Usability Issues in Product Design

As software interfaces migrate from the computer to become embedded in a multitude of everyday products, the scope to consider the hardware interface and the software interface under one unified approach becomes a possibility and a necessity.

As usability professionals and user interface designers, our work is mainly contained within the confines of the computer screen - the GUI or web-based software interface. Interaction touch points outside of this window are usually beyond our control. For example, it would not be practical (or advisable) to suggest redesigning the mouse in order to make a software application or website easier to use. We accept the limitations of these devices and we design interfaces to compensate or compliment them. However, as software interfaces migrate from the computer to become embedded in a multitude of everyday products, the scope to consider the hardware interface and the software interface under one unified approach becomes a possibility and a necessity.

Pervasive computing has given us processing power in almost every imaginable product, bringing with it more powerful and complex digital interfaces in these products. Take the Internet fridge from LG Electronics. In the past, watching the light come on while opening the door was as interactive as using a refrigerator got. Now the fridge can act as a communication centre for the family home, collecting emails, monitoring food consumption and allowing you to buy milk online before you run out! All this as well as keeping your food cold. As everyday products have become more intelligent and start to move on-line, the complexity of these interfaces has also increased. Thus the usefulness of products has become more dependent on the usability of the product interface. And as a result the usability of the interface can no longer be isolated from how the product works.

But doesn't integrated design happen anyway? What about the role of product designers and ergonomists? Strangely enough, the one-sided focus is often reciprocated in the realm of product design. Much care and attention is given to the design and layout of the tangible elements of the product interface, but the design and layout of the screen-interface and interaction is not always within the designers' scope. In many cases, standard interface components are bought off the shelf from OEM suppliers and 'adapted' to the product, leaving designers with little control. The scope of the human factors engineer or product designer to improve the interface is often limited to the outer edges of the display or to its physical attributes, such as control layout and visibility.

The real loser in this fragmented approach is the user. By not considering all elements of the interface together, the user interaction model becomes disjointed and products become difficult to use. The household VCR is a prime example of this approach. On an individual basis, all of the elements of the product interface are well designed, but when they come together the user interaction model fails, preventing most users from accessing even the basic product functionality (like setting it to record!). A unified task-based approach is what is required and as technology advances this need becomes more critical than ever.

Another example is interactive TV. The interface is still rendered by a form of HTML and general web-browser rules of interaction apply. It still appears on a screen, but now that screen is at the far side of the living room - effecting readability and impacting on the amount of information available on screen. Living room furniture has made the use of a keyboard cumbersome, and likewise the mouse is replaced by a remote control with cursor keys, impacting on user navigation. The end result is not just a different user environment but also a completely different user idiom. If the design of the remote is not useable, then navigation of the interface will be difficult. Similarly, the information architecture must take the limitations of the remote control and viewing into account.

In order to create an effective solution, both the product design and the interface design need to be evaluated and adjusted in sympathy with each other. This convergence of interface and product design has two significant effects on usability practice:

• The need to design, evaluate and test the interaction device in conjunction with the interface
• The need for more detailed and thorough research into the environmental factors that affect the normal operation or use of the product

Unlike traditional software, which is by and large intended for use in homes and offices, the range of user-environments for products is virtually limitless. Factors such as space, noise, temperature, operational weights and forces all need to be taken into account. Products and their software interfaces should always be tested in their intended environments and with real users.

Adopting a user-centred, task-based approach within the product development cycle will result in better-integrated and more useable products. However, as injection moulded or mass-produced components are more difficult and costly to change than software, early involvement in the design development process is essential. Iterative rounds of testing on basic product prototypes can help steer the design before any tooling or production has begun. But usability professionals need to be aware of basic product design principals and manufacturing capabilities in order to evaluate and propose solutions within a production context.