Leader-follower Dynamics Research Articles

Viscoelastic High-Molecular-Weight Hyaluronic Acid Hydrogels Support Rapid Glioblastoma Cell Invasion with Leader-Follower Dynamics.

Hyaluronic acid (HA), the primary component of brain extracellular matrix, is increasingly used to model neuropathological processes, including glioblastoma (GBM) tumor invasion. While elastic hydrogels based on crosslinked low-molecular-weight (LMW) HA are widely exploited for this purpose and have proven valuable for discovery and screening, brain tissue is both viscoelastic and rich in high-MW (HMW) HA, and it remains unclear how these differences influence invasion. To address this question, hydrogels comprised of either HMW (1.5 MDa) or LMW (60 kDa) HA are introduced, characterized, and applied in GBM invasion studies. Unlike LMW HA hydrogels, HMW HA hydrogels relax stresses quickly, to a similar extent as brain tissue, and to a greater extent than many conventional HA-based scaffolds. GBM cells implanted within HMW HA hydrogels invade much more rapidly than in their LMW HA counterparts and exhibit distinct leader-follower dynamics. Leader cells adopt dendritic morphologies similar to invasive GBM cells observed in vivo. Transcriptomic, pharmacologic, and imaging studies suggest that leader cells exploit hyaluronidase, an enzyme strongly enriched in human GBMs, to prime a path for followers. This study offers new insight into how HA viscoelastic properties drive invasion and argues for the use of highly stress-relaxing materials to model GBM.

Leader–follower dynamics during early social interactions matter for infant word learning

We know little about the mechanisms through which leader-follower dynamics during dyadic play shape infants' language acquisition. We hypothesized that infants' decisions to visually explore a specific object signal focal increases in endogenous attention, and that when caregivers respond to these proactive behaviors by naming the object it boosts infants' word learning. To examine this, we invited caregivers and their 14-mo-old infants to play with novel objects, before testing infants' retention of the novel object-label mappings. Meanwhile, their electroencephalograms were recorded. Results showed that infants' proactive looks toward an object during play associated with greater neural signatures of endogenous attention. Furthermore, when caregivers named objects during these episodes, infants showed greater word learning, but only when caregivers also joined their focus of attention. Our findings support the idea that infants' proactive visual explorations guide their acquisition of a lexicon.

Leadership and Followership Dynamics in Interprofessional Health Care Teams: Attending Physician Perspectives.

Effective interprofessional health care team (IHT) members collaborate to reduce medical errors, use resources effectively, and improve patient outcomes, making interprofessional collaboration imperative. Because physicians are often designated as the positional leaders of IHTs, understanding their perspectives on collaboration within IHTs could help to mitigate the disconnects between what is suggested in theory and what is happening in practice. This study aimed to explore leader-follower dynamics within medical teams that are commonly working in clinical care contexts. Using a constructivist approach, the authors conducted 12 individual, semistructured interviews from November 2022 to September 2023 with attending physicians who have led IHTs in perioperative (i.e., preoperative clinic, operating room, postoperative and recovery unit) or emergency department settings. The transcripts were analyzed from December 2022 to December 2023 using inductive thematic analysis. Three themes explained the physician perceptions of IHT leadership-followership dynamics: (1) physicians are comfortable sharing leadership intraprofessionally, (2) the clinical culture and environment constrain interprofessional followership and shared leadership, and (3) hierarchical models hold true even while active followers are appreciated, when appropriate. The data in this study suggest that, in perioperative and emergency department settings, shared leadership largely may not occur interprofessionally but occurs intraprofessionally. Participants suggested that the clinical culture and environment (i.e., legal concerns, hierarchical assumption, patient care ownership responsibilities) constrained interprofessional followership and shared leadership. On the basis of the study's findings and how they align with previous research, future research into interprofessional collaboration and followership roles should focus on what factors enable and constrain active followership and shared leadership. Such collaboration can only be achieved when active followership and shared leadership are allowed and promoted. These findings and others suggest that not all contexts are enabling such types of interprofessional collaboration due to legal concerns, hierarchical traditions, and patient ownership considerations.

