Social density processes regulate the functioning and performance of foraging human teams

Abstract

Social density processes impact the activity and order of collective behaviours in a variety of biological systems. Much effort has been devoted to understanding how density of people affects collective human motion in the context of pedestrian flows. However, there is a distinct lack of empirical data investigating the effects of social density on human behaviour in cooperative contexts. Here, we examine the functioning and performance of human teams in a central-place foraging arena using high-resolution GPS data. We show that team functioning (level of coordination) is greatest at intermediate social densities, but contrary to our expectations, increased coordination at intermediate densities did not translate into improved collective foraging performance, and foraging accuracy was equivalent across our density treatments. We suggest that this is likely a consequence of foragers relying upon visual channels (local information) to achieve coordination but relying upon auditory channels (global information) to maximise foraging returns. These findings provide new insights for the development of more sophisticated models of human collective behaviour that consider different networks for communication (e.g. visual and vocal) that have the potential to operate simultaneously in cooperative contexts.

Group size, communication, and familiarity effects in foraging human teams

“…There is evidence of this here: Smaller teams showed greater variation in foraging performance when compared to larger teams ( SD in proportion of “good” tokens collected = 10.88 vs. 4.98). If we compare our data to that collected using the same experimental paradigm in previous work (King et al., , ), we find the same pattern: Variance in proportion of “good” forage collected decreases with increasing foraging team size (Figure ). Thus, we cannot say for certain whether this is due simply to larger groups being able to search more patches and arrive at a consensus on the optimal patch more quickly, via observation and trial‐and‐error searching, or whether they did this by communicating their findings with each other.…”

“…Participant behavior was observed in a circular arena (diameter 6.4 m) containing six perimeter foraging patches (flip‐door plastic waste containers) arranged radially and equidistant at 3.2 m from a central home base (two plastic waste containers with slits for depositing tokens) equidistant from one another at 3.4 m apart ( sensu King et al., , ). Foraging patches each contained a mix of 500 “good” (red) and “bad” (yellow) tokens and foraging patches varied in quality from 5, 35, 50, 65, to 95 percent red tokens (Figure ).…”

“…Aware of the limitations in this approach, we opted for a middle‐ground social foraging paradigm, providing a more ecologically valid method than economic games, while also allowing for much more experimental control than traditional ethnographic field studies. Indeed, previous studies using this design have demonstrated the utility of this method, suggesting that small communicating groups forage more effectively than noncommunicating groups (Sumner & King, ), and that coordination, but not performance, is compromised at high forager densities (King et al., ). However, it is not known if, or how, other factors mediate the speed and accuracy of foraging human teams, especially in larger groups; indeed, there are clearly numerous potential mechanisms by which groups can reach consensus on the best foraging patches (King et al., ).…”

“…Indeed, previous studies using this design have demonstrated the utility of this method, suggesting that small communicating groups forage more effectively than noncommunicating groups (Sumner & King, ), and that coordination, but not performance, is compromised at high forager densities (King et al., ). However, it is not known if, or how, other factors mediate the speed and accuracy of foraging human teams, especially in larger groups; indeed, there are clearly numerous potential mechanisms by which groups can reach consensus on the best foraging patches (King et al., ). That said, given the importance of group size, communication, social bonding and cooperation in both humans and other animals (Freeberg, Dunbar, & Ord, ; King & Sueur, ; Tomasello, , ; Tomasello et al., ), we expected that these processes similarly regulate the functioning and performance of humans in a cooperative foraging task.…”

“…Search costs of foraging can be reduced, and group performance improved, if foragers cooperate by coordinating their behavior and exchanging information about encountered food items (Galef & Giraldeau, ; Laland, ; Tomasello, , ; Tomasello, Melis, Tennie, Wyman, & Herrmann, ; Valone, ). Although this requires that groups make fast, accurate consensus decisions about where and when to forage, we nonetheless know relatively little about what factors predict speed or accuracy of group decisions (King et al., , ). Such knowledge may have important consequences for understanding the functioning of modern day teams and organisations (Dyer, Johansson, Helbing, Couzin, & Krause, ; Pentland, ).…”