Standpoint explicitness and persuasive effect: a meta-analytic review of the effects of varying conclusion articulation in persuasive messages.

• Author: O'Keefe, Daniel J.

Argumentative explicitness is widely acknowledged as a normative ideal in the practice of argument. Advocates might resist such explicitness, though, fearing that it will compromise persuasive effectiveness. But it is an empirical question whether argumentative explicitness inevitably sacrifices instrumental success. This article addresses one facet of this question, by offering a meta-analytic review of the persuasive effects associated with the degree of articulation given to the advocate's overall conclusion.

BACKGROUND

Explicitness as a Normative Procedural Obligation

Addressing the empirical relationship between normatively good argument and persuasive outcomes requires some independently-motivated normative account (O'Keefe & Jackson, 1995). Among various ways of conceiving of the normative worth of arguments, the idea of focussing on advocates' conduct (rather than some disembodied abstract representation of argument) has attracted recent attention. For example, the pragma-dialectical approach (van Eemeren & Grootendorst, 1984) identifies rules of conduct appropriate for (different stages of) argumentative discussions. From this perspective, normative standards for argument consist of procedural obligations for advocates. Thus normatively good argumentation will be understood not as a matter of (e.g.) true premises and valid form, but as a matter of argumentative practice that satisfies specified procedural standards.

Obviously, developing a full-fledged description and defense of a set of procedural obligations for normatively good argumentation is a substantial undertaking. However, even without a finished analysis of all the procedural obligations associated with normatively good argumentation, one might nevertheless say with some confidence that one normative good in the conduct of advocates is (in some way or other) argumentative explicitness. That is, it is normatively desirable for advocates to explicitly state their viewpoints, without concealing relevant aspects of their views or reasoning. "Evasion, concealment, and artful dodging. . . are and should be excluded from an ideal model of critical discussion" (van Eemeren, Grootendorst, Jackson, & Jacobs, 1993, p. 173). Argumentation that is more explicit is better (normatively speaking) than argumentation that is less explicit, precisely because greater explicitness opens the advocated view for critical scrutiny.

Understood as a procedural obligation, explicitness in argumentation naturally takes a diversity of concrete instantiating forms. That is to say, a normative directive to "be explicit" can naturally be realized in different ways. The focus of the present report is the explicitness of the message's overall advocated position (that is, the degree of articulation of the message's overall conclusion, recommendation, standpoint).(1)

Explicitness as Threatening Persuasive Effectiveness

Advocates might understandably fear that standpoint explicitness can threaten persuasive effectiveness. Such fears have warrant. Most generally, explicitness enlarges the "disagreement space," in the sense that it puts more claims on the table for discussion - claims to which objections might be raised (for discussion of the idea of disagreement space, see van Eemeren et al., 1993, esp. pp. 95-96;Jackson &Jacobs, 1980). Each further articulation of an advocate's viewpoint invites closer scrutiny, counterargument, objection, rejection. Failing to be fully explicit might minimize the space for disagreement and thereby enhance persuasion.

Advocates might also fear that explicitness could produce "boomerang" persuasive effects (in which the audience changes in ways opposite to those sought by the advocate). Being too explicit might insult the audience (because the message would state the obvious) or anger it (because the message would seem too aggressive, too insistent, too directive), and perhaps induce reactance, a motivational state aimed at reestablishing threatened freedom of action (Brehm & Brehm, 1981).

Even if explicitness does not backfire, an advocate might think that less-explicit messages could be more persuasive because they invite the audience's active participation (in enthymematic persuasion). If message receivers have to "fill in the blanks" to complete the message's reasoning process, the act of spelling out the message's conclusion might lead them to be more persuaded than if the conclusion had been explicitly provided by the advocate.

Given such fears, an advocate might well decide to be less-than-fully explicit in articulating his or her overall conclusion. Broadly, there are two main ways in which advocates can be inexplicit about their overall standpoint. The first is simply to omit a statement of one's overall conclusion; that is, although the message contains appropriate materials to support the advocate's overall position, the message nevertheless leaves that conclusion unstated. The second is to state the overall conclusion, but to do so in a global (general, nonspecific) way; for instance, the advocate might identify the desired action, but describe it in a general rather than specific fashion.

