# 10.4: Group Decision Making

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Learning Objectives

1. Explain factors that can lead to process gain in group versus individual decision making.
2. Explain how groupthink can harm effective group decision making.
3. Outline the ways that lack of information sharing can reduced decision-making quality in group contexts.
4. Explain why brainstorming can often be counterproductive to sound decision making in groups.
5. Describe how group polarization can lead groups to make more extreme decisions than individuals.
6. Explore important factors that lead juries to make better or worse decisions.

In the previous section, we explored some of the important ways that being in a group affects individual group members’ behavior, and, in turn, influences the group’s overall performance. As well as achieving high levels of performance, another important task of groups is to make decisions. Indeed, we often entrust groups, rather than individuals, with key decisions in our societies—for example, those made by juries and political parties. An important question to ask here is whether we are right to trust groups more than individuals to reach sound decisions. Are many heads really better than one?

It turns out that this question can be a hard one to answer. For one thing, studying decision making is hard, because it is difficult to assess the quality of a decision on the basis of what was known at the time, independently of its outcome. This is particularly challenging as we naturally tend to look too much at the outcome when we evaluate decision making, a phenomenon known as the outcome bias. Moreover, studying decision making in laboratory environments has generally involved providing group members with more information than they would typically have in the real world (Johnson & Johnson, 2012), and so the results may not always generalize here.

Nevertheless, with these caveats in mind, it is possible to draw some tentative conclusions about when and why groups make better decisions than individuals, and also when and why they may end up making worse ones.

## Process Gains in Group versus Individual Decision Making

One important factor that helps groups to outperform individuals on decision-making tasks is the type of interdependence they have. In general, positively interdependent (cooperative) groups tend to make better decisions than both negatively interdependent (competitive) groups and individuals, particularly in complex tasks (Johnson & Johnson, 2012). These process gains come from a variety of factors. One is that when group members interact, they often generate new ideas and solutions that they would not have arrived at individually (Watson, 1931). Group members are also more likely than individuals to notice and correct mistakes that can harm sound decision making (Ziller, 1957). They additionally have better collective memory, meaning that many minds hold more relevant information than one, and superior transactive memory, which occurs when interactions between group members facilitate the recall of important material (Forsyth, 2010). Also, when individual group members share information that is unique to them, they increase the total amount of data that the group can then draw on when making sound decisions (Johnson & Johnson, 2012). Given these obvious advantages, are there ever times when groups might make less optimal decisions than individuals? If you have ever sat in a group where, with hindsight, a fairly foolhardy decision was reached, then you probably already have your own answer to that question. The more interesting question then becomes why are many heads sometimes worse than one? Let’s explore some of the most dramatic reasons.

## Process Losses Due to Group Conformity Pressures - Groupthink

Groups can make effective decisions only when they are able to make use of the advantages outlined above that come with group membership. However, these conditions are not always met in real groups. As we saw in the chapter opener, one example of a group process that can lead to very poor group decisions is groupthink.

Groupthink occurs when a group that is made up of members who may actually be very competent and thus quite capable of making excellent decisions nevertheless ends up making a poor one as a result of a flawed group process and strong conformity pressures (Baron, 2005; Janis, 2007).

Groupthink is more likely to occur in groups in which the members are feeling strong social identity—for instance, when there is a powerful and directive leader who creates a positive group feeling, and in times of stress and crisis when the group needs to rise to the occasion and make an important decision. The problem is that groups suffering from groupthink become unwilling to seek out or discuss discrepant or unsettling information about the topic at hand, and the group members do not express contradictory opinions. Because the group members are afraid to express ideas that contradict those of the leader or to bring in outsiders who have other information, the group is prevented from making a fully informed decision. Figure 10.3.1, “Antecedents and Outcomes of Groupthink,” summarizes the basic causes and outcomes of groupthink.

Figure 10.3.1 Antecedents and Outcomes of Groupthink

Although at least some scholars are skeptical of the importance of groupthink in real group decisions (Kramer, 1998), many others have suggested that groupthink was involved in a number of well-known and important, but very poor, decisions made by government and business groups. Key historical decisions analyzed in terms of groupthink include the decision to invade Iraq made by President George Bush and his advisors, with the support of other national governments, including those from the United Kingdom, Spain, Italy, South Korea, Japan, Singapore, and Australia; the decision of President John F. Kennedy and his advisors to commit U.S. forces to help with an invasion of Cuba, with the goal of overthrowing Fidel Castro in 1962; and the policy of appeasement of Nazi Germany pursued by many European leaders in 1930s, in the lead-up to World War II. Groupthink has also been applied to some less well-known, but also important, domains of decision making, including pack journalism (Matusitz, & Breen, 2012). Intriguingly, groupthink has even been used to try to account for perceived anti-right-wing political biases of social psychologists (Redding, 2012).

Careful analyses of the decision-making process in the historical cases outlined above have documented the role of conformity pressures. In fact, the group process often seems to be arranged to maximize the amount of conformity rather than to foster free and open discussion. In the meetings of the Bay of Pigs advisory committee, for instance, President Kennedy sometimes demanded that the group members give a voice vote regarding their individual opinions before the group actually discussed the pros and cons of a new idea. The result of these conformity pressures is a general unwillingness to express ideas that do not match the group norm.

The pressures for conformity also lead to the situation in which only a few of the group members are actually involved in conversation, whereas the others do not express any opinions. Because little or no dissent is expressed in the group, the group members come to believe that they are in complete agreement. In some cases, the leader may even select individuals (known as mindguards) whose job it is to help quash dissent and to increase conformity to the leader’s opinions.

