The Effectiveness of Evidence

Despite the widespread use of materials of support in all kinds of public communication, there is much to be learned about the effects of evidence in persuasive communication. McCroskey's (1969) summary of experimental research gives us several generalizations about evidence as a message variable. First, a source perceived by the audience as having low or moderate credibility can increase his or her credibility by using good evidence and can also increase the amount of immediate attitude change in the audience. (On the other hand, a source who is initially perceived as having high credibility has little to gain from use of evidence in terms of immediate change.) Second, to have an effect oh immediate attitude change or on perceived source credibility the speaker's evidence must be new to members of the audience. And third, using good evidence seems to have long-term effects on attitude change whether the speaker was initially perceived as having low, moderate, or high credibility (this is the case regardless of the quality of his or her delivery). McCroskey points out the need for further, more imaginative research on how evidence functions within a persuasive argument. Among the research questions he suggests are (1) which types of evidence (statistics, quotations, and .so on) have the greatest effect on attitude change and (2) whether the use of evidence to persuade functions differently in different cultures.

Visual Aids

Without question, visual aids make presentations more vivid and interesting. Visual aids include objects and models, demonstrations, illustrations (i.e., artwork, photos, tables, charts, handouts), as well as audiovisuals (i.e., audiotape, videotape, film, and slide/tape combinations). With the increasing sophistication and availability of computers, presentations are becoming more, and more dramatic with computer-generated graphics. Figures 10.1 through 10.3 give a few examples. The effective use of visual aids includes the following considerations:

1. Prepare the aids well in advance and get used to using them.

2. Keep all aids simple (based on the audience analysis, e.g., what is "simple" for IBM employees may be difficult for sixth-grade students).

3. Be sure the aids can be seen, heard, etc.

4. When using aids that require special equipment, such as videorecorders, overhead projectors, slide projectors, film projectors, screens, etc., be sure the equipment is available, delivered on time and to the right place, that it works, and that you know how to work it.

5. Be sure the aids suit the situation with respect to the size of the room and its capabilities (e.g., a room with an echo is problematic, as is a room without the capacity to dim the lights), and audience expectations.

6. Be sure the aid enhances the speech or is an integral part of the speech.

7. Talk to your audience and not the visual aid.

The important message here is that a visual aid is audience and situation specific. This makes it clear why an audience analysis is necessary.

Language

From the beginning of this book we have stressed the difficulties inherent in trying to create a meaning in the mind of another human being. In two-person and small-group communication, for example, we are concerned that the conno­tations of the words used be similar for all the people participating in a given transaction. In broader terms, we are concerned with the use of shared rather than private meaning. These concerns are multiplied many times over in public communication, where a message is likely to be long and complex, feedback between sender and receiver is apt to be quite limited, and the number of receivers increases sharply. In the following pages we shall explore some questions of style—some ways in which the clarity, appeal, and persuasiveness of a message are affected by the speaker's use of language.

Vividness

According to Collins et al. (1988) vividness, in the context of communication, means concrete and colorful language (p. 1). Compare, for example, the vagueness of "A period of unfavorable weather set in" with the more pointed "It rained every day for a week."

Vigorous writing and speaking are often grounded in specifics. Thus the various methods of support are important not only from a logical but from a stylistic point of view. Sometimes a speaker must discuss a subject that is relatively abstract—for example, the responsibilities of a free press or the three-part division of government—but the presentation becomes more vigorous, more capable of sustaining audience attention, if it is also somewhat concrete. In 1972, speaking about the need for equal power and representation of women in political life, Bella Abzug, congresswoman from New York, made her point in very specific terms.

Just a few weeks ago I sat in Congress and heard the President give the State of the Union Address. There were more than seven hundred of us seated on the main floor of the House. You may have heard the President say, "Here we have assembled the Government of the United States, the members of the House, the Senate, the Supreme Court, the Cabinet."

I looked around and of these 700 leaders of Government there were just 12 women. Could anything be more disgraceful? Eleven women out of 435 members of the House. One woman out of 100 in the Senate. No women in the Cabinet. No women on the Supreme Court, although the President has had four separate opportunities to appoint one. (Abzug, in Braden 1972 p 41)

Date: 2015-02-16; view: 856