Usability engineering started as a set of methods for developing usable computer-based software systems, originating from human-factors (ergonomics) research and human-computer interaction
research area (Nielsen 1993). Research forums, such as Human Factors and Ergonomics society, originally studied the development of physically ergonomic systems. The different approaches are described as follows:
Engineering is concerned with improving products from the point of view of mechanical and electrical design, and psychology is concerned with the study of the mind and behaviour. Human factors and ergonomics are concerned with adapting products to people, based upon their physiological and psychological capacities and limitations, the objective being to improve overall system performance (Stanton, 1998).
Norman (1998, 160) discusses the machine-centred view and human-centred view to product development. He identifies the attributes of humans and machines presented from a human- centred point of view as follows:
People Machines
Creative Unoriginal
Compliant Rigid
Attentive to change Insensitive to change
Resourceful Unimaginative
In the world around us and appliances in our hands, the software is increasingly embedded to the products and made invisible. The software is an intermediate to operate a device (for example process control of the paper machine) or it is fully invisible (for example TV remote control) to the user. Norman (1998) discusses the problem of intrusive technology in his book The Invisible Computer. He claims that many customer products are technology-centred. The problems of technology-centred products are, for example, unusable functions, overwhelming amount of functions, immature technologies and high price. As a promising solution for making simpler products and products that fit to humans Norman proposes human-centred multi-disciplinary product development. A particular method, Contextual design, is proposed.
Most HCI practitioners have to deal with pressured environment of a modern organisation, day- to-day concerns, such as funding, budgets, project and people management, teamwork and communication. Trenner and Bawa (1998) have collected 14 stories from different authors, mostly usability consultants, about the practical organisational problems that usability engineers face in commercial organisations. The main theme in Trenner and Bawa is that in order to perform successful usability engineering you need to have trustable management support. Karat and Dayton (1995) view the same problem from software engineering perspective:
In most cases of the design and development of commercial software, usability is not dealt with at the same level as other aspects of software engineering… [Software teams] have had difficulty integrating usability activities into software engineering practice.
Swanson (1994) notes that the core technology of the business should have certain innovations embedded in order to achieve cost-leadership, differentiation or niche:
• process enables better quality and differentiation
• novel products and services are needed for niche or differentiation
• integration enables better coordination and partnership and hence diminishes negative effects of division of labour. Integration is needed also for differentiated products and services.
Often the consumer products that need to be usable are the most personal and most often used products, such as a mobile phone or a watch. A special look at personal information appliances is taken in Information Appliances and Beyond (Bergman 2000). This book describes several examples from industry about taking the user-perspective, usability issues and social aspects into account in the product development. A particular value in this book is the formal definition of new concept Information appliance and the practical instantiations of the concept:
An information appliance is a computer-enhanced consumer device dedicated to a restricted cluster of tasks (p.28)…An information appliance is designed to perform a specific activity, such as music, photography, or writing. A distinguishing feature of information appliance is the ability to share information among themselves (p.3).
Personal computer is not an information appliance. Some of the key characteristics differentiating information appliances and PCs are (Mohage and Wagner 2000):
- limited purpose and functionality
- not necessarily extensible or upgradeable
- replacement expectation (the user may have to replace the entire device within a few years) - perceived as less expensive (versus PCs)
- perceived as less complicated to run and maintain (versus PCs) - very easy to learn and use
- no expectation of “expert users”
Mobile phones have these characteristics. Hence I also consider mobile phones as information appliances. Abowd (2001) notes "…But a convergent device has to be good at everything it does. It has to be a good phone, a good calendar, a good contact manager, and a good text- messaging/e-mail device. And it has to look nice, feel nice and fit easily in your pocket." The focus of usability engineering is inevitably shifting or extending from software development to the development of integrated smart products and information appliances. Product development of information appliances, such as smart phones, is based on fast CE (Valjus 1994). The pace is given by strong competition and business situation in the industry.
Casaday (1996) shares his own ideas and experiences about making usability work in the organisation. He says: "Usability is not a single quality, but it is made up of many goals that can be teased apart and handled somewhat distinctly. It is important to do that so we can focus resources and because some usability goals are actually in conflict and have to be traded off."
For example, short learning curve tends to be incompatible with very great efficiency (speed), and reliability may conflict with both flexibility and speed. Casaday provides a list of eight usability goals that should be prioritised (1: no importance, 10: essential to product success) in order to guide user interface design. Five of the goals are standard in the usability community, and three are new:
1. Understandable (new) 2. Learnable
3. Memorable 4. Efficient (fast) 5. Reliable (user errors)
6. Flexible (new) 7. Automated (new) 8. Satisfying (subjective)