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American Association for the Advancement of Science

For decision-making, less information may be more

The starling as an ecologically rational decision-maker: their response to context improves decisions when it matters most.
[Image courtesy of Alejandro Kacelnik]

A study on European starlings shows that when it comes to making decisions, it can help to have less information about the available choices but not always. Whether this "less-is-more" effect comes into play depends heavily on a species' ecological situation, the researchers report.

Here's an example, involving humans, of the less-is-more effect: When asked whether San Diego or San Antonio was the larger city, only two thirds of U.S. college students answered correctly. When students in Germany were asked the same question, they all got it right. This was because the German students had never heard of San Antonio and thus assumed that the city they recognized was larger. Thus, having less information actually helped the students choose the correct answer.

Esteban Freidin and Alex Kacelnik of the University of Oxford now report that that the less-is-more effect works for European starlings when they are choosing from multiple food treats at the same time, but not when they are evaluating a series of treats, one after the other.

The authors trained the birds to peck at colored keys that provided the same treat after different short delays. They also trained the birds to expect the key colors to occur as combinations. This provided more information about each choice.

The researchers found that this extra information hampered the birds' ability to choose the fastest treat when presented with multiple choices. But, when the birds were presented with a sequence of choices, having more information helped them make better choices.

These finding parallel the starlings' natural foraging behavior. As a bird probes the soil with its bill, it will detect a bit of food and then need to decide whether to go after this prey or to move on, expecting something better. The authors propose that for animals that forage in the wild, the ability to remember information about each choice may have been an evolutionary asset.

This research appears in the 18 November 2011 issue of the journal Science.