Information Exchange in Context: Effects of Gender Composition of Group,Accountability, and Intergroup Perception on Group Decision Making1

In the present study, the dissemination of shared and unshared information (cf. Stasser & Titus, 1985) in unstructured group discussion is analyzed. In previous experiments, several manipulations of the task itself were introduced, in search of conditions that could facilitate the exchange of unshared information. As such, these studies neglected the potential impact of context variables on group performance. In the present study, the effects of accountability, intergroup perception, and gender composition of group on information exchange are investigated. The results indicate that heterogeneous groups exchanged more information when a second group was present. Information exchange was not promoted by the presence of an outgroup for homogeneous groups. Groups in the accountability condition displayed more difficulties to reach agreement, but this did not lead to the mentioning of more information.     

自由讨论条件下群体决策质量的影响因素

通过实验室实验考察了自由讨论条件下群体决策质量的影响因素,并对Stasser所提出的信息取样模型进行了验证,结果发现：(1)部分证实Stasser的信息取样模型。在信息不分享的条件下,如果讨论前群体成员的偏好比较一致时,群体的确倾向于讨论分享信息和群体所偏好的候选人的信息;但如果讨论前的偏好不一致或任务难度较低时,这一结论难以成立。(2)自由讨论条件下,群体规模的增加会增加分享信息的讨论量,而对非分享信息的讨论程度则无显著影响。而在任务难度方面,只有任务难度较大的情况下才有分享信息的讨论优势。     

群体决策过程中的信息取样偏差

一般认为,决策群体的优势是能综合各个成员拥有的不完整信息,形成对所有决策备择方案的无偏差的认识,从而作出最佳选择。但“群体讨论中的有偏差信息取样模型’认为,群体在决策中往往表现出倾向于讨论两种信息：(1)各成员讨论前都拥有的信息;(2)支持成员在讨论前所偏好的信息。该实验通过模拟人员选拔决策形式的实验室实验,对这一模型的假设进行验证。研究结果表明,大多数群体选择了一开始受到大多数成员支持的候选人,而非实际的最佳人选;群体讨论非但未纠正,反而加强了成员对候选人原有的歪曲印象。     

Motivated information processing and group decision-making: Effects of process accountability on information processing and decision quality

Integrating dual-process models [Chaiken, S., & Trope, Y. (Eds.). (1999). Dual-process theories in social psychology. NewYork: Guilford Press] with work on information sharing and group decision-making [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, 1467-1478.], we predicted that groups with high epistemic motivation engage in more information-driven and less preference-driven interaction, and achieve better decisions. An experiment manipulating process accountability showed that groups under process accountability experienced greater need for more information, repeated unshared information more often, and more often chose the correct decision alternative. Mediation analysis established that epistemic motivation produced high quality decisions because it stimulated systematic information processing. Results also revealed that preference heterogeneity stimulated information-driven interaction and led to higher decision quality.     

Information sampling and group decision making: the effects of an advocacy decision procedure and task experience

Group discussions tend to focus on information that was previously known by all members (shared information) rather than information known by only 1 member (unshared information). If the shared information implies a suboptimal alternative, this sampling bias is associated with inaccurate group decisions. The present study examines the impact of 2 factors on information exchange and decision quality: (a) an advocacy group decision procedure versus unstructured discussion and (b) task experience. Results show that advocacy groups discussed both more shared and unshared information than free-discussion groups. Further, with increasing experience, more unshared information was mentioned in advocacy groups. In contrast, there was no such increase in unstructured discussions. Yet advocacy groups did not significantly improve their decision quality with experience.     

