臺灣博碩士論文加值系統

共同知識效果（common knowledge effect）是指，團體在討論中過於重視成員們先前共同擁有的知識，並使得團體決策偏向共同知識的現象。當團體決策需要交換成員獨有的訊息才能確認正確選項時（如在隱藏式檔案情境時），共同知識效果的出現會使得決策表現產生偏誤。以往有關共同知識效果的研究大部分是使用隨機分配的方式組成受試團體，基本上這些非自然形成的團體，成員間彼此互不認識，相當於陌生團體，但實際上，許多決策團體中的成員之前已經有過互動，甚至有過幾次共同決策的經驗，因此熟悉團體的決策表現值得我們進一步去探討。

有關團體熟悉性對共同知識效果的影響目前尚不明確。過去文獻指出，陌生團體中的成員會藉由討論共有訊息來建立信任感和提高自己的評價，導致共同知識效果的產生，而無法有效的進行非共有訊息的交換，使得團體決策正確性降低；而熟悉團體中的成員已經彼此認識，不再需要藉由討論共有訊息來提升自我評價，因此，熟悉團體較不會受到共同知識效果的影響，而較能有效的進行訊息交換以達成正確決策（Wittenbaum, Hubbell, & Zuckerman, 1999）。但從凝聚力的角度來看，熟悉團體的高凝聚力會導致從眾壓力的提高，使得熟悉團體中的成員因害怕破壞自己與團體的和諧關係，而避免提出與團體共識相抵觸的非共有訊息，反而是在熟悉團體中較容易產生共同知識效果（Hogg, 1992）。筆者預期團體成員對其決策作業類型的知覺不同，或許可以解釋上述團體熟悉性在共同知識效果上的結果之不一致。

本研究採用一個2（訊息分配：完整訊息檔案/隱藏式檔案） × 2（團體熟悉性：熟悉/陌生） × 2（作業類型：智力性作業/判斷性作業）的三因子受試者間實驗設計。受試者為中原大學學生，以同性別的三人為一團體，來進行「商人死亡案件」的決策作業，共有89組有效團體參與實驗。依變項為團體討論中的整體訊息討論量、非共有訊息交換量和團體決策正確性。
研究結果顯示，在完整訊息檔案情境中的團體，不論其作業類型和團體熟悉性為何，整體訊息討論量和決策正確性都大致相同。在隱藏式檔案情境中的團體，不論其熟悉性如何，在智力性作業上的非共有訊息交換量皆會大於判斷性作業，但只有陌生團體在智力性作業上的決策正確性會高於判斷性作業，熟悉團體在智力性作業上的決策正確性則與判斷性作業沒有差異。另一方面，在隱藏式檔案中的團體，不論其作業類型為何，熟悉團體的非共有訊息交換量皆會比陌生團體多，但熟悉團體的決策正確性卻都沒有比陌生團體高。

整體而言，熟悉團體的非共有訊息交換量大於陌生團體，即熟悉團體比較不會有共同知識效果的討論偏誤，但是熟悉團體的團體決策正確性卻不高於陌生團體。筆者以大多數法則使用的情形來解釋團體決策正確性上的結果，發現在隱藏式檔案中，熟悉團體傾向使用大多數法則來達成決策，因而導致團體決策偏向共同知識所支持的選項；陌生團體則是傾向使用訊息收集法則來達成決策，因此若有進行充分的非共有訊息交換，陌生團體的決策正確性有可能會比熟悉團體高。

The common knowledge effect refers to the phenomenon that decision-making groups are much more likely to discuss information that members shared before discussion than to discuss information that is held by individual members. Thus, group decisions are much more impacted by the shared information than by the unshared information. When unshared information is critical to identifying the superior decision option, such as, in hidden profiles, group performance would be biased by focusing on discussing the shared information. Most studies on the common knowledge effect have been conducted in laboratories. However, ecological decision groups usually are groups with members knowing each other, even had some experiences of joint decision making. Thus, the effectiveness of group decision making with various degree of group familiarity deserves more investigation.

The effects of group familiarity on common knowledge effect still are uncertain. When members do not know one another well, they may establish credibility and evaluates themselves through the communication of shared information. Thus, they intend to mention and repeat shared information, leading to the common knowledge effect. However, the members of familiar groups have already known one another, they may not need to establish credibility and evaluates themselves through the communication of shared information. Therefore, groups composed of familiar members would be less likely to exhibit the common knowledge effect and more likely to reach the correct group decision than groups composed of strangers (Wittenbaum, Hubbell, & Zuckerman, 1999). But from the perspective of cohesion, familiar groups have greater cohesion and conformity than stranger groups. Hence, members in familiar groups will consider harmonious relations are more important than decision quality. Therefore, groups composed of familiar members are likely to suppress conflicts and dismiss information that could incite them, and their decisions will be much more affected by the common knowledge than groups composed of strangers (Hogg, 1992). In the present study, it was proposed that task type might clarify the inconsistent effects of group familiarity on common knowledge effect.

