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Understanding Preattentive Visual Property
A preattentive visual property is one which is processed in your memory without any conscious effort. it’s processed and decoded in milliseconds even before you start to pay attention to parts and contents of the image.
The advantage of understanding preattentive visual property is that a designer can harness them to make it easier for your audience to quickly capture the message you intended for them. Since these properties are processed unconsciously, using them in your visualisations will make your audience decode your design very quickly.
Colin ware, in his book Information Visualization perception for design, listed four categories of preattentive visual attributes. They are:
- Spatial Position
Understanding each of these attributes will help you to improve your visuals. Let’s take a look at each of them sequentially.
Preattentive Visual Property- Form
Form has to do with orientation, line length, line width, curvature, size of element, shape, added marks, anything that has to do with the design form. For example, length can be manipulated to draw attention fast, a collection of elements that are circular with just one with a square shape will naturally draw the reader’s attention to the square shape. All these preattentive attributes belong to the “form” category.
This category is summarized below:
Preattentive Visual Property- Colour
Colour is a very useful and common preattentive property easily decoded by the brain. The choice of colours matters a lot. Hues(the measure of the colour itself) and intensities(contrast and lightness) are two properties of the colour which are easily processed by the brain and can be used to separate visual elements from their counterparts.
So, you must learn to use hues and intensities to distinguish an element in visualisation, in order to get the reader’s focus unconsciously.
Look at the image below, you will notice you see “Stop” first before anything.
Let’s take a look at some visualizations. Look at this donut chart below. The first two sections that catch your attention are the flood and the epidemics. The “epidemics” captures your attention because of “form”, that is the shape and size as discussed earlier while the “flood” captures your attention because of “colour”. The designer intentional wants you to be attracted to the flood, and he, therefore, gave it a unique colour.
Take a look at the design below too. The sections with high intensity of colours capture the reader’s attention first. He automatically decodes that it signifies a higher value. Hue and intensities are a good way to quickly send a message across.
Preattentive Visual Property – Movement
Movement is another property that easily catches peoples’ attention. Movement can either be in the form of flicker or in the form of a motion.
Take a look at the image below, you will notice you are first attracted to the blinking yellow colour. It’s a call to action, but care should be taken to avoid too much movement or animation, as this could be unpleasant to some readers.
Preattentive Visual Property – Spatial Positioning
Spatial positioning of elements also determines if a reader will easily grasp the message the visual is representing. 2D positioning which is one of the most commonly used spatial positioning places elements as if it’s on a flat surface, with only two dimensions x and y axes. The positioning of elements on such a scale determines how easily the brain will process it.
The positioning of elements on a 2D scale determines how the brain will easily capture it. Elements high up the y-axis and elements far towards the right on the x-axis are easily read as high values.
Summary principles for improved visuals
As a way of summary, the following highlight of the summary should be at your fingertips before starting your design.
- Bar Charts are not outdated. If Bar Chart is the best chart to present your data, please use it.
- Use bright and high contrast colours for elements you want to draw the attention of the readers to.
- Beware of too many colours on a single design.
- Start a line and bar chart from the origin (0,0), else you may be sending out wrong information.
- Start bar charts at 0 to allow your users to accurately evaluate length and differences between bars.
- Chart titles and subtitles should be eye-catching. The subtitle should present a basic summary of what you want the reader to see from the chart
- Always add a data source to your visualisation. It portrays transparency and integrity.
- Anytime you use a Pie Chart, observe the values you’re comparing. If the values are not distinct enough, the angles will also not be distinctive and hence will be difficult for the reader to comprehend. Do not use Pie Chart to compare variables above ten. It may look clumsy.
- Cater for your intended audience. Don’t use a chart your audience will not understand.
- Add images that will easily send you message across, to your design. Images are attractive