The Interface in the Environment - 'One size fits nobody'

At the outset of an interface design project we would normally conduct a detailed phase of user requirements gathering. We have discussed the various methods of conducting these in previous articles, but typically this includes stakeholder interviews and task analysis exercises. As many of you will be aware the results of this stage will lead to the development of user personas, task scenarios and ultimately lead to the development of wireframe screens of the interface. We tailor this approach to suit the job, so that specialised interfaces such as stock trading software will focus more on complex task analysis while mass-market interfaces such as Interactive TV will focus more on different user profiles. If the research and analysis is carried out well, then the resulting interaction design should be effective, allowing users to complete the required tasks easily. However, apart from the user and task there is one other key factor influencing the usability of the interface - the user environment.

A recent project that we carried out reminded me of the impact this can have on effective interface design or, to put it another way, how seemingly well designed interfaces can fail in deployment. Not that I really needed reminding, field visits and contextual enquiries are a well-worn paths to usable solutions, but when designing software interfaces that operate within the confines of a PC, we tend to make assumptions about the users environment. An office is an office right? So lets just focus on the task and the user? In certain cases this would be perfectly appropriate as the assumptions that we make about the office bears true, but generalising about work environments can lead to the same problems as generalising about users.

How many times have you looked inside the collar of a tee shirt and read the words 'One size fits all' when in fact 'One size fits nobody' would be closer to the truth.

So what are the environmental factors that affect the usability of an interface? What should you look out for on a field visit? Ironically many of the things to look out for are things you cannot see such as noise levels, temperature, time/frequency, lighting and space. The obvious goal of a field visit is to observe the interface or device in normal usage so particular attention should be focused in the immediate environment of the users workstation. A one-hour field visit can provide more useful information than days of user/stakeholder interviews. Lets look at these environmental factors in more detail.

Noise levels

Ambient noise levels are not normally an issue in office environments but in certain situations they can be critical. Industrial settings, public spaces, busy offices such as call centres or trading floors can have noise levels that affect the users ability to interact with devices. To begin with, high noise levels impact on the users ability to concentrate, making complex tasks more difficult to perform. Also, interfaces that provide audible feedback such as alert messages, alarms or warning beeps may be difficult to hear. Users may be wearing ear defenders as a health and safety requirement. In these situations relying on aural information alone to communicate a message is not advisable and could lead to critical problems.

Temperature

Interfaces designed for use outdoors, or in artificial environments such as cold stores need to take into account the bulky clothing like gloves and coats that the user may have to wear. These will make operating a keypad, mouse or a touch screen much more difficult. In specific cases allowances can be made to accommodate for these, by increasing the space between keys, minimising the need for typed input, offering simplified menu choices in order to reduce the complexity of the interaction.

Time and frequency of Use

One of the key advantages of making a filed visit is the opportunity to witness users carrying out tasks in natural setting. You can get a feel for how frequent the tasks are, what time pressure the user experiences. You will also observe any multi tasking that takes place and whether external distractions such as phone calls, or gaps in system functionality interrupt these tasks. Some software interfaces are used on a continual basis others are used 10 times a year or less. The less frequently it is used the steeper the learning curve is for the user and this should be reflected in the interaction design, whereas very frequent users are less tolerant of devices aimed at novice users - think of the helpful 'Paperclip' device in MS Office!

Work Space

Finally examine the space the task takes place in. Some aspects of the users workspace are products of how they interact with the task flow; other elements shape the task itself. The users workstation can be a mine of information relating to how they work. Clues can be piled high on desks such as post-it notes with passwords written on them, well marked calendars, reference materials, help texts etc. By observing a user performing at their workstation key insights can be learned. Does the task happen locally or does the user have to move to different locations to complete the task. For example some people have a printer on their desk, other offices will have a dedicated print room, possible on a different floor. This factor may have an impact on the type of feedback the interface gives the user and subsequently how the user completes the task.

The 'Doh!' factor

Finally, always be on the lookout for the unexpected. There is often one distinct issue, particular to certain projects or industries, which can throw a curveball right at the interaction model. These can be very difficult to spot without 'on-site' observation, and can create interesting challenges to the interface designer. While researching a touch screen interface for a printing machine, we discovered that during a particular phase of the cleaning process the operator's hands would get soiled with ink. In order to complete the process the operator had to interact with the touch screen, transferring the ink onto it. This made the remainder of the instructions and feedback difficult to read - until the screen was cleaned. Without witnessing the task being carried out, this problem might not have been discovered and could have migrated to the new interface.

All of the above environmental factors will impact on the users ability to use an interface. In extreme cases, failure to take one or more of these issues into account can result in critical usability problems. Contextual analysis or field trips provide a fast and effective method of checking for these external issues, and reduce the level of dependence on assumptions or guess work which will in turn speed up the design process.