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Research Needs for Human Factors (1983)

Chapter: User-Computer Interaction

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Suggested Citation:"User-Computer Interaction." National Research Council. 1983. Research Needs for Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/759.
×

5
USER-COMPUTER INTERACTION

INTRODUCTION

Electronic computers have probably had a more profound effect on our society, on our ways of living, and on our ways of doing business than any other technological creation of this century. Computers help manage our finances, checking accounts, and charge accounts. They help schedule rail and air travel, book theatre tickets, check out groceries, diagnose illnesses, teach our children, and amuse us with sophisticated games. Computers make it possible to erase time and distance through telecommunications, thereby giving us the freedom to choose the times and places at which we work. They help guide planes, direct missiles, guard our shores, and plan battle strategies. Computers have created new industries and have spawned new forms of crime. In reality, computers have become so intricately woven into the fabric of daily life that without them our civilization could not function as it does today. Small wonder that all these effects have been described as the results of a computer revolution.

Gantz and Peacock (1981) estimate that the total computer power available to U.S. businesses increased tenfold in the last decade, and that it is expected to double every two to four years. According to the most recently available estimates (U.S. Bureau of the Census, 1979), there are currently about 15 million computers, terminals, and electronic office machines in the United States. That number is expected to grow to about 30–35 million by 1985,

The principal authors of this chapter are Alphonse Chapanis, Nancy S.Anderson, and J.C.R.Licklider.

Suggested Citation:"User-Computer Interaction." National Research Council. 1983. Research Needs for Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/759.
×

at which time there will be roughly one computer-based machine for every three persons employed in the white-collar work force. Spectacular advances in computer technology have made this growth possible, decreasing the cost of computer hardware at the rate of about 30 percent a year during the past few decades (Dertouzos and Moses, 1980).

Computers are still not as widely accepted as they might be. In a study by Zoltan and Chapanis (1982) on what professionals think about computers, over 500 certified public accountants, lawyers, pharmacists, and physicians in the Baltimore area filled out a 64-item questionnaire on their experiences with and attitudes toward electronic computers. Six factors emerged from a factor analysis of the data. Factor I, the largest in terms of the variance accounted for, is a highly positive grouping of adjectives attesting to the competence and productivity of computers, such as efficient, precise, reliable, dependable, effective, and fast. Factor II, the second largest in terms of the variance accounted for, is made up of highly negative adjectives: dehumanizing, depersonalizing, impersonal, cold, and unforgiving.

Still another factor in the Zoltan-Chapanis study indicates discontent with computers in terms of their ease of use. The respondents thought that computers are difficult and complicated and that computing languages are not simple to understand. These views are apparent in their responses to such statements as: “I would like a computer to accept ordinary English statements” and “I would like a computer to accept the jargon of my profession,” both of which they agreed with strongly.

The findings of that study are generally in agreement with more informal reports in the popular press and other media about difficulties people have with computers and their use. Indeed, concerns about making computers easy to use can have serious economic consequences that may have to be faced by more and more computer manufacturers. For example, a small company in California was recently awarded a verdict for substantial monetary damages because of the inadequate performance of a computer that the company had purchased (Bigelow, 1981). In rendering his opinion substantiating the award, the presiding judge said, “It’s a particularly serious problem, it seems to me, in the computer industry, particularly in that part of the industry which makes computers for first-time users, and seeks to expand the use of computers by…

Suggested Citation:"User-Computer Interaction." National Research Council. 1983. Research Needs for Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/759.
×

targeting as purchasers businesses that have never used computers before, who don’t have any experience in them, and who don’t know what the consequences are of a defect and a failure” (Bigelow, 1981:94).

In Europe resistance to computerization has taken a somewhat different form than that in the United States. Television programs roughly equivalent to the American program 60 Minutes have been broadcast about the real and imagined evils of computers. Several countries—Austria, England, France, Germany, and Sweden among them—have prepared strict standards for the design of computer systems and have enacted federal laws restricting hours of work at computer terminals. Similar regulations may soon be in effect in this country. One difficulty is that current standards and regulations about computers are sometimes based on skimpy and unreliable data and sometimes on no data at all (Rupp, 1981). Whatever their origins, these events and trends are symptoms of fairly widespread uneasiness and malaise about computers, their usefulness, and usability. No one denies that computers are here to stay. The important question is: “How can we best design them for effective human use?” This chapter describes some of the research needed to answer that question.

Research needs are identified throughout the chapter. However desirable it might appear to assign specific priorities to each, we feel that it is difficult and risky to do so for at least three reasons. First, computer hardware, software, and interface design features are changing very rapidly (for a summary of the trends and progress in computer development see Branscomb, 1982). So, for example, the increased availability of modularly arranged components for microcomputers for personal use, in the office and at school as well as new networking and communications features allow design improvements to be made quickly by trial and error. As Nickerson (1969) has pointed out, such trial-and-error design improvements can be made more quickly than they could be by careful laboratory research studies.

