Some usability principles

 

There are around ten commonly recognised key usability principles – here we will discuss five of the more easily understood. Whilst this article discusses usability in the context of software applications, for illustration sake most of the examples are not computer or internet-based – though the principles can be transferred to this medium.

 

Clarity of purpose
This one could actually be described more as obviousness of functioning, though the two are similar and related. Put simply – a user should easily understand what a product should do, and how it does it. Or at the very least, the purpose and functioning of an object should become apparent through its usage.

 

Examples of this seemingly obvious concept abound. Consider a typical pop-up toaster, and how clearly this device communicates its operation to the user – where the bread goes, what needs to happen, etc. Or a pair of scissors – where one puts their fingers, and the action to invoke the device. Or an egg lifter. Or a pencil. Or a pencil sharpener.

 

Now consider the flip side of the same coin, and the exasperation that comes when a device’s functioning is in no way obvious from its appearance or form. The tin opener on a standard Swiss army knife is such an object, and baffles most people not accustomed to its operation (though this is an unfair example - as explained earlier, the designers of the Swiss knife have forsaken several usability principles for the over-riding concerns of portability and multi-purpose). The conventional staple remover is another such item – without explanation of how to use it, the user may well be at a loose end as to what it is or does.

 

Another way of phrasing this is something like “if a product needs an instruction manual, then it has failed”; though this is a little austere, it is largely correct.

 

Natural mapping
Two examples serve to illustrate this one – light switches and stove hot plates.

 

Anyone who has experienced the frustration of trying to locate a specific switch in a group panel that has been unintuitively wired to operate a specific light will know all about this one. If additional “features” like a dimmer are thrown into the mix, things get even more confusing.

 

Stove hot plates and their controlling unit provide another example of this principle. Generally, the physical arrangement of hot plates is a two by two grid, whereas the dials/buttons/knobs are usually – for reasons of space of aesthetic – arranged in a single row. There is no intuitive mapping between the two arrangements in this setup; a usable mapping would see the controls mirror the layout of the hot plates, in a stroke clearly communicating to the user which switch to use for which plate.

 

Intuitive layout
This one can be summarised as follows: “Put things where they ‘should’ go”. Whilst this one is open to cultural interpretation – think of the arrangement of the indicators and wiper controls on the stem of the steering column on German and Japanese cars – there are generally “sensible” places to locate things.

 

Prior to USB devices being as prevalent as they now are, USB ports were mostly located at the back of the computer – now that their usage has increased, the ports have moved round to the front of the machine, making for more accessible access.

 

Seat controls in a car provide good and bad examples of this principle. Many car seats are poor in their placement of the controls to move and adjust the seat, and it is difficult for a newcomer to even find them sometimes. The best example I have encountered is a smart German car that bundled all the controls into a single, simple and intuitive control that not only mapped the desired actions, but was also located in the most intuitive location, on the side of the seat.

 

System feedback
Nobody likes to be left in the dark – the desire to know what is going on at all times and remain in control is one of our most fundamental human characteristics. So it’s no surprise that when an object or system keeps us in the loop about what is happening and what to expect, we are happy, and when the opposite happens, we are not. For a change, some examples from computing system interfaces…

 

The expanding progress bar is a very good example of this, as it shows us several things simultaneously:

• • Firstly, and most importantly, that something is happening
• • Secondly, that there is a starting point and an end point to the operation
• • Thirdly, the point in the operation that we are currently in at any point
• • Fourthly, the rate that the operation is being completed at (or better still, the time still remaining to completion)

 

On the Internet, hyperlinks should be indicated by underlined text, but even if this convention is flouted, the browser still informs the user of the location of a hyperlink(s) on the page through the use of the cursor switch from a pointer (text) to a hand (hyperlink).

 

Another web convention – ‘the bread crumb’ – serves a dual purpose, not only indicating to the user the navigation path that brought them to their current location, but also a means of navigation back to any page in the bread crumb, by means of hyperlinks to the relevant web page(s).

 

Prevent user errors
I think the following example says everything that needs to be said about this one.

 

Some automatic cars do not allow the keys to be removed from the ignition without the car being in the Park setting… think how many mishaps this avoids, which could happen were the user to leave the car in neutral – something perfectly possible in most manual cars.

 

Don’t let users make errors in the first place.

 

There are several other basic usability principles, but if you keep the above-mentioned five in mind, you will be off to a good start.

 

Why is usability important?
There are many reasons why usable designs are important, but for brevity sake I will limit myself to three, in increasing order of relevance to most people.

 

• • Social – A usable product is more socially beneficial than a non-usable product. Think of all the stress, headaches and heartaches the world will be spared from by the creation of usable objects instead of those that are not usable.
• • Economical – A usable product requires less training, is simpler to demonstrate, understand and thus sell, and can be used by more users… which means that it has a bigger potential market.
• • Survival - If your product is not usable, users will not use it; if users don’t use your product, it’s only a matter of time until they switch to something that is. If your product is usable, users will be less likely to switch to another product, as it means an outlay of time, effort, energy and money.

 

And of course, a usable design will mean happier customers, which in itself is probably the biggest single reason to make the move…

 

Further reading
For more information on usability in general, read Donald Norman’s excellent book, “The design of everyday things”.

 

For usability information specific to the internet medium, see Jakob Neilsen’s website: http://www.useit.com/

 

About the author
carl warburg is director of operations at litmus digital, a south African agency specialising in usable digital solutions. Litmus digital is a strategic partner of specialist HR Technology company graylink and is currently supporting the development of soon-to-be released enhanced e-recruitment solution. Prior to starting litmus digital, carl worked in London for 8 years at razorfish and digitalTMW, delivering digital projects with strong usability focuses, for the likes of British Airways, Diageo, Nissan and Natwest.