June 2010 Edition
Computer Science Department, University of Cape Town
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DotDash Bank PLC has launched a new telephone-based banking service. Customers will be able to check balances, order chequebooks and statements and transfer money all at the press of a button. Users are presented with lists of choices and they select an option by pressing the appropriate touch-tone key on their handset. The system development team is certain that the system is technically very good – the speech synthesis used to speak out instructions/ options is the state-of-the-art and the database access times are very fast.
The new banking system described is clearly a success from a system point of view: the designers have thought about the technical demands of the system to achieve, for example, high through-put of database queries.
How, though, do users feel about the system?
The bank’s customers have responded badly to the new system. Firstly, users want to know why the system does not let them allow them to hear details of their most recent transactions, pay bills and do other common functions. Worse still, they find the large number of key-presses needed to find out a piece of information tedious and irritating. Often, users get lost in the list of choices, not sure of where they are in the system and what to do next.
From a human perspective the system is a real failure. It fails because it is not as useful as it might be and has very serious HCI problems – it fails because the designers have not fully considered what would be useful and usable from the customers’ point of view.
For an interactive system to be useful it should be goal centred. When a person uses a computer they will have one or more goals in mind – e.g., ‘work out my expenses for this month’; ‘buy a book on motor mechanics’. A useful interactive system is one that empowers users to achieve their goals. When you build an interactive system you should make sure you use a range of design and evaluation methods to discover the goals and associated system functionality that will make your system useful.
A cork-screw is a tool for opening bottles sealed with a cork. They are useful tools. However if you are a left-handed person most cork-screws are difficult to use. This is because they are designed for right-handed people. So, for a left-handed person the cork-screw has low usability (despite being useful).
Usability is about building a system that takes account of the users' capabilities and limitations. A system that has good usability is likely to have the following qualities:
Flexible. Users should be able to interact with a system in ways that best suit their needs. The system should be flexible enough to permit a range of preferences.
Robust. A system is robust if a user is given the means to achieve their goals, to assess their progress and to recover from any errors made.
In a later unit we will look at each of these aspects and consider ways in which they can be achieved.
What qualities does a usable system have?
Answer to this question can be found at the end of the chapter.