Second, practical considerations are likely to be significant determinants of what research can be performed. Operational computer systems rarely can be disrupted for research purposes, and up-to-date hardware and software as well as appropriate groups of users are not always available. Under these circumstances it takes great ingenuity to conduct human factors research on user-computer interactions that can produce useful, generaliz-

Suggested Citation:"User-Computer Interaction." National Research Council. 1983. Research Needs for Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/759.
×

able results. Constraints and opportunities are therefore more likely than assigned priorities to dictate what research is performed.

Third, there is a definite need for good human factors research in all the areas we discuss, even with the caveat that technology is changing rapidly and good research is difficult to conduct. With these qualifications in mind, we do provide at certain places in this chapter, short summaries indicating those research needs that we feel have higher priorities than others.

THE COMPUTER SYSTEM

Computer systems and their environments have been diagrammed and modeled in various ways. Figure 5–1 illustrates elements that are important from a human factors standpoint: the user, the task, the hardware, the software, the procedures, and the work environment. Together they cluster around what is commonly called the user-computer interface—that invisible surface that binds the various elements together. Diagramming a computer system in this way is to a large extent artificial, because the various elements cannot really be considered in isolation. As will be apparent later on, there are interactions among all of them. The figure is merely a convenient way of

FIGURE 5–1 Important Elements of Computer Systems

Source: Adapted from Chapanis (1982).

Suggested Citation:"User-Computer Interaction." National Research Council. 1983. Research Needs for Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/759.
×

structuring and organizing the subtopics of this chapter, which are described briefly below and treated in detail in subsequent sections.

  1. The Users. Beginning with the users is a natural starting point for any discussion of the human factors involved in computer systems. Focusing on users implies what is sometimes referred to as user-oriented design, rather than machine-oriented design. Perhaps the most important questions about users are “Who exactly are the users?” “What are their characteristics?” and “How can user requirements be translated into design requirements?”

  2. The Task. The second element is the task or the job that the user has to do with the computer. The complexity of the job, the kinds of information the operator needs to perform the job, and the constraints under which jobs must be performed are all relevant considerations in the human factors design of computer systems. Task requirements are discussed in the section on users.

  3. The Hardware. Hardware means input devices, output display, and signaling devices, and the work station that the computer operator has to use.

  4. The Software. Software generally refers to the data bases, computer programs, and procedures available in a computer system.

  5. Procedures. Procedures, manuals, and documentation are often included under software. They are shown separately in Figure 5–1 because the problems associated with manuals and documentation are somewhat different from those associated with programming languages, commands, and menus.

  6. The Work Environment. Generally speaking, computers and computer systems are found in relatively benign work environments. Nonetheless, some features of the work environment—excessive glare, noise, and sometimes dirt and vibration—have to be considered in the design of the user-computer interface. Since standard human factors recommendations and good engineering practice are usually adequate guides for designing most work environments in which computers are located, we do not cover environmental variables in this chapter.

USERS AND TASKS

Computer users today are almost as varied as people in general. Although there have been a number of attempts

Suggested Citation:"User-Computer Interaction." National Research Council. 1983. Research Needs for Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/759.
×

to categorize or classify computer users into various groups or along various dimensions, there is today no generally accepted way of doing either. Computer tasks, by contrast, can be classified under the same headings as are used in task analyses. Proceeding from the more global to the more detailed they are jobs, functions, tasks, and subtasks. According to Ramsey and Atwood (1979), most of the literature about computer tasks is at the job level. Some people think, however, that computer tasks cannot be classified in isolation, but that tasks interact with users and that the two must be treated together. Examples are: professional programmers designing systems, professionals using application programs with command languages, occasional users using application programs with menus. In short, classifying computer users and tasks is clearly in need of systematic work, and it is treated more fully in the sections that follow. We rely in our discussion on the exemplary review of the literature on human-computer interaction by Ramsey and Atwood (1979), which was supported by the Office of Naval Research.

Users

Attempts to classify users have followed one of several quite different approaches. The first is to categorize users into more-or-less distinct groups on the basis of their familiarity or sophistication with computers. This way of classifying users has yielded a large collection of names. Examples, in alphabetical order, are: casual users (Martin, 1973), computer professionals (Barnard et al., 1981), dedicated users (Martin, 1973), discretionary users (Bennett, 1979), experienced users (Shackel, 1981), familiar users (Ledgard et al., 1981), first-time users (A1-Awar et al., 1981), the general public (Shackel, 1981), general users (Miller and Thomas, 1977), inexperienced users (Dzida et al., 1978), naive users (Thompson, 1969), noncomputer specialists (Shackel, 1981), nonprogrammers (Martin, 1973), occasional users (Hammond et al., 1980), programmers (Martin, 1973), regular users (Dzida et al., 1978), and untrained users (Martin, 1973).