How and Why People Synchronize: An Integrated Perspective.

Academic AbstractInterpersonal synchrony, the alignment of behavior and/or physiology during interactions, is a pervasive phenomenon observed in diverse social contexts. Here we synthesize across contexts and behaviors to classify the different forms and functions of synchrony. We provide a concise framework for classifying the manifold forms of synchrony along six dimensions: periodicity, discreteness, spatial similarity, directionality, leader-follower dynamics, and observability. We also distill the various proposed functions of interpersonal synchrony into four interconnected functions: reducing complexity and improving understanding, accomplishing joint tasks, strengthening social connection, and influencing partners' behavior. These functions derive from first principles, emerge from each other, and are accomplished by some forms of synchrony more than others. Effective synchrony flexibly adapts to social goals and more synchrony is not always better. Our synthesis offers a shared framework and language for the field, allowing for better cross-context and cross-behavior comparisons, generating new hypotheses, and highlighting future research directions.

Neurophysiological markers of asymmetric emotional contagion: implications for organizational contexts.

Emotions play a vital role within organizations, impacting various crucial aspects of work such as job satisfaction, performance, and employee well-being. Understanding how emotional states spread in organizational settings is therefore essential. Recent studies have highlighted that a leader's emotional state can influence their followers, with significant consequences on job performance. Leaders thus possess the ability to influence their employees' psychological state and, consequently, their well-being. However, the biological underpinnings of emotional contagion from leaders to followers remain unexplored. The field of interpersonal (neuro)physiology, which involves recording brain and peripheral activity of multiple individuals during interactions, holds great potential for investigating this phenomenon. Analyzing the time-lagged synchronization of neurophysiological activity during interactions may serve as a measure of the leader's influence on their followers in organizational contexts. In this "mini review," we examine empirical studies that have employed interpersonal (neuro)physiology to quantify the asymmetrical contagion of emotions in different contexts. Asymmetrical contagion was operationalized as the unidirectional influence exerted by one individual (i.e., the "sender") to another one (i.e., the "receiver"), whereby the receiver's state can be predicted by the sender's one. The reviewed literature reveals that delayed synchronization of physiological states is a widespread phenomenon that may underpin the transmission of emotions. These findings have significant implications for various aspects of organizational life, including leader-to-employee communication, and could drive the development of effective leadership training programs. We propose that Organizational Neuroscience may benefit from including interpersonal neurophysiology in its methodological toolkit for laboratory and field studies of leader-follower dynamics.

A Cooperation–Competition Evolutionary Dynamic Model Over Signed Networks

Signed networks are widely applied to describe cooperative and competitive interaction relationships arising from various social, biological and physical systems. In this paper, a cooperation-competition evolutionary dynamic model is offered to explain the gradual evolution of the interaction relationship between neighboring nodes in signed networks. The core feature of our model is to portray the interaction relationship between neighboring nodes as a nonlinear function of the state difference, i.e., neighboring nodes cooperate with each other only if their state difference is within a limited range (called <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">cooperation range</i> ); otherwise they antagonize with each other. We investigate the leader-follower dynamics, and present the lower bound of the convergence rate by using the infinite norm of products of sub-stochastic matrices. For the leaderless dynamics, we establish algebraic conditions with respect to the state differences and the cooperation range for realizing consensus and polarization behaviors. Finally, numerical examples are provided to illustrate the evolution dynamics.

Mitochondrial transfer from cancer-associated fibroblasts increases migration in aggressive breast cancer.