The present study adopted a 2 (information distribution: full information profile/ hidden profile) × 2 (group familiarity: familiar group/ stranger group) × 2 (task type: intellective/ judgmental) between-subjects factorial <a href="http://www.ntsearch.com/search.php?q=design&v=56">design</a>. Dependent variables were the amount of total discussion, discussion focus, and the correctness of group choice. A total of 89 valid groups (three <a href="http://www.ntsearch.com/search.php?q=university&v=56">university</a> students with the same gender as a group) were randomly assigned to eight experimental conditions. Each participant read a murder mystery, and then each group discussed the case to indicate a suspect.

Experimental results showed that, in the full information profile, regardless of task type, the amount of total discussion and the proportion of group choice correctness were identical between the familiar group and the stranger group. Furthermore, regardless of group familiarity, the amount of total discussion and the proportion of group choice correctness were the same between the intellective task and the judgmental task. In hidden profiles, regardless of group familiarity, groups with intellective tasks focused more on unshared information than groups with judgmental tasks. In the same profile condition, the stranger group with the intellective task chose the correct suspect more often than the stranger group with the judgmental task; the proportions of choice correctness were identical between the intellective task and the judgmental task for the familiar groups. Furthermore, in the hidden profile, regardless of task type, familiar groups focus more on the unshared information than stranger groups, but familiar groups failed to choose the correct suspect more often than stranger groups.

In sum, familiar groups focused more on the unshared information than stranger groups, familiar groups thus showed less discussion bias of the common knowledge effect. Nevertheless, familiar groups did not choose the correct suspect more often than stranger groups. The inconsistent findings in the discussion focus and choice correctness could be explained by considering decision strategies adopted by the groups. In hidden profiles, familiar groups preferred employing the majority rule to make decisions, whereas stranger groups preferred exploiting the information pooling strategy to make decisions. A model reconciling the above findings was developed and explicitly discussed.

目次

緒論 1
一、動機與目的 1
二、共同知識效果的代表性研究 3
三、共同知識效果的理論解釋 5
集體訊息抽樣模式 6
偏好協商模式 6
共同顯揚 9
二元歷程模式 11
四、減緩共同知識效果的研究 14
專家性 14
作業類型 17
時間壓力 19
團體熟悉性 22

研究假設 32
一、完整訊息檔案情境 33
二、隱藏式檔案情境 34

方法 37
一、研究對象 37
二、實驗設計 37
獨變項的操弄 38
依變項的測量 40
三、實驗材料 40
四、實驗程序 41

結果 42
一、獨變項的操弄檢核 43
訊息分配 43
作業類型 44
團體熟悉性 44
二、團體討論內容 44
評分者間信度 45
整體訊息討論量 45
非共有訊息交換量 49
關鍵訊息討論量 54
三、團體決策正確性 60
討論前的個人選擇 64

討論 67

總結與建議 77
一、總結 77
二、建議 78

參考文獻 80

附錄一、決策作業的題本（完整的訊息檔案） 84
附錄二A、智力性作業的指導語 110
附錄二B、判斷性作業的指導語 111
附錄三、決策作業的訊息內容 112
附錄四、人際網絡問卷 115
附錄五、事後問卷 116
附錄六、個人決策作業單 117
附錄七、團體決策作業單 118
附錄八、內容分析紀錄單 119
附錄九、內容分析原則 123

