Note: As of June 2013, this post is out of date. To learn more about visual hierarchy and why it matters, we recommend chapter 2, "Hierarchy," of our book Visual Usability: Principles and Practices for Designing Digital Applications. You can find out more about Visual Usability in our blog post about the book.This post is the fourth in an occasional series of tips for developers and other non-designers who don't have a designer to work with when needed, who want to improve the aesthetics (and usability) of their apps or who want insight into the designer's approach.
The single biggest issue we see in web application UI design is a lack of visual hierarchy – the arrangement and treatment of elements that represents their relative importance.
Developing a strong visual hierarchy is important because the presentation of elements will communicate to users whether you “design” those elements or not. Considering placement, treatment and use is essential to creating applications that make sense.
Left: lack of hierarchy – no clear direction is implied.
Right: variation in relative size, placement and treatment start to indicate a hierarchy.
When presented with a screen for the first time, users need to quickly grasp what they can do on the screen, how they can do it and why they might want to (i.e., what effect their actions will have). Establishing a visual system that outlines each element or group of elements’ relative importance will direct the eye, affecting the order of when elements are seen as well as user behavior – if form fields are filled out, if submit buttons are clicked, if links are found, and so on.
There are several factors that can be manipulated to establish visual hierarchy, with the main ones being placement on the screen, use of color, size of elements, font selection and treatment. We’ve already covered using type to establish a hierarchy, but now we’re going to review things at the higher level; future posts will address other factors individually and provide practical tips.
Super-brief introduction to the principles of visual hierarchy
Placing an element like a dot in a frame like a screen or a box creates a relationship between the element and the frame. The location of the element in the frame affects perception (Hofmann).
Left: Stable, static placement.
Right: Unstable, active placement. Movement is implied. Which dot looks more important? Which combination keeps the attention of the eye?
Placing more than one element in a frame creates relationships between the elements and between the elements and the frame. If shape, color and size are the same, relationships are based on proximity – how close the elements are to one another and the frame – which gives each object a perceived visual weight. Perceived visual weight is a key component of visual hierarchy – more weight equals more important.
Left: Which carries more visual weight? The single dot off-center or the four dots in the center?
Right: What about here? Less proximity (spacing) and upper placement create more visual weight than greater spacing and lower placement. This arrangement starts to suggest a hierarchy – that the group of dots in the upper left are more important yet somewhat related to the group in lower area.
The principles of perception hinted at in these dot/frame illustrations apply to web application elements as well.
Visual hierarchy on the web
In order to have a hierarchy, things need to be presented so that the more important things have more visual weight or prominence than less important things. Following are some ways to establish hierarchy.
In the Western world we read from left to right and top to bottom. This affects how we “read” screens as well. We know from eye tracking studies (Nielsen) that quadrant “1” is viewed more than the others. The “Inverted Pyramid” principle supports this as well (Lidwell, Holden and Butler).
Based on the principles of proximity and size, we know that small elements tucked very close to larger elements such as a border or edge – so that they appear as being inside the larger thing - are seen as less important than elements with more space all around them.
Elements with a lot of white space around them are viewed as important (take another look at the single dot in the center of a box).
Elements that are shown similarly to one another are seen as related. If one thing is more or less important than another thing, it should be treated differently – highlighted in some way.
A single element treated differently (highlighted) from similar elements nearby has greater visual weight and may be perceived as more important.
Large elements are seen as more important in comparison to smaller elements. Obvious, but only Apple seems to have mastered this consistently.
Defining a hierarchy
The main thing to consider when making decisions about where to place elements on a screen and how to treat them visually is to identify what most people need to do (or what an organization might want them to do) on the screen; and if that's more than one thing, the priority of the desired interactions. (For example, “we want everyone to sign up or log in, but if they don’t want to we at least want them to complete the checkout process.”) Ideally this effort is informed by 3-4 key user scenarios that have been defined with input from stakeholders or direct knowledge of user behavior.
An explicit way to define a hierarchy is to list the elements you need to have on your screen and number them from most to least important. An element is a unit of content or functionality. Your list may be something like this:
• search box
• submit/cancel buttons
• automatic update widget (for blog and twitter)
• latest 5 items
• featured content text
• promotional headline
• cart widget
• global navigation
• local navigation
• login area
• content areas
There can be more than one element with the same number – they will need to be treated in a way that suggests equal importance. The prioritized list serves as a blueprint for defining visual hierarchy, and can be used when making decisions about placement, size, color and treatment.
Next: Screen layout basics
1. Don’t Make Me Think by Steve Krug
2. "Communicating with Visual Hierarchy" by Luke Wroblewski
3. Graphic Design Manual by Armin Hofmann
4. Eyetracking research - findings from Nielsen Norman Group's usability studies using eye tracking technology
5. Universal Principles of Design by Lidwell, Holden & Butler