Another way of categorizing users has focused more on the nature of the user’s job. This has produced such categories as: analysts (S.L.Smith, 1981), clerical workers (Stewart, 1974), managers (Eason, 1974), operators (Smith, 1981), programmers (Martin, 1973), rugged opera-

Suggested Citation:"User-Computer Interaction." National Research Council. 1983. Research Needs for Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/759.
×

tors (Martin, 1973), service personnel (Smith, 1981), specialists (Stewart, 1974), and technical users (Ramsey and Atwood, 1979).

Quite a different way of classifying users is in terms of underlying personal characteristics. Thus, Ramsey and Atwood suggest obtaining data about users’ abilities, acquired skills, general background (including formal education), sex, age, attitude measures, mechanical (perhaps also spatial) aptitudes, vocabulary test performance, recency and length of training periods, training scores, cognitive decision style, and general intelligence.

Another classification of users’ characteristics would include data on the following:

  1. Sensory capacities, e.g., visual acuity

  2. Motor abilities, e.g., typing skills

  3. Anthropometric dimensions, for hardware design

  4. Intellectual capacities, e.g., general intelligence and special abilities in order to evaluate reading levels for information presented

  5. Learned cognitive skills, including familiarity with the English language

  6. Mathematical and logical skills

  7. Experience with computers and proficiency in training

  8. Personality, e.g., attitudes toward computers

Shneiderman (1980), by contrast, classifies users only according to their semantic and syntactic knowledge about computers. This way of classifying users yields the simple matrix shown in Figure 5–2.

The diversity of approaches that have been taken to this problem indicates that we need research to understand and identify which of many possible user characteristics are important for software design. In addition, research is needed to understand how to express and translate user characteristics into terms that can be used in systems design, i.e., into specifications for designers of system software.

It is important to recognize that all users, whether they are seasoned systems programmers or less experienced users, continue to learn as newer systems are developed and/or updated. For that reason, Cuff (1980) has suggested that we need to consider the casual user of computers as well as expert or naive users. Additional dimensions of user behaviors could give us evidence of the functionality of systems, e.g., the range of tasks

Suggested Citation:"User-Computer Interaction." National Research Council. 1983. Research Needs for Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/759.
×

FIGURE 5–2 Classification of Users According to the. Extent of Their Semantic and Syntactic Knowledge

Source: Adapted from Shneiderman (1980).

users can perform with a given system, how long it takes a user to learn a system or a system update, and the time it takes a user to perform a particular task or job. We need to know what kinds of errors users make when learning new systems as well as how many errors are made and how often they are made or repeated, how well users adapt to changes in system software (robustness) that are “upward compatible,” and how users rate subjectively the quality of the output or product and the systems that perform their set of tasks.

When we look at what is currently known about the novice compared with the expert user, it appears that the former is generally engaged in problem solving and is very susceptible to task-structure variations. The expert systems programmer typically interacts with a computer as a routine cognitive skill and is somewhat immune to structural variations in the tasks performed (see Moran,

  

Upward compatible means that commands and features used in an older version of software are still available in a newer version, although the newer version may provide new commands or features that are more efficient for accomplishing the same ends.

Suggested Citation:"User-Computer Interaction." National Research Council. 1983. Research Needs for Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/759.
×

1981; Mayer, 1981). A simple dialog in the software that is computer-initiated and tutorial in nature is probably more appropriate for the occasional and naive user, but an abbreviated, user-initiated dialog appears to be more appropriate for the experienced user. It is clear that we need to gather more data about problem-solving strategies and preferences across different types of tasks for different levels of users.

Of particular concern is that the research methods used in evaluating user characteristics for hardware design have been used in studies evaluating user characteristics for software design. It is not known if these research methods are appropriate for evaluating software use or which methods will provide the most information to designers. Moran (1981) has addressed this issue in part.

Perhaps the two most pressing research needs in this area are to find some meaningful way of classifying or categorizing users and translating user characteristics into specific recommendations that can be used in the design of computer hardware, software, and documentation.

Tasks

Most computer and human factors specialists agree that a task taxonomy is needed and that system designers need a set of benchmark tasks to evaluate hardware/software development and changes. A task structure provides the rules of the game that determine the range of actions users can and cannot take (Moran 1981). Tasks can vary in several ways. They may (1) fulfill different functions for the user, e.g., professional, educational, or home hobby functions, (2) require different forms of language such as natural language, BASIC, COBOL, or APL, and (3) be performed on different kinds of systems.