These two means correspond to two distinct lines of empirical research examining the persuasive effects of variation in conclusion articulation. In one line (labelled here studies of "conclusion omission"), investigators have compared messages with or without a statement of the advocate's overall conclusion. That is, what is compared are messages containing some explicit statement of the advocate's overall point with messages in which the conclusion is omitted (not explicitly stated). For example, Struckman-Johnson and Struckman-Johnson (1996) compared AIDS public service announcements with and without an explicit recommendation to use condoms.

The other body of studies concerns the degree of specificity of the description of the advocated action (here termed studies of "conclusion specificity"). The comparison contrasts messages that provide only a general description of the advocate's recommended action with messages that provide a more specific (detailed) recommendation; that is, both messages contain an explicitlystated conclusion (in the form of an explicitly-identified desired action), but one conclusion is more detailed. For example, Evans, Rozelle, Lasater, Dembroski, and Allen (1970) compared messages giving relatively general and unelaborated dental-care recommendations with messages giving more detailed, specific recommendations.

Taken together, these two bodies of research speak to the broad question of the persuasive effects of variations in argumentative conclusion explicitness. But each is also of interest in its own right as an examination of a factor potentially influencing advocacy outcomes. The two message variations are distinguishable (though related), and might have distinctive effects, with distinctive explanations, moderators, and so on. Thus it will be useful to consider previous discussions of these two variations.

Prior Discussions of Conclusion Articulation Effects

Conclusion omission. Many summary discussions of the persuasion effects research literature include some treatment of studies of the effects of including or omitting message conclusions (e.g., Burgoon, 1989; Cohen, 1964; McGuire, 1985; O'Keefe, 1990; Perloff, 1993; Petty & Cacioppo, 1981; Reardon, 1981). These discussions commonly suggest that the relative effectiveness of stating and omitting conclusions varies as a function of other (moderator) variables. The most frequently mentioned possible moderating factors involve the hearer's ability and willingness to draw the appropriate conclusion when left unstated; hence variables such as the receiver's intelligence (which bears on ability) and initial opinion (which bears on willingness) are often mentioned as possible moderators (see, e.g., Burgoon, 1989, pp. 144-145; Cohen, 1964, pp. 6-8; McGuire, 1985, pp. 271-272; O'Keefe, 1990, pp. 159-161; Perloff, 1993, pp. 169-170; Petty & Cacioppo, 1981, p. 76; Reardon, 1981, p. 142). The general expectation is that explicit conclusions may not be necessary to, and might even impair, persuasive success for intellectually more capable audiences and for audiences initially favorable to the advocated view (since such audiences should be able and willing to reason to the advocated conclusion). However, these discussions commonly consider only a small portion of the relevant literature; typically, two or three studies are mentioned, even though (as will be seen) many more relevant investigations exist.

Conclusion specificity. Surprisingly, conventional summary descriptions of the persuasion effects literature do not discuss research concerning the effects of a message's providing a detailed, specific (as opposed to general) description of the recommended action. The summaries mentioned above, for instance, do not address this subject.(2)

Indeed, studies of this message variation evince little recognition of related work. For example, among the relevant studies (as listed in Table 2), Mann and Hill (1984) cite Geller (1973) and Geller, Witmer, and Orebaugh (1976), but no other relevant papers; Stout and Sego (1994a) cite Leventhal, Singer, and Jones (1965), but no other relevant paper; no paper cites either Piccolino (1966) or Wright (1979); Frantz (1994) cites none of the others. In short, even to investigators studying the effects of variations in recommendation specificity, this body of research has been largely invisible. Not surprisingly, then, this research has never before been systematically reviewed.

Because these studies have not previously been collected or reviewed, there is no developed analysis of how this message variation might influence persuasive effects. That is, this is a largely untheorized domain. But it is easy to see how greater specificity might reduce persuasive effectiveness through the same mechanisms as could influence...