July 24, 2009

Are Ants More Rational Than Humans?

University researchers suggest that ants can accomplish a task more rationally than humans.

However, this doesn't necessarily mean that people are "stupider" than ants, according to the research teams from Arizona State University and Princeton University.

Study leaders Stephen Pratt and Susan Edwards say that humans and animals simply often make irrational choices when faced with very challenging decisions.

Pratt wrote in the journal Proceedings of the Royal Society: Biological Sciences that this paradoxical outcome is based on apparent constraint, as most individual ants know of only a single option, and the colony's collective choice self-organizes from interactions among many poorly-informed ants.

The researchers studied the process of nest selection in the ant, Temnothorax curvispinosus "“ a type of ant that establishes colonies in cavities as small as an acorn and are skillful in finding new places to roost.

The challenge before the colony was to "choose" a nest, when offered two options with very similar advantages.

The team discovered that in collective decision-making, the ants lack of individual options translated into more accurate outcomes by minimizing the chances for individuals to make mistakes.

Pratt believes this leads to a "wisdom of crowds" approach during their normal activities.

"Rationality in this case should be thought of as meaning that a decision-maker, who is trying to maximize something, should simply be consistent in its preferences," Pratt said.

For example, animals trying to maximize their fitness should always rank options such as food sources, mates, or nest sites according to their fitness contribution.

He explained that if the fitness returns of two different options have not changed, that means that it would be irrational to prefer choice 'A' to 'B' on Tuesday and then to prefer 'B' to 'A' on Wednesday.

"Typically we think having many individual options, strategies and approaches are beneficial," Pratt adds, "but irrational errors are more likely to arise when individuals make direct comparisons among options."

Prior research over the occurrence of irrationalities has offered insight into cognitive mechanisms and constraints, as well as how collective decision-making occurs.

The researcher's discoveries could one day translate into new approaches in the development of artificial intelligence.

"A key idea in collective robotics is that the individual robots can be relatively simple and unsophisticated, but you can still get a complex, intelligent result out of the whole group," said Pratt, a member of Heterogeneous Unmanned Networked Team (HUNT), a project to enable to development of bio-inspired solutions to engineering problems.

He said the ability to function without complex central control is really desirable in an artificial system.

"The idea that limitations at the individual level can actually help at the group level is potentially very useful," he added.

He acknowledged that it was difficult to determine what these findings potentially say about understanding human social systems.

"It's at least worth entertaining the possibility that some strategic limitation on individual knowledge could improve the performance of a large and complex group that is trying to accomplish something collectively," he concluded.


Image Caption:  Ants are more rational collective decision makers than humans. Credit: Stephen Pratt/Arizona State University


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