An outcome of the high levels of conformity found in these groups is that the group begins to see itself as extremely valuable and important, highly capable of making high-quality decisions, and invulnerable. In short, the group members develop extremely high levels of conformity and social identity. Although this social identity may have some positive outcomes in terms of a commitment to work toward group goals (and it certainly makes the group members feel good about themselves), it also tends to result in illusions of invulnerability, leading the group members to feel that they are superior and that they do not need to seek outside information. Such a situation is often conducive to poor decision making, which can result in tragic consequences.

Interestingly, the composition of the group itself can affect the likelihood of groupthink occurring. More diverse groups, for instance, can help to ensure that a wider range of views are available to the group in making their decision, which can reduce the risk of groupthink. Thinking back to our case study, the more homogeneous the group are in terms of internal characteristics such as beliefs, and external characteristics such as gender, the more at risk of groupthink they may become (Kroon, Van Kreveld, & Rabbie, 1992). Perhaps, then, mixed gender corporate boards are more successful partly because they are better able to avoid the dangerous phenomenon of groupthink.

## Cognitive Process Losses - Lack of Information Sharing

Although group discussion generally improves the quality of a group’s decisions, this will only be true if the group discusses the information that is most useful to the decision that needs to be made. One difficulty is that groups tend to discuss some types of information more than others. In addition to the pressures to focus on information that comes from leaders and that is consistent with group norms, discussion is influenced by the way the relevant information is originally shared among the group members. The problem is that group members tend to discuss information that they all have access to while ignoring equally important information that is available to only a few of the members, a tendency known as the shared information bias (Faulmüller, Kerschreiter, Mojzisch, & Schulz-Hardt, 2010; Reimer, Reimer, & Czienskowski (2010).

## Research Focus

Poor Information Sharing in Groups

In one demonstration of the shared information bias, Stasser and Titus (1985) used an experimental design based on the hidden profile task, as shown in Table 10.1. Students read descriptions of two candidates for a hypothetical student body presidential election and then met in groups to discuss and pick the best candidate. The information about the candidates was arranged so that one of the candidates (Candidate A) had more positive qualities overall in comparison with the other (Candidate B). Reflecting this superiority, in groups in which all the members were given all the information about both candidates, the members chose Candidate A 83% of the time after their discussion.

Table 10.3.1 Hidden Profiles

Group member Information favoring Candidate A Information favoring Candidate B
X a1, a2 b1, b2, b3
Y a1, a3 b1, b2, b3
Z a1, a4 b1, b2, b3
This is an example of the type of “hidden profile” that was used by Stasser and Titus (1985) to study information sharing in group discussion. Stasser, G., & Titus, W. (1985). Pooling of unshared information in group decision making: Biased information sampling during discussion. Journal of Personality and Social Psychology, 48(6), 1467–1478. (The researchers’ profiles were actually somewhat more complicated.) The three pieces of favorable information about Candidate B (b1, b2, and b3) were seen by all of the group members, but the favorable information about Candidate A (a1, a2, a3, and a4) was not given to everyone. Because the group members did not share the information about Candidate A, Candidate B was erroneously seen as a better choice.

However, in some cases, the experimenters made the task more difficult by creating a “hidden profile,” in which each member of the group received only part of the information. In these cases, although all the information was potentially available to the group, it was necessary that it be properly shared to make the correct choice. Specifically, in this case, in which the information favoring Candidate B was shared, but the information favoring Candidate A was not, only 18% of the groups chose A, whereas the others chose the inferior candidate. This occurred because although the group members had access to all the positive information collectively, the information that was not originally shared among all the group members was never discussed. Furthermore, this bias occurred even in participants who were given explicit instructions to be sure to avoid expressing their initial preferences and to review all the available facts (Stasser, Taylor, & Hanna, 1989).

Although the tendency to share information poorly seems to occur quite frequently, at least in experimentally created groups, it does not occur equally under all conditions. For one, groups have been found to better share information when the group members believe that there is a correct answer that can be found if there is sufficient discussion (Stasser & Stewart, 1992), and if they are forced to continue their discussion even after they believe that they have discussed all the relevant information (Larson, Foster-Fishman, & Keys, 1994). These findings suggest that an important job of the group leader is to continue group discussion until he or she is convinced that all the relevant information has been addressed.

The structure of the group will also influence information sharing (Stasser & Taylor, 1991). Groups in which the members are more physically separated and thus have difficulty communicating with each other may find that they need to reorganize themselves to improve communication. And the status of the group members can also be important. Group members with lower status may have less confidence and thus be unlikely to express their opinions. Wittenbaum (1998) found that group members with higher status were more likely to share new information. However, those with higher status may sometimes dominate the discussion, even if the information that they have is not more valid or important (Hinsz, 1990). Groups are also likely to share unique information when the group members do not initially know the alternatives that need to be determined or the preferences of the other group members (Mojzisch & Schulz-Hardt, 2010; Reimer, Reimer, & Hinsz, 2010).

Findings showing that groups neither share nor discuss originally unshared information have very disconcerting implications for group decision making because they suggest that group discussion is likely to lead to very poor judgments. Not only is unshared information not brought to the table, but because the shared information is discussed repeatedly, it is likely to be seen as more valid and to have a greater influence on decisions as a result of its high cognitive accessibility. It is not uncommon that individuals within a working group come to the discussion with different types of information, and this unshared information needs to be presented. For instance, in a meeting of a design team for a new building, the architects, the engineers, and the customer representatives will have different and potentially incompatible information. Thus leaders of working groups must be aware of this problem and work hard to foster open climates that encourages information sharing and discussion.