MAU程序和自由讨论的群体决策质量比较

采用实验室研究方法,比较了在信启、不分享条件下多特征效用模型(MAU)决策程序和自由讨论对群体决策质量的影响,并对影响MAU决策质量的主要因素进行了初步探讨。结果发现：(1)MAU程序可以较好地克服群体动力学方面的一些消极影响,表现出挖掘信息(尤其是非分享信息)的充分性。但MAU程序在被试的态度和社会交互作用等心理效标上并未显示出优势;(2)在MAU条件下,群体规模的增大对分享和非分享信息的讨论量无显著影响。而任务难度效应要和群体规模一起才能起到作用。     

Children's collaborative recall of shared and unshared information

This study examined age differences in collaborative inhibition and the role of inter‐subjectivity, collective information sampling (CIS) and collaborative inhibition for the collaborative recall of shared and unshared information in groups of 7‐ and 9‐year‐old children. Three‐hundred and thirteen 7‐ and 9‐year‐old children recalled memorized wordlists either in real or nominal groups of three. All group members either recalled the same items, or each group member was given some unique items. Nine‐year‐olds, but not 7‐year‐olds, recalled significantly more items in nominal than real groups, a phenomenon called collaborative inhibition. Groups whose interactions were characterized by higher numbers of inter‐subjective exchanges recalled fewer words than groups low in inter‐subjectivity. In both age groups, a higher proportion of shared compared with unshared information was recalled consistent with processes of CIS. However, 7‐year‐olds recalled more unshared items than predicted, suggesting that collaborative inhibition additionally contributes to the recall of shared and unshared items.     

The sampling of critical,unshared information in decision-making groups: the role of an informed minority

A collective information sampling model and observations of discussion content suggest that decision-making groups often fail to disseminate unshared information. This paper examines the role that a fully-informed minority may play in facilitating the sampling and consideration of unshared information. University students read a mystery and then met in four-person groups to discuss the case. When critical clues were unshared among three members before discussion, a fully informed fourth member (informed minority) promoted the discussion of these critical clues when participants thought the mystery had a demonstrably correct answer (solve set) but not when they thought the clue may have been insufficient to solve definitively the case (judge set). None the less, under both solve and judge sets, the informed minority increased the likelihood that the group would identify the correct suspect. Social combination, information sampling, and minority influence interpretations of the results are discussed. © 1998 John Wiley & Sons, Ltd.     

任务难度、决策培训诸因素对群体决策的影响

通过3人群体的人员选拔模拟实验。考察了任务难度、群体结构和决策培训三个变量对群体决策信息取样的影响。结果显示：(1)部分证明了Stasser的信息取样模型,分享信息具有讨论的优势,同时偏好是影响群体决策的中介因素,但是,该模型只适合于任务难度较大的情况;(2)设立具有信息管理作用的领导者这种群体结构在信息取样中没有表现出主效应,它只是通过与决策培训和任务难度一起对信息取样产生影响;(3)策略计划和信息警戒性的决策培训对信息取样有影响,一定程度上提高了非分享信息的讨论比例,然而这种影响仅发生在任务难度小或适中的情况下。决策培训对信息取样的影响发生在讨论的开始部分,并影响了讨论前的个体偏好;(4)群体结构和决策培训具有交互作用,从而影响了群体讨论的信息取样,群体结构和决策培训都受到任务难度的影响。     

The effect of information distribution on collaborative inhibition

Two experiments examined collaborative memory for information that was studied by all group members (shared items) and information that was studied by only a subset of group members (unshared items). In both experiments significant collaborative inhibition (reduced output of the collaborative groups relative to the pooled output of individuals) was obtained for both shared and unshared information. In Experiment 1 the magnitude of collaborative inhibition was larger for unshared items than for shared items, possibly because unshared items were less likely to be acknowledged and thus incorporated into the groups’ recall. In Experiment 2 the magnitude of collaborative inhibition for shared and unshared information was equivalent once all participants were provided with the category name associated with the shared and unshared items. The results of the experiments are discussed in relation to the retrieval strategy disruption hypothesis of collaborative inhibition and the role of social process variables, such as acknowledgement, in influencing collaborative inhibition across situations involving memory of shared and unshared information.     

