The Myopia of Crowds: A Study of Collective Evaluation on Stack Exchange

TL;DR

This study examines how users on Stack Exchange rely on simple visual cues and heuristics, rather than comprehensive evaluation, to select best answers, which may impair collective decision accuracy as answer volume increases.

Contribution

It reveals the cognitive heuristics influencing answer selection on Stack Exchange and highlights their impact on the reliability of crowd judgments.

Findings

Users rely on answer salience and order as heuristics.

Acceptance of an answer influences voting behavior.

Heuristics become more influential with more answers.

Abstract

Crowds can often make better decisions than individuals or small groups of experts by leveraging their ability to aggregate diverse information. Question answering sites, such as Stack Exchange, rely on the "wisdom of crowds" effect to identify the best answers to questions asked by users. We analyze data from 250 communities on the Stack Exchange network to pinpoint factors affecting which answers are chosen as the best answers. Our results suggest that, rather than evaluate all available answers to a question, users rely on simple cognitive heuristics to choose an answer to vote for or accept. These cognitive heuristics are linked to an answer's salience, such as the order in which it is listed and how much screen space it occupies. While askers appear to depend more on heuristics, compared to voting users, when choosing an answer to accept as the most helpful one, voters use acceptance itself as a heuristic: they are more likely to choose the answer after it is accepted than before that very same answer was accepted. These heuristics become more important in explaining and predicting behavior as the number of available answers increases. Our findings suggest that crowd judgments may become less reliable as the number of answers grow.