Given its obvious pitfalls, an interesting question to ask is why the shared information bias seems to be so pervasive. Recalling the confirmation bias that we discussed in the chapter on social cognition, perhaps it reflects this tendency played out at the group level, where group members collaborate to provide confirmatory evidence for each other’s positions. Leading on from this, it could also reflect the tendency for people to wish to use groups to reinforce their own views. Perhaps sometimes groups become places where people seek to mutually validate each other’s shared perspectives, to the detriment of them searching out the alternatives. If these ideas are correct, given that we often choose to associate with similar others, then it may be important to seek out the views of group members that are likely to be most different from our own, in seeking to weaken the damaging effects of the shared information bias (Morrow & Deidan, 1992).

## Cognitive Process Losses - Ineffective Brainstorming

One technique that is frequently used to produce creative decisions in working groups is known as brainstorming. The technique was first developed by Osborn (1953) in an attempt to increase the effectiveness of group sessions at his advertising agency. Osborn had the idea that people might be able to effectively use their brains to “storm” a problem by sharing ideas with each other in groups. Osborn felt that creative solutions would be increased when the group members generated a lot of ideas and when judgments about the quality of those ideas were initially deferred and only later evaluated. Thus brainstorming was based on the following rules:

• Each group member was to create as many ideas as possible, no matter how silly, unimportant, or unworkable they were thought to be.
• As many ideas as possible were to be generated by the group.
• No one was allowed to offer opinions about the quality of an idea (even one’s own).
• The group members were encouraged and expected to modify and expand upon other’s ideas.

Researchers have devoted considerable effort to testing the effectiveness of brainstorming, and yet, despite the creativeness of the idea itself, there is very little evidence to suggest that it works (Diehl & Stroebe, 1987, 1991; Stroebe & Diehl, 1994). In fact, virtually all individual studies, as well as meta-analyses of those studies, find that regardless of the exact instructions given to a group, brainstorming groups do not generate as many ideas as one would expect, and the ideas that they do generate are usually of lesser quality than those generated by an equal number of individuals working alone who then share their results. Thus brainstorming represents still another example of a case in which, despite the expectation of a process gain by the group, a process loss is instead observed.

A number of explanations have been proposed for the failure of brainstorming to be effective, and many of these have been found to be important. One obvious problem is social loafing by the group members, and at least some research suggests that this does cause part of the problem. For instance, Paulus and Dzindolet (1993) found that social loafing in brainstorming groups occurred in part because individuals perceived that the other group members were not working very hard, and they matched they own behavior to this perceived norm. To test the role of social loafing more directly, Diehl and Stroebe (1987) compared face-to-face brainstorming groups with equal numbers of individuals who worked alone; they found that face-to-face brainstorming groups generated fewer and less creative solutions than did an equal number of equivalent individuals working by themselves. However, for some of the face-to-face groups, the researchers set up a television camera to record the contributions of each of the participants in order to make individual contributions to the discussion identifiable. Being identifiable reduced social loafing and increased the productivity of the individuals in the face-to-face groups; but the face-to-face groups still did not perform as well as the individuals.

Even though individuals in brainstorming groups are told that no evaluation of the quality of the ideas is to be made, and thus that all ideas are good ones, individuals might nevertheless be unwilling to state some of their ideas in brainstorming groups because they are afraid that they will be negatively evaluated by the other group members. When individuals are told that other group members are more knowledgeable than they are, they reduce their own contributions (Collaros & Anderson, 1969), and when they are convinced that they themselves are experts, their contributions increase (Diehl & Stroebe, 1987).

Although social loafing and evaluation apprehension seem to cause some of the problem, the most important difficulty that reduces the effectiveness of brainstorming in face-to-face groups is that being with others in a group hinders opportunities for idea production and expression. In a group, only one person can speak at a time, and this can cause people to forget their ideas because they are listening to others, or to miss what others are saying because they are thinking of their own ideas, a problem known as production blocking. Considered another way, production blocking occurs because although individuals working alone can spend the entire available time generating ideas, participants in face-to-face groups must perform other tasks as well, and this reduces their creativity.

Diehl and Stroebe (1987) demonstrated the importance of production blocking in another experiment that compared individuals with groups. In this experiment, rather than changing things in the real group, they created production blocking in the individual conditions through a turn-taking procedure, such that the individuals, who were working in individual cubicles, had to express their ideas verbally into a microphone, but they were only able to speak when none of the other individuals was speaking. Having to coordinate in this way decreased the performance of individuals such that they were no longer better than the face-to-face groups.

Follow-up research (Diehl & Stroebe, 1991) showed that the main factor responsible for productivity loss in face-to-face brainstorming groups is that the group members are not able to make good use of the time they are forced to spend waiting for others. While they are waiting, they tend to forget their ideas because they must concentrate on negotiating when it is going to be their turn to speak. In fact, even when the researchers gave the face-to-face groups extra time to perform the task (to make up for having to wait for others), they still did not reach the level of productivity of the individuals. Thus the necessity of monitoring the behavior of others and the delay that is involved in waiting to be able to express one’s ideas reduce the ability to think creatively (Gallupe, Cooper, Grise, & Bastianutti, 1994).

Although brainstorming is a classic example of a group process loss, there are ways to make it more effective. One variation on the brainstorming idea is known as the nominal group technique (Delbecq, Van de Ven, & Gustafson, 1975). The nominal group technique capitalizes on the use of individual sessions to generate initial ideas, followed by face-to-face group meetings to discuss and build on them. In this approach, participants first work alone to generate and write down their ideas before the group discussion starts, and the group then records the ideas that are generated. In addition, a round-robin procedure is used to make sure that each individual has a chance to communicate his or her ideas. Other similar approaches include the Delphi technique (Clayton, 1997; Hornsby, Smith, & Gupta, 1994) and Synectics (Stein, 1978).

Contemporary advances in technology have created the ability for individuals to work together on creativity tasks via computer. These computer systems, generally known as group support systems, are used in many businesses and other organizations. One use involves brainstorming on creativity tasks. Each individual in the group works at his or her own computer on the problem. As he or she writes suggestions or ideas, they are passed to the other group members via the computer network, so that each individual can see the suggestions of all the group members, including their own.

