scholarly journals Quorums enable optimal pooling of independent judgements

2018 ◽  
Author(s):  
James Marshall ◽  
Ralf H.J.M. Kurvers ◽  
Jens Krause ◽  
Max Wolf
Keyword(s):  
Decision Making ◽  
Signal Detection ◽  
Signal Detection Theory ◽  
Detection Theory ◽  
Collective Decision ◽  
Majority Voting ◽  
Single Shot ◽  
Collective Decision Making ◽  
Trade Offs ◽  
Speed Accuracy

Majority-voting and the Condorcet Jury Theorem pervade thinking about collective decision-making. Thus, it is typically assumed that majority-voting is the best possible decision mechanism, and that scenarios exist where individually-weak decision-makers should not pool information. Condorcet and its applications implicitly assume that only one kind of error can be made, yet signal detection theory shows two kinds of errors exist, ‘false positives’ and ‘false negatives’. We apply signal detection theory to collective decision-making to show that majority voting is frequently sub-optimal, and can be optimally replaced by quorum decision-making. While quorums have been proposed to resolve within-group conflicts, or manage speed-accuracy trade-offs, our analysis applies to groups with aligned interests undertaking single-shot decisions. Our results help explain the ubiquity of quorum decision-making in nature, relate the use of sub- and super-majority quorums to decision ecology, and may inform the design of artificial decision-making systems.Impact StatementTheory typically assumes that majority voting is optimal; this is incorrect – majority voting is typically sub-optimal, and should be replaced by sub-majority or super-majority quorum voting. This helps explain the prevalence of quorum-sensing in even the simplest collective systems, such as bacterial communities.

scholarly journals Quorums enable optimal pooling of independent judgements in biological systems

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
James AR Marshall ◽  
Ralf HJM Kurvers ◽  
Jens Krause ◽  
Max Wolf
Keyword(s):  
Decision Making ◽  
Signal Detection ◽  
Signal Detection Theory ◽  
Detection Theory ◽  
Collective Decision ◽  
Majority Voting ◽  
Editorial Note ◽  
Single Shot ◽  
Collective Decision Making ◽  
Speed Accuracy

Collective decision-making is ubiquitous, and majority-voting and the Condorcet Jury Theorem pervade thinking about collective decision-making. Thus, it is typically assumed that majority-voting is the best possible decision mechanism, and that scenarios exist where individually-weak decision-makers should not pool information. Condorcet and its applications implicitly assume that only one kind of error can be made, yet signal detection theory shows two kinds of errors exist, ‘false positives’ and ‘false negatives’. We apply signal detection theory to collective decision-making to show that majority voting is frequently sub-optimal, and can be optimally replaced by quorum decision-making. While quorums have been proposed to resolve within-group conflicts, or manage speed-accuracy trade-offs, our analysis applies to groups with aligned interests undertaking single-shot decisions. Our results help explain the ubiquity of quorum decision-making in nature, relate the use of sub- and super-majority quorums to decision ecology, and may inform the design of artificial decision-making systems.Editorial note: This article has been through an editorial process in which the authors decide how to respond to the issues raised during peer review. The Reviewing Editor's assessment is that all the issues have been addressed (<xref ref-type="decision-letter" rid="SA1">see decision letter</xref>).

scholarly journals Speed versus accuracy in decision-making ants: expediting politics and policy implementation

2008 ◽  
Vol 364 (1518) ◽  
pp. 845-852 ◽  
Author(s):  
Nigel R Franks ◽  
François-Xavier Dechaume-Moncharmont ◽  
Emma Hanmore ◽  
Jocelyn K Reynolds
Keyword(s):  
Decision Making ◽  
Quorum Sensing ◽  
Policy Implementation ◽  
Positive Feedback ◽  
High Speed ◽  
Collective Decision ◽  
Collective Decision Making ◽  
Tandem Running ◽  
Trade Offs ◽  
Speed Accuracy

Compromises between speed and accuracy are seemingly inevitable in decision-making when accuracy depends on time-consuming information gathering. In collective decision-making, such compromises are especially likely because information is shared to determine corporate policy. This political process will also take time. Speed–accuracy trade-offs occur among house-hunting rock ants, Temnothorax albipennis . A key aspect of their decision-making is quorum sensing in a potential new nest. Finding a sufficient number of nest-mates, i.e. a quorum threshold (QT), in a potential nest site indicates that many ants find it suitable. Quorum sensing collates information. However, the QT is also used as a switch, from recruitment of nest-mates to their new home by slow tandem running, to recruitment by carrying, which is three times faster. Although tandem running is slow, it effectively enables one successful ant to lead and teach another the route between the nests. Tandem running creates positive feedback; more and more ants are shown the way, as tandem followers become, in turn, tandem leaders. The resulting corps of trained ants can then quickly carry their nest-mates; but carried ants do not learn the route. Therefore, the QT seems to set both the amount of information gathered and the speed of the emigration. Low QTs might cause more errors and a slower emigration—the worst possible outcome. This possible paradox of quick decisions leading to slow implementation might be resolved if the ants could deploy another positive-feedback recruitment process when they have used a low QT. Reverse tandem runs occur after carrying has begun and lead ants back from the new nest to the old one. Here we show experimentally that reverse tandem runs can bring lost scouts into an active role in emigrations and can help to maintain high-speed emigrations. Thus, in rock ants, although quick decision-making and rapid implementation of choices are initially in opposition, a third recruitment method can restore rapid implementation after a snap decision. This work reveals a principle of widespread importance: the dynamics of collective decision-making (i.e. the politics) and the dynamics of policy implementation are sometimes intertwined, and only by analysing the mechanisms of both can we understand certain forms of adaptive organization.

