First, they all are word recognition devices, that is, they do not recognize continuous speech. Second, they are capable of responding only to vocabularies of restricted size. Third, they are user-dependent, that is, they must be programmed to learn to recognize words spoken by a particular person and will generally respond accurately only to that person’s voice. Speech recognition machines that can respond to connected speech or that are speaker-independent are well beyond the current state of technology.

Despite these important limitations, speech input to computers can be successful and useful. There is not, however, a good base of research findings on the conditions under which speech recognition machines can be used effectively even with their limitations. For example, how much useful work can be done with vocabularies of various sizes? How effectively can people be trained to leave pauses between words in connected speech so that individual words can be recognized? How effortful is it to speak while deliberately leaving pauses between words? If vocabularies of restricted size must be used, how effectively can one construct complex inputs with the available words? What rules of grammar and syntax must be observed if one is restricted to a limited vocabulary? What should that vocabulary be? The conditions under which speech recognition devices can be used most effectively is virtually an unexplored area of research that should be vigorously pursued. One example of research in the use of voice input to operate a distributed computer network has been conducted at the Navy Postgraduate School by Poock (1980).

Output Devices

Although teletypewriters and alphanumeric cathode ray tube (CRT) displays are the most common forms of output devices used in computer systems, there are numerous other possibilities: plasma displays; light-emitting diodes (LED) and liquid crystal displays; tactile displays; audio displays, including synthetic speech; graphical displays; laser displays; and even psychophysiological output devices. The state of the art of these various output devices is summarized in Table 5–3, which is based on Ramsey and Atwood (1979).



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Research Needs for Human Factors First, they all are word recognition devices, that is, they do not recognize continuous speech. Second, they are capable of responding only to vocabularies of restricted size. Third, they are user-dependent, that is, they must be programmed to learn to recognize words spoken by a particular person and will generally respond accurately only to that person’s voice. Speech recognition machines that can respond to connected speech or that are speaker-independent are well beyond the current state of technology. Despite these important limitations, speech input to computers can be successful and useful. There is not, however, a good base of research findings on the conditions under which speech recognition machines can be used effectively even with their limitations. For example, how much useful work can be done with vocabularies of various sizes? How effectively can people be trained to leave pauses between words in connected speech so that individual words can be recognized? How effortful is it to speak while deliberately leaving pauses between words? If vocabularies of restricted size must be used, how effectively can one construct complex inputs with the available words? What rules of grammar and syntax must be observed if one is restricted to a limited vocabulary? What should that vocabulary be? The conditions under which speech recognition devices can be used most effectively is virtually an unexplored area of research that should be vigorously pursued. One example of research in the use of voice input to operate a distributed computer network has been conducted at the Navy Postgraduate School by Poock (1980). Output Devices Although teletypewriters and alphanumeric cathode ray tube (CRT) displays are the most common forms of output devices used in computer systems, there are numerous other possibilities: plasma displays; light-emitting diodes (LED) and liquid crystal displays; tactile displays; audio displays, including synthetic speech; graphical displays; laser displays; and even psychophysiological output devices. The state of the art of these various output devices is summarized in Table 5–3, which is based on Ramsey and Atwood (1979).

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Research Needs for Human Factors TABLE 5–3 Computer Output Devices With Some of Their Principal Features and References Type of Display Features References Refreshed CRT The ordinary, refreshed Cathode ray tube (CRT) is currently the basic computer display. A good deal of data exist concerning appropriate visual properties of CRT displays. Studies that have compared user performance using CRTs with performance using other display devices, however, do not provide a satisfactory basis for selection decisions. Shurtleff (1980)★ Storage tube CRT For some graphical applications, direct-view storage tubes may be preferable to refreshed displays. The storage tube allows very high-density, flicker-free displays but imposes significant constraints on interactive dialog. Although information exists concerning the basic functional advantages and disadvantages of such displays, no empirical data pertaining to human factors concerns were found. Steele (1971) Plasma panel Plasma panel displays are inherently “dot” or punctuate displays, and studies of symbol generation methods are relevant. Little empirical information exists on human performance aspects of plasma displays per se.   Teletypewriter Reasonable guidelines exist with repeat to the design of teletypwriter terminals, including both physical and Dolotta (1970)