A number of research programs have found that electronic brainstorming is more effective than face-to-face brainstorming (Dennis & Valacich, 1993; Gallupe, Cooper, Grise, & Bastianutti, 1994; Siau, 1995), in large part because it reduces the production blocking that occurs in face-to-face groups. Groups that work together virtually rather than face-to-face have also been found to be more likely to share unique information (Mesmer-Magnus, DeChurch, Jimenez-Rodriguez, Wildman, & Schuffler, 2011). Each individual has the comments of all the other group members handy and can read them when it is convenient. The individual can alternate between reading the comments of others and writing his or her own comments and therefore is not required to wait to express his or her ideas. In addition, electronic brainstorming can be effective because it reduces evaluation apprehension, particularly when the participants’ contributions are anonymous (Connolly, Routhieaux, & Schneider, 1993; Valacich, Jessup, Dennis, & Nunamaker, 1992).

In summary, the most important conclusion to be drawn from the literature on brainstorming is that the technique is less effective than expected because group members are required to do other things in addition to being creative. However, this does not necessarily mean that brainstorming is not useful overall, and modifications of the original brainstorming procedures have been found to be quite effective in producing creative thinking in groups. Techniques that make use of initial individual thought, which is later followed by group discussion, represent the best approaches to brainstorming and group creativity. When you are in a group that needs to make a decision, you can make use of this knowledge. Ask the group members to spend some time thinking about and writing down their own ideas before the group begins its discussion.

## Group Polarization

One common decision-making task of groups is to come to a consensus regarding a judgment, such as where to hold a party, whether a defendant is innocent or guilty, or how much money a corporation should invest in a new product. Whenever a majority of members in the group favors a given opinion, even if that majority is very slim, the group is likely to end up adopting that majority opinion. Of course, such a result would be expected, since, as a result of conformity pressures, the group’s final judgment should reflect the average of group members’ initial opinions.

Although groups generally do show pressures toward conformity, the tendency to side with the majority after group discussion turns out to be even stronger than this. It is commonly found that groups make even more extreme decisions, in the direction of the existing norm, than we would predict they would, given the initial opinions of the group members. Group polarization is said to occur when, after discussion, the attitudes held by the individual group members become more extreme than they were before the group began discussing the topic (Brauer, Judd, & Gliner, 2006; Myers, 1982). This may seem surprising, given the widespread belief that groups tend to push people toward consensus and the middle-ground in decision making. Actually, they may often lead to more extreme decisions being made than those that individuals would have taken on their own.

Group polarization was initially observed using problems in which the group members had to indicate how an individual should choose between a risky, but very positive, outcome and a certain, but less desirable, outcome (Stoner, 1968). Consider the following question:

Frederica has a secure job with a large bank. Her salary is adequate but unlikely to increase. However, Frederica has been offered a job with a relatively unknown startup company in which the likelihood of failure is high and in which the salary is dependent upon the success of the company. What is the minimum probability of the startup company’s success that you would find acceptable to make it worthwhile for Frederica to take the job? (choose one)

1 in 10, 3 in 10, 5 in 10, 7 in 10, 9 in 10

Research has found group polarization on these types of decisions, such that the group recommendation is more risky (in this case, requiring a lower probability of success of the new company) than the average of the individual group members’ initial opinions. In these cases, the polarization can be explained partly in terms of diffusion of responsibility (Kogan & Wallach, 1967). Because the group as a whole is taking responsibility for the decision, the individual may be willing to take a more extreme stand, since he or she can share the blame with other group members if the risky decision does not work out.

But group polarization is not limited to decisions that involve risk. For instance, in an experiment by Myers and Kaplan (1976), groups of students were asked to assess the guilt or innocence of defendants in traffic cases. The researchers also manipulated the strength of the evidence against the defendant, such that in some groups the evidence was strong and in other groups the evidence was weak. This resulted in two groups of juries—some in which the majority of the students initially favored conviction (on the basis of the strong evidence) and others in which a majority initially favored acquittal (on the basis of only weak evidence). The researchers asked the individuals to express their opinions about the guilt of the defendant both before and after the jury deliberated.

As you can see in Figure 10.3.2, “Group Polarization,” the opinions that the individuals held about the guilt or innocence of the defendants were found to be more extreme after discussion than they were, on average, before the discussion began. That is, members of juries in which the majority of the individuals initially favored conviction became more likely to believe the defendant was guilty after the discussion, and members of juries in which the majority of the individuals initially favored acquittal became more likely to believe the defendant was innocent after the discussion. Similarly, Myers and Bishop (1970) found that groups of college students who had initially racist attitudes became more racist after group discussion, whereas groups of college students who had initially antiracist attitudes became less racist after group discussion. Similar findings have been found for groups discussing a very wide variety of topics and across many different cultures.

Figure 10.3.2 Group Polarization

The juries in this research were given either strong or weak evidence about the guilt of a defendant and then were either allowed or not allowed to discuss the evidence before making a final decision. Demonstrating group polarization, the juries that discussed the case made significantly more extreme decisions than did the juries that did not discuss the case. Data are from Myers and Kaplan (1976).

Group polarization does not occur in all groups and in all settings but tends to happen most often when two conditions are present: First, the group members must have an initial leaning toward a given opinion or decision. If the group members generally support liberal policies, their opinions are likely to become even more liberal after discussion. But if the group is made up equally of both liberals and conservatives, group polarization would not be expected. Second, group polarization is strengthened by discussion of the topic. For instance, in the research by Myers and Kaplan (1976) just reported, in some experimental conditions, the group members expressed their opinions but did not discuss the issue, and these groups showed less polarization than groups that discussed the issue.

