The study in this paper aims to further our understanding of communication in large anonymous pop... more The study in this paper aims to further our understanding of communication in large anonymous populations composed of simple agents which interact through short and highly unreliable messages. We focus on the rumor-spreading problem, and initiate the study of reliable rumor-spreading under communication noise. Specifically, the noisy rumor-spreading problem considers a population of n anonymous agents, with one distinguished source agent representing the environment associated with an opinion (a bit B in {0,1}). Few agents obtain noisy samples of this bit and all agents use noisy interactions to guarantee that eventually, all agents hold the correct opinion B with high probability. Our model for communication is extremely weak and follows the push gossip communication paradigm: In each synchronous round each agent that wishes to send information delivers a message to a randomly chosen anonymous agent. Since our objective is to study restricted communication channels, we assume that each message can contain only one bit (essentially representing an opinion). The system is furthermore assumed to be so noisy that the bit in each message sent is flipped independently with probability $1/2-\eps$, for small $\eps$, that is, it carries only $H(\eps)$ amount of entropy. Even in this severely restricted, stochastic and noisy setting we give natural protocols that solve the noisy rumor-spreading problem efficiently. In particular, our protocol run in $O(\frac{1}{\eps^2}\log n)$ rounds and use $O(\frac{1}{\eps^2} n \log n)$ messages (or bits) in total. These bounds are both asymptotically optimal. Our efficient, robust, and simple algorithms suggest balancing between silence and transmission, synchronization, and majority-based decisions as important ingredients towards understanding collective communication schemes in anonymous and noisy natural populations.
Social groups often need to overcome differences in individual interests and knowledge to reach c... more Social groups often need to overcome differences in individual interests and knowledge to reach consensus decisions. Here, we combine experiments and modeling to study conflict resolution in emigrating ant colonies during binary nest selection. We find that cohesive emigration, without fragmentation, is achieved only by intermediate-sized colonies. We then impose a conflict regarding the desired emigration target between colony subgroups. This is achieved using an automated selective gate system that manipulates the information accessible to each ant. Under this conflict, we find that individuals concede their potential benefit to promote social consensus. In particular, colonies resolve the conflict imposed by a persistent minority through "majority concession," wherein a majority of ants that hold first-hand knowledge regarding the superior quality nest choose to reside in the inferior one. This outcome is unlikely in social groups of selfish individuals and emphasizes the importance of group cohesion in eusocial societies.
HAL (Le Centre pour la Communication Scientifique Directe), Jul 10, 2017
Tout observateur averti des fourmis est familier des deplacements de ces insectes le long de chem... more Tout observateur averti des fourmis est familier des deplacements de ces insectes le long de chemins dits de fourragement. Ces pistes chimiques, souvent longues de dizaines de metres, relient une source de nourriture et le nid et permettent a un grand nombre d’individus de se deplacer rapidement entre ces deux endroits...
