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INTRODUCTION At present, software for specific applications and user-computer interfaces are aggressively developed in industry, but they are designed largely with only the designer's intuition as guide and often without empirical testing with end users. Two observations made in a popular software magazine point out the resulting problem: The computer systems and software we have today are too damn complicated for the end user. There is too much to learn, too many fiddly details, too much jargon, too much said that shouldn't be and not enough said that should be . . . (A. Johnson-Liaird, Software News, Apt il 1982) . Data processing still has one ongoing problem to solve: the end user 'n dissatisfaction with today's systems. The entire industry has been grappling with this problem of ergonomics, or the Interface between human and machine. In the case of data processing, ergonomics involves the development of ~user-friendly. systems which can be operated by the user at the terminal and which generate results that the user can understand and utilize (M. Parks, Software News, February 1983). Because of such difficulties, some industry and academic research groups are developing an interest in gathering and building appropriate guidelines from basic research and incorporating these guidelines and observa- ~cions of users' behavior into the design process. A new field has emerged called software psychology or the psychology of human-computer interaction. It is in a very exciting state--a relatively new amalgam of 1

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2 experimental/cognitive psychology, computer science, business, and engineering. The field is growing in a variety of sectors. There are more human factors groups in industry than ever before. Approximately 50 universities in this country and abroad have PhD programs in human-computer inter- action, which are housed in psychology, computer science, social sciences, engineering, business, and English departments (Mantel and Smelcer, 1984). Many more schools offer one or more courses in the area. The Association for Computing Machinery has a Special Interest Group for Computer-Buman Interaction (SIGCHI). The Human Factors Society has a group called the Computer Systems Technical Group, which is concerned with human factors aspects of interactive computing systems, the data processing environment, and software development. Consumer demand for computers is increasing at a rapid pace, and many schools are acquiring computers for tutoring and the word-processing and mathematical tools that they provide. The systems that sell are those that provide the right usability and functionality--that provide the right design for the end user. TEE NEED FOR NEW METRODS Designing systems to fit the end user is a difficult process. The field is searching for new methods. Classical experimental design. (e.g., controlled factorial designs) may not be appropriate for industrial nettings in which cost-effectiveness and timeliness are major concerns. Rowever, tests of single, intuition- driven designs with users, measuring their performance and satisfaction, do not advance our general knowledge about designs and do not indicate why certain features are good or bad. There are, however, hybrid methods being used in industry, and new, more complex laboratory tests being constructed to assess users' performance in and under- standing of complex systems. These methods are described below, along with their advantages and disadvantages and where they f it into the product development cycle. Each method is annotated with references to a few key articles that repor t its use .

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3 THE PRODUCT DEVELOPMENT CYCLE Software products are typically developed in three general stages: 1. Analysis--the product's functionality and initial hardware/software constraints are determined, analysis is made of the product's projected costs and benefits, and a development schedule is projected. Design--the product is designed, first at the level of functional specifications and later in complete de ta il. then coded and tes ted, ending with a running system. 3. Implementation--the product is distributed and installed in its f inal locations, and users are trained and then operate the equipment At all three stages human factors considerations appear: , 1. In assessing user n' needs and capabilities dur ing the analys is phase In designing and redesigning the system with human factors pr inciples of usability, and in testing prototypes with end users dur ing the design stage; and 3. In monitoring use of the system after its implementation, gather ing information for redesign to correct errors or to add new, useful features. Sin what follows the methods appropriate to each of these stages are described. These methods, or their variants, are useful for both laboratory research and industry. They may be used in the slower, more con- trolled environment of the laboratory, where research is designed to study people's performance on complex tasks. And they contribute equally to design and evaluation in industry, where timeliness is frequently considered to be more important than the ability to generalize from the results.