What is Human-Computer Interaction

HCI is a term used to mean either human-computer interaction or human computer interface. The former is the more common usage, though in the United States computer-human interaction (CHI) is sometimes used. It replaces the older and rather sexist man-machine interface or interaction (MMI), though in some ways MMI is to be preferred as it implies a breadth of study which is useful in the development of human-computer systems. It indicates that potentially computer interfaces of one sort or another will operate at all levels of our lives. The term human-machine interaction would certainly be an even better choice since it might serve as a reminder that computers are gradually infiltrating more and more of the machinery and equipment commonly used, and sometimes the interfaces and functionality of those everyday machines are hard for users to fathom. However, in this book the term HCI is used and is taken to mean human-computer interaction unless stated otherwise. Human computer interaction is the study of the relationships which exist between human users and the computer systems they use in the performance of their various tasks.

HCI endeavours to provide an understanding of both the human user and the computer system, in an effort to make the interactions between the two easier and more satisfying. However, the emphasis should always be on the user. HCI is a discipline concerned with the optimisation of these two complex systems; computers are highly complex machines and human users are highly complex organisms. Human-computer interaction seeks to provide an understanding of how users function, the tasks they need to perform and the way in which a computer system needs to be structured to facilitate the easy carrying out of those tasks. The aim is to create computer applications that will make users more efficient than they would be if they performed their tasks with an equivalent manual system. This last point is very important, since all too often computerized applications are produced that do not make the user's task easier and more satisfying, nor do they save time. To understand users it is necessary to understand the processes, capabilities and predilections that they might bring to the tasks they perform. This will involve an understanding and knowledge of such things as memory, vision, cognition, hearing, touch and motor skills. The computer system will need to be understood in terms of what it can do for users and how it might best communicate with them. Finally, the user's task has to be understood according to what it is, its relationship to other tasks and how it might best be accomplished using the computer system. Understanding all of these very complex parts is not easy. But hopefully, during the course of the following chapters, some of that complexity will become much more familiar and easier to comprehend.

Today it is necessary to add to these studies a wider understanding of the environment in which the user is active and performing tasks. Any good designer of a modern human-computer system should consider carefully the characteristics of the organization in which the tasks are performed. This requires an understanding of the sociology of the user's environment as users do not perform tasks in isolation nor is any task an isolated task. Thus, in studying human-computer interaction it is necessary to take a very broad approach and to consider as a matter of course socio-technical design and the solutions that this might give to the problems of designing systems for particular environments. Just as it is unrealistic to assume that all tasks are thesame, so is it unrealistic to presume that all users are the same, or that all organizations act in a similar way. The task of HCI is to design for people, for tasks and for environments. If HCI is to be effective then it needs to consider all of these aspects in the design and development of human-computer systems. Later in the book the role of socio-technical design and its application for the realm of HCI will be examined. In understanding the building blocks that can be used in the construction of human-computer systems, it is important to consider how the various potentials might be maximized. The interface has to play up to their strengths and compensate for their weaknesses. This is possible only if there is an understanding of the capabilities of each of those elements. To this end, anyone wishing to practise HCI needs to obtain a firm understanding of what the building blocks consist of, how they operate, and how they might interact with each other in a system. Thus, one of the primary roles of HCI is one of understanding and clarification.

HCI is a multi-disciplined field. This means that it leans heavily upon other areas of expertise which, in turn, provide significant inputs to its operation and a framework for its practices. It needs to gain its inputs from many other associated areas of study because it has to understand both the computer system, the human user and the task the user is performing. The ability to develop a computer system will require an understanding of computer engineering, programming languages, input/output devices and so on. An understanding of the user will require an appreciation of human behaviour, of social interaction, of environment, attitudes, motivation, and so on. An understanding of task requires a means of identifying what is being done and why and in what type of environment. Some readers may find Figure 1.1 rather frightening. They may fear that it means that they will need to know all about psychology, sociology, ergonomics and various other diverse and complicated subject areas before they can even approach the study of human-computer interaction. Of course, this would be impossible. All of the subject areas mentioned above are suitable for study in their own right, so to take them on board at the same time as studying HCI would require an unacceptable effort on the part of an average person. But rather than being frightening, Figure 1.1 should be seen as a mark of HCI's strength. The vast inputs from other subjects make the study of HCI a source of inspiration and excitement. It means that experts in human-computer interaction can bring to HCI a wealth of knowledge obtained from very diverse sources. In the past, HCI practitioners have come from many different fields, although many have a background in psychology. They have brought to the subject a vast range of skills, attitudes and abilities. However, in the past it has been very unlikely that any one person would have all of the expertise that was needed for the development of a human-computer system. Thus, HCI practitioners have often formed part of software development teams.

