Both information and social cohesion determine collective decisions in animal groups

Abstract

During consensus decision making, individuals in groups balance personal information (based on their own past experiences) with social information (based on the behavior of other individuals), allowing the group to reach a single collective choice. Previous studies of consensus decision making processes have focused on the informational aspects of behavioral choice, assuming that individuals make choices based solely on their likelihood of being beneficial (e.g., rewarded). However, decisions by both humans and nonhuman animals systematically violate such expectations. Furthermore, the typical experimental paradigm of assessing binary decisions, those between two mutually exclusive options, confounds two aspects common to most group decisions: minimizing uncertainty (through the use of personal and social information) and maintaining group cohesion (for example, to reduce predation risk). Here we experimentally disassociate cohesion-based decisions from information-based decisions using a three-choice paradigm and demonstrate that both factors are crucial to understanding the collective decision making of schooling fish. In addition, we demonstrate how multiple informational dimensions (here color and stripe orientation) are integrated within groups to achieve consensus, even though no individual is explicitly aware of, or has a unique preference for, the consensus option. Balancing of personal information and social cues by individuals in key frontal positions in the group is shown to be essential for such group-level capabilities. Our results demonstrate the importance of integrating informational with other social considerations when explaining the collective capabilities of group-living animals.collective intelligence | golden shiner | behaviour | Bayesian U nderstanding the mechanisms of social influence and collective intelligence is a key challenge in contemporary science (1-5) and is essential for achieving progress in a variety of fields ranging from the organization of gregarious and social organisms (6-8) to the dynamics of information exchange in human societies (1-4). In animal groups, effective distributed decision making occurs across a range of taxa and environmental contexts (7, 9-17), making them an excellent model in which to study the evolved capabilities of collectives. Individuals in groups must balance personal information, accumulated from their own past experiences, with potentially conflicting social information, gleaned from the behavior of conspecifics. Additionally, achieving a single consensus choice is often crucial to maintaining group cohesion, and individuals that make a dissenting choice may find themselves isolated, increasing their risk of predation (18). Thus, additional social considerations-such as attempting to minimize the risk of isolation-may bias individual decisions away from what might be predicted from purely informational considerations (19)(20)(21)(22). Both humans (23-25) and nonhuman animals (26-31) have been shown to make such biased decisions, which are not b...

Individual habitat transitions of Atlantic herring Clupea harengus in a human-modified coastal system

“…Older herring are more experienced, repeated spawners, balancing personal information based on past experiences with social information based on the behaviour of other individuals (see e.g. Miller et al 2013). This trade-off, involving higher predation risk, can be explained by higher probability of successful recruitment due to spawning taking place in better conditions (Candolin 1998).…”

Information Flow in Animal-Robot Interactions

“…In social organisms that move in groups, it has been shown that the actions of a few nearest neighbors contribute largely to such cues [2]. In this respect, determining the flow of information between interacting individuals can reveal how they prioritize sensory modalities [3], infer the directionality of information flow [4][5][6], quantify leadership roles in animal groups [7], and determine the effectiveness of engineered stimuli in the laboratory studies [8][9][10]. These motivations to measure information flow are similar to those encountered in the study of networks of dynamical systems, where tools from information theory have been used to detect causal relationships [11][12][13], locate driving nodes [14], and quantify the strength of network connections [15].…”

Emergent oscillations assist obstacle negotiation during ant cooperative transport

“…Finally, the collective motion has to comply with environmental constraints such as boundaries or obstacles (16,17). When analyzing group motion, it is the interaction between these factors that must be considered (9,14,18). Observations suggest that such interactions could trigger transitions between different global modes of collective motion (17).…”