Consistency: Doing the Same Thing Can Be Useful!

Another day, another design post, but this post is not going to be that huge because I’ve already shown you several examples of what I’m talking about today. Systems are more usable when similar parts are expressed in similar ways – that’s why OS X’s steady convergence with iOS is probably going to bring more people to both platforms than lose grumpy people who don’t like the ‘new’ interface. If one Apple platform allows you the familiarity to use any other, the consistency will make people happy.

And that’s today’s principle for discussion: consistency. Again, it’s from Universal Principles of Design, Lidwell et al, Revised, 2010. People will learn new things more quickly, focus on the right things and be able to transfer their knowledge more easily if the system is consistent. There are four basic considerations and I’m going to show them to you in exactly the same format that I’ve been using for all of these posts. Well, I’ve been trying to be consistent. It’s possibly been similar enough that when you see bold italic you think ‘design principle’ and when you see a bulleted list with leading bolds you think ‘aspect’ or ‘facet’. Sorry for the priming but I’m trying to make a point here 🙂 Anyway, here are the four kinds of consistency.

1. Aesthetic consistency: Is everything similar or the same in terms of style and appearance? I adopted a standard template for my lectures in one course, with strong visual indicators of transitions to different modes. As a result, students always knew which lecture they were in and what was expected of them in terms of participation and activity.
2. Functional consistency: This is consistency in what things mean and how they’re used. How do students hand-in their work – do they always do the same things to make a hand-in work? Does button X always produce result Y? We can also use pre-existing knowledge of function to our benefit and save ourselves the effort of having to teach someone how to approach our work, from scratch. Use existing knowledge of functional actions, and their associated symbols, to make your work easier. (Here’s a thinking point: the save Icon for many systems is an image of a 3.5″ floppy disk. I polled my students and over 70% of them had only seen the disk in this context. What does ‘save’ look like in a cloud-based context?)
3. Internal consistency: The elements inside your system or set of materials should be consistent with each other. Once you’ve learned one part of the system, the others won’t surprise you by being completely different. This also makes people believe that you have actually bothered to design a system, rather than stitch it together out of other, inconsistent, parts.
4. External consistency: How do your objects, materials or systems work inside the overall environment of your students? This is a tricky one because innovation sometimes means that you’re out of step (let’s say ahead of step) with other people. Just because nobody else uses lecture recordings and you do isn’t a violation of external consistency. However, there will be core design standards across most areas (to at least a degree) and adherence to these is important or it’s easy for students to get confused. If you are diverging from this standard, you must take the additional effort to address the inconsistency to reduce confusion.

As Lidwell notes, aesthetic and functional consistency should be considered in almost everything we do – aesthetic consistency allows us to produce a distinct idea, and functional consistency makes it easier for people to learn. The other requirements drive the need for internal and external specifications that work and are observed. All we’re really doing here is trying to make it easier for people to learn, and that should never really be that controversial.

(Wait, what was that about priming? And haven’t you mentioned that before? Yes, I have. Further discussion is coming soon.)