Though they bring to the design of the interface considerable expertise and skill, they will also need to supplement this knowledge with sorties into different disciplines as and when this extra information is required. Figure 1.2 suggests some contributions that the various areas might make. For example, it could be argued that the use of graphic artists might be a good idea to help with the design of screen displays or of icons since they would be accustomed to presenting information in an appropriate and eye catching way. The student of HCI should be aware of the fact that it might be necessary to go much further afield than knowledge of the user, the task and computers in order to solve a particular problem for a particular system. Building a human-computer system might well involve seeking help from another expert who is not directly involved in the design or development of computer systems. It is the knowledge of what sort of information is needed in order to solve a particular problem that the study of human-computer interaction will hopefully provide. HCI still has much to learn from other subject areas as it is still a relatively young field of interest and it is still being defined. All too often, a mention of HCI still gets the response 'What's that?' a sure sign of its youth. Certainly, the amount of input from each field varies according to the area of HCI being examined and probably it also depends on the person who is practising it. Some HCI practitioners view HCI as a branch of computer science and place the emphasis on the development of software. Others see it as a branch of psychology and spend their time studying people. Still others may see HCI as a branch of ergonomics and will place the emphasis on human capabilities. HCI courses and research can occur in computer studies or computer science departments, departments of psychology or departments of ergonomics. Depending on the subject area of the hosting discipline the nature of the focus for HCI will differ. Although a theoretical framework is necessary for the continued strength of the subject, theory alone is insufficient if it is not applied to the real world (Faulkner, 1995). Therefore, HCI needs a strong link with computing if it is to influence the software engineers of the future. In my own School of Computing, first year software development students study the problems of interface design as a matter of course. It is hoped that by exposing them early to the idea of user friendly design, they will see this as a natural part of the development of good software. When you are first learning how to program, the user seems to be the least of your worries, so it is a measure of the good work done by both the lecturers concerned with the delivery of that course and the students themselves that software is built that does attempt to consider the user. At the end of the day, HCI must deliver systems that are easier for the end user. The theory must be applied and must produce tangible results. What remains true though is that all the time that HCI is involved in an attempt to solve the problem of how to make interaction with computers easier it will continue to draw upon material as and when it is needed.

For example, f it was found that better interfaces could be built by using human abilities of taste then HCI would need to address more closely the problems of taste based interfaces. Many HCI practitioners would like to see HCI take on a larger role in the development of entire systems and to consider some of those aspects currently tackled by ergonomics too. As systems develop it is likely that the areas of study will expand accordingly. HCI is not a discipline for those people who prefer their knowledge to be relatively static. HCI is constantly changing and evolving a the ability to build better systems develops. This tends to require a greater use. Furthermore, because HCI draws so heavily upon other areas of study, it understanding of the way in which human beings operate with the systems they has to readjust its own findings and practices as the body of knowledge in the other fields is added to or altered as part of the ongoing process of the development of ideas. As well as being mutable, the material HCI has to deal with is often complex and contradictory because human beings are highly complex and some people necessary would say contradictory too. To create better systems for people it is to know about the person, the task being performed and the environment in which that task will be carried out. That way, good systems can be built that will actually fulfil the real needs of the user. These will be systems that will be used by the user because they do really help to perform the task required of them. In other words, it can be said that the aim of HCI is to know the user and to understand the task the user is trying to perform. If the designer of a computer application knows the user and also understands the task that this user is performing then there is a better chance of providing an appropriate system. Above all, if an understanding of user and task exists then the likelihood is that a system will be built that the user will adopt in preference to any other available tools that may or may not be computerized. The coming chapters will examine both the end-user and the task being performed and the ways in which computerized systems can be built to make the performance of the task more efficient and more pleasant for the end user. In building the human-computer interface designers are helping to create a human-computer system which will be both efficient and satisfying to use. HCI practitioners are concerned with both these aspects of efficiency and user satisfaction, since a user who is satisfied with a system is likely to be far more efficient. 1.3 The importance of HCI Today, computers are widely used by people who although they may be experts in their particular field, for example medicine, banking or flying aircraft, are not necessarily computer experts. In other words, they might know a great deal about the task they want to perform but nothing or very little, about the computer they use. It is important to recognize that the users may well be experts in their own right since an acknowledgement of this may well prevent the development of a system that talks down to them. It is necessary to accept that there is no real need for experts in other fields to become computer experts as well, any more than there is any need for people to be telephone engineers before they can use a telephone. It ought to be possible to produce computer systems that enable the user to perform the task without first acquiring a detailed knowledge of computer systems. The user's knowledge of the task ought to be quite sufficient to enable the successful completion of the task with the aid of a computer. If the human-computer system is properly built, the user will actually ignore it and will not notice that it is there. The very best systems and the very best interfaces will be overlooked entirely by the user. A good computer system, like a good pair of shoes, should feel natural, comfortable and fit without the user being aware of it.