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Research Needs for Human Factors   functional properties. See the discussion of keyboards in Table 5–1.   Line printer Research on typography is voluminous and directly applicable. Research dealing directly with the line printer used in computer output is scanty but consistent with findings of typographic research (e.g., mixed upper-lower case is best for reading comprehension). Guidelines are not known to exist but could be constructed with additional survey of typographic research literature. Use of line printers for “pseudographic” displays is common but little discussed in the literature. Pseudographics is an inexpensive way to convey simple graphical information and should probably be used more widely in batch applications. Cornog and Rose (1967)★ Lewis (1972)★★ Ling (1973) Poulton and Brown (1968)★★ Laser displays Reasonable human factors guidelines with respect to visual properties have been proposed, but these displays are not widely used. Gould and Makous (1968) Tactile displays Although some tactile displays have been proposed or even developed, little human factors research has been done other than that concerned with prosthetics. Noll (1972) Psychophysiological displays Psychophysiological input is technically feasible now, but psychophysiological displays are still only a topic for research.   Large-screen displays There is conflicting evidence with respect to the performance effects of large-group versus individual displays. Landis et al. (1967)★★ Smith and Duggar

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Research Needs for Human Factors Type of Display Features References   The main advantages of large-screen displays are a larger display area and the existence of a single display that is clearly the same for all viewers. Unfortunately, higher display content is not achievable due to the resolution limits of existing technology (e.g., light valve displays) and may be unachievable in principle, since the large-screen display usually subtends a smaller visual angle than an individual display located close to the user. (1965)★★ Speech and synthetic speech Although speech output clearly has many advantages over other output modes for interpersonal communication, there is essentially no information on the conditions for which speech would be an appropriate computer output. Chapanis (1975, 1981)★ ★The reference presents survey or questionnaire data or summarizes experimental results. ★★The reference contains user performance data or relatively detailed results of controlled experimental work. Source: Adapted from Ramsay and Atwood (1979).

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Research Needs for Human Factors CRT Displays Enough research has been done on CRT displays to support guidelines for their design (Galitz, 1981; Shurtleff, 1980). Although the two handbooks available do not answer all the questions designers may have, they cover a substantial number of them. Most of their recommendations are supported by research data, and those that are not seem reasonable. The two most important unresolved questions concern the size of displays and the use of colored displays. With regard to size, Shurtleff (1980) has devoted a chapter to questions of legibility as related to display size, but he has nothing to say about the more important question of how much information can be presented on screens of various sizes. Military applications of computer displays, for example, in cockpits, must be small by necessity. How small can they be and still be legible? How can information best be presented on small displays? The converse problem may occur when many people must view the same display. In that case the relevant questions are: How large can displays be? How can information best be presented on large displays? These are not questions relating simply to the legibility of the information presented on displays of various size; such questions can easily be resolved on the basis of available data. What is needed is research on the interactions between display size and the amount of information that can be most effectively presented. Questions on the use of color on CRT displays is also still essentially unresolved. The advantages of color coding for identification purposes are, of course, well documented, but the long-term effects of working with colored CRT displays for data entry, inquiry, or interactive dialog are not known. Although many people seem to like colored displays, others find them annoying and garish. The scanty research evidence available seems to show that colored CRT displays produce no substantial performance benefits. More research may enable designers to make informed decisions about the possible benefits of color on CRTs versus their cost and other disadvantages. Alternatives to CRT Displays Very little human factors research has been done on displays other than CRTs. Of particular interest are

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Research Needs for Human Factors synthetic speech displays. Computer-generated speech is now available in a variety of devices, and the quality of the speech in some of these devices is quite good. The situations in which computer-generated speech is a viable alternative to visual displays, however, are not known. Basic research paralleling that on speech input is needed to produce defensible recommendations about applications in which speech output can or should be used. Workplace Design Computer displays and input devices are generally assembled into work stations consisting of terminals, consoles, desks, and chairs. There is, of course, a very large and useful literature on the physical layout of workplaces (see, for example, Van Cott and Kinkade, 1972), but there is very little empirical research on work station design specifically for computer-related tasks and settings. The importance of these problems is highlighted by a great deal of literature, mostly from Europe, about complaints from workers using CRT devices (see, for example, Grandjean and Vigliani, 1980). Similar complaints from a consortium of labor unions in the United States were received by the National Institute of Occupational Safety and Health (NIOSH) in 1979. The general nature of these complaints was that employees using CRT terminals experienced a variety of symptoms including headaches, general malaise, eyestrain, and other visual and musculoskeletal problems. In response to these complaints NIOSH conducted an extensive investigation of computer work stations in three companies in the San Francisco Bay area (Murray et al., 1981). The study consisted of four phases: (1) radiation measurements, (2) industrial hygiene sampling, (3) a survey of health complaints and psychological mood states, and (4) ergonomics and human factors measurements. Although radiation from CRTs had long been suspected as a potential health hazard, the NIOSH study seems to have conclusively ruled it out. X-ray, ultraviolet, and radio-frequency radiation in all sites and at all work stations tested was either not detectable or was well below acceptable occupational levels. Similar negative conclusions were reached about the chemical environment. Hydrocarbon, carbon monoxide, acetic acid, and formaldehyde levels in and around work stations were not appreciably different from what one would find in an ordinary living environment.