表目次

表一、四人團體中每位成員在討論前接受到的訊息數 4
表二、共同知識效果研究之實驗內容與研究結果 30
表三、本研究對於團體討論內容與決策正確性之預期 33
表四、完整訊息檔案情境中每位成員分配到的有關線索數量 38
表五、隱藏式檔案情境中各成員分配到的訊息數量 38
表六、各實驗情境中之有效團體數 42
表七、獨變項的操弄檢核結果 43
表八、各實驗情境中有檢視評分者間信度的團體數 45
表九、各情境團體的整體訊息討論量之平均數和標準差 46
表十、團體討論內容之變異數分析摘要表 46
表十一、訊息分配與作業類型在整體訊息討論量上的平均值和標準差 46
表十二、訊息分配與作業類型在整體討論量上之變異數分析摘要表 47
表十三、各情境中的整體訊息討論量之結果 48
表十四、在整體訊息討論量上的假設與資料分析結果之異同 48
表十五、各情境的團體非共有訊息交換量之平均值和標準差 50
表十六、各情境團體的非共有訊息交換量之變異數分析摘要表 50
表十七、隱藏式檔案中非共有訊息交換量之結果 51
表十八、在非共有訊息交換量上的假設與資料分析結果之異同 51
表十九、各情境團體的共有訊息討論量之平均數和標準差 52
表二十、各情境團體的非共有訊息討論量之平均數和標準差 53
表二十一、各情境團體的細節訊息討論量之平均數和標準差 53
表二十二、各情境團體在三種訊息種類討論量上之變異數分析摘要 53
表二十三、各情境中的關鍵訊息討論量之平均數和標準差 55
表二十四、各情境團體的關鍵訊息討論量之變異數分析摘要表 55
表二十五、訊息分配與作業類型在關鍵訊息討論量上的平均值和標準差 56
表二十六、訊息分配與作業類型在關鍵訊息討論量上之變異數分析摘要表 57
表二十七、各情境中關鍵訊息討論量之結果 57
表二十八、關鍵訊息討論量上的結果與假設之異同 57
表二十九、各情境中非共有訊息交換量之平均數和標準差（新指標） 59
表三十、非共有訊息交換量之變異數分析摘要表（新指標） 59
表三十一、隱藏式檔案中非共有訊息交換量之結果（新指標） 59
表三十二、非共有訊息交換量上的結果與假設之異同（新指標） 60
表三十三、正確選擇之團體數及其百分比 61
表三十四、各情境團體決策正確性之階層對數線性分析摘要表 61
表三十五、各情境中團體決策正確性之結果 62
表三十六、團體決策正確性上的假設與資料分析結果之異同 63
表三十七、完整訊息檔案中的大多數個人選擇與團體選擇之關係 65
表三十八、隱藏式檔案中的大多數個人選擇與團體選擇之關係 65
表三十九、各情境團體使用大多數法則的情形 66
表四十、研究假設與資料分析結果之異同 67
表四十一、與Gruenfeld (1996)之比較 75

圖目次

圖一、從共同顯揚發展出來的集體訊息抽樣簡化模式 10
圖二、集體訊息抽樣模式與偏好協商模式 12
圖三、二元歷程模式 13
圖四、本研究結果形成之理論架構圖 76