In addition, almost all system designers recognize that the user’s interface with a computer system changes as tasks or jobs change. The user interface includes any part of the computer system that the user comes in contact with physically, perceptually, or conceptually. The user’s conceptual model of the system to be used to perform a given task is part of that interface. Thus, we also need research to understand how to discover a user’s conceptual model(s) when he or she is interfacing with the computer.

Models suggested by Moran (1981) involve explicit information processes that spell out step-by-step the

Suggested Citation:"User-Computer Interaction." National Research Council. 1983. Research Needs for Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/759.
×

mental operations the user must go through to complete the task application. These models need to be based on a psychological theory of users. One example of specific models that describe individual user differences in understanding calculator languages is described by Mayer and Bayman (1981).

It would be helpful if a subset of the task taxonomy or benchmark tasks could be integrated into the accounting systems of computers so that system designers could be provided with statistical data about tasks and users. These statistics on users should include information about the user type and systems used as well as errors in usage. One example of a keystroke-level model for evaluating performance is described by Card et al. (1980).

Of primary need are systematic studies of the conceptual models of users when they interact with a variety of hardware and software systems to do specified sets of tasks, e.g., text editing, numerical problem solving, or querying data bases. These studies should choose successful methodologies for producing results that can be directly applied to system design, or they should include new methods for evaluating the interactions of user characteristics with task requirements. Another pressing problem is the development of a meaningful task taxonomy that includes both behavioral and cognitive elements for a set of four or five different representative tasks.

COMPUTER HARDWARE

Computer hardware cannot be designed in isolation because the kind of hardware available on a computer terminal determines in part the kinds of dialog and the kinds of command languages that can be implemented in the system. Ideally, decisions about important aspects of computer dialogs should precede decisions about terminal hardware. In practice, the reverse often occurs. While recognizing that these interactions exist and that they are important in design, we discuss the human factors aspects of computer hardware with only passing reference to their software implications.

Input Devices

Designers of interactive computer systems can select from an array of devices for inserting information into computers. Table 5–1, modified from the work of Ramsey

Suggested Citation:"User-Computer Interaction." National Research Council. 1983. Research Needs for Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/759.
×

TABLE 5–1 Computer Input Devices With Some of Their Principal Features and References

Input Device

Features

References

Keyboard

The vast majority of past research on input devices has dealt with keyboards. Reasonable and fairly detailed guidelines exist with respect to the physical properties of keys and keyboards and—to a lesser extent—their layout, logical properties, operating procedures, etc. Guidelines for alphabetic keyboards are particularly good, and those for numeric keypads are reasonable. Function keyboards are rather system-dependent; guidelines can specify their physical properties but can only suggest methods and basic principles for function selection and layout. It is not clear that chorded keyboards are viable except in highly specialized situations.

Alden et al. (1972)

Seibel (1972)

Light pen, light gun—a wand with a light detecting tip used to determine the specific point on a display it touches.

Light pens can be used effectively for cursor placement and text selection, command construction, and for interactive graphical dialogs in general, including drawing. There is evidence, however, that greater accuracy may be possible with a mouse in discrete tasks and with a trackball in drawing tasks. Mode mixing, as by alternating use of light pen and keyboard, can significantly disrupt performance, since the light pen must be picked up and replaced with each interval of use. Continuous use of a light pen, at least on commercially available Cathode ray tube (CRT) terminals with vertical display surfaces, can be quite fatiguing. There has been no known research on desirable physical and logical properties for light pens.

English et al. (1967)

Goodwin (1975)★★

Irving et al. (1976)

Suggested Citation:"User-Computer Interaction." National Research Council. 1983. Research Needs for Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/759.
×

Joystick—a vertical stick generally used to move a display cursor in a direction corresponding to the direction of stick movement.

There are many studies of the use of joysticks for continuous tracking tasks, but few studies of their use for discrete or continuous operand selection or graphical input tasks. The studies that have been performed have found the mouse, light pen, and trackball preferable in terms of speed, accuracy, or both. Joysticks are sometimes used for windowing and zooming control in graphical displays. No research on this topic was found, although the results of tracking studies may be applicable here. Otherwise, no clear recommendations for joystick properties have emerged, even with respect to basic issues like position versus rate versus acceleration control. These issues may be fairly task-specific.

Card et al. (1978)

English et al. (1967)

Irving et al. (1976)

Trackball—a partially exposed ball in a fixed base rotated by the hand generally used to move a displayed cursor in a direction corresponding to the direction of movement of ball rotation.