<p><b>a.</b> The experimental setup. The recruiter ant (circled) returns to the... more <p><b>a.</b> The experimental setup. The recruiter ant (circled) returns to the nest’s entrance chamber (dark, 9cm diameter, disc) after finding the immobilized food item (arrow). Group size is ten. <b>b.</b> A <i>pdf</i> of the number of interactions that an ant experiences before meeting the same ant twice. The <i>pdf</i> is compared to uniform randomized interaction pattern. Data summarizes <i>N</i> = 671 interactions from seven experiments with a group size of 6 ants. <b>c.</b> Interactions of stationary ants with moving ants were classified into three different messages (‘a’ to ‘c’) depending on the moving ants’ speed. The noise at which messages were confused with each other was estimated according to the response of the recipient, initially stationary, ants (see <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1006195#sec016" target="_blank">Materials and methods</a>). Gray scale indicates the estimated overlap between every two messages <i>δ</i>(<i>i</i>, <i>j</i>). Note <i>δ</i> = min(<i>δ</i>(<i>i</i>, <i>j</i>)) ≈ 0.3. Data collected over <i>N</i> = 278 interactions. <b>d.</b> The mean time it takes an ant that is informed about the food to recruit two nest-mates to exit the nest is presented for two group size ranges. Error bars represent standard error of the means over <i>N</i> = 24 experiments.</p
Journal of Statistical Mechanics: Theory and Experiment, 2022
The echo-chamber effect is a common term in opinion dynamic modeling to describe how a person’s o... more The echo-chamber effect is a common term in opinion dynamic modeling to describe how a person’s opinion might be artificially enhanced as it is reflected back at her through social interactions. Here, we study the existence of this effect in statistical mechanics models, which are commonly used to study opinion dynamics. We show that the Ising model does not exhibit echo-chambers, but this result is a consequence of a special symmetry. We then distinguish between three types of models: (i) those with a strong echo-chamber symmetry, that have no echo-chambers at all; (ii) those with a weak echo-chamber symmetry that can exhibit echo-chambers but only if there are external fields in the system, and (iii) models without echo-chamber symmetry that generically have echo-chambers. We use these results to construct an efficient algorithm to efficiently and precisely calculate magnetization in arbitrary tree networks. Finally, we apply this algorithm to study two systems: phase transitions ...
1Ant colonies regulate foraging in response to their collective hunger, yet the mechanism behind ... more 1Ant colonies regulate foraging in response to their collective hunger, yet the mechanism behind this distributed regulation remains unclear. Previously, by imaging food flow within ant colonies we showed that the frequency of foraging events declines linearly with colony satiation ([1]). Our analysis implied that as a forager distributes food in the nest, two factors affect her decision to exit for another foraging trip: her current food load and its rate of change. Sensing these variables can be attributed to the forager’s individual cognitive ability. Here, new analyses of the foragers’ trajectories within the nest imply a different way to achieve the observed regulation. Instead of an explicit decision to exit, foragers merely tend toward the depth of the nest when their food load is high and toward the nest exit when it is low. Thus, the colony shapes the forager’s trajectory by controlling her unloading rate, while she senses only her current food load. Using an agent-based mo...
Biological systems can share and collectively process information to yield emergent effects, desp... more Biological systems can share and collectively process information to yield emergent effects, despite inherent noise in communication. While man-made systems often employ intricate structural solutions to overcome noise, the structure of many biological systems is more amorphous. It is not well understood how communication noise may affect the computational repertoire of such groups. To approach this question we consider the basic collective task of rumor spreading, in which information from few knowledgeable sources must reliably flow into the rest of the population. In order to study the effect of communication noise on the ability of groups that lack stable structures to efficiently solve this task, we consider a noisy version of the uniform PULL model. We prove a lower bound which implies that, in the presence of even moderate levels of noise that affect all facets of the communication, no scheme can significantly outperform the trivial one in which agents have to wait until dire...
Frontiers in Applied Mathematics and Statistics, 2021
Cooperative transport of large food loads by Paratrechina longicornis ants demands repeated decis... more Cooperative transport of large food loads by Paratrechina longicornis ants demands repeated decision-making. Inspired by the Evidence Accumulation (EA) model classically used to describe decision-making in the brain, we conducted a binary choice experiment where carrying ants rely on social information to choose between two paths. We found that the carried load performs a biased random walk that continuously alternates between the two options. We show that this motion constitutes a physical realization of the abstract EA model and exhibits an emergent version of the psychophysical Weber’s law. In contrast to the EA model, we found that the load’s random step size is not fixed but, rather, varies with both evidence and circumstances. Using theoretical modeling we show that variable step size expands the scope of the EA model from isolated to sequential decisions. We hypothesize that this phenomenon may also be relevant in neuronal circuits that perform sequential decisions.
A new study relates the properties of Drosophila melanogaster social networks to group compositio... more A new study relates the properties of Drosophila melanogaster social networks to group composition and demonstrates how they may be altered using behavioral priming and genetic manipulations.