Cancer-associated fibroblasts (CAFs) have distinct roles within the tumor microenvironment, which can impact the mode and efficacy of tumor cell migration. CAFs are known to increase invasion of less-aggressive breast cancer cells through matrix remodeling and leader-follower dynamics. Here, we demonstrate that CAFs communicate with breast cancer cells through the formation of contact-dependent tunneling nanotubes (TNTs), which allow for the exchange of cargo between cell types. CAF mitochondria are an integral cargo component and are sufficient to increase the 3D migration of cancer cells. This cargo transfer results in an increase in mitochondrial ATP production in cancer cells, whereas it has a negligible impact on glycolytic ATP production. Manually increasing mitochondrial oxidative phosphorylation (OXPHOS) by providing extra substrates for OXPHOS fails to enhance cancer cell migration unless glycolysis is maintained at a constant level. Together, these data indicate that tumor-stromal cell crosstalk via TNTs and the associated metabolic symbiosis is a finely controlled mechanism by which tumor cells co-opt their microenvironment to promote cancer progression and may become a potential therapeutic target.

Proactive or reactive? Neural oscillatory insight into the leader–follower dynamics of early infant–caregiver interaction

We know that infants' ability to coordinate attention with others toward the end of the first year is fundamental to language acquisition and social cognition. Yet, we understand little about the neural and cognitive mechanisms driving infant attention in shared interaction: do infants play a proactive role in creating episodes of joint attention? Recording electroencephalography (EEG) from 12-mo-old infants while they engaged in table-top play with their caregiver, we examined the communicative behaviors and neural activity preceding and following infant- vs. adult-led joint attention. Infant-led episodes of joint attention appeared largely reactive: they were not associated with increased theta power, a neural marker of endogenously driven attention, and infants did not increase their ostensive signals before the initiation. Infants were, however, sensitive to whether their initiations were responded to. When caregivers joined their attentional focus, infants showed increased alpha suppression, a pattern of neural activity associated with predictive processing. Our results suggest that at 10 to 12 mo, infants are not routinely proactive in creating joint attention episodes yet. They do, however, anticipate behavioral contingency, a potentially foundational mechanism for the emergence of intentional communication.

Minimal Leader Selection in General Linear Multi-Agent Systems With Switching Topologies: Leveraging Submodularity Ratio

In multi-agent systems with leader-follower dynamics, choosing a subset of agents as leaders is a critical step in achieving the desired coordination performance. In this study, by considering consensus tracking for general linear multi-agent systems under switching topologies, we address the problem of selecting a minimum-size set of leaders by leveraging the submodularity ratio. First, using the dwell time technique, a criterion is derived to ensure that the states of all agents can converge to a reference trajectory that is directly tracked by each leader. Second, exploiting the derived consensus tracking criterion, the metrics with a structure of the Euclidean distance between specific vectors and the space spanned by an iteratively updated matrix are established to identify a set of leaders, and then the corresponding bound of the submodularity ratio is proposed. Third, combining the derived criterion and the constructed metrics, a leader selection scheme is presented together with three polynomial-time algorithms, and the related provable optimality bound of each algorithm can be obtained by leveraging the proposed bound of the submodularity ratio. Finally, illustrative examples are provided to verify the effectiveness of the proposed leader selection scheme.

Analysis of Energy-Driven Leader-Follower Hierarchy During Collective Cancer Cell Invasion.

Many solid tumors can invade the surrounding three-dimensional (3D) tissue in a collective manner, and increasing evidence suggests that collective migration makes cancer cell clusters more invasive and metastatic than individual cells. A cohesive cohort of cancer cells can have many advantages over individual cells, including more efficient bioenergetics that have been recently identified. Minimization of bioenergetic costs during collective cell migration drives leader-follower dynamics and contributes to enhanced cancer invasion. Hence, it is critical to understand the migratory and bioenergetic dynamics of cancer collective invasion. While analysis of structures and dynamics in a 3D space has been a challenging task, here we describe a widely applicable method to analyze the energy-driven leader-follower hierarchy during cancer collective invasion. An in vitro tumor spheroid model is employed to reproduce the in vivo collective behaviors of cancer cells while allowing high spatiotemporal resolution imaging, where the leader-follower dynamics can be analyzed by tracking nuclear positions. As glucose is one of the main energy sources that fuel cancer cell migration, the quantification of glucose uptake along the invading strands provides an estimate of the energy demand associated with collective invasion. Finally, we describe a method to quantify the dynamics of intracellular energy level using the PercevalHR ATP:ADP ratio biosensor.