Group polarization has also been observed in important real-world contexts, including financial decision making in corporate boardrooms (Cheng & Chiou, 2008; Zhu, 2010). It has also been argued that the recent polarization in political attitudes in many countries, for example in the United States between the “blue” Democratic states versus the “red” Republican states, is occurring in large part because each group spends time communicating with other like-minded group members, leading to more extreme opinions on each side. And some have argued that terrorist groups develop their extreme positions and engage in violent behaviors as a result of the group polarization that occurs in their everyday interactions (Drummond, 2002; McCauley, 1989). As the group members, all of whom initially have some radical beliefs, meet and discuss their concerns and desires, their opinions polarize, allowing them to become progressively more extreme. Because they are also away from any other influences that might moderate their opinions, they may eventually become mass killers.

Group polarization is the result of both cognitive and affective factors. The general idea of the persuasive arguments approach to explaining group polarization is cognitive in orientation. This approach assumes that there is a set of potential arguments that support any given opinion and another set of potential arguments that refute that opinion. Furthermore, an individual’s current opinion about the topic is predicted to be based on the arguments that he or she is currently aware of. During group discussion, each member presents arguments supporting his or her individual opinions. And because the group members are initially leaning in one direction, it is expected that there will be many arguments generated that support the initial leaning of the group members. As a result, each member is exposed to new arguments supporting the initial leaning of the group, and this predominance of arguments leaning in one direction polarizes the opinions of the group members (Van Swol, 2009). Supporting the predictions of persuasive arguments theory, research has shown that the number of novel arguments mentioned in discussion is related to the amount of polarization (Vinokur & Burnstein, 1978) and that there is likely to be little group polarization without discussion (Clark, Crockett, & Archer, 1971). Notice here the parallels between the persuasive arguments approach to group polarization and the concept of informational conformity.

But group polarization is in part based on the affective responses of the individuals—and particularly the social identity they receive from being good group members (Hogg, Turner, & Davidson, 1990; Mackie, 1986; Mackie & Cooper, 1984). The idea here is that group members, in their desire to create positive social identity, attempt to differentiate their group from other implied or actual groups by adopting extreme beliefs. Thus the amount of group polarization observed is expected to be determined not only by the norms of the ingroup but also by a movement away from the norms of other relevant outgroups. In short, this explanation says that groups that have well-defined (extreme) beliefs are better able to produce social identity for their members than are groups that have more moderate (and potentially less clear) beliefs. Once again, notice the similarity of this account of polarization to the notion of normative conformity.

Group polarization effects are stronger when the group members have high social identity (Abrams, Wetherell, Cochrane, & Hogg, 1990; Hogg, Turner, & Davidson, 1990; Mackie, 1986). Diane Mackie (1986) had participants listen to three people discussing a topic, supposedly so that they could become familiar with the issue themselves to help them make their own decisions. However, the individuals that they listened to were said to be members of a group that they would be joining during the upcoming experimental session, members of a group that they were not expecting to join, or some individuals who were not a group at all. Mackie found that the perceived norms of the (future) ingroup were seen as more extreme than those of the other group or the individuals, and that the participants were more likely to agree with the arguments of the ingroup. This finding supports the idea that group norms are perceived as more extreme for groups that people identify with (in this case, because they were expecting to join it in the future). And another experiment by Mackie (1986) also supported the social identity prediction that the existence of a rival outgroup increases polarization as the group members attempt to differentiate themselves from the other group by adopting more extreme positions.

Taken together then, the research reveals that another potential problem with group decision making is that it can be polarized. These changes toward more extreme positions have a variety of causes and occur more under some conditions than others, but they must be kept in mind whenever groups come together to make important decisions.

## Social Psychology in the Public Interest

Decision Making by a Jury

Although many countries rely on the decisions of judges in civil and criminal trials, the jury is the foundation of the legal system in many other nations. The notion of a trial by one’s peers is based on the assumption that average individuals can make informed and fair decisions when they work together in groups. But given all the problems facing groups, social psychologists and others frequently wonder whether juries are really the best way to make these important decisions and whether the particular composition of a jury influences the likely outcome of its deliberation (Lieberman, 2011).

As small working groups, juries have the potential to produce either good or poor decisions, depending on many of the factors that we have discussed in this chapter (Bornstein & Greene, 2011; Hastie, 1993; Winter & Robicheaux, 2011). And again, the ability of the jury to make a good decision is based on both person characteristics and group process. In terms of person variables, there is at least some evidence that the jury member characteristics do matter. For one, individuals who have already served on juries are more likely to be seen as experts, are more likely to be chosen as jury foreperson, and give more input during the deliberation (Stasser, Kerr, & Bray, 1982). It has also been found that status matters—jury members with higher-status occupations and education, males rather than females, and those who talk first are more likely be chosen as the foreperson, and these individuals also contribute more to the jury discussion (Stasser et al., 1982). And as in other small groups, a minority of the group members generally dominate the jury discussion (Hastie, Penrod, & Pennington, 1983), And there is frequently a tendency toward social loafing in the group (Najdowski, 2010). As a result, relevant information or opinions are likely to remain unshared because some individuals never or rarely participate in the discussion.

Perhaps the strongest evidence for the importance of member characteristics in the decision-making process concerns the selection of death-qualified juries in trials in which a potential sentence includes the death penalty. In order to be selected for such a jury, the potential members must indicate that they would, in principle, be willing to recommend the death penalty as a punishment. In some countries, potential jurors who indicate being opposed to the death penalty cannot serve on these juries. However, this selection process creates a potential bias because the individuals who say that they would not under any condition vote for the death penalty are also more likely to be rigid and punitive and thus more likely to find defendants guilty, a situation that increases the chances of a conviction for defendants (Ellsworth, 1993).