scholarly journals The wisdom of crowds for visual search

2017 ◽  
Vol 114 (21) ◽  
pp. E4306-E4315 ◽  
Author(s):  
Mordechai Z. Juni ◽  
Miguel P. Eckstein
Keyword(s):  
Decision Making ◽  
Visual Search ◽  
Signal Detection ◽  
Signal Detection Theory ◽  
Detection Theory ◽  
Majority Voting ◽  
Weighted Averaging ◽  
Simple Majority ◽  
Wisdom Of Crowds ◽  
The Wisdom Of Crowds

Decision-making accuracy typically increases through collective integration of people’s judgments into group decisions, a phenomenon known as the wisdom of crowds. For simple perceptual laboratory tasks, classic signal detection theory specifies the upper limit for collective integration benefits obtained by weighted averaging of people’s confidences, and simple majority voting can often approximate that limit. Life-critical perceptual decisions often involve searching large image data (e.g., medical, security, and aerial imagery), but the expected benefits and merits of using different pooling algorithms are unknown for such tasks. Here, we show that expected pooling benefits are significantly greater for visual search than for single-location perceptual tasks and the prediction given by classic signal detection theory. In addition, we show that simple majority voting obtains inferior accuracy benefits for visual search relative to averaging and weighted averaging of observers’ confidences. Analysis of gaze behavior across observers suggests that the greater collective integration benefits for visual search arise from an interaction between the foveated properties of the human visual system (high foveal acuity and low peripheral acuity) and observers’ nonexhaustive search patterns, and can be predicted by an extended signal detection theory framework with trial to trial sampling from a varying mixture of high and low target detectabilities across observers (SDT-MIX). These findings advance our theoretical understanding of how to predict and enhance the wisdom of crowds for real world search tasks and could apply more generally to any decision-making task for which the minority of group members with high expertise varies from decision to decision.

Robustness of the a b Signal Detection Theory Model of Decision Making

2007 ◽  
Vol 51 (18) ◽  
pp. 1263-1267
Author(s):  
Ernesto A. Bustamante ◽  
Brittany L. Anderson ◽  
Amy R. Thompson ◽  
James P. Bliss ◽  
Mark W. Scerbo
Keyword(s):  
Decision Making ◽  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Signal Detection ◽  
Signal Detection Theory ◽  
Classical Model ◽  
Empirical Evaluation ◽  
Detection Theory ◽  
Theory Model ◽  
Extreme Responses

Bustamante, Fallon, and Bliss (2006) showed that the a b Signal Detection Theory (SDT) model was more parsimonious, generalizable, and applicable than the classical SDT model. Additionally, they demonstrated that both models provided statistically equivalent and uncorrelated measures of sensitivity and bias under ideal conditions. The purpose of this research was to show the robustness of the a b model for handling extreme responses. We conducted an empirical evaluation of operators' decision-making and two Monte Carlo simulations. Results from the empirical study showed that the a b model provided equivalent yet independent measures of decision-making accuracy and bias, whereas the classical model failed to provide independent measures in the presence of extreme responses. The Monte Carlo simulations showed a similar trend for the superiority of the a b model. Results from this research provide evidence to support the use of the a b model instead of the classical model.

Democracy in the Firm

2021 ◽  
pp. 38-59
Author(s):  
Hervé Crès ◽  
Mich Tvede
Keyword(s):  
Decision Making ◽  
Political Stability ◽  
Collective Decision ◽  
Majority Voting ◽  
Optimal Rate ◽  
Collective Decision Making ◽  
Market Failures ◽  
Democratic Principle ◽  
The Social ◽  
Decision Making Problem

The problem of collective decision-making arising from market failures is addressed using the democratic principle applied within the assembly of shareholders. A basic requirement is imposed (the Pareto principle): collective choices should not be at odds with the interests of all shareholders, as expressed by their preferences. This requirement puts bounds on what the collective can choose: it should remain within the set of averages of what the shareholders want. Further refining these bounds, a notion of political stability is proposed; it is defined with respect to (super) majority voting. One searches for the smallest rate of super majority for which a stable collective choice exists. This optimal rate is reviewed under classical assumptions from the social choice literature. It is shown how the dimensionality of the collective decision-making problem and the polarization of the electorate critically impact political stability, and hence the optimal rate of super majority.

Speed–cohesion trade-offs in collective decision making in ants and the concept of precision in animal behaviour

2013 ◽  
Vol 85 (6) ◽  
pp. 1233-1244 ◽  
Author(s):  
N.R. Franks ◽  
T.O. Richardson ◽  
N. Stroeymeyt ◽  
R.W. Kirby ◽  
W.M.D. Amos ◽  
...  
Keyword(s):  
Decision Making ◽  
Animal Behaviour ◽  
Collective Decision ◽  
Collective Decision Making ◽  
Trade Offs

The Application of Signal Detection Theory to Decision-Making in Forensic Science

2001 ◽  
Vol 46 (2) ◽  
pp. 14962J ◽  
Author(s):  
Victoria L. Phillips ◽  
Michael J. Saks ◽  
Joseph L. Peterson
Keyword(s):  
Decision Making ◽  
Signal Detection ◽  
Forensic Science ◽  
Signal Detection Theory ◽  
Detection Theory
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