The Informative Herd: why humans and other animals imitate more when conditions are adverse

TL;DR

This paper proposes a general decision-making model based on estimating the probability that options are good, explaining why humans and animals imitate more in adverse conditions across diverse species and contexts.

Contribution

It introduces a novel model of social decision-making that accounts for increased imitation in negative situations, unifying diverse observations across taxa.

Findings

Enhanced imitation occurs in negative situations across species.

The proposed model accurately predicts increased imitation behavior.

Fish and human data support the model's predictions.

Abstract

Decisions in a group often result in imitation and aggregation, which are enhanced in panic, dangerous, stressful or negative situations. Current explanations of this enhancement are restricted to particular contexts, such as anti-predatory behavior, deflection of responsibility in humans, or cases in which the negative situation is associated with an increase in uncertainty. But this effect is observed across taxa and in very diverse conditions, suggesting that it may arise from a more general cause, such as a fundamental characteristic of social decision-making. Current decision-making theories do not explain it, but we noted that they concentrate on estimating which of the available options is the best one, implicitly neglecting the cases in which several options can be good at the same time. We explore a more general model of decision-making that instead estimates the probability that each option is good, allowing several options to be good simultaneously. This model predicts with great generality the enhanced imitation in negative situations. Fish and human behavioral data showing an increased imitation behavior in negative circumstances are well described by this type of decisions to choose a good option.