Monday, September 30, 2013

Collective Decision Making Fail

Field study shows group decision making not always the best
Aug 1, 2013,

team studies ants looking for a new nest:

The team noted that when one of the nests was obviously far superior to the other, both the colony as a whole, and individual ants more often chose the better option. What was surprising, however, was that individuals had a slightly better hit rate then the colony as a whole.

When a colony "decides" it needs a new nest, scout ants are sent out to find a new site. When one of the scout ants finds one it likes, it releases a chemical that attracts another of the colony members. If that member also likes the site it too will release a chemical attracting another ant and so on. The site that gets the most "votes" is the one eventually chosen by the colony. But, when a single ant is forced (by the researchers) to make a decision about which site to pick, it has to look at all the options and make a decision on its own—that takes more time than the multiple ant approach because in that scenario, individual ants only ever review one site—its more efficient. It's also more likely to lead to errors of course and that's why the colony as a whole tended to choose the wrong best site more often than the single ants—when the choice was obvious—who could make the decision without having to waste time thinking it over.

Ant colonies outperform individuals when a sensory discrimination task is difficult but not when it is easy, PNAS, Published online before print July 29, 2013, doi: 10.1073/pnas.1304917110

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