Phase transition to two-peaks phase in an information cascade voting experiment
/* https://arxiv.org/pdf/1112.2816.pdf */
Observational learning is an important information aggregation mechanism. However, it occasionally leads to a state in which an entire population chooses a sub-optimal option. In this study, the researchers conducted an experiment in which subjects answered a two-choice quiz sequentially with and without information about the prior subjects’ choices. The subjects who could copy others are called herders.
The instinct to imitate others led to the remarkably slow convergence of information aggregation as the herder’s ratio p approached 100%. A stochastic model based on the herder’s microscopic copying rule predicted the information cascade transition between the one-peak (p < pc) and the two-peaks phases (p > pc). In the one-peak phase, information aggregation works and the majority’s choice is always correct when the independents choose the correct choice rather than the incorrect one. In the two-peaks phase, the majority’s choice is not necessarily correct. The coexistence of the optimal (Z(∞,T) > 1/2) and the sub-optimal (Z(∞, T ) < 1/2) states occurs there.
Couple limitation in this experiment are the following. The herder does not have information and it is necessary to follow the majority if he wants to choose a correct answer. There occurs a information cascade transition relies heavily on the results of the simulation study of the stochastic model. In addition, the experiments were performed with students at universities, and the scope of the subjects is thus very restricted. The robustness of the conclusion should be established by further experiments.