Collective Personality and Our Environment

We are all familiar with the concept of the personality of an individual. We are less familiar with group- or collective personalities (although most teachers can tell you at length about the personalities of each of their classes). The concept is the same: whereas an individual personality relates to an individual's consistent behaviors across time and contexts, a collective personality relates to a group's consistent behaviors across time and contexts. Collective personalities can be strongly influenced by the composition and size of the animal group, but also by the environment.

Social insects, such as ants, bees, and social spiders, provide interesting examples of collective personalities because their survival is dependent on group decision-making. The architecture of the nest or web of the colony is particularly relevant because the behavior of the colony determines the architecture, but the architecture can also determine the behavior of the colony.

Groups of social spiders were either: 1) allowed to remain in their original web for the duration of the experiment, 2) transferred to a new but similar structure every 9 days, at which point they had to construct a new but similar web, or 3) transferred to a new and different structure every 9 days, at which point they had to construct a new and different web. The spider groups were measured repeatedly for their predatory behaviors on these webs, specifically looking at the time it took for the first individual to move towards the prey, the time it took for the first individual to attack the prey, and the number of attackers.

The researchers found that the time it took to attack and the number of attackers were both consistent and repeatable as long as the web structure was similar (i.e. for the groups allowed to remain in their original webs and for the groups that had to build new but similar webs). This suggests that these may be elements of the collective personalities of these social spider groups. Interestingly, although these personality traits remained the most consistent when the web was undisturbed, they remained fairly consistent even in the extreme condition of complete loss and reconstruction of the web on a similar structure. However, if the spiders were transferred to a new structure and were forced to construct a different type of web, their time to attack and number of attackers were strongly affected. This demonstrates that the consistency of habitat structure plays a key role in the consistency of behavior.

This study has interesting implications for other forms of group behavior: Perhaps destructive group behaviors such as mobbing, rioting, or stampeding could be reduced by significant and frequent changes in the physical environment. On the flip side, if your group is being particularly constructive, try to keep your environment as stable as possible.

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Further reading:

Modlmeier, A.P., Forrester, N.J. and Pruitt, J.N. Habitat structure helps guide the emergence of colony-level personality in social spiders, Behav Ecol Sociobiol (2014) 68:1965-1972. DOI 10.1007/s00265-014-1802-z

Image Credits:

Tinga_2012 05 20_1198 by Harvey Barrison at Wikimedia Commons.