| An Introduction to the work of Stephen Pratt: | ||
| My research addresses how social insects cooperatively perform complex
collective tasks in the absence of any form of central control. I mainly
work on ants of the genus Leptothorax, a colony of which is shown in the
video. These ants are ideal for studying the mechanisms underlying collective
behavior, because their colonies are small enough that all workers can be
individually marked, using tiny drops of paint, and because they thrive
in artificial nests made of cardboard walls sandwiched between microscope
slides. The form of these nests, closely matching the thin rock crevices
or plant cavities that they naturally inhabit, facilitates detailed video
image analysis of every relevant social interaction. These techniques have been applied to a striking example of collective decision-making, in which emigrating colonies choose the better of two nest sites, even when few ants visit both sites. This ability relies on a multi-stage decision process used by the minority of active ants who organize the move. An active ant initiates recruitment to a promising site only after a delay that varies inversely with site quality. Recruitment creates positive feedback on the number of ants visiting the site, but the quality-dependent delay ensures that feedback is stronger to better nests. The ants amplify this difference by using two distinct forms of recruitment: a slow method for their fellow active ants, and a faster method for the passive ants and brood that make up the bulk of the colony. The ants first use the slow method, switching to rapid transport only after a quorum of ants has been summoned to the new site. The quorum requirement raises the accuracy of the colony’s decision by reducing the likelihood of carrying passive ants to an inferior site. In this way, the colony is able to make an informed decision based on all relevant information, even though no single ant knows more than a portion of the problem. |
for additional reading, here is an article
in the journal Science discussing how viewing ants in the
framework of a computer network can further the understanding of their behavior.
Mentioned are Stephen Pratt and Iain Couzin... Getting
the Behavior of Social Insects to Compute |
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