The trackball appears to be effective for both discrete and continuous operand selection and graphical input tasks, and it may yield the best performance when graphical inputs must be alternated with keyboard input. No empirical data on physical properties were found, but some such data are thought to exist in the tracking literature.

Irving et al. (1976)

Suggested Citation:"User-Computer Interaction." National Research Council. 1983. Research Needs for Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/759.
×

Input Device

Features

References

Mouse—a small device rolled by hand on a surface generally used to move a displayed cursor in a direction corresponding to the direction of movement of the mouse.

Although the mouse is not in widespread use, there is evidence that it is an effective device for text selection. No data are known concerning its physical properties, or its use in other tasks.

Card et al. (1978)

Engelbart (1973)

English et al. (1967)

Graphical input tablet—a flat surface which detects the position and movement of a hand-held stylus generally used to generate a drawing on a display.

Graphical input tablets are capable of fairly high pointing accuracy (within 0.08 cm, according to one study). They are commonly used for freehand drawing but may be inferior for discrete position input tasks. They may also involve a performance decrement due to low stimulus-response compatibility when the drawing surface is separate from the display surface.

English et al. (1967)

Myer (1968)

Suggested Citation:"User-Computer Interaction." National Research Council. 1983. Research Needs for Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/759.
×

Touch panel—a device which overlays the display and senses the location touched by a finger or stylus.

No empirical performance data were found dealing with the touch panel. While its inherent resolution limits may preclude serious use for fine discrete position and continuous position input, it feels natural and may become a common device for more coarse positioning and selection from lists.

Hlady (1969)

Johnson (1977)

Knee control

A knee control has been used in one research study for discrete position input. It is not known to be in use otherwise and seems unlikely to see serious use.

English et al. (1967)

Thumbwheels, switches, potentiometers

These have been studied primarily outside the computer systems domain and are discussed in standard human factors reference sources. They are not often used as input devices for interactive computer systems.

Chapanis (1972)

Tactile input devices

Although some tactile input devices have been proposed, little human factors research has been done on them other than that concerned with prosthetics.

Noll (1972)

Psychophysiological input devices

Electromyographic signals have provided superior performance in some control tasks to joysticks and other manual control devices. Use of heart rate, keyboard response latency, electroencephalographic input, etc. is technologically feasible, although sophisticated input is not yet achievable via these methods. There are ethical and legal problems as well as technological difficulties. Significant human factors

Slack (1971)

Wargo et al. (1967)

Suggested Citation:"User-Computer Interaction." National Research Council. 1983. Research Needs for Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/759.
×

Input Device

Features

References

 

data were not found with respect to computer-related use of these techniques.

 

Automated speech recognition

The current state of this technology limits its use to relatively simple input tasks. Even in these there are problems with different speakers, noise, etc. Although speech input seems like a very desirable and natural input mode and is clearly preferred over other communication modes for interpersonal communication, it is not clear whether it will prove to be widely applicable for human-computer interaction tasks. Very little information was found that would assist the designer in recognizing tasks for which speech input is appropriate or in selecting an appropriate speech input device.

Addis (1972)★★

Bezdel (1970)

Braunstein and Anderson (1961)

Chapanis (1975, 1981)★★

Turn (1974)

Hand printing for optical character recognition (or for subsequent entry by typist)

The constrained hand printing required for optical character recognition (OCR) input results in low input rates and sometimes high recognition-error rates as well. Although manual transcription of such data clearly cannot be avoided in many cases, the preponderance of evidence suggests that direct keyboard entry yields better performance than printing, with a little practice, even when users are not skilled typists. Some error and input rate data on hand printing exists, along with some information about the effect of various printing contraints on input performance.

Apsey (1976)

Devoe (1967)

Masterson and Hirsch (1962)

L.B.Smith (1967)

Strub (1971)

Suggested Citation:"User-Computer Interaction." National Research Council. 1983. Research Needs for Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/759.
×

Mack sensing

As with hand printing, this form of transcription results in lower input rates than does practiced but unskilled typing. Some error and input rate data exist. May be slightly faster than constrained hand printing.

Devoe (1967)

Kulp and Kulp (1972)

Punched cards

Keypunching performance differs significantly from ordinary typing because of differences in both the machine and the typical data to be keyed. Some reasonably good data exist on keypunch timing and error rates.

Neal (1977)

Touch-tone telephone

Several studies suggest that the touch-tone telephone is a satisfactory device for occasional use as a computer terminal, even by naive computer users. It seems clear, though, that it is not a satisfactory device for prolonged interaction or for significant amounts of nonnumeric input.

Miller (1974)

Smith and Goodwin (1970)

Witten and Madams (1977)

The reference contains user performance data or relatively detailed results of controlled experimental work.