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Research Needs for Human Factors The results of the survey of health complaints were quite different, however. They show that operators of visual display terminals (VDT) experienced a greater number of health complaints, particularly related to emotional and gastrointestinal problems, than did comparable operators who did not work with VDTs. These findings, according to the NIOSH report, demonstrate a level of emotional distress for the VDT operators that could have potential long-term health consequences. The NIOSH study concludes, however, that it is quite likely that the emotional distress shown by the VDT operators is more related to the type of work activity than to the use of VDTs per se. With the growing number of VDTs in our society, it is clearly of considerable importance to establish how much of worker complaints can be traced to VDTs and how much to other factors (Ketchel, 1981; M.J. Smith, 1981). This is a research question that urgently needs to be investigated. The NIOSH report has more to say about the ergonomic and human factors aspects of the computer workplace than about any other aspect of computer work. Keyboard heights, table and chair designs, viewing distances and viewing angles, copy holders, and other aspects of work station design all come in for criticism. Computer work stations in America appear to be as poorly designed as those in Europe (see Grandjean and Vigliani, 1980; Brown et al., 1982), forcing operators to adopt strained postures and to contend with glare and generally substandard viewing conditions (Ketchel, 1981). Although basic data for good work station design are available, they need to be assembled in a good set of guidelines specifically oriented toward such design. This also appears to be an urgent research need. General Problems Three general problems relating to computer hardware have received almost no attention: (1) the design of transportable terminals and data, (2) the design of robust computer systems for military purposes, and (3) the design of computer terminals for use in unusual or exotic environments, for example, in moving vehicles or under water. Spectacular advances in microelectronics have made it possible to package enormous computing power into small packages. The full potential of this miniaturization has

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Research Needs for Human Factors not yet been realized or explored. We need human factors research leading to the design and use of transportable terminals, including input and output devices and data in the form of cassettes. Most computer systems are designed for use in benign environments. As the use of computers becomes more common in the military services, data will be urgently needed on how to design them for the rough treatment they are almost certain to receive under operational conditions. Vibration, high-g forces, immersion in water, and perhaps other environmental conditions affect machines as well as their operators. Certain input devices, for example, light pens or even keyboards, may be difficult or impossible to use when the computer and the operator are subjected to excessive movement, vibration, or g-forces. We have essentially no information about the usability of computers or the design of computers for use under such conditions. Although this may not be an immediate problem, it is certain to become increasingly important as computers are integrated into complex systems for use in harsh, exotic, or unusual environments. COMPUTER SOFTWARE Software has many different meanings to computer scientists and computer analysts who develop or use computer programs that include command languages, dialog systems, and specialized applications systems with data bases. Software may have originally been synonymous with computer programs, but in general software now consists of “the operational requirements for a system, its specifications, design, and programs, all its user manuals and guides, and its maintenance documentation” (Mills, 1980:417). Research in human factors in software has evaluated the human-computer interface with command languages, programming languages, dialog systems, and feedback and error management. Frequently the human factors studies have emphasized ease of use and ease of learning as well as efficiency of completing the problem-solving tasks on the computer. The recent experimental and observational studies were summarized in the special issue on human factors in Computing Surveys (1981), the IBM Systems Journal (1981), and in articles in Human Factors, the International Journal of Man Machine Studies, and Ergonomics. In addition, there are exemplary technical

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Research Needs for Human Factors reports, such as Williges and Williges (1981), Ledgard et al. (1981), Shneiderman (1980), and the proceedings of the Conference on Human Factors in Computer Systems (Institute for Computer Sciences and Technology, 1982). The more popular trade magazines, e.g., the April 1982 issue of BYTE, also feature articles on human factors in software design. Many authors express the need for additional careful research studies in software design and criticize many current results as incomplete and inconsistent due to poor methodology, use of subject populations limited to particular types of users (e.g., college students), inadequate experimental designs, and misuse or poor use of statistics. Selected useful guidelines for software designers are found in Engle and Granda (1975) and the recent reports by Williges and Williges (1981) and Ehrenreich (1981). Although there exist guidelines as well as selected research studies in human factors issues in software, considerable research needs to be done in order to provide information of use to system designers of software. The research efforts needed in human factors in software design can be divided into two areas: (1) methodological studies and (2) substantive studies of software design features for the end user. The two areas are not always independent, and some research studies require attention to both. In either case we are concerned about human factors research in software systems with which end users interact or interface, not about research in programming language design per se; this is usually the concern of the computer programmer or systems analyst. In the methodological area, research is needed on how to develop a suitable simulation capability for the design of dialog and interface systems. We need to understand how to evaluate present software systems as well as how to mock up new systems for testing and evaluation with end users. The choice of dependent variables in evaluating software is not clear. We know little about how to collect user statistics on the ease of learning of new software, how to record errors and complex response-time metrics from end users in time-sharing systems, and how to measure user satisfaction. Research is needed on what components of usability are most important for different kinds of users and applications (see Shackel, 1981). One of the problems in this area is that we don’t know how to do research on these topics. There is no agreed-

