Data from: Group choices seemingly at odds with individual preferences

Numerous studies have focused on the influence of the social environment and the interactions between individuals on the collective decision-making of groups. They showed, for example, that attraction between individuals is at the origin of an amplification of individual preferences. These preferences may concern various environmental cues such as biomolecules that convey information about the environment such as vanillin, which, for some insects, is an attractant. In this study, we analysed how the social context of the cockroaches of the species Periplaneta americana modifies preferences when individuals are offered two shelters, of which one is vanillin scented. One of the principal results of our study is that isolated individuals stay longer and more frequently in a vanillin-scented shelter, while groups choose more frequently the unscented one. Moreover, the proportion of sheltered insects is larger when the group selects the unscented shelter. Our experimental results and theoretical model suggest that the individual preference is not inverted when insects are in a group but, rather, the response to vanillin decreases the attraction between individuals. As a result, aggregation is favoured in the unscented shelter, leading therefore to a collective inversion.已有大量研究围绕社会环境的影响效应，以及个体间互动对群体集体决策的作用机制展开。例如，此类研究证实，个体间的吸引作用是个体偏好放大效应的源头。这类偏好可指向各类环境线索，例如传递环境信息的生物分子——香兰素（vanillin），其对部分昆虫而言属于引诱剂。本研究以美洲大蠊（Periplaneta americana）为研究对象，分析其社会背景如何改变个体偏好：实验为试虫提供两处庇护所，其中一处带有香兰素气味。本研究的核心结果之一显示：孤立个体在带有香兰素气味的庇护所内停留时长更久、频次更高，而群体则更倾向于选择无气味的庇护所。此外，当群体选择无气味庇护所时，聚集于庇护所内的试虫比例更高。我们的实验结果与理论模型均表明：昆虫处于群体环境中时，其个体偏好并未发生反转，反而对香兰素的响应会削弱个体间的吸引作用。由此，无气味庇护所更易促成个体聚集，最终引发集体决策的反转。