Initial Opinion Research Articles

Opinion formation in Ising networks

Why do votes in a political setting tend to eventually fall along party lines even when initial opinions are varied and members heterogeneous? And what explains occasional defections? Phenomena illustrative of an eventual confluence of opinions across party, group, or clan—and occasional fractures in the party line—are familiar in other sociological settings as well, in online social networks, gatherings, club memberships, or affiliations to religious, social, or sports groups, in which clan or party allegiances are present. We isolate the rôle of the party in such settings in a sanitized model of interaction inspired by Ising spin glasses in statistical physics. We show that even the slightest, party-influenced statistical bias in interactions results in a marked tendency towards partisan outcomes. In contrast, defections from the party line arise when the party only provides an umbrella organization for like-minded individuals and affects interactions at a remove.

Opinion dynamics in activity-driven networks

Social interaction between individuals constantly affects the development of their personal opinions. Previous models such as the Deffuant model and the Hegselmann-Krause (HK) model have assumed that individuals only update their opinions after interacting with neighbors whose opinions are similar to their own. However, people are capable of communicating widely with all of their neighbors to gather their ideas and opinions, even if they encounter a number of opposing attitudes. We propose a model in which agents listen to the opinions of all their neighbors. Continuous opinion dynamics are investigated in activity-driven networks with a tolerance threshold. We study how the initial opinion distribution, tolerance threshold, opinion-updating speed, and activity rate affect the evolution of opinion. We find that when the initial fraction of positive opinion is small, all opinions become negative by the end of the simulation. As the initial fraction of positive opinions rises above a certain value —about 0.45— the final fraction of positive opinions sharply increases and eventually equals 1. Increased tolerance threshold δ is found to lead to a more varied final opinion distribution. We also find that if the negative opinion has an initial advantage, the final fraction of negative opinion increases and reaches its peak as the updating speed λ approaches 0.5. Finally we show that the lower the activity rate of individuals, the greater the fluctuation range of their opinions.

Fitness voter model: Damped oscillations and anomalous consensus.

We study the dynamics of opinion formation in a heterogeneous voter model on a complete graph, in which each agent is endowed with an integer fitness parameter k≥0, in addition to its + or - opinion state. The evolution of the distribution of k-values and the opinion dynamics are coupled together, so as to allow the system to dynamically develop heterogeneity and memory in a simple way. When two agents with different opinions interact, their k-values are compared, and with probability p the agent with the lower value adopts the opinion of the one with the higher value, while with probability 1-p the opposite happens. The agent that keeps its opinion (winning agent) increments its k-value by one. We study the dynamics of the system in the entire 0≤p≤1 range and compare with the case p=1/2, in which opinions are decoupled from the k-values and the dynamics is equivalent to that of the standard voter model. When 0≤p<1/2, agents with higher k-values are less persuasive, and the system approaches exponentially fast to the consensus state of the initial majority opinion. The mean consensus time τ appears to grow logarithmically with the number of agents N, and it is greatly decreased relative to the linear behavior τ∼N found in the standard voter model. When 1/2<p≤1, agents with higher k-values are more persuasive, and the system initially relaxes to a state with an even coexistence of opinions, but eventually reaches consensus by finite-size fluctuations. The approach to the coexistence state is monotonic for 1/2<p<p_{o}≃0.8, while for p_{o}≤p≤1 there are damped oscillations around the coexistence value. The final approach to coexistence is approximately a power law t^{-b(p)} in both regimes, where the exponent b increases with p. Also, τ increases respect to the standard voter model, although it still scales linearly with N. The p=1 case is special, with a relaxation to coexistence that scales as t^{-2.73} and a consensus time that scales as τ∼N^{β}, with β≃1.45.