Although there are at least some member characteristics that have an influence upon jury decision making, group process, as in other working groups, plays a more important role in the outcome of jury decisions than do member characteristics. Like any group, juries develop their own individual norms, and these norms can have a profound impact on how they reach their decisions. Analysis of group process within juries shows that different juries take very different approaches to reaching a verdict. Some spend a lot of time in initial planning, whereas others immediately jump right into the deliberation. And some juries base their discussion around a review and reorganization of the evidence, waiting to take a vote until it has all been considered, whereas other juries first determine which decision is preferred in the group by taking a poll and then (if the first vote does not lead to a final verdict) organize their discussion around these opinions. These two approaches are used about equally often but may in some cases lead to different decisions (Hastie, 2008).

Perhaps most important, conformity pressures have a strong impact on jury decision making. As you can see in Figure 10.3.3, when there are a greater number of jury members who hold the majority position, it becomes more and more certain that their opinion will prevail during the discussion. This is not to say that minorities cannot ever be persuasive, but it is very difficult for them. The strong influence of the majority is probably due to both informational conformity (i.e., that there are more arguments supporting the favored position) and normative conformity (people are less likely to want to be seen as disagreeing with the majority opinion).

Figure 10.3.3 Conformity in Juries

This figure shows the decisions of six-member mock juries that made “majority rules” decisions. When the majority of the six initially favored voting guilty, the jury almost always voted guilty, and when the majority of the six initially favored voting innocent, the jury almost always voted innocence. The juries were frequently hung (could not make a decision) when the initial split was three to three. Data are from Stasser, Kerr, and Bray (1982).

Research has also found that juries that are evenly split (three to three or six to six) tend to show a leniency bias by voting toward acquittal more often than they vote toward guilt, all other factors being equal (MacCoun & Kerr, 1988). This is in part because juries are usually instructed to assume innocence unless there is sufficient evidence to confirm guilt—they must apply a burden of proof of guilt “beyond a reasonable doubt.” The leniency bias in juries does not always occur, although it is more likely to occur when the potential penalty is more severe (Devine et al., 2004; Kerr, 1978).

Given what you now know about the potential difficulties that groups face in making good decisions, you might be worried that the verdicts rendered by juries may not be particularly effective, accurate, or fair. However, despite these concerns, the evidence suggests that juries may not do as badly as we would expect. The deliberation process seems to cancel out many individual juror biases, and the importance of the decision leads the jury members to carefully consider the evidence itself.

Key Takeaways

• Under certain situations, groups can show significant process gains in regards to decision making, compared with individuals. However, there are a number of social forces that can hinder effective group decision making, which can sometimes lead groups to show process losses.
• Some group process losses are the result of groupthink—when a group, as result of a flawed group process and strong conformity pressures, makes a poor judgment.
• Process losses may result from the tendency for groups to discuss information that all members have access to while ignoring equally important information that is available to only a few of the members.
• Brainstorming is a technique designed to foster creativity in a group. Although brainstorming often leads to group process losses, alternative approaches, including the use of group support systems, may be more effective.
• Group decisions can also be influenced by group polarization—when the attitudes held by the individual group members become more extreme than they were before the group began discussing the topic.
• Understanding group processes can help us better understand the factors that lead juries to make better or worse decisions.

Exercises and Critical Thinking

1. Consider a time when a group that you belonged to experienced a process gain, and another time showed a process loss in terms of decision making. Which of the factors discussed in this section do you think help to explain these two different outcomes?
2. Describe a current social or political issue where you have seen groupthink in action. What features of groupthink outlined in this section were particularly evident? When in your own life have you been in a group situation where groupthink was evident? What decision was reached and what was the outcome for you?
3. When have you been in a group that has not shared information effectively? Why do you think that this happened and what were the consequences?
4. Outline two situations, one when you were in a group that used brainstorming and you feel that it was helpful to the group decision-making process, and another when you think it was a hindrance. Why do you think the brainstorming had these opposite effects on the groups in the two situations?
5. What examples of group polarization have you seen in the media recently? How well do the ideas of normative and informational conformity explain why polarization occurred in these situations? What other factors might also have been at work?
6. If you or someone you knew had a choice to be tried by either a judge or a jury, taking into account the research in this section, which would you choose, and why?

## References

Abrams, D., Wetherell, M., Cochrane, S., & Hogg, M. (1990). Knowing what to think by knowing who you are: Self-categorization and the nature of norm formation, conformity, and group polarization. British Journal of Social Psychology, 29, 97–119.

Baron, R. S. (2005). So right it’s wrong: Groupthink and the ubiquitous nature of polarized group decision making. In M. P. Zanna (Ed.), Advances in experimental social psychology (Vol. 37, pp. 219–253). San Diego, CA: Elsevier Academic Press.

Bornstein, B. H., & Greene, E. (2011). Jury decision making: Implications for and from psychology. Current Directions in Psychological Science, 20(1), 63–67.

Brauer, M., Judd, C. M., & Gliner, M. D. (2006). The effects of repeated expressions on attitude polarization during group discussions. In J. M. Levine & R. L. Moreland (Eds.), Small groups (pp. 265–287). New York, NY: Psychology Press.

Cheng, P.-Y., & Chiou, W.-B. (2008). Framing effects in group investment decision making: Role of group polarization. Psychological Reports, 102(1), 283–292.

Clark, R. D., Crockett, W. H., & Archer, R. L. (1971). Risk-as-value hypothesis: The relationship between perception of self, others, and the risky shift. Journal of Personality and Social Psychology, 20, 425–429.

Clayton, M. J. (1997). Delphi: A technique to harness expert opinion for critical decision-making tasks in education. Educational Psychology, 17(4), 373–386. doi: 10.1080/0144341970170401.