★★The reference presents survey or questionnaire data or summarizes experimental results.

Source: Adapted from Ramsey and Atwood (1979).

Suggested Citation:"User-Computer Interaction." National Research Council. 1983. Research Needs for Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/759.
×

and Atwood (1979), lists 16 different kinds of input devices, comments on some of their features, and identifies the principal references to studies of these devices. Since the situation has not changed materially since the Ramsey-Atwood report was issued, its findings are still valid.

By far most of the work on computer input devices has been done on keyboards; the literature is large and varied. Seibel’s chapter in the Van Cott and Kinkade (1972) handbook is a good starting point for anyone interested in these problems. Ramsey and Atwood reference a number of studies done after Seibel’s chapter was written, and there is a fair amount of even newer work, e.g., Hirsch (1981) and Hornsby (1981). The available literature on keyboards is sufficient to answer most practical questions. This is no longer an area urgently in need of extensive research.

The situation with regard to alternative input devices, such as light pens, touch panels, and hand printing, is different. Most of the work that has been done on these devices has compared two or more input devices in specific applications. There are not many studies of this kind in the literature, although Card et al. (1978) did evaluate the speed and accuracy of four devices for text selection. Research is needed that will lead to a set of recommendations about the kinds of input devices that are best suited to general classes of tasks (e.g., text input, input of numerical data, selection of commands and operands from displays, discrete positional [graphical] input, and continuous positional [graphical] input) and perhaps to general classes of work environments.

A much more serious concern is that there have been practically no studies of the optimal design of input devices, except for keyboards. That is, given that a light pen is better than a keyboard for some applications, how exactly would one design the best light pen for the job? Research is clearly needed on the optimal design parameters of all input devices other than keyboards.

Voice input to computers deserves special treatment because (1) it does not involve a physical mechanism that the user manipulates as such and (2) speech as a human output is distinctly different from the movements of fingers, hands, or feet that are required for the activation of most conventional computer input devices.

Speech has a number of characteristics that theoretically make it an attractive candidate for computer inputs,

Suggested Citation:"User-Computer Interaction." National Research Council. 1983. Research Needs for Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/759.
×

TABLE 5–2 Recommendations for the Use of Auditory and Visual Forms of Presentation

Use auditory presentation if:

Use visual presentation if:

1.

The message is simple.

1.

The message is complex.

2.

The message is short.

2.

The message is long.

3.

The message will not be referred to later.

3.

The message will be referred to later.

4.

The message deals with events in time.

4.

The message deals with location in space.

5.

The message calls for immediate action.

5.

The message does not call for immediate action.

6.

The person’s visual system is overburdened.

6.

The person’s auditory system is overburdened.

7.

The receiving location is too bright or dark-adaptation integrity is necessary.

7.

The receiving location is too noisy.

8.

The job requires continual movement.

8.

The job allows for a stationary position.

 

Source: Deatherage (1972).

to be of any practical use to a computer designer. For example, how is a designer to decide whether a message is simple or complex?

What we clearly need is a detailed, comprehensive, and quantitative set of guidelines about the precise conditions under which speech input to computers is and is not desirable. These guidelines should consider the user, the task, and the work environment in which computers are located.

Although some very good speech recognition machines are available, they have some important limitations.

Suggested Citation:"User-Computer Interaction." National Research Council. 1983. Research Needs for Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/759.
×

It is fast, effective, versatile, flexible, and requires little effort. Moreover, almost everyone knows how to talk, so that training is generally unnecessary. One of the principal reasons why speech input is not widely used, however, is that technology has not been able to provide us with speech recognition capabilities that even begin to approximate those of human listeners. Nonetheless, the state of the art is advancing rapidly. There are now some very good speech recognition devices available and their capabilities are certain to increase greatly in the foreseeable future.

Although speech has some distinct advantages as a medium of communication, it is also easy to identify applications in which speech input to computers would not be desirable. Some of these applications involve certain kinds of users (for example, persons with speech impediments), others the task (for example, intricate mathematical and chemical formulae are not easily described orally), and still others the work environment (speech input is not very efficient in noisy environments). For more reliable guidance about applications in which the voice should or should not be used, the only source of help are recommendations comparing visual and auditory forms of presentation (see Table 5–2).

Table 5–2, and others like it in the human factors literature, suffer from four major defects. First, the recommendations are oriented more toward output devices rather than input devices—that is, they do not compare speech with other possible forms of data input. However attractive speech may appear as an input medium, some data are available suggesting that it is not necessarily the solution for all situations (see, for example, Braunstein and Anderson, 1961). Second, recommendations such as those in Table 5–2 are not specifically oriented toward computer applications. Third, these comparisons are not sufficiently comprehensive to be of much use to computer designers. For example, none of these comparisons considers in detail user characteristics or the work environment in which computers are used. Some environments have rows and rows of computer terminals in close proximity. Imagine the babble that might result if 50 operators were inputting information by voice simultaneously into computers! Finally, existing comparisons of vision and audition provide information that is too vague

Suggested Citation:"User-Computer Interaction." National Research Council. 1983. Research Needs for Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/759.
×

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).

