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Wisdom of Individuals versus Wisdom of Crowds

Temnothorax rugatulus

A group of Temnothorax ants labeled with different colors. *Image source: Alex Wild.

Researchers have long recognized the advantages of collective intelligence during the performance of goal-oriented tasks by social animals. However, sometimes individual insight may outweigh collective intelligence in certain situations. Whether individual insight or collective intelligence is better depends on the nature and difficult of tasks. In order to determine the circumstances when one of the two outweigh the other, Takao Sasaki and co-workers from University of Arizona, conducted a study on Temnothorax rugatulus (Temnothorax ants) , known for their house-hunting skills, and found that individual choices outperform collective choices on easy tasks while the wisdom of crowds might be more advantageous for difficult tasks. The new findings has been published on recent PNAS.

The researchers prepared a dark box (control) and a bright box, both of which are darker than the ants’ original nest site. They enticed the ants to abandon the original nest and nest in the new sites. Temnothorax ants prefer dark places, hence, choosing to nest in darker box can be seen as a right choice. In the experiment, the researchers tried to make sure all conditions of the dark box and the bright box were better than the original nest. By varying quality, represented by the level of the sites’ interior brightness, the researchers continuously decreased the difference between the bright box and the original nest and recorded the times that temnothorax ants made the right choice, both individually and collectively.

 Temnothorax experiment setup

Selective nesting experiment: the left top image is the dark box (control), which is better in all conditions than the original nest (the below image). The right top image shows the bright box as the comparison nest. *Image source: Takao Sasaki et al. Ant colonies outperform individuals when a sensory discrimination task is difficult but not when it is easy. PNAS 2013

From the statistical report, the authors report that when the qualitative differences between the alternative nest sites choices were small, colonies were more likely to choose the better of two nest sites than individual ants. On the contrary, when the qualitative difference between the choices were large, individuals outperformed colonies in choosing the better site, suggesting that the collective intelligence may be more advantageous for difficult perception and discrimination tasks than for simple ones.

Using a mathematical model, the researchers discovered that positive feedback between colony members could help the colony integrate information and outweigh individual insights in tasks that call for perception of subtle differences. However, such a feedback mechanism may result in suboptimal choices of colonies during the performance of relatively easy perception tasks.

The researchers noted that the findings might help us understand the conditions under which collective decision-making and individual judgment should be selectively applied.

 a group of Temnothorax ants

The temnothorax ants used in this study. Each of the ants was labeled with unique colors. *Image source:James S. Waters & Takao Sasaki.

two Temnothorax ants

The leader temnothorax ant (below) is guiding another ant to the new nest site. *Image source: James S. Waters & Takao Sasaki.

Temnothorax ants and new nest
A group of temnothorax ants gathered around the nest site. *Image source: James S. Waters & Takao Sasaki.

Image sourceJames S. Waters & Takao Sasaki;Alex Wild