The study in this paper aims to further our understanding of communication in large anonymous pop... more The study in this paper aims to further our understanding of communication in large anonymous populations composed of simple agents which interact through short and highly unreliable messages. We focus on the rumor-spreading problem, and initiate the study of reliable rumor-spreading under communication noise. Specifically, the noisy rumor-spreading problem considers a population of n anonymous agents, with one distinguished source agent representing the environment associated with an opinion (a bit B in {0,1}). Few agents obtain noisy samples of this bit and all agents use noisy interactions to guarantee that eventually, all agents hold the correct opinion B with high probability. Our model for communication is extremely weak and follows the push gossip communication paradigm: In each synchronous round each agent that wishes to send information delivers a message to a randomly chosen anonymous agent. Since our objective is to study restricted communication channels, we assume that each message can contain only one bit (essentially representing an opinion). The system is furthermore assumed to be so noisy that the bit in each message sent is flipped independently with probability $1/2-\eps$, for small $\eps$, that is, it carries only $H(\eps)$ amount of entropy. Even in this severely restricted, stochastic and noisy setting we give natural protocols that solve the noisy rumor-spreading problem efficiently. In particular, our protocol run in $O(\frac{1}{\eps^2}\log n)$ rounds and use $O(\frac{1}{\eps^2} n \log n)$ messages (or bits) in total. These bounds are both asymptotically optimal. Our efficient, robust, and simple algorithms suggest balancing between silence and transmission, synchronization, and majority-based decisions as important ingredients towards understanding collective communication schemes in anonymous and noisy natural populations.
Social groups often need to overcome differences in individual interests and knowledge to reach c... more Social groups often need to overcome differences in individual interests and knowledge to reach consensus decisions. Here, we combine experiments and modeling to study conflict resolution in emigrating ant colonies during binary nest selection. We find that cohesive emigration, without fragmentation, is achieved only by intermediate-sized colonies. We then impose a conflict regarding the desired emigration target between colony subgroups. This is achieved using an automated selective gate system that manipulates the information accessible to each ant. Under this conflict, we find that individuals concede their potential benefit to promote social consensus. In particular, colonies resolve the conflict imposed by a persistent minority through "majority concession," wherein a majority of ants that hold first-hand knowledge regarding the superior quality nest choose to reside in the inferior one. This outcome is unlikely in social groups of selfish individuals and emphasizes the importance of group cohesion in eusocial societies.
HAL (Le Centre pour la Communication Scientifique Directe), Jul 10, 2017
Tout observateur averti des fourmis est familier des deplacements de ces insectes le long de chem... more Tout observateur averti des fourmis est familier des deplacements de ces insectes le long de chemins dits de fourragement. Ces pistes chimiques, souvent longues de dizaines de metres, relient une source de nourriture et le nid et permettent a un grand nombre d’individus de se deplacer rapidement entre ces deux endroits...
