INTERACTION AND INTERFACES MODEL OF THE INTERACTION
- 1. UNIT - 2 INTERACATION AND INTERFACES
- 2. THE INTERACTION: INTRODUCTION • Interaction models help us to understand what is going on in the interaction between user and system. • They address the translations between what the user wants and what the system does. • There are a number of ways in which the user can communicate with the system. • At one extreme is batch input, in which the user provides all the information to the computer at once and leaves the machine to perform the task. • This approach does involve an interaction between the user and computer but does not support many tasks well.
- 3. MODELS OF INTERACTION • Interaction involves at least two participants: the user and the system. • Both are complex, as we have seen, and are very different from each other in the way that they communicate and view the domain and the task. • The interface must therefore effectively translate between them to allow the interaction to be successful. • This translation can fail at a number of points and for a number of reasons. • The use of models of interaction can help us to understand exactly what is going on in the interaction and identify the likely root of difficulties.
- 4. FRAMEWORKS AND HCI • As well as providing a means of discussing the details of a particular interaction, frameworks provide a basis for discussing other issues that relate to the interaction. • The ACM SIGCHI Curriculum Development Group presents a framework similar to that presented here, and uses it to place different areas that relate to HCI.
- 6. ERGONOMICS • Ergonomics (or human factors) is traditionally the study of the physical character- istics of the interaction: • how the controls are designed, the physical environment in which the interaction takes place, and the layout and physical qualities of the screen. • A primary focus is on user performance and how the interface enhances or detracts from this. • In seeking to evaluate these aspects of the interaction, ergonomics will certainly also touch upon human psychology and system constraints. • It is a large and established field, which is closely related to but distinct from HCI, and full coverage would demand a book in its own right.
- 7. INTERACTION STYLES • Interaction can be seen as a dialog between the computer and the user. • The choice of interface style can have a profound effect on the nature of this dialog. • Here we introduce the most common interface styles and note the different effects these have on the interaction. • There are a number of common interface styles including • command line interface • menus • natural language • question/answer and query dialog • form-fills and spreadsheets • WIMP point and click • three-dimensional interfaces.
- 8. ELEMENTS OF WIMP INTERFACE • We have already noted the four key features of the WIMP interface that give it its name – windows, icons, pointers and menus – and we will now describe these in turn. • There are also many additional interaction objects and techniques commonly used in WIMP interfaces, some designed for specific purposes and others more general. • We will look at buttons, toolbars, palettes and dialog boxes. Together, these elements of the WIMP interfaces are called widgets, and they comprise the toolkit for interaction between user and system.
- 9. The WIMP interface • Currently many common environments for interactive computing are examples of the WIMP interface style, often simply called windowing systems. • WIMP stands for windows, icons, menus and pointers (sometimes windows, icons, mice and pull-down menus), and is the default interface style for the majority of interactive computer systems in use today, especially in the PC and desktop workstation arena. • Examples of WIMP interfaces include Microsoft Windows for IBM PC compatibles, MacOS for Apple Macintosh compatibles and various X Windows-based systems for UNIX.
- 10. Point-and-click interfaces • In most multimedia systems and in web browsers, virtually all actions take only a single click of the mouse button. • You may point at a city on a map and when you click a window opens, showing you tourist information about the city. • You may point at a word in some text and when you click you see a definition of the word. • You may point at a recognizable iconic button and when you click some action is performed. • This point-and-click interface style is obviously closely related to the WIMP style.
- 11. INTERACTIVITY • It is worth remembering that interactivity is the defining feature of an interactive system. This can be seen in many areas of HCI. • For example, the recognition rate for speech recognition is too low to allow transcription from tape, but in an airline reservation system, so long as the system can reliably recognize yes and no it can reflect back its understanding of what you said and seek confirmation. • Speech-based input is difficult, speech-based interaction easier. Also, in the area of information visualization the most exciting developments are all where users can interact with a visualization in real time, changing parameters and seeing the effect.
- 12. THE CONTEXT OF THE INTERACTION • We have been considering the interaction between a user and a system, and how this is affected by interface design. • This interaction does not occur within a vacuum. We have already noted some of the physical factors in the environment that can directly affect the quality of the interaction. • This is part of the context in which the interaction takes place. But this still assumes a single user operating a single, albeit complex, machine. In reality, users work within a wider social and organizational context.
- 13. EXPERIENCE • Shopping is an interesting example to consider. • Most internet stores allow you to buy things, but do you go shopping? Shopping is as much about going to the shops, feeling the clothes, being with friends. • You can go shopping and never intend to spend money. • Shopping is not about an efficient financial transaction; it is an experience.
- 14. Physical design and engagement • Designers are faced with many constraints: Ergonomic You cannot physically push buttons if they are too small or too close. • Physical The size or nature of the device may force certain positions or styles of control, for example, a dial like the one on the washing machine would not fit on the MiniDisc controller; • high-voltage switches cannot be as small as low- voltage ones
- 15. Physical design and engagement • Legal and safety Cooker controls must be far enough from the pans that you do not burn yourself, but also high enough to prevent small children turning them on. • Context and environment The microwave’s controls are smooth to make them easy to clean in the kitchen. • Aesthetic The controls must look good. • Economic It must not cost too much!
- 16. PARADIGMS: INTRODUCTION • The primary objective of an interactive system is to allow the user to achieve particular goals in some application domain, that is, the inter- active system must be usable. • The designer of an interactive system, then, is posed with two open questions • 1. How can an interactive system be developed to ensure its usability? • 2. How can the usability of an interactive system be demonstrated or measured?
- 17. PARADIGMS: INTRODUCTION • One approach to answering these questions is by means of example, in which successful interactive systems are commonly believed to enhance usability and, there- fore, serve as paradigms for the development of future products. • We believe that we now build interactive systems that are more usable than those built in the past. • We also believe that there is considerable room for improvement in designing more usable systems in the future.
- 18. PARADIGM FOR INTERACTION • In the 1940s and 1950s, the significant advances in computing consisted of new hard- ware technologies. • Mechanical relays were replaced by vacuum electron tubes. • Tubes were replaced by transistors, and transistors by integrated chips, all of which meant that the amount of sheer computing power was increasing by orders of magnitude.
- 19. Video display units • As early as the mid-1950s researchers were experimenting with the possibility of presenting and manipulating information from a computer in the form of images on a video display unit (VDU). • These display screens could provide a more suitable medium than a paper printout for presenting vast quantities of strategic information for rapid assimilation. • The earliest applications of display screen images were developed in military applications, most notably the Semi- Automatic Ground Environment (SAGE) project of the US Air Force.
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