Collaros, P. A., & Anderson, I. R. (1969). Effect of perceived expertness upon creativity of members of brainstorming groups. Journal of Applied Psychology, 53, 159–163.

Connolly, T., Routhieaux, R. L., & Schneider, S. K. (1993). On the effectiveness of group brainstorming: Test of one underlying cognitive mechanism. Small Group Research, 24(4), 490–503.

Delbecq, A. L., Van de Ven, A. H., & Gustafson, D. H. (1975). Group techniques for program planning: A guide to nominal group and delphi processes. Glenview, IL: Scott, Foresman.

Dennis, A. R., & Valacich, J. S. (1993). Computer brainstorms: More heads are better than one. Journal of Applied Psychology, 78, 531–537.

Devine, D. J., Olafson, K. M., Jarvis, L. L., Bott, J. P., Clayton, L. D., & Wolfe, J. M. T. (2004). Explaining jury verdicts: Is leniency bias for real? Journal of Applied Social Psychology, 34(10), 2069–2098.

Diehl, M., & Stroebe, W. (1987). Productivity loss in brainstorming groups: Toward the solution of a riddle. Journal of Personality and Social Psychology, 53(3), 497–509.

Diehl, M., & Stroebe, W. (1991). Productivity loss in idea-generating groups: Tracking down the blocking effect. Journal of Personality and Social Psychology, 61(3), 392–403.

Drummond, J. T. (2002). From the Northwest Imperative to global jihad: Social psychological aspects of the construction of the enemy, political violence, and terror. In C. E. Stout (Ed.), The psychology of terrorism: A public understanding (Vol. 1, pp. 49–95). Westport, CT: Praeger Publishers/Greenwood Publishing Group.

Ellsworth, P. C. (1993). Some steps between attitudes and verdicts. In R. Hastie (Ed.), Inside the juror: The psychology of juror decision making. New York, NY: Cambridge University Press.

Faulmüller, N., Kerschreiter, R., Mojzisch, A., & Schulz-Hardt, S. (2010). Beyond group-level explanations for the failure of groups to solve hidden profiles: The individual preference effect revisited. Group Processes and Intergroup Relations, 13(5), 653–671.

Forsyth, D. (2010). Group dynamics (5th ed.). Belmont, CA: Wadsworth.

Gallupe, R. B., Cooper, W. H., Grise, M.-L., & Bastianutti, L. M. (1994). Blocking electronic brainstorms. Journal of Applied Psychology, 79(1), 77–86.

Hastie, R. (1993). Inside the juror: The psychology of juror decision making. New York, NY: Cambridge University Press.

Hastie, R. (2008). What’s the story? Explanations and narratives in civil jury decisions. In B. H. Bornstein, R. L. Wiener, R. Schopp, & S. L. Willborn (Eds.), Civil juries and civil justice: Psychological and legal perspectives (pp. 23–34). New York, NY: Springer Science + Business Media.

Hastie, R., Penrod, S. D., & Pennington, N. (1983). Inside the jury. Cambridge, MA: Harvard University Press.

Hinsz, V. B. (1990). Cognitive and consensus processes in group recognition memory performance. Journal of Personality and Social Psychology, 59(4), 705–718.

Hogg, M. A., Turner, J. C., & Davidson, B. (1990). Polarized norms and social frames of reference: A test of the self-categorization theory of group polarization. Basic and Applied Social Psychology, 11(1), 77–100.

Hornsby, J. S., Smith, B. N., & Gupta, J. N. D. (1994). The impact of decision-making methodology on job evaluation outcomes: A look at three consensus approaches. Group and Organization Management, 19(1), 112–128.

Janis, I. L. (2007). Groupthink. In R. P. Vecchio (Ed.), Leadership: Understanding the dynamics of power and influence in organizations (2nd ed., pp. 157–169). Notre Dame, IN: University of Notre Dame Press.

Johnson, D.W., & Johnson, F.P. (2012). Joining together – group theory and group skills (11th ed). Boston: Allyn and Bacon.

Kerr, N. L. (1978). Severity of prescribed penalty and mock jurors’ verdicts. Journal of Personality and Social Psychology, 36(12), 1431–1442.

Kogan, N., & Wallach, M. A. (1967). Risky-shift phenomenon in small decision-making groups: A test of the information-exchange hypothesis. Journal of Experimental Social Psychology, 3, 75–84.

Kramer, R. M. (1998). Revisiting the Bay of Pigs and Vietnam decisions 25 years later: How well has the groupthink hypothesis stood the test of time? Organizational Behavior and Human Decision Processes, 73(2–3), 236–271.

Kroon, M. B., Van Kreveld, D., & Rabbie, J. M. (1992). Group versus individual decision making: Effects of accountability and gender on groupthink. Small Group Research, 23(4), 427-458.

Larson, J. R. J., Foster-Fishman, P. G., & Keys, C. B. (1994). The discussion of shared and unshared information in decision-making groups. Journal of Personality and Social Psychology, 67, 446–461.

Lieberman, J. D. (2011). The utility of scientific jury selection: Still murky after 30 years. Current Directions in Psychological Science, 20(1), 48–52.

MacCoun, R. J., & Kerr, N. L. (1988). Asymmetric influence in mock jury deliberation: Jurors’ bias for leniency. Journal of Personality and Social Psychology, 54(1), 21–33.

Mackie, D. M. (1986). Social identification effects in group polarization. Journal of Personality and Social Psychology, 50(4), 720–728.

Mackie, D. M., & Cooper, J. (1984). Attitude polarization: Effects of group membership. Journal of Personality and Social Psychology, 46, u575–585.

Matusitz, J., & Breen, G. (2012). An examination of pack journalism as a form of groupthink: A theoretical and qualitative analysis.Journal Of Human Behavior In The Social Environment, 22 (7), 896-915.

