Accurate decisions in an uncertain world: collective cognition increases true positives while decreasing false positives

Abstract

In a wide range of contexts, including predator avoidance, medical decisionmaking and security screening, decision accuracy is fundamentally constrained by the trade-off between true and false positives. Increased true positives are possible only at the cost of increased false positives; conversely, decreased false positives are associated with decreased true positives. We use an integrated theoretical and experimental approach to show that a group of decision-makers can overcome this basic limitation. Using a mathematical model, we show that a simple quorum decision rule enables individuals in groups to simultaneously increase true positives and decrease false positives. The results from a predator-detection experiment that we performed with humans are in line with these predictions: (i) after observing the choices of the other group members, individuals both increase true positives and decrease false positives, (ii) this effect gets stronger as group size increases, (iii) individuals use a quorum threshold set between the average true-and false-positive rates of the other group members, and (iv) individuals adjust their quorum adaptively to the performance of the group. Our results have broad implications for our understanding of the ecology and evolution of group-living animals and lend themselves for applications in the human domain such as the design of improved screening methods in medical, forensic, security and business applications.

Fitness landscapes among many options under social influence

“…Numerous studies suggest that about 5% of informed individuals are enough to guide a social group (e.g., schooling fish) to a destination Wolf et al, 2013;. Among that minority, this "pied piper" effect is augmented by intensity of direction , which we might generalize as the "intensity of choice" , or the accumulation of knowledge .…”

A reappreciation of ‘conformity’

“…Moreover, for reasons of informational accuracy, it may well matter if one individual 'cries wolf' 10 times, or if 10 individuals (independently) do so once (e.g. see Wolf, Kurvers, Ward, Krause, & Krause, 2013). We conjecture that the adaptive value of relying on indiscriminate sampling of behaviours versus relying on the aggregate knowledge of similarly poised, unpredictabilityreducing conspecifics will differ to the extent that under certain conditions, one particular bias is expected to evolve (at the expense of the other).…”

Ants work harder during consensus decision-making in small groups

“…In a wide range of animals including fish [8], some primates [5] and insects [9,10], decisions are shared among a variable proportion of the group, and a group-level consensus manifests as an emergent product of the combined actions of multiple individuals [1,4]. Shared decisions allow information to be pooled, and this 'wisdom of the crowds' effect has long been recognized as a means by which groups can make more accurate decisions than individuals [3,[11][12][13][14][15][16]. Group size varies markedly between and within animal societies, however, raising the question of how small groups perform relative to large groups, and how investment in decisionmaking varies with group size.…”