08 March 2013

Ant Crowdsourcing

Welcome back. Before you walk through a doorway and forget everything about last Friday’s blog post, Crowdsourcing and Science, I thought I’d highlight a somewhat related research study. The study was also on crowdsourcing, though the crowdsourcing was by ants--insects, not your parents’ sisters.

Researchers at Arizona State University found that, when faced with too much information about where to locate a new nest site, the ants relied on the wisdom of the crowd.

Ants (multiple websites)

Finding a New Nest

The ant species studied, Temnothorax rugatulus, dwell in relatively small colonies--seldom larger than a few hundred workers--in rock crannies in forests in western U.S. and parts of Europe.

If for whatever reason the ants have to move to a different nest, they execute a highly structured home-finder search, sending scouts out to examine possible nest sites. But since their habitat offers a huge number of possible sites, each scout assesses only a small subset of the sites.

If a scout is happy with what she finds (e.g., size of the entrance and cavity), she returns to the colony, announces her finding via a pheromone chemical, and is accompanied back to the site by another ant.

If that second ant agrees that the site has potential, she will return to the colony and replicate the process with a third ant. If, on the other hand, the second ant isn’t impressed, she goes back and in essence keeps her thoughts about the scout’s taste to herself. If enough ants eventually approve of a site, the colony adopts the new home.

Nest-Finding Experiment

Although T. rugatulus’s nest-finding process does not require individual ants to compare sites, the experiment assessed the nest-comparing ability of single ants versus that of whole colonies. Single ants and colonies were induced to choose between two possible sites, one good, one poor; and also choose from eight possible sites, half of which were good, half poor.

Individual ants did well choosing the better of two sites but often selected a poor site when choosing from the eight sites. In contrast, when colonies were allowed to act as a crowd and send out more than a single scout, they did equally well selecting from two sites or from eight sites.

Wrap Up

The investigators concluded that the individual ants experienced cognitive overload--more options led to worse decisions. By sharing the assessment, the colony avoids overburdening individuals, selects well and survives.

The report extrapolates from ants to humans, noting that with the increase in data for decision-making, cognitive overload is becoming an issue for humans. I’ll accept that, though I thought we accepted it over 15 years ago. I recall managers begging for better tools to manage and integrate data to improve decision making to prevent cognitive overload. Crowdsourcing certainly helped. Thanks for stopping by.


Study report in Current Biology. 22:19:R827-R829 (9 Oct 2012):
Write up of study in Inside Science (5 Nov 2012): http://www.insidescience.org/?q=content/when-ants-get-together-make-decision/834

1 comment:

Bill Teng said...

Interesting. This sounds similar to swarm intelligence of birds, bees, etc. There was a recent (2012) video on Thomas Seeley (Cornell) and swarm intelligence in bees.