Leader-follower relationships are commonly hypothesized as a fundamental mechanism underlying collective behaviour in many biological and physical systems. Understanding the emergence of such behaviour is relevant in science and engineering to control the dynamics of complex systems toward a desired state. In prior works, due in part to the limitations of existing methods for dissecting intermittent causal relationships, leadership is assumed to be consistent in time and space. This assumption has been contradicted by recent progress in the study of animal behaviour. In this work, we leverage information theory and time series analysis to propose a novel and simple method for dissecting changes in causal influence. Our approach computes the cumulative influence function of a given individual on the rest of the group in consecutive time intervals and identify change in the monotonicity of the function as a change in its leadership status. We demonstrate the effectiveness of our approach to dissect potential changes in leadership on self-propelled particles where the emergence of leader-follower relationship can be controlled and on tandem flights of birds recorded in their natural environment. Our method is expected to provide a novel methodological tool to further our understanding of collective behaviour.
- Award ID(s):
- 1849446
- PAR ID:
- 10214047
- Date Published:
- Journal Name:
- Scientific Reports
- Volume:
- 10
- Issue:
- 1
- ISSN:
- 2045-2322
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
more » « less
Abstract -
Social groups such as schools of fish or flocks of birds display collective dynamics that can be modulated by group leaders, which facilitate decision-making toward a consensus state beneficial to the entire group. For instance, leaders could alert the group about attacking predators or the presence of food sources. Motivated by biological insight on social groups, we examine a stochastic leader–follower consensus problem where information sharing among agents is affected by perceptual constraints and each individual has a different tendency to form social connections. Leveraging tools from stochastic stability and eigenvalue perturbation theories, we study the consensus protocol in a mean-square sense, offering necessary-and-sufficient conditions for asymptotic stability and closed-form estimates of the convergence rate. Surprisingly, the prediction of our minimalistic model share similarities with observed traits of animal and human groups. Our analysis anticipates the counterintuitive result that heterogeneity can be beneficial to group decision-making by improving the convergence rate of the consensus protocol. This observation finds support in theoretical and empirical studies on social insects such as spider or honeybee colonies, as well as human teams, where inter-individual variability enhances the group performance.more » « less
-
more » « less
Abstract Investigating how children think about leadership may inform theories of the gender gaps in leadership among adults. In three studies (
N = 492 U.S. children ages 5–10 years), we investigated (1) whether children expect those who claim leadership roles within a peer group to elicit social support and cooperation from the group, (2) children’s own interest and self-efficacy in such roles, and (3) the influence of contextual cues (e.g., how leader roles are described) on children’s reasoning about and interest in leadership. We also explored differences based on children’s race/ethnicity. In Study 1, girls expected lower social support for child leaders than boys did. However, in Study 2, we found no evidence that girls are less interested in leadership. In addition, interest in leadership increased with age among White girls but decreased among White boys and girls and boys of color. In Study 3, we tested whether interest in a leader role is boosted (particularly among girls) by describing the role as helpful for the group and by providing gender-balanced peer role models. Regardless of gender, children in the helpful or “communal” (vs. “agentic”) leader condition were more interested in the leader role, anticipated stronger social support and cooperation from others, and reported higher self-efficacy as leaders. The gender composition of role models had little impact. This research underscores the early development of children’s attitudes toward leadership and highlights the potential value in early interventions to nurture children’s leadership ambitions. -
more » « less
The ability of primary tumor cells to invade into adjacent tissues, followed by the formation of local or distant metastasis, is a lethal hallmark of cancer. Recently, locomoting clusters of tumor cells have been identified in numerous cancers and associated with increased invasiveness and metastatic potential. However, how the collective behaviors of cancer cells are coordinated and their contribution to cancer invasion remain unclear. Here we show that collective invasion of breast cancer cells is regulated by the energetic statuses of leader and follower cells. Using a combination of in vitro spheroid and ex vivo organoid invasion models, we found that cancer cells dynamically rearrange leader and follower positions during collective invasion. Cancer cells invade cooperatively in denser collagen matrices by accelerating leader–follower switching thus decreasing leader cell lifetime. Leader cells exhibit higher glucose uptake than follower cells. Moreover, their energy levels, as revealed by the intracellular ATP/ADP ratio, must exceed a threshold to invade. Forward invasion of the leader cell gradually depletes its available energy, eventually leading to leader–follower transition. Our computational model based on intracellular energy homeostasis successfully recapitulated the dependence of leader cell lifetime on collagen density. Experiments further supported model predictions that decreasing the cellular energy level by glucose starvation decreases leader cell lifetime whereas increasing the cellular energy level by AMP-activated kinase (AMPK) activation does the opposite. These findings highlight coordinated invasion and its metabolic regulation as potential therapeutic targets of cancer.
-
There is a growing recognition of the need for interdisciplinarity in science, technology, engineering and mathematics (STEM) education. The purpose of the present study is to identify antecedents, processes, and outcomes of an interdisciplinary, collaborative conference and ongoing collaboration. The Breaking Boundaries in STEM education conference was developed with multiple goals, including fostering collaborative interdisciplinary scientific writing for publication among teacher-scholars who participated in one of three interdisciplinary working groups. One hundred teacher-scholars with interest in STEM education participated in the conference. A comparative study of three working groups from the conference was conducted using a triangulation of qualitative and quantitative methods. Surveys and behavioral observations were completed at the conference, and phone interviews with attendees were conducted 3-4 months later. Groups varied in their readiness to collaborate. Several themes emerged that might explain why one group was highly productive, one group was moderately productive, and one group was not productive at completing publications after the conference. Groups with a narrower disciplinary span, stronger leadership presence, a paper champion, motivated leader, and a leader with a strong recent history of publishing on the topic, were more ready to collaborate, and they experienced faster, smoother completion of publications. Further research and more passage of time, such as a few years, is needed to determine the quantity, quality, span of disciplinarity, novelty, and generativity of the publications over time. The generalizability of these themes to other interdisciplinary collaborative studies is briefly discussed.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1038/s41598-020-75551-2
