictionary of anatomy and neurology close at hand.
But there’s salvation: Kosslyn’s Graph Design for the Eye and Mind is a welcome tool for communications specialists tasked with making complex ideas visual and clear.
Deliberately targeting the practioner, Kosslyn actualizes the theory of Image and Brain into easy to implement principles of cognition. The book is roughly divided into three parts: theory, practical applications, and caveats and provides ample visual examples of DOs and DON’Ts. Although focused in this book on guiding the development of graphs, the principles apply to the design of almost any interpretive visuals.
The first three chapters of the more accessible Graph Design for the Eye and Mind distill Kossyln’s earlier work into the cognitive underpinnings of why his suggestions and recommendations for the design of visuals that aid the communication of ideas are empirically solid. Still, the first three chapters are an intriguing “slog” through almost epistemological theories of how we see what we see. They are a little slower going for those readers who what to get on with it, break out their crayons and begin to draw/color/graph. However, it’s well worth the time spent. Kosslyn begins with the eight psychological principles of effective graphics in his first chapter “looking with the Mind and Eye” he groups the principles into three directives:
- Connect with your audience
- Principle of Relevance
- Principle of Appropriate Knowledge
- Direct and Hold Attention
- Principle of Salience
- Principle of Descriminability
- Principle of Perceptual Organization
- Promote Understanding and Memory
Principle of Compatibility
- Principle of Informative Changes
- Principle of Capacity Limitations
In a few paragraphs, and often with an illustration, Kosslyn explains each principle and how it contributes to its directive … such as how the principle of relevance and the principle of appropriate knowledge further the design goal of connecting with the audience. These principles guide the graph designer’s choices as he or she seeks to create a graphic that attracts and holds its intended audience’s attention and then communicates it information clearly, without a lot of what Edouard Tufte calls “chart junk.” For example, in his brief explanation of the Principle of Perceptual Organization, Kosslyn writes:
Consider the following observations: … a row of reflectors on a dim highway or a formation of geese flying overhead is seen as a single pattern, not as individual objects; former gymnasts watching Olympic gymnasts see much more than do people who are watching the sport for the first time. These consequences of the way our eyes and mind work. The mind is not a camera. We actively organize and make sense of the world, and when we do so we are at the mercy of the wiring of our brains.
Some of these principles may seem like a firm grasp of the obvious, but Kosslyn breaks them down into actionable information. Immediately after his above description of the Principle of Perceptual Organization, for example, he goes on to tease out its four key aspects:
- Input channels could be said to loosely correspond to difference “focuses” or lenses of a camera, giving us different amounts of light and visual acuity.
- Three-dimensional interpretation simply refers to our tendency to view “visual patterns as if they are three-dimensional objects,” automatically translating objects on a page or screen as if they were three-dimensional.
- Integrated versus separated dimensions merely refers to the fact that we see some related aspects “together,” so that when we pay attention to the height of a rectangle, we automatically pay attention to its width (11). The importance of this aspect is that “such integral dimensions cannot be used effectively to convey different types of information.”
- Grouping laws are simply the rules by which our minds work to organize the visual data. Kosslyn’s elucidates five – which are, in less fancy terms – the tools of any good designer.
In other words, a designer can show relatedness by keeping objects in close proximity (clusters), showing continuation… through line, size or even graduation in hue, using similar shapes, colors, or size, suggesting similar direction (common fate) or even the same style, good form.
- Law of proximity
- Law of good continuation
- Law of similarity
- Law of common fate
- Law of good form
The second and third chapters complete the “theoretical” section of the book. The second “Choosing a Graph Format” helps readers understand the appropriateness of certain types of graphs -- pie charts, scatterplots etc. -- to their data. The third, “Creating the Framework, Labels and Title” can be viewed almost as description for the step by step thought process of creating graphs.
These three chapters are best read together as they form the basis of the practical advice for creating the individual typesof graphs discussed throughout the rest of the book.
The next set of chapters – 4 through 7 – discuss the relevant techniques and issues associated with the various types of graphs.
- Chapter 4: Creating Pie Graphs, Divided-Bar Graphs and Visual Tables
- Chapter 5: Creating Bar-Graph Variants
- Chapter 6: Creating Line-Graph Variants and Scatter plots
- Chapter 7: Creating Color, Filling and Optional Components
These hands on chapters are chockablock full of practical information, with copious illustrations and are designed to be independent of each other. But don’t be fooled by the techie sounding titles – there’s useful information for any type of interpretive graphic – for example, in Chapter 5. Even if you are not working with line graphs, Kosslyn’s advice to position labels at the ends of the lines (page 148) – based on the principle of grouping laws for good continuation, is useful for all sorts of diagrams and illustrations.
The third and last section of the book can be called the “Caveats” section. George Orwell’s words, “Art is Propaganda,” should make us attentive to the “purpose” each graph or visual is purportedly illustrating, but in Chapter 8, Kosslyn dissects the techniques of obfuscation and misdirection used to sway perception. For example, highlight a fat line graph can powerfully suggest that higher numbers were reached than was actually the case (page 220). Again, Kosslyn provides plentiful examples to illustrate the neutral presentation and then the manipulation. The final chapter of the book is a broad based compendium of other “recommendations” for visuals… the recommendations themselves have roots in the principles Kosslyn enumerates in the earlier chapters, but in closing, he shows how they relate to line art drawings, maps, flow charts and other illustrations besides graphs.
© 2010 Chopeta Lyons