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Research Needs for Human Factors upon set of empirical methodologies for conducting research studies about software issues. The studies that have been done are frequently context-specific and/or about one or two software features and are difficult to generalize and integrate with other data in the area. Examples include evaluations of a given command asking users to translate the abbreviated form into English, effects of modifications of conditional nesting structures in FORTRAN, user efficiency of indentations to locate single bugs in PASCAL, and modifications in a language used in teaching at the University of Toronto. A research program undertaken by a multidisciplinary group at Virginia Polytechnic Institute and State University by Williges and Enrich sponsored by the Office of Naval Research [human-computer interaction and decision behavior, NR SRO-101] is attempting to develop principles of effective human-computer interaction, including establishment of a user’s model of command languages. This research is interdisciplinary and programmatic in nature. Another set of methodological studies is needed to discover how to develop guidelines and what kinds of guidelines for software characteristics are most useful for system designers and engineers; for example, Smith has described his ideas and progress in this area in the proceedings of the Conference on Human Factors in Computing Systems (Institute for Computer Sciences and Technology, 1982). In a substantive area, research is needed to understand the control of users’ input accuracy through “clever” or “novel” feedback during actual user experiences as well as what the “format structures” should be for providing feedback on errors that users make. Data needs to be collected on how best to provide effective error correction features, help messages, and what range of default procedures should be provided to aid user efficiency. We need research to evaluate how important feedback and system response time are for improving user efficiency or ease of use. There is a need for methodology and quantification of user ease and efficiency. At present, studies evaluate different types of commands in a laboratory rather than in real-use settings, and it is not clear that the most effective commands in the laboratory are applicable in applied system uses. We need information on what length of commands (one, two, or three words) or how many (enter only one and wait for system response or enter six at once) are preferred by casual users rather than expert software programmers.

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Research Needs for Human Factors A variety of studies are needed in order to evaluate how best to develop natural language dialog systems and in particular what kinds of language-based models of human communication are most appropriate for commands in operating systems, editing systems, knowledge-based systems, and query systems for human computer interactions (e.g., Reisner, 1981). Additional reseach is needed to understand how to develop knowledge-based systems for a variety of users. Knowledge-based systems are developed by a formulation of the application problem, designing and constructing the knowledge base of expertise, developing schemes of inference, search, or problem solving, winning the confidence of experts, and evaluating the programs for production versions. Examples of knowledge-based systems, frequently referred to as expert systems, include assisting users in such tasks as: (1) deducing molecular structures from the output of mass spectrometers, (2) advising when and where to drill for ore, and (3) diagnosing blood infections. It should be noted that there are three different kinds of end users of these systems, only the first of which is a user in a conventional information retrieval system: (1) in getting answers to problems, the user as client, (2) in improving the system’s knowledge, the user as a tutor, and (3) in harvesting the knowledge base, the user as pupil. A summary of recent research related to knowledge-based or expert systems can be found in L.C. Smith (1980). Some of the major features of these systems, including the schemes of inference or problem-solving approaches used in defining structures for the knowledge bases, are reviewed by Feigenbaum (1978). A recently developed specialty is software associated with special graphics displays. At present the development of both hardware and software for graphics use are at the gadget stage. We need to know how to design software modules for graphics use, what modules are best for various graphics features in addition to points, lines, and circles, and how to mix keyboard and pen inputs in ways other than up and down arrows and drawing pad devices. Most graphic software has hierarchical levels for command use; it is unknown if different levels are needed or how many are needed and which commands are best to use at each level. Also, the best ways for interacting among the hierarchically ordered levels of commands for draw and edit and the method for terminating are unknown. We need more information about what icons, menus, and special symbols should be used in creating

