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.



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Research Needs for Human Factors 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.

OCR for page 95
Research Needs for Human Factors 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