Keep it all together
Three levels of consistency can be applied to the design of an application. First, an app can be consistent within itself. Taking a step out, an app can be consistent with previous versions of itself. Finally, an app can be consistent with something greater than itself, namely the suite of products to which it belongs. (Arguably, another level also exists, which is consistency with people’s expectations, but that topic is outside scope and is instead categorized as Precedents.)
Consistency within an application is important because it conveys a sense of stability, instills a feeling of trust and improves discoverability. Preserving user-modifiable settings, such as window dimensions and locations, increases the sense of stability by giving the perception that the app knows where all the user’s data lives and where it belongs. Thus, when a user sets up his or her onscreen environment, their particular layout should stay the same until it’s further customized. Additionally, users trust an app that keeps it’s promises across various screens. This means a user control that performs a certain function should perform that same function in another context. Done correctly, users should be able to learn an action sequence in one part of the system and apply it again to get similar results in other places. Alternatively, a user control shouldn’t look alike if it actually does significantly different things. For example, a critical error warning should flash a dramatically different display from a trivial help screen or inconsequential reminder. Lastly, an example of helping discoverability is having a menu command dimmed rather than omitted when it does not apply to a selected object. This allows the remaining elements to stay dominant while also informing the user of the full range of possibility.
Consistency with earlier versions of the product helps users adapt to the new system more rapidly, and increases conversion rate if a high brand value is associated with the original product. Touching on the first point, when a user is familiar with how an application has worked before, then there’s almost no learning curve if the updated product is very similar to its previous iteration. The nuance here isn’t remembering to keep things consistent with the past, but is rather having the foresight to design it beautifully the first time. An additional benefit that often goes overlooked is the fact that users have brand loyalty to products they love. As the saying goes, “if it ain’t broke, don’t fix it.” On the flip-side, when a product doesn’t quite meet user expectations, the next release is a great time to break the principle of consistency and roll out something new and improved.
Perhaps the most elegant application of consistency is keeping elements the same across different products. It is almost magical when a user is able to open up a program they have never seen before and navigate it with relative ease due to prior interaction with other apps in the same family. Consistency in the interface allows users to learn where the controls are in one app, and apply that knowledge to other apps within the same system. In fact, Apple feels this is so important that not only do they offer guidelines on how to keep menu bars consistent, they also give tips on how to keep sub-menu items consistent, going so far as to even suggest how to keep keyboard shortcuts for those sub-menu items consistent.
To further understand the principle of consistency, one can analyze the Microsoft Office suite as a case study. Starting with a single application in the package, MS Word 2010 displays consistency in itself by using the same typefaces and color scheme across various tabs. It also uses similar spacing and design among the various buttons within any given tab. When shifting the size of the application window, the individual icons simply shrink down rather than change form in most cases. As a result, this consistency successfully conveys a sense of continuation throughout the app.
To truly showcase the significance of consistency with previous versions, rather than compare the current iteration of MS Word with its predecessor, it might actually be more useful to compare MS Word 2003 to MS Word 2007 when the ribbon interface was originally released. As it turns out, implementing a ribbon UI is more efficient in aggregate than simply having menu items. However, there was significant backlash when the ribbon was introduced and there will likely be additional outrage as the concept continues to be rolled out with Windows 8. The fact of the matter is that most users weren’t dissatisfied with the new ribbon, but were retaliating merely because people are naturally averse to change.
Moving on, the Microsoft Office is quite successful at employing consistency across the entire product line to its advantage. Users who recognize the ribbon UI and the “back-end” UI found within Word automatically know how to work with them in Excel, PowerPoint, and Outlook. In fact, users can even grasp less commonly used products such as Visio or Access with relative ease if they have mastered the controls of other Office software. It is interesting to note that Mindjet attempts to take full advantage of this principle by employing the ribbon structure, a blue-tinted color scheme, and a MS Office icon set to its flagship MindManager product. In conclusion, Microsoft has had great success in using the principles of consistency to lower user frustation and increase user adoption of its products. Therefore, one should make sure that an app is consistent on all three levels to help the user keep it all together.