| FutureScope | August 1999 |
Components of the User InterfaceThe user interface is critical in the development of computer systems. While an implementation may be complicated, the user interface hides the complexity and provides an easy to understand and easy to use system. The interface must operate at least on two levels for used frequently applications.
In many ways, the user interface is like to the elephant in the story of the seven blind men. One person may see the interface as a hardware issue, while others observe the syntax. In fact, the interface involves cognitive (psychological), environmental, functional, hardware and software factors. In this report, we will examine an overview of these factors and the two models of the interface.. Graphically, their relationships are shown in in Figure 1. Figure 1 Fundamental to the user interface are the cognitive factors. For over fifteen years, it has been known that the user develops a mental model of the software. If we want to control the interface, we must first apply well-known psychological principles to the design of the semantic model. These factors are further used in defining the the interface. The importance of these factors can not be over emphasized enough. Using a computer is a task, a mental task. All the information and research results obtained in this field of psychology are applicable to the design of user interfaces. The Semantic model contains the essence of the interface. It defines the objects, their properties and their operations. Research has shown that users develop a mental model of an application. If we want ease of use, we must first define the mental map we expect the user to employ when learning about the system. All too often, the semantic model is not systemically designed, but "falls out" of the software design process. It becomes a mixture with the syntactic model and the interface. The result can be an application that is difficult to use. Objects or operations may not behave consistently. The results of this model can assist in the design of the application. This is especially true if an object oriented development process is used. The Syntactic model is the set of commands that forms the basis of the interface. While there may be a large number of operations, two or more can be grouped together within one command. It is this command that is implemented within the interface. We can think of the command in the syntactic model level as a skeleton, only awaiting flesh and skin for its final form to be seen. For example, there may a command in the syntactic model that has two parameters and three options. In a Windows interface, it will appear as a set of drop-down. In another interface, using speech input, the command is a series of words. The primary objective of a good user interface is to provide to the user a system that is easy to use and highly productive under task conditions. In the design of the semantic model atomic operations are determined by examining a task. Without a thorough knowledge of the task, it is impossible to develop a functional application. Not only must the components of the task be determined, but their frequency and the projected frequency of using the application must be noted. A different interface would be used for a task that is highly repetitive than for one occasionally used. Environmental factors may play a part in an interface design. For example using a sound to indicate an error will not be effective where the ambient sound is loud, nor should it be used where quiet is necessary. Other issues such as light levels and the proximity of individuals will play a role in the interface design. Environmental issues are not limited to physical factors. In the beta version of one well known contact manager, it became obvious that the developers worked in a location where all telephone calls in the area code were local. By not considering the environment in other areas, they would have released a product that might have been limited. The hardware components limit the choice of interface. While we normally consider user interface hardware components items such as screens, mice and keyboards, they include internal hardware such as audio boards. In most cases, the interface must be designed around an existing hardware configuration. For example, all audio boards have an input for speech. All that is necessary from the hardware perspective is a microphone, something that is inexpensive and easy to install. The software components are divided between the operating system, applications such as speech or the application itself. For example, the video and basic hardware components, such as the mouse and keyboard, are also controlled by the operating system. Depending upon the access given to the application, they may be modified. A number of I/O technologies such as speech recognition and anamation are controlled by separate software. Unless APIs (Application Program Interfaces) are supplied by the vendor, it is unlikely that their controls can be accessed. It is in the latter area, the greatest flexibility can emerge. The designer of the interface can use all the available tools available in the interface. Careful choice of input and display techniques, menus and layout can transform a mundane application to one that shines. This is the only part of a program most users will see. Vendors – Develop methodologies that will take into account the models and components of the interface discussed above. Have at leas one person in your organization be responsible for user interfaces. That person must have a background in the research of user interface design, not just someone who can design a screen. In future issues we will examine development methodologies, software tools and hardware that will improve the quality of your user interface.
Users – As you choose software make the user interface a critical element for evaluation. Do not only consider the interface as an untrained person would use it. Assume the person used it on a frequent basis – is it economical in user movements? Use testing methodologies. If you don’t have any, we will discuss this issue in the future. Entire contents (C) 1999 by Integrated Business Information Systems Ltd.. (IBIS, www.ibisl.com) All rights reserved. Reproduction of this publication in any form without prior written permission is forbidden. The information contained herein has been obtained from sources believed to be reliable. IBIS disclaims all warranties as to the accuracy, completeness or adequacy of such information. IBIS shall have no liability for errors, omissions or inadequacies in the information contained herein or for interpretations thereof. The reader assumes sole responsibility for the selection of these materials to achieve its intended results. The opinions expressed herein are subject to change without notice. |
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