Optimal Collective Decision-Making in Social Insects

Lead Research Organisation: University of Sheffield
Department Name: Computer Science

Abstract

Social insects are model systems for studying collective decision-making, decentralised control, and self-organisation. Our own recent theoretical work has laid the foundations for analysis of optimal decision-making during emigration: we were the first to show how simple models can be parameterised to implement statistically optimal decision-making by social insect colonies, in which an optimal compromise between speed and accuracy of decisions is achieved. This proposal has two aims: first, to validate empirically these predictions with ants and honeybees, using experiments with the latest technology for tracking individuals. Second, to extend the models and their optimality analysis to more sophisticated decision-tasks, including novel decision-problems that have not received theoretical treatment before: in particular, a social insect colony must simultaneously attempt to sample its environment optimally for uncertain information on available alternatives, and at the same time optimally decide between these alternatives. These theoretical investigations will inform and be informed by novel experiments with ants and honeybees. These two species have converged on almost identical collective decision-making mechanisms, that differ however in subtle but important details in their implementation. This proposal will hire two post-doctoral research assistants, one to undertake theoretical work in Bristol under the direction of Dr James Marshall, and one to undertake experimental work with ants in Bristol under the direction of Prof Nigel Franks, and with honeybees in Arizona under the direction of Dr Anna Dornhaus and with the advice of Prof Tom Seeley. This project also forms part of a larger research programme: our novel theoretical perspective, which motivates this proposal, was achieved by synthesising ideas from social insect behaviour, evolutionary psychology and vertebrate neuroscience. The study of decision-making in humans and other vertebrates enjoys a sound theoretical footing, based on provably optimal decision-making procedures. As our previous work has shown, there are striking parallels between models of neural decision-making circuits in the primate brain, and models of collective decision-making in social insect colonies. This allows very similar optimality analysis techniques to be applied to both. There are also interesting differences, however, between brains and social insect colonies: in particular, as stated above, social insect colonies must actively sample information from their environment, rather than receiving information on available alternatives at equal and unvarying rates, as assumed by some neural models. Of course, this is actually a false dichotomy: some decision-making tasks in the brain, such as active perception, also require strategies for simultaneous sampling and decision-making. Thus we see this research programme at the interface of collective behaviour and brain behaviour as a genuine synthesis, with each field able to provide fundamental insights to the other. For the purposes of this proposal, however, one particular benefit of working with social insect colonies, compared to neural systems, is their ease of experimental observation and manipulation.

Technical Summary

Social insects are model systems for studying collective decision-making, decentralised control, and self- organisation. Our own recent theoretical work has laid the foundations for analysis of optimal decision-making during emigration: we were the first to show how simple models can be parameterised to implement statistically optimal decision- making by social insect colonies, in which an optimal compromise between speed and accuracy of decisions is achieved. This proposal has two aims: first, to validate empirically these predictions with ants and honeybees, using experiments with the latest technology for tracking individuals. Second, to extend the models and their optimality analysis to more sophisticated decision-tasks, including novel decision-problems that have not received theoretical treatment before: in particular, a social insect colony must simultaneously attempt to sample its environment optimally for uncertain information on available alternatives, and at the same time optimally decide between these alternatives. Our modelling and analysis currently rests on the Sequential Probability Ratio Test (SPRT), the provably optimal strategy for choosing between two alternatives in the minimum expected time for a desired expected error rate. We will generalise our models to decisions over more than two alternatives and analyse their optimality. We will also take a Bayesian approach to analysing these decision-making models. To tackle the problem of simultaneous sampling and decision-making we will develop new theory, possibly combining elements of SPRT with Gittins Indices. We will then develop biologically-plausible models that implement solutions to this problem. The above theoretical investigations will inform and be informed by a full programme of novel experiments with ants and honeybees. These two species have converged on almost identical collective decision-making mechanisms, that differ however in subtle but important details in their implementation.