The Collective Preference for Shared Information

Decision-making groups prefer to discuss shared information that all members know instead of unshared information that a single member knows. This bias toward discussing shared information can lead groups to make suboptimal decisions when unshared information is critical for good decision making. This preference for discussing shared information may stem from group members' positive evaluations of each other's task capabilities when shared information is communicated. Members who already are perceived as capable (i.e., those high in status, experts, and leaders) need not bolster their image by communicating shared information. Instead, they discuss unshared information more than members perceived as less capable. As members low in status gain respect by communicating shared information, they may risk mentioning unshared information later during discussion. Assigning group leaders, informing members of their expert roles, and allowing ample time for discussion may increase groups' discussion of unshared information.     

Quality of decision making and group norms.

Two studies investigated the impact of group norms for maintaining consensus versus norms for critical thought on group decisions in a modification of the biased sampling paradigm (G. Stasser & W. Titus, 1985). Both studies showed that critical norms improved the quality of decisions, whereas consensus norms did not. This effect appeared to be mediated by the perceived value of shared and unshared information: Consensus norm groups valued shared information more highly than critical groups did, and valence was a good predictor of decision outcome. In addition, the 2nd study showed that the group norm manipulation has no impact on individual decisions, consistent with the assumption that this is a group effect. Results suggest that the content of group norms is an important factor influencing the quality of group decision-making processes and that the content of group norms may be related to the group's proneness for groupthink.     

The Rank-Order Effect in Group Decision Making

Many studies indicate that group discussion candisproportionately reflect information known by all group members,at the expense of information known to only one group member, andthis is associated with suboptimal group decisions (Stasser &Titus, 1985). The present study examined the impact of threeprocedural factors on information sharing and quality of groupdecision: (a) group decision procedure (an instruction to "rankorder the alternatives" vs "choose the best alternative"), (b)information access during group discussion (reliance on memory vscomplete access), and (c) communication technology (computer vsface to face). Three-person groups worked on an investment decisionthat was structured as a hidden-profile task where criticalinformation was distributed unevenly prior to group discussion. Thedata provided support for a rank-order effect: Groups instructedto rank order the alternatives, compared to groups instructed tochoose the best alternative, were more likely to fully consider allof the alternatives, exchange information about unpopularalternatives, and make the best decision. But these effects onlyoccurred in face-to-face groups. In computer-mediated groups, therewas general information suppression and no effect of group decisionprocedure. Access to information during group discussion increaseddiscussion of both unique and common information, in theface-to-face conditions, but had no effect on group decisionquality. Taken together, the data suggest that procedural aspectsof group discussion may help overcome the impact of prediscussionpreferences on information processes and group decision.     

The effect of information distribution on collaborative inhibition

Two experiments examined collaborative memory for information that was studied by all group members (shared items) and information that was studied by only a subset of group members (unshared items). In both experiments significant collaborative inhibition (reduced output of the collaborative groups relative to the pooled output of individuals) was obtained for both shared and unshared information. In Experiment 1 the magnitude of collaborative inhibition was larger for unshared items than for shared items, possibly because unshared items were less likely to be acknowledged and thus incorporated into the groups' recall. In Experiment 2 the magnitude of collaborative inhibition for shared and unshared information was equivalent once all participants were provided with the category name associated with the shared and unshared items. The results of the experiments are discussed in relation to the retrieval strategy disruption hypothesis of collaborative inhibition and the role of social process variables, such as acknowledgement, in influencing collaborative inhibition across situations involving memory of shared and unshared information.     

When is one head better than two? Interdependent information in group decision making

Research on information exchange in group decision making has frequently assumed that information items have independent meanings. Relaxing this assumption raises new issues and presents new possibilities. In the experiment presented here, dyads worked on hidden profile decision tasks in which pairs of unshared information items had interdependent meanings. Dyad decisions were more likely to be accurate when each pair of interdependent items was allocated to a single member (a “connected” hidden profile) than when each pair of interdependent items was separated between the two members (a “disconnected” hidden profile). These information distributions influenced the degree to which dyads considered unshared information. Cognitive load was manipulated, and it impaired decision makers’ ability to identify connections among interdependent information items. The differentiated distribution of information inherent in transactive memory systems moderated the negative effects of cognitive load on dyad decisions.     

