Taking a Quick Vote Under Pressure

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Science  24 Oct 2003:
Vol. 302, Issue 5645, pp. 537
DOI: 10.1126/science.302.5645.537c

When making decisions, individual animals face a tradeoff between speed and accuracy (or between reaction time and error rate). When time is limited—for instance, when environmental conditions are adverse—the accuracy of decisions may be compromised.

Franks et al. investigated whether such tradeoffs exist when decision-making involves many individuals. Their experimental subject is an ant species, Leptothorax albipennis, which uses “quorum sensing” when choosing a new nest site: Once a certain threshold number of individual ants gather at a potential new nest site, there is an acceleration in the recruitment of the remaining colony members. Under harsh conditions such as wind, the househunting ants choose a new site more rapidly, by lowering the quorum threshold needed for site selection. In these circumstances, where fewer individuals are effectively making the decision, the ants are more prone to choose inferior sites even when aware of the presence of better sites. Under benign conditions, the quorum threshold is raised, and the ants take their time. — AMS

Proc R. Soc. London Ser. B 10.1098/rspb.2003.2527 (2003).

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