Effects of social group size on information transfer and task allocation

Abstract

SummarySocial animals exchange information during social interaction. The rate of interaction and, hence, the rate of information exchange, typically changes with density and density may be affected by the size of the social group. We investigate models in which each individual may be engaged in one of several tasks. For example, the different tasks could represent alternative foraging locations exploited by an ant colony. An individual's decision about which task to pursue depends both on environmental stimuli and on interactions among individuals. We examine how group size affects the allocation of individuals among the various tasks. Analysis of the models shows the following. (1) Simple interactions among individuals with limited ability to process information can lead to group behaviour that closely approximates the predictions of evolutionary optimality models, (2) Because per capita rates of social interaction may increase with group size, larger groups may be more efficient than smaller ones at tracking a changing environment, (3) Group behaviour is determined both by each individual's interaction with environmental stimuli and by social exchange of information. To keep these processes in balance across a range of group sizes, organisms are predicted to regulate per capita rates of social interaction and (4) Stochastic models show, at least in some cases, that the results described here occur even in small groups of approximately ten individuals.

The effect of individual variation on the structure and function of interaction networks in harvester ants

“…The presence of unusually interactive individuals has an effect on information flow similar to that of two other, not mutually exclusive, well-studied processes: increasing the total number of interactions, and dynamically increasing interaction rate in response to environmental cues. Both of these processes increase the speed of information flow by increasing the rate at which individuals interact [51,65]. Empirical studies show that social insects increase the number of interactions in response to environmental information, as in our Changing model.…”

Specialization and group size: brain and behavioural correlates of colony size in ants lacking morphological castes

“…Typically, when a colony has few individuals, all workers perform similar tasks; but as a colony grows, workers become increasingly more specialized in specific tasks. Theory predicts higher task specialization in larger colonies [5,7,8], but empirical studies to date have generated conflicting support [9][10][11].…”

The response of foraging Argentine ants, Linepithema humile, to disturbance

“…A heightened rate of social interaction increases the speed with which information can spread through a group and may allow individuals to assess environmental danger more rapidly (Adler and Gordon 1992;Gordon et al 1993). Rapid rates of social encounter are facilitated by large or dense groups (Pacala et al 1996). Hence, the decrease in time taken to resume feeding with increasing group size may reflect a heightened rate of information collection and therefore a more rapid decision by disturbed individuals.…”