I had the recollection that Mercier & Sperber would have cited evidence for humans being good at making decisions in group, and looked it up. Apparently their interpretation is that group meetings are bad in those cases where everyone feels like they need to express an opinion, even when there’s no need for one. Another difference is that they discuss decision-making in situations in which an objective correct answer exists (so that everyone can verify it once it has been proposed), which is probably not the case for most business decisions.
If people are skilled at both producing and evaluating arguments, and if these skills are displayed most easily in argumentative settings, then debates should be especially conducive to good reasoning performance. Many types of tasks have been studied in group settings, with very mixed results (for recent reviews, see Kerr & Tindale 2004; Kerr et al. 1996). The most relevant findings here are those pertaining to logical or, more generally, intellective tasks “for which there exists a demonstrably correct answer within a verbal or mathematical conceptual system” (Laughlin & Ellis 1986, p. 177). In experiments involving this kind of task, participants in the experimental condition typically begin by solving problems individually (pretest), then solve the same problems in groups of four or five members (test), and then solve them individually again (posttest), to ensure that any improvement does not come simply from following other group members. Their performance is compared with those of a control group of participants who take the same tests but always individually. Intellective tasks allow for a direct comparison with results from the individual reasoning literature, and the results are unambiguous. The dominant scheme (Davis 1973) is truth wins, meaning that, as soon as one participant has understood the problem, she will be able to convince the whole group that her solution is correct (Bonner et al. 2002; Laughlin & Ellis 1986; Stasson et al. 1991). This can lead to big improvements in performance. Some experiments using the Wason selection task dramatically illustrate this phenomenon (Moshman & Geil 1998; see also Augustinova 2008; Maciejovsky & Budescu 2007). The Wason selection task is the most widely used task in reasoning, and the performance of participants is generally very poor, hovering around 10% of correct answers (Evans 1989; Evans et al. 1993; Johnson-Laird & Wason 1970). However, when participants had to solve the task in groups, they reached the level of 80% of correct answers.
Several challenges can be leveled against this interpretation of the data. It could be suggested that the person who has the correct solution simply points it out to the others, who immediately accept it without argument, perhaps because they have recognized this person as the “smartest” (Oaksford et al. 1999). The transcripts of the experiments show that this is not the case: Most participants are willing to change their mind only once they have been thoroughly convinced that their initial answer was wrong (e.g., see Moshman & Geil 1998; Trognon 1993). More generally, many experiments have shown that debates are essential to any improvement of performance in group settings (for a review and some new data, see Schulz-Hardt et al. 2006; for similar evidence in the development and education literature, see Mercier, in press b). Moreover, in these contexts, participants decide that someone is smart based on the strength and relevance of her arguments and not the other way around (Littlepage & Mueller 1997). Indeed, it would be very hard to tell who is “smart” in such groups – even if general intelligence were easily perceptible, it correlates only .33 with success in the Wason selection task (Stanovich & West 1998). Finally, in many cases, no single participant had the correct answer to begin with. Several participants may be partly wrong and partly right, but the group will collectively be able to retain only the correct parts and thus converge on the right answer. This leads to the assembly bonus effect, in which the performance of the group is better than that of its best member (Blinder & Morgan 2000; Laughlin et al. 2002; 2003; 2006; Lombardelli et al. 2005; Michaelsen et al. 1989; Sniezek & Henry 1989; Stasson et al. 1991; Tindale & Sheffey 2002). Once again there is a striking convergence here, with the developmental literature showing how groups – even when no member had the correct answer initially – can facilitate learning and comprehension of a wide variety of problems (Mercier, in press b).
According to another counterargument, people are simply more motivated, generally, when they are in groups (Oaksford et al. 1999). This is not so. On the contrary, “the ubiquitous finding across many decades of research (e.g., see Hill 1982; Steiner 1972) is that groups usually fall short of reasonable potential productivity baselines” (Kerr & Tindale 2004, p. 625). Moreover, other types of motivation have no such beneficial effect on reasoning. By and large, monetary incentives, even substantial ones, fail to improve performance in reasoning and decision-making tasks (Ariely et al., 2009; Bonner & Sprinkle 2002; Bonner et al. 2000; Camerer & Hogarth 1999; and, in the specific case of the Wason selection task, see Johnson-Laird & Byrne 2002; Jones & Sugden, 2001). Thus, not any incentive will do: Group settings have a motivational power to which reasoning responds specifically.
The argumentative theory also helps predict what will happen in nonoptimal group settings. If all group members share an opinion, a debate should not arise spontaneously. However, in many experimental and institutional settings (juries, committees), people are forced to discuss, even if they already agree. When all group members agree on a certain view, each of them can find arguments in its favor. These arguments will not be critically examined, let alone refuted, thus providing other group members with additional reasons to hold that view. The result should be a strengthening of the opinions held by the group (for a review, see Sunstein 2002; for a recent illustration, see Hinsz et al. 2008). Contra Sunstein’s law of group polarization, it is important to bear in mind that this result is specific to artificial contexts in which people debate even though they tend to agree in the first place. When group members disagree, discussions often lead to depolarization (Kogan & Wallach 1966; Vinokur & Burnstein 1978). In both cases, the behavior of the group can be predicted on the basis of the direction and strength of the arguments accessible to group members, as demonstrated by research carried out in the framework of the Persuasive Argument Theory (Vinokur 1971), which ties up with the prediction of the present framework (Ebbesen & Bowers 1974; Isenberg 1986; Kaplan & Miller 1977; Madsen 1978).
I had the recollection that Mercier & Sperber would have cited evidence for humans being good at making decisions in group, and looked it up. Apparently their interpretation is that group meetings are bad in those cases where everyone feels like they need to express an opinion, even when there’s no need for one. Another difference is that they discuss decision-making in situations in which an objective correct answer exists (so that everyone can verify it once it has been proposed), which is probably not the case for most business decisions.