Suggested Citation:"User-Computer Interaction." National Research Council. 1983. Research Needs for Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/759.
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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)

Suggested Citation:"User-Computer Interaction." National Research Council. 1983. Research Needs for Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/759.
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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

Suggested Citation:"User-Computer Interaction." National Research Council. 1983. Research Needs for Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/759.
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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).

Suggested Citation:"User-Computer Interaction." National Research Council. 1983. Research Needs for Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/759.
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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

Suggested Citation:"User-Computer Interaction." National Research Council. 1983. Research Needs for Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/759.
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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.

Suggested Citation:"User-Computer Interaction." National Research Council. 1983. Research Needs for Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/759.
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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

Suggested Citation:"User-Computer Interaction." National Research Council. 1983. Research Needs for Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/759.
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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

Suggested Citation:"User-Computer Interaction." National Research Council. 1983. Research Needs for Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/759.
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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-

Suggested Citation:"User-Computer Interaction." National Research Council. 1983. Research Needs for Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/759.
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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.

Suggested Citation:"User-Computer Interaction." National Research Council. 1983. Research Needs for Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/759.
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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

Suggested Citation:"User-Computer Interaction." National Research Council. 1983. Research Needs for Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/759.
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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

Suggested Citation:"User-Computer Interaction." National Research Council. 1983. Research Needs for Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/759.
×

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

Suggested Citation:"User-Computer Interaction." National Research Council. 1983. Research Needs for Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/759.
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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.

Suggested Citation:"User-Computer Interaction." National Research Council. 1983. Research Needs for Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/759.
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conclusion is that now is the time to make a strong research attack on computer-based documentation, including self-instructional programs, coherent system-wide help systems, documentation keyed to the behavior of programs (so that an error calls forth an explanation of what went wrong), and programming languages that write programs to explain themselves.

Capturing the Intent of the Creators of the System

As suggested earlier, documentation must be viewed as a part of the overall system that interacts with other parts of the overall system. The time dimension—the history—of the overall system is a very important base of the interaction. Most systems are developed through efforts to improve earlier systems, and those that do not are developed from some kind of design activity in the minds of system designers. (Programs are systems, of course, so the same can be said of programs). The intentions of the improvers and designers are crucially important to understanding what the systems do, how they work, and how they should be used—but intentions tend not to be captured in the plans and designs. A computer program, for example, usually tells how to do something, not what it is that is being done, and it is very difficult to reconstruct the programmer’s intentions from the program. Research on this topic may or may not improve the situation, but it clear that the situation needs to be improved. A broad view of documentation is important. The right approach may be to create computer-based design and upgrading metasystems, within which improvers and designers would work under constant monitoring, with as much emphasis on recording intentions and goals as on devising the means for achieving them. Note that this notion, if not developed with sensitivity to privacy issues, could lead to serious ethical problems.

Dynamic Graphics and Documentation

Although documentation was, in earlier days, primarily print on paper, some documentation has been available in other media, such as recorded speech and movies. The latter offered, at considerable cost, the advantages of kinematic graphics and moving gray-scale and color pictures. The computer promises to reduce the cost of

Suggested Citation:"User-Computer Interaction." National Research Council. 1983. Research Needs for Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/759.
×

preparing kinematic graphics by having a single, static program create dynamic multidimensional patterns that develop over time. The video disk promises to reduce the cost of storing and playing back all kinds of information, especially pictorial information. Together the computer and the video disk may open up a new era for dynamic graphic documentation. At present the computer can select and present in a few milliseconds any one of the approximately 55,000 pictures on a video disk. It can run off sequences of continuous frames as a movie or skip around under program control and show fast slide sequences. What it selects can be conditioned, of course, by the responses of the viewer or viewers. These capabilities present an exciting opportunity to explore and develop new approaches to documentation.

Another exciting opportunity is being studied under the rubric of program visualization. The computer is capable, of course, of displaying representations of its own internal operation. It can present sequences of symbols representing the program that is being executed and the data on which the program is operating. Alternatively, it can present graphs, diagrams, and pictures to tell the person at the console what the program should be doing and what it is in fact doing. This latter approach to documentation, which requires sophisticated graphic display not widely available in the past, is now economically as well as technically feasible. The hope is that iconic displays will prove superior to symbolic displays in presenting the broad picture of the behavior of computer programs and systems and in helping people deal with their intrinsic complexity. With the iconic approach, it may be possible to provide something analogous to a zoom lens, through which one would be able to monitor and control the broad picture as long as everything proceeds according to plan, then focus on the offending details as soon as trouble arises.