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Research Needs for Human Factors graphics. Methods have been developed for partitioning a display screen into multiple, sometimes overlapping windows, each monitoring an independent process. There has been very little research on how best to make use of this kind of capability. We know little about how to use color effectively for different kinds of graphics displays and applications. Several of the above research recommendations have been recognized by Moran (1981), who also suggests that further research is needed to understand users’ conceptual models in interacting with a variety of software systems. In addition, Thomas and Carroll (1981) and Miller (1981) have emphasized that the areas of most needed research are in the human-to-computer communication process, including research on the advantages and disadvantages of natural language software systems for different tasks. Computers have become more a part of all office systems today, and we need to study what impact the new computer technology has on organizations and their structures as well as the effects on decision making of the new management information systems (Federico, 1980). As a final point, it should be noted that we need research on the interaction between hardware and software design features as new developments such as voice input and video disks become more commonly incorporated into all types of computer systems. Important research that should be done involves first the design and analysis of new methodologies for conducting software research, and second, users’ conceptual models of software systems, including natural language systems for a variety of tasks. Also, we need to understand how to develop and evaluate additional knowledge-based systems for users as client, tutor, and/or pupil. Also needed are studies conducted to understand what software features would facilitate effective use of graphics in different tasks. DOCUMENTATION Documentation was once defined as printed matter that describes or explains how a system of some kind works or should be used. The documentation was necessarily separate from the system unless the system itself was a thing of print on paper. In the context of the computer, however, documentation can be part and parcel of the

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Research Needs for Human Factors system it describes or explains. Recent experience indicates that on-line documentation has many advantages over print-on-paper documentation. It cannot get lost or separated from the system. Inasmuch as the user is working with the computer, the computer can monitor what the user is doing and help find the parts of the documentation that are pertinent to the user’s current activity and current quandary. When the user thinks he or she understands what to do the computer can help do it—and may be able to try it out in a tentative way that will not cause much trouble if the user’s understanding is faulty. The possibilities are obviously revolutionary. Because on-line documentation is relatively new, however, not much is known about how to design and implement it effectively. Clearly the first priority for research in documentation is to explore, evaluate, and improve techniques of on-line documentation. On-line documentation within the system is not the answer to all needs for documentation, of course. Some computer systems (such as batch-processing systems and automatic process-control systems) are noninteractive, and others (such as many avionics systems) do not have enough memory or storage to make on-line documentation feasible. Documentation for such systems is, by and large, not very satisfactory. There is still need, therefore, for improved external documentation, documentation that is associated with the system but not in it. Wright (1981) has several useful suggestions for documentation designers, including suggested aids that take the form of heuristics for analyzing the user’s interaction with the text. Her suggestions also consider types of users and the user’s (reader’s) purpose rather than the producer designer’s (writer’s) purpose as a classification for documents. Of course, external documentation need not necessarily be print-on-paper documentation. It is an interesting idea to associate a “documentation computer” with the system to which the documentation pertains. In some instances, the documentation computer might be a small machine, even a portable one, taking the place of a few manuals; other instances—those that have veritable libraries of documentation—might require a documentation computer system of significant size. In an experimental system on an aircraft carrier, for example, the computer system that handles documentation is a network of about

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Research Needs for Human Factors 30 PERQs★ that are 16-bit, chip-based “personal” computers of substantial capability. Documentation as Part of an Overall System The aircraft carrier project introduces a concept that will no doubt be very important in the future: Documentation and what users do with it are parts of a larger system. If the use of documentation leads to the discovery of a defective part, inventory must be checked and ordering may have to be done. If the use of documentation leads to isolation of a software bug, software maintenance work must be done. It would be convenient and would foster efficiency if the same system that handled documentation also handled inventory and software maintenance. To improve the overall effectiveness of documentation, research is needed on the interactions of documentation with other parts of the overall task support system. Computer-Based Versus Print-on-Paper Documentation The discussion thus far has focused on computer-based documentation, even when the system being documented is not itself an interactive computer system. That choice reflects the judgment that research in computer-based documentation is more likely to make a major payoff than ongoing research in print-on-paper documentation. The latter research has led to many improvements and the total effect has been significant, but, insofar as conventional documentation is concerned, diminishing returns have set in. Computer-based documentation, by contrast, with the capability of the computer, offers hope of a very major advance. While computer-based documentation is not a new concept by any means, it has just recently begun to be studied systematically. The “help systems” and the “tutorials” of the 1960s and 1970s were written without the benefit of research of the kind that was devoted, for example, to programming languages. As a result, it has been said, the help systems needed help systems and the tutorials needed tutors. Our ★   PERQ is a trademark of the Three Rivers Computer Corporation.