McCauley, C. R. (1989). Terrorist individuals and terrorist groups: The normal psychology of extreme behavior. In J. Groebel & J. H. Goldstein (Eds.), Terrorism: Psychological perspectives (p. 45). Sevilla, Spain: Universidad de Sevilla.

Mesmer-Magnus, J. R., DeChurch, L. A., Jimenez-Rodriguez, M., Wildman, J., & Shuffler, M. (2011). A meta-analytic investigation of virtuality and information sharing in teams. Organizational Behavior and Human Decision Processes, 115(2), 214–225.

Mojzisch, A., & Schulz-Hardt, S. (2010). Knowing others’ preferences degrades the quality of group decisions. Journal of Personality and Social Psychology, 98(5), 794–808.

Morrow, K. A., & Deidan, C. T. (1992). Bias in the counseling process: How to recognize and avoid it. Journal of Counseling and Development, 70, 571-577.

Myers, D. G. (1982). Polarizing effects of social interaction. In H. Brandstatter, J. H. Davis, & G. Stocher-Kreichgauer (Eds.), Contemporary problems in group decision-making (pp. 125–161). New York, NY: Academic Press.

Myers, D. G., & Bishop, G. D. (1970). Discussion effects on racial attitudes. Science, 169(3947), 778–779. doi: 10.1126/science.169.3947.778

Myers, D. G., & Kaplan, M. F. (1976). Group-induced polarization in simulated juries. Personality and Social Psychology Bulletin, 2(1), 63–66.

Najdowski, C. J. (2010). Jurors and social loafing: Factors that reduce participation during jury deliberations. American Journal of Forensic Psychology, 28(2), 39–64.

Osborn, A. F. (1953). Applied imagination. Oxford, England: Scribner’s.

Paulus, P. B., & Dzindolet, M. T. (1993). Social influence processes in group brainstorming. Journal of Personality and Social Psychology, 64(4), 575–586.

Redding, R. E. (2012). Likes attract: The sociopolitical groupthink of (social) psychologists. Perspectives On Psychological Science, 7 (5), 512-515.

Reimer, T., Reimer, A., & Czienskowski, U. (2010). Decision-making groups attenuate the discussion bias in favor of shared information: A meta-analysis. Communication Monographs, 77(1), 121–142.

Reimer, T., Reimer, A., & Hinsz, V. B. (2010). Naïve groups can solve the hidden-profile problem. Human Communication Research, 36(3), 443–467.

Siau, K. L. (1995). Group creativity and technology. Psychosomatics, 31, 301–312.

Stasser, G., Kerr, N. L., & Bray, R. M. (1982). The social psychology of jury deliberations: Structure, process and product. In N. L. Kerr & R. M. Bray (Eds.), The psychology of the courtroom(pp. 221–256). New York, NY: Academic Press.

Stasser, G., & Stewart, D. (1992). Discovery of hidden profiles by decision-making groups: Solving a problem versus making a judgment. Journal of Personality & Social Psychology, 63, 426–434.

Stasser, G., & Taylor, L. A. (1991). Speaking turns in face-to-face discussions. Journal of Personality and Social Psychology, 60,675–684.

Stasser, G., Taylor, L. A., & Hanna, C. (1989). Information sampling in structured and unstructured discussions of three- and six-person groups. Journal of Personality and Social Psychology, 57(1), 67–78.

Stasser, G., & Titus, W. (1985). Pooling of unshared information in group decision making: Biased information sampling during discussion. Journal of Personality and Social Psychology, 48(6), 1467–1478.

Stein, M. I. (1978). Methods to stimulate creative thinking. Psychiatric Annals, 8(3), 65–75.

Stoner, J. A. (1968). Risky and cautious shifts in group decisions: The influence of widely held values. Journal of Experimental Social Psychology, 4, 442–459.

Stroebe, W., & Diehl, M. (1994). Why groups are less effective than their members: On productivity losses in idea-generating groups. European Review of Social Psychology, 5, 271–303.

Valacich, J. S., Jessup, L. M., Dennis, A. R., & Nunamaker, J. F. (1992). A conceptual framework of anonymity in group support systems. Group Decision and Negotiation, 1(3), 219–241.

Van Swol, L. M. (2009). Extreme members and group polarization. Social Influence, 4(3), 185–199.

Vinokur, A., & Burnstein, E. (1978). Novel argumentation and attitude change: The case of polarization following group discussion. European Journal of Social Psychology, 8(3), 335–348.

Watson, G. (1931). Do groups think more effectively than individuals? In G. Murphy & L. Murphy (Eds.), Experimental social psychology. New York: Harper.

Winter, R. J., & Robicheaux, T. (2011). Questions about the jury: What trial consultants should know about jury decision making. In R. L. Wiener & B. H. Bornstein (Eds.), Handbook of trial consulting (pp. 63–91). New York, NY: Springer Science + Business Media.

Wittenbaum, G. M. (1998). Information sampling in decision-making groups: The impact of members’ task-relevant status. Small Group Research, 29(1), 57–84.

Zhu, H. (2010). Group polarization on corporate boards: Theory and evidence on board decisions about acquisition premiums, executive compensation, and diversification. (Doctoral dissertation). University of Michigan, Ann Arbor, Michigan.
Ziller, R. (1957). Group size: A determinant of the quality and stability of group decision. Sociometry, 20, 165-173.

## Contributors

Charles Stangor (University of Maryland), Rajiv Jhangiani (Kwantlen Polytechnic University), and Hammond Tarry (Adler School of Professional Psychology). The OpenStax name, OpenStax logo, OpenStax book covers, OpenStax CNX name, and OpenStax CNX logo are not subject to the creative commons license and may not be reproduced without the prior and express written consent of Rice University. For questions regarding this license, please contact support@openstax.org.

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