Documentation in the Form of Knowledge Bases

Conventional documentation takes the forms of natural language text, diagrams, sketches, pictures, and tables of data; it is designed exclusively to be read by eye. New forms of documentation are becoming essential: pointer structures, semantic networks, procedural networks, and production rules, documentation designed to be

Suggested Citation:"User-Computer Interaction." National Research Council. 1983. Research Needs for Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/759.
×

interpreted by computer programs. Such documentation will probably be used first in interactive computer systems to help end users or programmers and maintenance workers, but in due course it will be used also in fully automatic systems sophisticated enough to read their own documentation and restructure themselves to overcome difficulties and maximize performance. Some work has already been done on such documentation in the field of artificial intelligence; much more needs to be done. It is essential to couple research on documentation closely with other research pertinent to the systems in which it will be used—for example, with work on interactive tutorial systems for end users, interactive maintenance systems, and robotic maufacturing systems.

Computer Systems to Facilitate Conventional Documentation

The foregoing emphasis on computer-based documentation expresses our conviction that it is the high-payoff area within the documentation field, but it should not be taken to imply that conventional documentation is dead. We think that two main foci have the greatest potential payoff for research in conventional documentation: (1) understanding the target group of people that the documentation is intended to help and the tasks in which they will be engaged when they use the documentation and (2) using computer systems, with good editors, formatters, and composers to facilitate creation and production of c onventional documentation.

The theme of understanding the users is developed elsewhere in this chapter. Great advances have been made in the last few years in the design of computer-based systems for creating and producing conventional documents, and research in that area has much new technology to work on. Indeed, research is needed to develop the capability to make the new editors, formatters, and composers easy to use in order to facilitate the preparation of documentation that will make them and other systems easy to use. Kruesi, for example, supported by the Office of Naval Research (NR 196–160), is investigating the relationship between the types of documentation provided to programmers and their performance on a wide variety of software-related tasks.

In summary, research should be emphasized in several areas pertinent to documentation: (1) techniques of

Suggested Citation:"User-Computer Interaction." National Research Council. 1983. Research Needs for Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/759.
×

on-line documentation, (2) interactions and information flows between document subsystems and other subsystems, (3) efforts to capture the intent of designers and upgraders of systems, (4) dynamic graphics and the video disk, (5) dynamic graphics and program visualization, (6) knowledge bases, (7) understanding the uses and users of documentation, and (8) computer-based systems for the development of conventional documentation. Of these suggestions two primary research needs are to know how and when to use display documentation with graphics and what program visualization techniques are most helpful to users.

SUMMARY AND CONCLUSIONS

The primary research recommendatons in the areas of users, tasks, hardware, software, and documentation include a major emphasis on developing new methodologies to evaluate what is meant by ease of use in human-computer interaction. Does ease of use mean the extent to which it is easy to learn to use a computer; does it imply good design of hardware and software for a variety of naive, casual, and professional users; does it mean that any task can be done quickly and without errors; does it encompass a component of judged satisfaction about use; or does it mean all of these?

We need to know what user characteristics are important determinants of successful human-computer interaction for a specified set of tasks, such as data base inquiries, computation and accounting problems, and editor or word processing functions. In the area of hardware design, more research is needed to evaluate alternatives to keyboard input (including voice input), uses of color in displays, the best sizes of displays, and alternatives to CRT displays. Studies in evaluating software are barely beginning to provide data for design use. We don’t yet know how to conduct systematic research studies in software design, what independent variables are most important, and what dependent variables of human-computer interaction should be recorded. We don’t have data to support the design of a simulation facility to effectively evaluate commands in operating systems, editing systems, knowledge-based systems, and query systems. We need to understand users’ conceptual models in interacting with specific software systems, and we need more information about the advantages and disadvan-

Suggested Citation:"User-Computer Interaction." National Research Council. 1983. Research Needs for Human Factors. Washington, DC: The National Academies Press. doi: 10.17226/759.
×

tages of natural language software systems. Documentation may well become part of the available software for users; when and how to display documentation is an important area for research. Research is needed on how best to use graphics and special knowledge bases to facilitate uses of documentation either on line or in manuals. Current documentation is designer-oriented rather than user-oriented, and the perspectives should be changed so that documentation is used more effectively.

Although the research needs outlined are numerous, a major emphasis in this chapter is on systematic studies that include all four substantive variables—user and task characteristics, hardware, software, and documentation—and the interaction of these components with a clear-cut set of studies to define ease of use.

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