Leader–Follower Dynamics in Complex Obstacle Avoidance Task

A question that many researchers in social robotics are addressing is how to create more human-like behaviour in robots to make the collaboration between a human and a robot more intuitive to the human partner. In order to develop a human-like collaborative robotic system, however, human collaboration must first be better understood. Human collaboration is something we are all familiar with, however not that much is known about it from a kinematic standpoint. One dynamic that hasn’t been researched thoroughly, yet naturally occurs in human collaboration, is for instance leader–follower dynamics. In our previous study, we tackled the question of leader–follower role allocation in human dyads during a collaborative reaching task, where the results implied that the subjects who performed higher in the individual experiment would naturally assume the role of a leader when in physical collaboration. In this study, we build upon the leader–follower role allocation study in human dyads by observing how the leader–follower dynamics change when the collaborative task becomes more complex. Here, the study was performed on a reaching task, where one subject in a dyad was faced with an additional task of obstacle avoidance when performing a 2D reaching task, while their partner was not aware of the obstacle. We have found that subjects change their roles throughout the task in order to complete it successfully, however looking at the overall task leader the higher-performing individual will always dominate over the lower-performing one, regardless of whether they are aware of the additional task of obstacle avoidance or not.

Leader-follower dynamics in real historical time: a Markovian test of non-linear causality between sail and steam (co-)development

ABSTRACT The most dramatic changes in modern shipping occurred with the application of new industrial-age technologies to oceanic transportation. In metal-hulled and engine-powered trading platforms, industrial-age steamers (especially tramps and liners) lead to marked increases in the average tonnage of a typical vessel crossing the seas of an expanding global economy. Some of the most important developments had to do with the substitution of traditional wind-driven ships by successive cohorts of vessels exploiting the comparative advantages of mechanization. In this paper, we deploy a set of both established and less-orthodox quantitative approaches to historical commercial shipping time-series so as to model the (complex) relationship between steam and sail performance. We find that, indeed, there is evidence of leader-follower dynamics during the later part of 19th century. This process of ‘creative destruction’ was non-linear.

Getting Ahead While Getting Along: Followership as a Key Ingredient for Shared Leadership and Reducing Team Conflict.

Followership and leadership provide two distinct but complementary sets of behaviors that jointly contribute to positive team dynamics. Yet, followership is rarely measured in shared leadership research. Using a prospective design with a sample of leaderless project teams, we examined the interdependence of leadership and followership and how these leader-follower dynamics relate to relationship conflict at the dyadic and team level. Supporting the reciprocity of leader-follower dynamics, social relations analyses revealed that uniquely rating a teammate higher on effective leadership was associated with being rated higher by that same person on effective followership. Additionally, team members with a reputation as an effective leader also tended to be viewed as an effective follower. As expected, team levels of leadership were tightly linked to team levels of followership. Connecting these results to relationship conflict at the dyadic level, we found that uniquely rating someone as an effective follower or an effective leader would decrease the likelihood of experiencing interpersonal conflict with that person and that having a reputation for effective followership or effective leadership relates negatively to being viewed as a conflict hub within the team. Finally, effective followership was significantly negatively related to team levels of conflict, but we did not find a significant relation between effective leadership and relationship conflict at the team level. Our results highlight that followership is not only a necessary ingredient for high levels of shared leadership to exist within a team, but it underpins more functional team interactions.

