Biases in Collective Decision-Making – Part 3

We come to our last article on biases in collective decision-making. In the previous articles we dealt with the first two biases, that of groupthink and bias of information sharing. The last bias we will discuss is that of the phenomenon of polarization or the group polarization.


What is group polarization? 

This phenomenon with a rather barbaric name is defined in 1976 by David G. Myers (1). He describes it as “the accentuation of the tendency initially dominant in the group”. This accentuation intervenes whatever the subject of the conversation. The origin of group polarization comes from risky shift, a phenomenon which also appears within groups, but which is defined as the tendency to move towards the most risky decisions.
To illustrate the phenomenon of polarization, here is a short experiment realized by Marisa Zavalloni and Serges Moscovici in 1969 (2):

Individuals need to think about a decision individually, on a given topic of discussion. After making a decision individually, they are grouped together  to find a consensus decision. Then, finally, the group is again broken up, and individuals have to decide on their final decision.

Following these different conditions, the final decision of each group member evolved towards the group’s most extreme position.


For a group to be in a situation of polarization, 4 conditions must be concomitant:

  • The phenomenon always revolves around a discussion.
  • The points of view of members of the group are diverse and create exchanges.
  • The diversity of trade is part of a trend corresponding to the current intellectual climate of the time (also known as the Zeitgeist).
  • Involvement of members in the discussion. It will depend on the affinity of  members of the group with the topic of discussion launched. Engagement in the discussion will also depend on the spatial organization of the group, if members are face-to-face, the polarization will tend to emerge more quickly since there will be many more dialogues.

For example, in 1977, Geneviève Paicheler (3) wanted to verify the conditions of implementation of the phenomenon of polarization, and more particularly that of the Zeitgeist:

The experience takes place while the feminist movement is very present in France. An accomplice of the experimenter infiltrated within a group of feminists and defended either a feminist point of view or an anti-feminist point of view. When the feminist point of view was forbidden,  attitudes of  members of the (women) group were accentuated. But as soon as the accomplice defended a contrary point of view, the point of view of members of the group did not increase and did not suffer a decrease.

Here, we note that the phenomenon of polarization corresponds to an accentuation of the way of thinking which existed beforehand, within the group.

The phenomenon of polarization, as soon as it is installed in a group, has several consequences. Maria Augustinova and Dominique Oberlé, in 2013 (4) reveal two possible consequences:

  • Polarization as a dangerous phenomenon of the group: especially for groups advocating violence such as terrorists. It is an extreme of positions of all members of the group.
  • Polarization as a faculty of innovation: it would allow non-existent positions in the group, to see the light of day. Indeed, polarization could promote a change in habits through active participation in discussions.

We know how the phenomenon of polarization appears and certain consequences when it takes place within a group. But why does this happen?

Some authors have given us some explanations. Here are three that could explain the phenomenon.

Explanations of group polarization, 

Explanation 1:

First of all, remember, we discussed in the first article about the group, the concept of prototyping. In 1970, Henri Tajfel (5) announced that the prototypical position of a group made it possible to distinguish itself from other groups. Polarization is characterized by the search for this position, which is ideal for all members.

Explanation 2:

Michael Brauer, Charles M. Judd and Melissa D. Gliner, in 1998 (6) introduce the intra-personnel factor. When a member of the group repeats the content of an attitude, it strengthens that attitude. Similarly, the more information is repeated by someone, the more the phenomenon of polarization will take hold.

Explanation 3:

Polarization may be due to the strengthening of the initial trend present in the group. This reinforcement would result from the taking into account and taking into account in a discussion, new arguments in favor of this trend.



The phenomenon of polarization is a state of the group by which members make decisions. It evidently biases these by accentuating them. We will retain that this phenomenon can allow the worst as the best within groups. Authors do not specifically find ways to avoid it, but we know today, how it happens and why it appears.

Here ends the trilogy of articles on collective decision-making biases. Today three are scientifically known and validated. But people in their social relations are entities in constant motion. The environment, culture, etc. play an important role in the evolution of groups. It would not be surprising to see a bias in the coming years, based on the use of new technologies.

If you found this article interesting and if you have an idea about the future evolution of the groups, feel free to comment. 

Références :

(1) : Myers, D;g., & Lamm, H. (1976). The Group Polarization Phenomenon. Psychological Bulletin, 83 (4), 602-627.

(2) : Moscovici, S., & Zavalloni, M. (1969). the group as a polarizer of attitudes. Journal of Personality and social Psychology, 12, 125-135.

(3) : Paicheler, G. (1977). Norms and attitude change II: The phenomenon of bipolarization. European Journal of Social Psychology, 7, 1-14.

(4) : Augustinova, M., & Oberlé, D. (2013). Psychologie sociale du groupe au travail : Réfléchir, travailler et décider. Paris : de Boeck

(5) : Tajfel, H. (1970). Experiments in intergroup descrimination. Scientific American, 223, 96-102.

(6) : Brauer, M., Judd., C.M., & Gliner, M.D. (1998). L’influence de la verbalisation répétée sur la polarisation des attitudes. In J.L. Beauvois, R.V. Joule, & J.M. Monteil (Eds.), Perspectives cognitives et conduites sociales (Vol. 6). Neuchâtel : Delachaux et Niestlé.

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