le travail à l'écran de visualisation work with display units

THE USE OF STANDARDS FOR MEASURING AND EVALUATING SOFTWAREUSABILITYEva Brenner Wallius, IBM Nordic Laboratories, Stockholm, SwedenThe usability of a program has become a functional characteristic of similar importanceas more traditional types of performance variables. This has resulted in an increasingneed for measuring and evaluation methods that makes it possible to compare theusability of different programs, or different versions of the same program.Standardized procedures or benchmark tests for measurement and evaluations is thetraditional approach to meet such needs. There are however, some important issuesconcerning usability that should be considered before such a standard procedure isproposed.DEVELOPING HUMAN-COMPUTER I NTE RATI ON STANDARDSJ KaratUser Interface Institute, IBM Watson Research Center, Box 704, Yorktown Heights, NY,10598With increasing presence of computers in society, there have been calls from anumber of sources for standardization of human-computer interfaces. Suchstandardization could contribute to the quality of computer software if the standardshelped produce systems which both matched the needs and capabilities of users, andenabled them to easily acquire knowledge needed to use the systems and transferpreviously learned skills. One question that we can ask of the science base we areattempting to apply to HCI design is whether or not such standards might possibly bebased on theory. While it is not possible to offer a theoretically based HCI standard atthis time, theoretical research in cognitive psychology can offer some suggestions fordevelopers of standards.In many ways the problems of applying psychological knowledge to the design of thecognitive components of the user interface is more difficult than the physiologicalaspects. The objective goals for making a display legible or a keyboard responsiveare more easily quantified than those for making a user interface easy to learn or easyto use. It is easier to define muscle fatigue, and to state that a keyboard should nottake a user to acquire the knowledge necessary to carry out an arbitrary task. To alarge extent it is this difficulty in defining the problem which makes progress in the areaseem so elusive. While psychologists have learned a great deal about humancognition, there is both a great deal which is not known and considerable difficultyapplying what is known to the fuzzy area of interface design. An important step thatneeds to be taken is for an objective statement of the problem to be developed. Weneed something more than easy to learn and use to guide the work.The position presented here is that while there are some general rules of humancognition which are fairly well established, there is not yet sufficient knowledge to putforth a rule based design guide for general purpose systems based on cognitiveprinciples. There is some high level guidance that can be provided, but it is in thenature of guidelines rather than formal rules. Some examples of problem areas whichhave yet to be addressed in developing useful information for system development willbe presented.While we wait for developments in the science, there is something to be learned fromthe study of human cognition which can be applied to interface design. It is more of aprocess recommendation concerning how to go about developing guidelines orstandards that an actual set of design rules or standards. The message from thescience is that understanding the task to be carried out in terms of the necessarycognitive components is a necessary first step to understanding human behavior on atask. This contribution is more in the methodology than in the rules, although simpleknowledge of the rules incorporated in the process can provide some useful guidance.If design projects really began by addressing the question "What must the users knowand what must they do to use the system", and the answers were carefully analyzed,many improvements would be made. Unfortunately, though this seems to be simplecommon sense, the practice of the methodology is very rare. While there are isolatedventures into using an information processing framework to improve interface design,a more complete examination of interaction with systems to do work is needed.KEYWORDS: standardizationTEV 1989 — DEUXIÈME CONFÉRENCE SCIENTIFIQUE INTERNATIONALE • MONTRÉAL • SECOND INTERNATIONAL SCIENTIFIC CONFERENCE — WDU 1989196TEV 1989 — DEUXIÈME CONFÉRENCE SCIENTIFIQUE INTERNATIONALE • MONTREAL • SECOND IN'ITiRNATIONAI. SCIENTIFIC CONFERENCE — WWDU 1989193