Broadbeck, F. C., Kerschreiter, R., Mojzisch, A., Fery, D., & Schulz-Hardt, S. (2002). The dissemination of critical, unshared information in decision-making groups: The effects of pre-discussion dissent. European Journal of Social Psychology, 32, 35-56.
Cartwright, D. (1968). The nature of group cohesiveness. In D. Cartwright and A. Zander (Eds.), Group Dynamics: Research and Theory (3rd ed.). New York: Harper & Row.
De Dreu, C. K. W., & West, M. A. (2001). Minority dissent and team innovation: The importance of participation in decision making. Journal of Applied Psychology, 86, 1191-1201.
Festinger, L. (1954). A theory of social comparison. Human Relations, 1, 117-140.
Flowers, M. L. (1977). A laboratory test of some implication of Janis’ groupthink hypothesis. Journal of Personality and Social Psychology, 35, 888-896
Gigone, D., & Hastie, R. (1993). The common knowledge effect: Information sharing and group judgment. Journal of Personality and Social Psychology, 65, 959-974.
Gigone, D., & Hastie, R. (1997). The impact of information on small group choice. Journal of Personality and Social Psychology, 72, 132-140.
Goethals, G. R., & Darley, J. M. (1977). Social comparison theory: An attributional approach. In J. M. Suls & R. L. Miller (Eds.), Social comparison theory (pp. 259-278). Washington, DC: Hemisphere.
Greitemeyer, T. & Schulz-Hardt, S. (2003). Preference-consistent evaluation of information in the hidden profile paradigm: Beyond group-level explanations for the dominance of shared information in group decisions. Journal of Personality and Social Psychology, 84, 322-339.
Gruenfeld, D. H., Mannix, E. A., Williams, K. Y., & Neale, M. (1996). Group composition and decision making: How member familiarity and information distribution affect process and performance. Organizational Behavior and Human Decision Processes, 67, 1-15
Heaton, A. W., & Kruglanski, A. W. (1991). Person perception by introverts and extraverts under time pressure: Effects of need for closure. Personality and Social Psychology Bulletin, 17, 161-165.
Hogg, M. A. (1992). The social psychology of group cohesiveness: From attraction to social identity. New York: New York University Press.
Hollander, E. P. (1958). Conformity, status, and idiosyncrasy credit. Psychological Review, 65, 117-127.
Janis, I. L. (1982). Groupthink: Psychological studies of policy decisions and fiascos. Boston: Houghton Mifflin.
Karau, S. J., & Kelly, J. P. (1992). The effects of time scarcity and time abundance on group performance quality and interaction process. Journal of Experimental Social Psychology, 28, 542-571.
Kelly, J. R., Jackson, J. W., ＆ Hutson-Comeaux, S. L. (1997). The effects of time pressure and task differences on influence modes and accuracy in decision-making groups. Personality and Social Psychology Bulletin, 23, 10-22.
Kelly, J. R., & Karau, S. J. (1999). Group decision making: The effects of initial preferences and time pressure. Psychology Bulletin, 25, 1342-1354.
Larson, J. R., & Jr., Foster-Fishman, P. G., & Franz, T. M. (1998). Leadership style and the discussion of shared and unshared information in decision-making groups. Personality and Social Psychology Bulletin, 24, 482-495.
Laughlin, P. R. (1980). Social combination processes of cooperative problem-solving groups on verbal intellective tasks. In M. Fishbein (Ed.), Process in Social Psychology (Vol. 1, pp. 127-155). Hillsdale, NJ: Erlbaum.
Laughlin, T. A. & Ellis (1986). Demonstrability and social combination processes on mathematical intellective tasks. Journal of Experimental Social Psychology, 22, 177-189.
Lavery, T. A., & Franz, T. M. (1999). The role of information exchange in predicting group accuracy on a multiple judgment task. Basic and Applied Social Psychology, 21, 281-289.
Markus, H. R., & Kitayama, S. (1991). Culture and the Self: Implications for Cognition, Emotion, and Motivation. Psychological Review, 98, 224-253.
Newcomb, T. M. (1961). The acquaintance process. New York: Holt, Rinehart, & Winston.
Sanna, L. J., & Schotland, R. L. (1990). Valence of anticipated evaluation and social facilitation. Journal of Experimental Social Psychology, 26, 82-92.
Schittekatte, M., & Hiel, A. V. (1996). Effects of partially shared information and awareness of unshared information on information sampling. Small Group Research, 27, 431-449.
Simons, T., Pelled, L. H., Smith, K. A. (1999). Making use of difference: Diversity, debate, and decision comprehensiveness in top management teams. Academy of Management Journal, 42, 662-673.
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.
Stasser, G. & Titus, W. (1987). Effects of information load and percentage of common information on the dissemination of unique information during group discussion. Journal of Personality and Social Psychology, 53, 81-93.
Stasser, G. (1988). Computer simulation as a research tool: The DISCUSS model of group decision making. Journal of Experimental and Social Psychology, 24, 393-422.
Stasser, G., & Stewart, D. D. (1992). Discovery of hidden profiles by decision-making groups: Solving a problem versus making a judgment. Journal of Personality and Social Psychology, 63, 426-434.
Stasser, G., & Stewart, D. D., & Wittenbaum, G. M. (1995). Expert roles and information exchange during discussion: The importance of knowing who knows what. Journal of Experimental Social Psychology, 31, 224-265.
Stasser, G., Vaughan, S. I., & Stewart, D. D. (2000). Pooling unshared information: The benefits of knowledge how access to information is distributed among group members. Organizational Behavior and Human Decision Processes, 82, 102-116.
Stewart, D. D., & Stasser, G. (1995). Expert role assignment and information sampling during collective recall and decision making. Journal of Personality and Social Psychology, 69, 619-628.
Tesser, A., & Cornell, D. P. (1991). On the confluence of self processes. Journal of Experimental Social Psychology, 27, 501-526.
Wegner, D. M. (1986). Transactive memory: A contemporary analysis of the group mind. In B. Mullen & G. R. Goethals (Eds.), Theories of Group Behavior (pp. 185-208). New York: Springer-Verlag.
Winquist, J. R., & Larson, J. R. (1998). Information pooling: When it impacts group decision-making. Journal of Personality and Social Psychology, 74, 371-377.
Wittenbaum, G. M. (1998). Information sampling in decision-making groups: The impact oh member’s task-relevant status. Small Group Research, 29, 57-84.
Wittenbaum, G. M. (2000). The bias toward discussing shared information: Why are high status group members immune? Communication Research, 27, 379-401.
Wittenbaum, G. M., Hubbell, A. P., & Zuckerman, C. (1999). Mutual enhancement: Toward an understanding of the collective preference for shared information. Journal of Personality and Social Psychology, 77, 967-978.
Wittenbaum, G. M., & Park, E. S. (2001). The collective preference for shared information. American Psychology Society, 10, 70-73.
Zajonc, R. B. (1968). Attitudinal effects of mere exposure. Journal of Personality and Social Psychology, 9, 1-28.