A3 Information cascade in committee

Topic

The committee information cascade is the third anomaly in this category, describing a mechanism distinct from both groupthink and analysis paralysis: each committee member mimics the first speaker, setting aside their own information rather than contributing it to the deliberation. Unlike groupthink—where dissent is silenced for fear of social sanction by the group—here, each member may be acting perfectly rationally from their own perspective: they infer, based on what previous speakers said or how they voted, that this accumulated information outweighs their own, and they adjust their contribution accordingly.

The variable triggering this anomaly is the correlation between the order of speaking or voting and the final outcome—as opposed to the correlation between that outcome and the information actually available to the group. As long as the outcome remains primarily correlated with the available information, each contribution adds something new to the deliberation; however, when the order of speaking predicts the outcome better than the available information does, the group has ceased to aggregate information and has instead begun to aggregate merely the sequence in which members spoke.

This anomaly shares a superficial symptom with groupthink—a convergence that excludes relevant information available to the group—but arises through a different process: groupthink suppresses dissent due to social pressure regarding group cohesion, whereas the committee information cascade leads members to discard their own information based on a rational, albeit mistaken, inference regarding the relative value of others' information. It also shares its name—though not its mechanism—with the viral misinformation cascade described in the context of social diffusion and contagion: the latter spreads through an extensive network at a speed that outpaces correction, while the former occurs within a small committee, dictated by the very order in which members speak, without requiring an extensive network to materialize.

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