More data = better decisions, right? Not always. When you are getting more information than you can process within a specific time period information overload starts creeping. Confusion, stress, anxiety and low motivation usually follow. Can we prevent that?
In general, the more information you have, the more accurate your decisions will be. But at some point, the trend reverses, and the more information you have, the less accurate your decisions are (recommended reading: this paper for causes and consequences of information overload and the – poor – Wikipedia article).
Too often you can root causes of information overload to poor information and report design and poor information management skills. Let me exemplify. Can you memorize this sequence?
It is not easy. Let’s try again:
Better, but not good enough. Let’s try this one:
You’ll probably recognize these as the Fibonacci numbers, a sequence of numbers where each is the sum of the two preceding numbers.
So, you’ve tried to memorize a string of 16 digits. Then five strings of three or four digits. Then a word, “Fibonacci”. Which was the easiest?
Small scale information overload: working memory management
Let’s assume for the sake of discussion that information overload takes place when the information you try to manage exceeds the capacity of your working memory (it goes much beyond that, of course). Let’s also assume that there are five slots of working memory that you can use to store chunks of data.
As you can see, there is no room in working memory for the first sequence, the second barely fits and the third uses only one slot, for exactly the same data.
While you can’t do much to add more slots to your working memory, you can have an active role at the design of those chunks and by that greatly improve the way you handle data and reduce the danger of information overload.
There’s a thread in Edward Tufte’s forums where he discusses Miller’s classic paper, “The Magical Number Seven, Plus or Minus Two: Some Limits on our Capacity for Processing Information“. Tufte rightly argues that:
… the deep point of Miller’s paper is to suggest strategies, such as placing information within a context, that extend the reach of memory beyond tiny clumps of data.
By providing context or some sort of linking between “tiny clumps of data” you can create a single chunk of data. This is a basic strategy for information management and visualization.
Just be aware of the limits of our working memory and understand what you can do to maximize its capacity. This is a great starting point to design better charts.
Simple tip: avoid a back-and-forth movement
Minimizing the need for a back-and-forth movement is a practical application of the these principles.
We decode a chart with multiple series by reading the legend and storing the meaning in our working memory. If there are more series than the available memory, a pendular eye movement between the legend and the plot area occurs. Try to prevent that by directly labeling the series (specially in line and pie charts) or make sure that you really need all those series. If you do, a panel could be a better option.
When you have two related charts in two different slides in a presentation your audience will probably want to compare them, and a back-and-forth movement between slides happens again. Try to change the presentation design so that both charts are placed in a single slide, making comparisons easier.
Photo credit: catd mitchell