Working Paper: CEPR ID: DP9098
Authors: Rebecca Morton; Marco Piovesan; Jean-Robert Tyran
Abstract: We experimentally investigate information aggregation through majority voting when some voters are biased. In such situations, majority voting can have a ?dark side?, i.e. result in groups making choices inferior to those made by individuals acting alone. We develop a model to predict how two types of social information shape efficiency in the presence of biased voters and we test these predictions using a novel experimental design. In line with predictions, we find that information on the popularity of policy choices is beneficial when a minority of voters is biased, but harmful when a majority is biased. In theory, information on the success of policy choices elsewhere de-biases voters and alleviates the inefficiency. In the experiment, providing social information on success is ineffective. While voters with higher cognitive abilities are more likely to be de-biased by such information, most voters do not seem to interpret such information rationally.
Keywords: biased voters; information aggregation; majority voting
JEL Codes: C92; D02; D03; D7
Edges that are evidenced by causal inference methods are in orange, and the rest are in light blue.
| Cause | Effect |
|---|---|
| majority of voters are unbiased (D72) | superior outcomes (I14) |
| majority is biased (J15) | inferior choices (D01) |
| social information on the popularity of policies (D72) | lower efficiency (D61) |
| social information about the popularity of policies (D72) | harm decision-making (D91) |
| information about past successes (C52) | help debias voters (D72) |
| social information on success (Z13) | no significant debiasing effect (D91) |