The moderating influence of error timing on follower perceptions of leader error

PurposeThis study aims to examine how the characteristics of leader errors impact perceptions and reactions of followers, particularly their willingness to follow a leader in the future and perceptions of error severity. Expanding upon the leader error and transgressions literature, this study considers how the timing of an error may influence how the error is interpreted.Design/methodology/approachThis study’s sample included 283 students engaged in a 2 × 2 factorial designed laboratory experiment. Multiple regression analyses were conducted to determine whether error timing moderated the relationship between error type and two outcomes, willingness to follow and perceived error severity.FindingsRelationship errors resulted in the worst outcomes and perceptions regardless of when they occurred. Task errors were judged as less impactful when occurring early in a task than later in a task. These results suggest that followers are more accepting of task leader errors when they have opportunities to recover from them, but consistently judge relationship errors as damaging.Practical implicationsOrganizations should carefully consider the impact of leader errors and their context and develop strategies for error management and recovery.Originality/valueThis research addresses calls from scholars for greater consideration of temporality as a contextual variable in leader-follower dynamics, as well as those to take a more follower-centric approach to leadership research. This study also replicates prior leader error research and extends leader error theories to provide new avenues for future research.

Analyzing multidimensional movement interaction with generalized cross-wavelet transform.

Humans are able to synchronize with musical events whilst coordinating their movements with others. Interpersonal entrainment phenomena, such as dance, involve multiple body parts and movement directions. Along with being multidimensional, dance movement interaction is plurifrequential, since it can occur at different frequencies simultaneously. Moreover, it is prone to nonstationarity, due to, for instance, displacements around the dance floor. Various methodological approaches have been adopted for the study of human entrainment, but only spectrogram-based techniques allow for an integral analysis thereof. This article proposes an alternative approach based upon the cross-wavelet transform, a state-of-the-art technique for nonstationary and plurifrequential analysis of univariate interaction. The presented approach generalizes the cross-wavelet transform to multidimensional signals. It allows to identify, for different frequencies of movement, estimates of interaction and leader-follower dynamics across body parts and movement directions. Further, the generalized cross-wavelet transform can be used to quantify the frequency-wise contribution of individual body parts and movement directions to overall movement synchrony. Since both in- and anti-phase relationships are dominant modes of coordination, the proposed implementation ignores whether movements are identical or opposite in phase. The article provides a thorough mathematical description of the method and includes proofs of its invariance under translation, rotation, and reflection. Finally, its properties and performance are illustrated via four examples using simulated data and behavioral data collected through a mirror game task and a free dance movement task.

Leader–Follower Role Allocation for Physical Collaboration in Human Dyads

People often find themselves in situations where collaboration with others is necessary to accomplish a particular task. In such cases, a leader–follower relationship is established to coordinate a plan to achieve a common goal. This is usually accomplished through verbal communication. However, what happens when verbal communication is not possible? In this study, we observe the dynamics of a leader–follower relationship in human dyads during collaborative tasks where there is no verbal communication between partners. Using two robotic arms, we designed a collaborative experimental task in which subjects perform the task individually or coupled together through a virtual model. The results show that human partners fall into the leader–follower dynamics even when they cannot communicate verbally. We demonstrate this in two steps. First, we study how each subject in a collaboration influences task performance, and second, we evaluate whether both partners influence it equally or not using our proposed sorting method to objectively identify a leader. We also study the leader–follower dynamics by analysing the task performance of partners during their individual sessions to predict the role distribution in a dyad. Based on the results of our prediction method, we conclude that the higher-performing individual performance will assume the role of a leader in collaboration.

