抄録
Collective intelligence is a mechanism to aggregate information held by many agents and generate
useful information. In order for the generated information to be useful, it is a sufficient condition that
the agents should independently generate information to be aggregated. On the other hand, in the case
of humans, as they give priority to the return of each individual, not to the accuracy of the collective
intelligence, they often use social learning and imitate the choices and actions of others. Independence of
information to be aggregated is not preserved and the collective intelligence mechanism does not function.
We conducted an information cascade experiment using two-choice general knowledge quizzes. When quizzes
are easy, collective intelligence functions and the correct answer rate improves. However, when the quizzes
are difficult, it becomes random whether the correct answer rate improves or deteriorates This change is a
phase transition due to a change in the number of stable states of nonlinear Polya urn process. The essence
of the phase transition is whether the in
uence of the rst subject's choice (Domino effect) percolates or not
in the in nitely long subjects' sequence.