Related Projects

Project Reference Relationship Related To Start End Award Value
BB/G02166X/1 01/09/2009 30/09/2010 £496,953
BB/G02166X/2 Transfer BB/G02166X/1 01/10/2010 19/10/2012 £325,185
 
Title The Swarm 
Description "'The Swarm' is a dynamic new immersive opera and sound project about honey bee swarms. It narrates the story of the perilous journey of migrating honey bees through a city with their queen after she is deposed by her daughter and forced to leave the hive, taking half the colony with her. In their search for a new home they encounter a deadly extractor fan, a thunder storm and a fierce debate over two potential sites to build a hive. With just one last meal of honey for energy, how will they reach a collective decision on where to relocate?" 
Type Of Art Performance (Music, Dance, Drama, etc) 
Year Produced 2016 
Impact Media appearances by composers, e.g. composer Heloise Tunstall-Behrens on BBC Radio 4's Midweek programme on February 21st 2017 (http://www.bbc.co.uk/programmes/b08byp5p) 
URL http://www.thequorum.co.uk/present/
 
Description 1. We discovered a novel form of signalling in honeybee swarms, the stop-signal, used in addition to the waggle-dance and previously only observed in foraging honeybee colonies; 2. We constructed and analysed a model of this behaviour, showing that it implements a sophisticated value-sensitive decision-making strategy that resolves problems associated with earlier models that compromise between speed and accuracy of decision-making; 3. We theoretically analysed the decision-making mechanism implemented by stop-signalling, revealing various novel aspects of value-sensitive decision-making including deadlock breaking, speed-accuracy trade-offs, and Weber's law-like behaviour. This mechanism may inform the study of transcriptional networks within cells and neural circuits within brains; 4. We discovered, using micro-RFID technology and network analysis, that in ant emigrations a minority of highly competent individuals do most of the decision-making.
Exploitation Route The development of the value-sensitive decision-making perspective, and the particular mechanistic model constructed, is of broad importance, since diverse natural systems should be faced with decisions of this nature. The results are already attracting the interests of experimental psychologists and cognitive neuroscientists and microbiologists. Additionally, the value-sensitive mechanism described is suitable for development of decentralised decision-making algorithms for artificial systems, such as groups of robots trying to reach a consensus decision about which of several possible courses of action is most rewarding.
Sectors Digital/Communication/Information Technologies (including Software),Other

 
Description Findings from the research have contributed inspiration to a new musical and dance production, 'The Swarm', shown in Liverpool and in London: (http://www.thequorum.co.uk) Findings from the research have been assimilated into the development of a new collective human intelligence tool for opinion sharing, by the startup Unanimous AI (http://unanimous.ai)
First Year Of Impact 2013
Sector Digital/Communication/Information Technologies (including Software),Culture, Heritage, Museums and Collections,Other
Impact Types Cultural,Societal

 
Description ERC Consolidator Grant
Amount € 1,413,705 (EUR)
Funding ID 647704 
Organisation European Research Council (ERC) 
Sector Public
Country European Union (EU)
Start 08/2015 
End 07/2020
 
Description Dynamical systems modelling with Naomi Leonard 
Organisation Princeton University
Country United States 
Sector Academic/University 
PI Contribution The BBSRC-funded team provided a model and expertise in statistical decision-theory and behavioural ecology.
Collaborator Contribution The partner provided expertise in dynamical systems analysis of the model
Impact Multi-discplinary: mathematics (dynamical systems analysis), biology (collective behaviour, animal decision-making)
Start Year 2012
 
Description Honeybee investigations with Tom Seeley and Kirk Visscher 
Organisation Cornell University
Country United States 
Sector Academic/University 
PI Contribution New experimental collaboration with internationally-recognised honeybee experts
 
Description BBC Horizon interview 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Nigel Franks interviewed about ant research as part of 'Out of Control' BBC Horizon programme

no actual impacts realised to date
Year(s) Of Engagement Activity 2012
 
Description Groningen Lecture in Theoretical Biology 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Other academic audiences (collaborators, peers etc.)
Results and Impact Talk led to discussions with on relevance of project outputs for microbiology

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Year(s) Of Engagement Activity 2014
 
Description Media coverage of honeybee stop-signalling paper 
Form Of Engagement Activity A magazine, newsletter or online publication
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact Extensive international media coverage of 2012 Science paper, online, in print, and broadcast. UK press coverage included Daily Mail, UK radio coverage included Radio 1 and BBC Radio Sheffield, international radio coverage included German National Radio.

no actual impacts realised to date
Year(s) Of Engagement Activity 2011
 
Description Through the Wormhole with Morgan Freeman interview 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? Yes
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact James Marshall and Nigel Franks interviewed about parallels between ant and brain decision-making, as part of the 2013 season of Through the Wormhole with Morgan Freeman (episode 4, 'How do Aliens Think?'). Aired June 19 2013 on Discovery's Science Channel)

no actual impacts realised to date
Year(s) Of Engagement Activity 2013