Dyadic leader–follower dynamics change across situations in captive house sparrows

Abstract Individuals can behave as either leaders or followers in many taxa of collectively moving animals. Leaders initiate movements and may incur predation risks, while followers are thought to be more risk-averse. As a group encounters different challenges and ecological situations, individuals in the group may change their social role. We investigated leader and follower roles using dyads of captive house sparrow (Passer domesticus) during both exploration of a novel environment and a simulation of predator attack. During the exploration of a novel environment, individuals behaved consistently either as leaders or followers. However, in the simulated attack tests, individuals in the dyads switched their roles, with “followers” leading the escape flights and “leaders” following them. Our study provides evidence of 1) consistent differences between individuals in behavior during social escape and 2) a relationship between social roles across different situations. We suggest that such relationship hinges on individual risk-taking tendencies, which manifest through different social roles across different ecological situations. We further speculate that risk-taking individuals might gain benefits by following risk-averse individuals during an escape flight.

Becoming morally disengaged: how long does it take?

PurposeLeadership is a time-dependent process and a recent leadership research trend posits a central role of time-based variables. The dyadic tenure plays a keystone role in understanding leader–follower dynamics, especially as regards leader ethics. In line with this, from a social learning theory perspective, the authors propose a model that explains how and when ethical leaders' behaviors influence subordinates' moral disengagement.Design/methodology/approachWith a sample of 220 employees, the present study tests the conditional indirect effect of ethical leadership on followers' moral disengagement via instrumental ethical climate (IEC), using dyadic tenure as the moderator variable. The analyses were conducted with Hayes PROCESS macro.FindingsResults suggested that IEC fully mediates the relationship between ethical leadership and moral disengagement. Thus, when followers perceive low levels of ethical leadership, they notice higher levels of IEC, which is positively related to moral disengagement. However, IEC perception only influences moral disengagement when dyadic tenure approaches the third year.Originality/valueThis paper answers calls to include time-based variables in leadership studies. Hence, using dyadic tenure, this study gives support to previous propositions that were still awaiting empirical test.

Where have all the followers gone?

In this short article, we explore and problematise the axiomatic assumption of follower in the field of leadership studies notably the leader–follower axiom as the essential foundation of much leadership theorising. We do so, firstly by drawing on our experiences of exploring followership conceptually, and secondly, by reviewing conversations with executive MBA students. From these sources, we argue that the absence of identifications with followership offers a challenge to leadership assumptions around the socio-materiality of followers and their relations with leaders within organisational contexts. This leads us to questions like: what if follower identifications do not typically exist or are rejected in everyday organisational working contexts – despite discursive labelling of individuals as followers or following practices? Would or should leadership research and its examination of leader–follower dynamics fundamentally change and in what ways? We explore these questions and suggest very different orientations that might appear with regards to notions of the leadership relationship, leading and following dynamics, practice-based attention to leadership and perhaps very different approaches to leadership development. Such a (re)appraisal of the leadership lexicon may move notions of follower identification out of social constructions of organisational leadership and towards social media (Facebook, Twitter and Instagram) – where the phenomenon of being a follower is ever present, but is redefined as a phenomenon of vicarious fantasy associated with interest, curiosity and entertainment.

Shared Zones of Optimal Functioning: A Framework to Capture Peak Performance, Momentum, Psycho–Bio–Social Synchrony, and Leader–Follower Dynamics in Teams

By bridging the literature on shared mental models and the individual zones of optimal functioning, the author advances a new framework called the shared zones of optimal functioning. The shared zones of optimal functioning is a probabilistic methodology designed to (a) capture optimal and suboptimal performance experiences in teams, (b) track team momentum through the analysis of within-team performance fluctuations, and (c) estimate within-team psycho–bio–social synchrony and leader–follower dynamics (i.e., leader–follower dichotomy, shared leadership). To test the shared zones of optimal functioning framework, three dyadic juggling teams were asked to juggle for 60 trials, while having their performance, arousal, pleasantness, and attentional levels recorded. Ordinal logistic regression, frequency counts, and cross-correlation analyses revealed that each team showed idiosyncratic affective and attentional levels linked to optimal performance, team momentum patterns, and leader–follower dynamics. The implications of these findings for the development of high-performing teams and specific avenues of future research are discussed throughout.