Therefore, the aim of HCI should be to build computer applications that are jargon free and easy to use to the degree that all the user sees is the task and not the computer system at all! Although many people working with computers find them fascinating and rewarding, the same is not true of everyone. Therefore, designers of systems have to understand the centrality of the user's task above all else. It is the task that is important, not the means by which the task is done. Indeed, it could well be that the replacement computerized system creates a sense of loss in the user for the old manual system. I was once told by a graphic designer that although the computerized system he used was fast, efficient and relatively easy to use, he missed his compass, his pencils and rulers and the feel of the various pieces of equipment as he changed between them. He felt that he had lost some of his skills. As designers of computerized systems we need to take such sentiments seriously and to remember that the loss of tools and a perceived loss of skill are both stiff competition to our systems, however good we might think they are. Our computerized solution needs to make up for the fact that it does take away this close relationship between the craftsperson and the tools of the trade. If we fail to understand this then in some vital respect we fail to understand the user and the task being done. It is the duty of systems designers to understand these feelings of the user and to make the system so easy and natural to use that the user is able to concentrate on the task alone. The loss of the manual system will not be mourned because the user is able to concentrate on the interesting and creative aspects of the task without worrying about incidental difficulties that may have got in the way with the manual system. It is an economic fact of life that the cost of software is still relatively high and a competitive edge is more difficult to achieve for software companies wishing to sell their products. The interface to a system might just give it the desirable edge over that competition. Certainly, many users will judge software on the basis of the interface; after all the interface is the only part they see, and they will prefer one system over another because of its perceived relative ease. Once users have adopted a particular piece of software they are liable to remain with that product for all sorts of reasons, some of which are examined below:

1 The initial cost will make an immediate change to another system unlikely unless there is a pressing need for a change.

2 Upgrades to the application will hopefully build on the existing system and will not require a whole new way of thinking about the task So the user is unlikely to wish to swap to another product because of the retraining involved.

3 Software development houses usually offer reduced prices for upgrades, provided that an earlier version has been purchased. This will encourage customers to stay with their original choice of package. 4 The way in which the software encourages a user to think about the task will mean that the user comes to see that software as being intuitive.

Once organizations are using a particular piece of software, or computer system, it is difficult for them to extricate then mselves, especially if they are a large organization and the software is used throughout that organization. This is referred to as being locked into a particular system. The cost of retraining an entire staff, both in terms of financial outlay and time, might well be prohibitive. Even where the cost in financial terms is not considerable, the task of retraining is not to be taken on lightly: people do not like to scrap skills they already have. The interface, therefore, must reduce the trauma of learning and maximize the ease of transition from the existing system to the new system. Therefore, it can be said that the first impression the interface creates on the user continues to be of prime importance to those wishing to sell their products. The differences between two pieces of software might be minimal or non existent in terms of performance and functionality, how quickly a task is performed and what tasks can be performed with the computer application. But the choice between the two products might seem to be profound to the end user who may well choose one rather than the other on the basis of how easy it appears to be to learn and to use. It is expensive to train users of computer systems. The task of training involves both the learner and the trainer to be released from their usual tasks, although it is possible that the trainer's task is training! It has to be remembered that learners will be unable to be left alone to carry out the task until they are proficient in the use of the new system. It might be they require support for some time after the initial training has been completed, before they are sufficiently confident with the new system.

The computer is just a tool and the employee is employed to perform a task. However, the tool is not important in itself and any necessary training is therefore a means to an end rather than an end in itself. For all of the reasons discussed above, employees often resent having to spend time learning new systems and certainly employers would prefer that training was not necessary or, if it is absolutely essential, that it is kept to an absolute minimum. Employees who are either training or being trained are, as far as business is concerned, effectively unproductive. They might be learning something or teaching something but nothing tangible is actually produced. Therefore, it is true to say that a system that is easy and natural to use will save the organization money in the long run since it will require less training and less time spent in supporting the learner of the new system. Such a system is much more likely to be used than a system that requires more time spent on it both in terms of learning and in user support. Lastly, as computer system pervade more aspects of our daily lives,it is likely that legislation will gradually become wider in its application to software.there is already have some legislation that can be applied to software and its fitness for purpose..

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