Deliberation increases the wisdom of crowds

The aggregation of many independent estimates can outperform the most accurate individual judgment. This centenarian finding, popularly known as the 'wisdom of crowds', has recently been applied to problems ranging from the diagnosis of cancer to financial forecasting. It is widely believed that the key to collective accuracy is to preserve the independence of individuals in a crowd. Contrary to this prevailing view, we show that deliberation and discussion improves collective wisdom. We asked a live crowd (N=5180) to respond to general knowledge questions (e.g. the height of the Eiffel Tower). Participants first answered individually, then deliberated and made consensus decisions in groups of five, and finally provided revised individual estimates. We found that consensus and revised estimates were less biased and more diverse than what a uniform aggregation of independent opinions could achieve. Consequently, the average of different consensus decisions was substantially more accurate than aggregating the independent opinions. Even combining as few as four consensus choices outperformed the wisdom of thousands of individuals. Our results indicate that averaging information from independent debates is a highly effective strategy for harnessing our collective knowledge.

[1]  Michelle K. Smith,et al.  Why Peer Discussion Improves Student Performance on In-Class Concept Questions , 2009, Science.

[2]  S. Asch Opinions and Social Pressure , 1955, Nature.

[3]  D. Sperber,et al.  "Two heads are better" stands to reason. , 2012, Science.

[4]  F. Galton One Vote, One Value , 1907, Nature.

[5]  J. Bohman,et al.  Deliberative Democracy: Essays on Reason and Politics , 1997 .

[6]  N. Dalkey,et al.  An Experimental Application of the Delphi Method to the Use of Experts , 1963 .

[7]  Lu Hong,et al.  Groups of diverse problem solvers can outperform groups of high-ability problem solvers. , 2004, Proceedings of the National Academy of Sciences of the United States of America.

[8]  M. Sigman,et al.  Neglect in Human Communication: Quantifying the Cost of Cell-Phone Interruptions in Face to Face Dialogs , 2015, PloS one.

[9]  N. Harvey,et al.  Taking Advice: Accepting Help, Improving Judgment, and Sharing Responsibility☆☆☆ , 1997 .

[10]  S. Huffmon Expert Political Judgment: How Good Is It? How Can We Know? , 2006 .

[11]  C. Sunstein Infotopia: How Many Minds Produce Knowledge , 2006 .

[12]  Richard P. Larrick,et al.  The wisdom of select crowds. , 2014, Journal of personality and social psychology.

[13]  David Moshman Molly Geil,et al.  Collaborative Reasoning: Evidence for Collective Rationality , 1998 .

[14]  D. Helbing,et al.  How social influence can undermine the wisdom of crowd effect , 2011, Proceedings of the National Academy of Sciences.

[15]  C. Frith,et al.  Equality bias impairs collective decision-making across cultures , 2015, Proceedings of the National Academy of Sciences.

[16]  D. Myers,et al.  The group polarization phenomenon. , 1976 .

[17]  P. Latham,et al.  References and Notes Supporting Online Material Materials and Methods Figs. S1 to S11 References Movie S1 Optimally Interacting Minds R�ports , 2022 .

[18]  Tamara Niella,et al.  Nudging Cooperation in a Crowd Experiment , 2016, PloS one.

[19]  J. Dessalles,et al.  Arguing, reasoning, and the interpersonal (cultural) functions of human consciousness , 2011, Behavioral and Brain Sciences.

[20]  Christophe Ley,et al.  Detecting outliers: Do not use standard deviation around the mean, use absolute deviation around the median , 2013 .

[21]  Gonzalo G. de Polavieja,et al.  Improving Collective Estimations Using Resistance to Social Influence , 2015, PLoS Comput. Biol..

[22]  Matthew D. Lieberman,et al.  Does Rejection Hurt? An fMRI Study of Social Exclusion , 2003, Science.

[23]  H. Sebastian Seung,et al.  A solution to the single-question crowd wisdom problem , 2017, Nature.

[24]  P. R. Laughlin,et al.  Groups perform better than the best individuals on letters-to-numbers problems: effects of group size. , 2006, Journal of personality and social psychology.