Effects of Personality Distribution on Collective Behavior

Abstract

Optimizing group success is challenging for multi-robot systems, especially for large systems such as robot swarms where even simple individual interaction rules can lead to complex group behavior. Studies of natural systems have shown that heterogeneous groups can outperform homogeneous groups, especially when individual differences lead to role or niche specialization. This happens even when the individuals are seemingly identical. Although individuals within a group may appear physically identical, they can vary widely in their personality, which significantly affects their behavior. However, determining the most effective composition of personalities in a group is particularly difficult in natural systems given the ambiguities of animal personalities and the physical challenges of repeated evaluations. Using a biologicallybased collective movement model, we evaluate different personality distributions to determine their effect on the overall success of the group. Results show that although there are distributions that are clearly more effective than others, in many cases, there is a broad range of distributions that results in high group success. Furthermore, experiments using variable, or adaptive, personalities demonstrate that successful distributions are stable equilibriums as initially extreme distributions converge to these successful distributions as personalities change.

Task syndromes: linking personality and task allocation in social animal groups

“…They also can experience increased foraging success ( Dyer et al 2009a ; Pruitt et al 2012; Aplin et al 2014; Pruitt and Keiser 2014 ) and more effective anti-predator behavior ( Wright et al 2016 ). Additionally, the efficiency of collective movement to resources can improve with increased among-individual variation in behavior ( Couzin et al 2005 ; Dussutour et al 2008 ; Nicolis et al 2008 ; Michelena et al 2010 ; Eskridge and Schlupp 2014 ; Planas-Sitja et al 2015 ). Fitness in groups with greater among-individual variation can also be more robust to variable environments than that of homogeneous groups ( Goulet et al 2016 ).…”

Variation in personality can substitute for social feedback in coordinated animal movements

“…where the P J of a given responder r within a group of N individuals depends on a single parameter α′. This can be understood as a parameter defining the magnitude of a personality trait 27,43,53 , which influences collective movement decisions by altering the individual probability of joining, with higher values associated with lower joining probability. In our model, the parameter α′ has no effect on the probability of initiating a movement.…”

“…Capuchin monkeys are arboreal primates that form small groups (4-40 individuals) of multiple males/females of different ages and must collectively move between foraging sites frequently (see Methods for more details). The dataset used by Petit et al 10 comprised 255 collective movements of a group of Capuchin monkeys, which has been the focus of a series of theoretical and observational studies 10,42,43 , including the original model in Eqs. 1 and 2.…”

“…Thus, the initial movement will become a collective movement only if a number of other individuals follow the initiator 42 . These movements are characterised by an all-ornothing, U-shaped, pattern of the number of responders following the initiator 10,[42][43][44] . Thus, initiations that are not joined are common but unsuccessful, those joined by many individuals are common and successful, while intermediate numbers of joiners are rare (see Fig.…”

“…However, most of these previous studies have excluded the potential effects of variability among individuals. Recent models of self-organised processes indicate that personality variation among group members 27,43 and social affiliation between individuals [53][54][55] are important for explaining the emergence of collective patterns. For instance, several authors have shown that, against theoretical expectations, some individuals can be more successful initiators 42,50,53 or more inclined to follow 52,54 than others during collective decisions.…”