Persuasive Communication - How Audiences Decide. 2nd Edition

Audience Decision-Making Expertise 29

The Causes of Groups of Experts’ Normally Inferior Performance

One might expect groups of experts to outperform individual experts and to match the perfor-

mance of linear models. After all, a crowd’s average answer to a factual question is typically more

accurate than an individual’s answer, given that the average of many different answers cancels out

the errors of individual answers.^261 So it’s a surprise to learn that groups usually make decisions that

are inferior to those made by their most expert members and may perform considerably worse than

even their average members on some tasks.^262

Majorities/pluralities, not the most knowledgeable members, “win” most of the time.^263

Majority/plurality rule has been observed in a variety of group-level audience decisions, includ-

ing decisions made by mock juries,^264 groups of investors,^265 groups of voters,^266 budgetary

committees,^267 and teams of recruiters.^268 Even when they know the right answers to factual

questions, minority members tend to succumb to majority pressure and act against their better

judgment.^269

Majority/plurality rule is particularly prevalent when a group does not share a schema for

making the decision they need to make.^270 Thus, it may not enhance group performance if

a minority of group members has the expertise needed to make a good decision since many

group members may neither appreciate their expertise or use it. Without a shared schema, the

majority of group members may assume the most confi dent and verbose among them is the

most expert,^271 although these traits rarely correlate with accuracy.^272

The Importance of Expert Audiences Despite Their Limitations

While acknowledging the limitations of experts to weight decision criteria appropriately and their

deviations from normative decision-making processes, professionals must still understand experts

and be able to convince them.

Expert audiences have the fi nal say in most decisions and are not likely be replaced altogether

by linear models any time soon. The judgments of expert audiences are perceived as fairer than the

judgments of linear models.^273 Expert audiences are still indispensable for selecting, weighting, and

measuring the criteria that go into linear models^274 and for discovering new decision criteria.^275 In

addition, expert audiences have the ability to recognize rare but highly diagnostic cues that may not

TABLE 1.2 The Decision Performance of Experts Depends on Their Domain

Better Performance

Domains Concerning Things

Poorer Performance

Domains Concerning People

Weather forecasting Clinical psychology

Astronomy Astrology

Aeronautics Student admissions

Agriculture Law

Chess Behavioral research

Physics Counseling

Mathematics Human resources

Accounting Parole granting

Actuarial statistics Stock market investing

Source: Adapted from Shanteau (1992)