The dissemination of critical,unshared information in decision‐making groups: the effects of pre‐discussion dissent

Previous research in group decision making has found that in situations of a hidden profile (i.e. the best choice alternative is hidden from individual members as they consider their pre‐discussion information), unshared information is disproportionately neglected and sub‐optimal group choices are highly likely. In an experimental study, three‐person groups decided which of three candidates to select for a professorial appointment. We hypothesised that minority dissent in pre‐discussion preferences improves the consideration of unshared information in groups and increases the discovery rate of hidden profiles. As predicted, consideration of unshared information increased with minority dissent. The expectation of an improvement of group decision quality was partially supported. In diversity groups (i.e. each member prefers a different alternative) consideration of unshared information and group decision quality was significantly higher than in simple minority groups. Results are discussed in the light of theories of minority influence. The benefits of using the hidden profile paradigm with minority and diversity groups for theory development in the area of group decision making are highlighted. Copyright © 2002 John Wiley & Sons, Ltd.     

Social validation in group decision-making: Differential effects on the decisional impact of preference-consistent and preference-inconsistent information

Shared information has a stronger impact on group decisions than unshared information. A prominent explanation for this phenomenon is that shared information can be socially validated during group discussion and, hence, is perceived as more accurate and relevant than unshared information. In the present study we argue that this explanation only holds for preference-inconsistent information (i.e., information contradicting the group members’ initial preferences) but not for preference-consistent information. In Experiments 1 and 2 participants studied the protocol of a fictitious group discussion. In this protocol, we manipulated which types of information were socially validated. As predicted, social validation increased the decisional impact of preference-inconsistent but not preference-consistent information. In both experiments the effect of social validation was mediated by the perceived quality of information. Experiment 3 replicated the results of the first two experiments in an interactive setting in which two confederates discussed a decision case face-to-face with one participant.     

Preference-consistent evaluation of information in the hidden profile paradigm: beyond group-level explanations for the dominance of shared information in group decisions

Common explanations for the failure of groups to solve so-called hidden profiles focus on group processes, namely insufficient discussion of unshared information and premature consensus on a suboptimal alternative. As 2 experiments show, even in the absence of such group processes, hidden profiles are hardly ever solved. In Experiment 1, participants first received individual information about a personnel selection task and then read a group discussion protocol containing full information exchange. If the individual information was misleading (hidden profile), most participants failed to detect the correct alternative. In Experiment 2, it was determined that this effect is due to preference-consistent evaluation of information that constitutes an individual-level process mediating the failure of group members to solve hidden profiles.     

Younger and older adults’ collaborative recall of shared and unshared emotional pictures

Although a group of people working together recalls more items than any one individual, they recall fewer unique items than the same number of people working apart whose responses are combined. This is known as collaborative inhibition, and it is a robust effect that occurs for both younger and older adults. However, almost all previous studies documenting collaborative inhibition have used stimuli that were neutral in emotional valence, low in arousal, and studied by all group members. In the current experiments, we tested the impact of picture-stimuli valence, picture-stimuli arousal, and information distribution in modulating the magnitude of collaborative inhibition. We included both younger and older adults because there are age differences in how people remember emotional pictures that could modulate any effects of emotion on collaborative inhibition. Results revealed that when information was shared (i.e., studied by all group members), there were robust collaborative inhibition effects for both neutral and emotional stimuli for both younger and older adults. However, when information was unshared (i.e., studied by only a single group member), these effects were attenuated. Together, these results provide mixed support for the retrieval strategy disruption account of collaborative inhibition. Supporting the retrieval strategy disruption account, unshared study information was less susceptible to collaborative inhibition than shared study information. Contradicting the retrieval strategy disruption account, emotional valence and arousal did not modulate the magnitude of collaborative inhibition despite the fact that participants clustered the emotional, but not neutral, information together in memory.