<p><b>a.</b> The experimental setup. The recruiter ant (circled) returns to the... more <p><b>a.</b> The experimental setup. The recruiter ant (circled) returns to the nest’s entrance chamber (dark, 9cm diameter, disc) after finding the immobilized food item (arrow). Group size is ten. <b>b.</b> A <i>pdf</i> of the number of interactions that an ant experiences before meeting the same ant twice. The <i>pdf</i> is compared to uniform randomized interaction pattern. Data summarizes <i>N</i> = 671 interactions from seven experiments with a group size of 6 ants. <b>c.</b> Interactions of stationary ants with moving ants were classified into three different messages (‘a’ to ‘c’) depending on the moving ants’ speed. The noise at which messages were confused with each other was estimated according to the response of the recipient, initially stationary, ants (see <a href="http://www.ploscompbiol.org/article/info:doi/10.1371/journal.pcbi.1006195#sec016" target="_blank">Materials and methods</a>). Gray scale indicates the estimated overlap between every two messages <i>δ</i>(<i>i</i>, <i>j</i>). Note <i>δ</i> = min(<i>δ</i>(<i>i</i>, <i>j</i>)) ≈ 0.3. Data collected over <i>N</i> = 278 interactions. <b>d.</b> The mean time it takes an ant that is informed about the food to recruit two nest-mates to exit the nest is presented for two group size ranges. Error bars represent standard error of the means over <i>N</i> = 24 experiments.</p
Journal of Statistical Mechanics: Theory and Experiment, 2022
The echo-chamber effect is a common term in opinion dynamic modeling to describe how a person’s o... more The echo-chamber effect is a common term in opinion dynamic modeling to describe how a person’s opinion might be artificially enhanced as it is reflected back at her through social interactions. Here, we study the existence of this effect in statistical mechanics models, which are commonly used to study opinion dynamics. We show that the Ising model does not exhibit echo-chambers, but this result is a consequence of a special symmetry. We then distinguish between three types of models: (i) those with a strong echo-chamber symmetry, that have no echo-chambers at all; (ii) those with a weak echo-chamber symmetry that can exhibit echo-chambers but only if there are external fields in the system, and (iii) models without echo-chamber symmetry that generically have echo-chambers. We use these results to construct an efficient algorithm to efficiently and precisely calculate magnetization in arbitrary tree networks. Finally, we apply this algorithm to study two systems: phase transitions ...
1Ant colonies regulate foraging in response to their collective hunger, yet the mechanism behind ... more 1Ant colonies regulate foraging in response to their collective hunger, yet the mechanism behind this distributed regulation remains unclear. Previously, by imaging food flow within ant colonies we showed that the frequency of foraging events declines linearly with colony satiation ([1]). Our analysis implied that as a forager distributes food in the nest, two factors affect her decision to exit for another foraging trip: her current food load and its rate of change. Sensing these variables can be attributed to the forager’s individual cognitive ability. Here, new analyses of the foragers’ trajectories within the nest imply a different way to achieve the observed regulation. Instead of an explicit decision to exit, foragers merely tend toward the depth of the nest when their food load is high and toward the nest exit when it is low. Thus, the colony shapes the forager’s trajectory by controlling her unloading rate, while she senses only her current food load. Using an agent-based mo...
Biological systems can share and collectively process information to yield emergent effects, desp... more Biological systems can share and collectively process information to yield emergent effects, despite inherent noise in communication. While man-made systems often employ intricate structural solutions to overcome noise, the structure of many biological systems is more amorphous. It is not well understood how communication noise may affect the computational repertoire of such groups. To approach this question we consider the basic collective task of rumor spreading, in which information from few knowledgeable sources must reliably flow into the rest of the population. In order to study the effect of communication noise on the ability of groups that lack stable structures to efficiently solve this task, we consider a noisy version of the uniform PULL model. We prove a lower bound which implies that, in the presence of even moderate levels of noise that affect all facets of the communication, no scheme can significantly outperform the trivial one in which agents have to wait until dire...
Frontiers in Applied Mathematics and Statistics, 2021
Cooperative transport of large food loads by Paratrechina longicornis ants demands repeated decis... more Cooperative transport of large food loads by Paratrechina longicornis ants demands repeated decision-making. Inspired by the Evidence Accumulation (EA) model classically used to describe decision-making in the brain, we conducted a binary choice experiment where carrying ants rely on social information to choose between two paths. We found that the carried load performs a biased random walk that continuously alternates between the two options. We show that this motion constitutes a physical realization of the abstract EA model and exhibits an emergent version of the psychophysical Weber’s law. In contrast to the EA model, we found that the load’s random step size is not fixed but, rather, varies with both evidence and circumstances. Using theoretical modeling we show that variable step size expands the scope of the EA model from isolated to sequential decisions. We hypothesize that this phenomenon may also be relevant in neuronal circuits that perform sequential decisions.
A new study relates the properties of Drosophila melanogaster social networks to group compositio... more A new study relates the properties of Drosophila melanogaster social networks to group composition and demonstrates how they may be altered using behavioral priming and genetic manipulations.
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