WHAT IS DEMENTIA FRIENDLY? DEVELOPMENT AND VALIDATION OF A NOVEL TOOL TO MEASURE STIGMA ASSOCIATED WITH DEMENTIA

Dementia Friendly communities and initiatives are increasingly considered as a critical part of dementia care delivery, yet there is no universally accepted model of what constitutes “dementia friendly”. Medical and other sectors have suggested awareness, inclusion, formal benefits, and informal services as potential goals of becoming dementia friendly, but there is no direct link between these system-based changes and outcomes of Persons with Dementia. To prioritize communities' and societies' efforts to become dementia friendly in a person-centered design, we conducted a series of four structured focus groups involving Persons with Dementia and their primary caregivers, comparing their lived experiences with potential improvement in awareness, inclusion, formal benefits, informal services, and other non-medical formal services. Based on the outcomes of these focus groups, we developed and validated a novel tool to measure stigma associated with dementia. 27 Persons with Dementia and 23 caregivers participated in the four focus groups (49 from US and 1 from UK). While initial opinions on the necessary steps towards becoming dementia friendly differed between individuals and families, the structured interviews from each focus group converged on reducing external stigma associated with dementia as the first step towards improving inclusion, formal benefits, and informal services. Based on published measures of stigma associated with mental health from the US and UK, we developed the Beliefs and Attitudes Towards Dementia Survey. This survey consists of 25 Likert-scale questions to assess attitudes towards characteristics and needs of Persons with Dementia; respect/tolerance, social inclusion, and formal services for Persons with Dementia; and biological vs. behavioral contribution to the development of dementia. The survey was validated in 30 cognitively normal subjects with highly reproducible results (average Cornbach's alpha value of 0.876, range of 0.688–1.000). To the best of our knowledge, this is the first person-centered process to identify stigma associated with dementia as a key barrier towards dementia friendly communities and initiatives. In follow-up, we developed the first validated tool to assess external stigma associated with dementia (the disease) and Persons with Dementia so that future intervention studies can effectively quantify changes in attitudes towards Persons with Dementia.

Éminence Grise Coalitions: On the Shaping of Public Opinion

We consider an opinion network of multiple individuals with dynamics evolving via a general time-varying continuous time consensus algorithm. In such a network, a subset of individuals forms an eminence grise coalition (EGC) if the individuals in that subset are capable of leading the entire network to agreeing on any desired opinion through a cooperative choice of their own initial opinions. In this endeavor, the coalition members are assumed to have access to full profile of the coupling graph of the network as well as the initial opinions of all other individuals. We establish the existence of a minimum size EGC and develop a nontrivial set of tight upper and lower bounds on that size. Thus, even when the coupling graph does not guarantee convergence to a global or multiple consensus, a generally restricted coalition of individuals can steer public opinion toward a desired consensus, provided they can cooperatively adjust their own initial opinions. Geometric insights into the structure of EGCs are also given.

Partial convergence of heterogeneous Hegselmann-Krause opinion dynamics

In opinion dynamics, the convergence of the heterogeneous Hegselmann-Krause (HK) dynamics has always been an open problem for years which looks forward to any essential progress. In this short note, we prove a partial convergence conclusion of the general heterogeneous HK dynamis. That is, there must be some agents who will reach static states in finite time, while the other opinions have to evolve between them with a minimum distance if all the opinions does not reach consensus. And this result leads to the convergence of two special case of heterogeneous HK dynamics: the minimum confidence threshold is large enough, or the initial opinion difference is small enough.

Status, Networks, and Opinion Change: An Experimental Investigation

This study evaluates two prominent sociological theories of interpersonal influence: status characteristics theory and social influence network theory. In application to status settings, we test social influence network theory and its established measurement model as well as a recent “modular integration” that operationalizes social influence network theory’s central constructs by incorporating assumptions from status characteristics theory. The two formulations are systematically examined within an open interaction experiment where groups of two, three, and four participants discussed their initial opinions and formed final opinions on two separate issues. Participants were randomly assigned to status positions, which status characteristics theory emphasizes as normative foundations of influence in small task-oriented groups. Analyses of group-level and individual-level opinion change support social influence network theory as it has been used in the past and suggest that status characteristics theory shows promise in modeling the influence networks that drive opinion change at the individual level.

Soft-control for collective opinion of weighted DeGroot model

The DeGroot model is a classic model to study consensus of opinion in a group of individuals (agents). Consensus can be achieved under some circumstances. But when the group reach consensus with a convergent opinion value which is not what we expect, how can we intervene the system and change the convergent value? In this paper a mechanism named soft control is first introduced in opinion dynamics to guide the group’s opinion when the population are given and evolution rules are not allowed to change. According to the idea of soft control, one or several special agents, called shills, are added and connected to one or several normal agents in the original group. Shills act and are treated as normal agents. The authors prove that the change of convergent opinion value is decided by the initial opinion and influential value of the shill, as well as how the shill connects to normal agents. An interesting and counterintuitive phenomenon is discovered: Adding a shill with an initial opinion value which is smaller (or larger) than the original convergent opinion value dose not necessarily decrease (or increase) the convergent opinion value under some conditions. These conditions are given through mathematical analysis and they are verified by the numerical tests. The authors also find out that the convergence speed of the system varies when a shill is connected to different normal agents. Our simulations show that it is positively related to the degree of the connected normal agent in scale-free networks.

Characteristics of isothermal Fokker–Planck equation for opinion-cluster involved with self-thinking

In this paper, we investigate two types of isothermal Fokker–Planck equation to demonstrate the opinion-cluster involved with self-thinking. Firstly, the isothermal Fokker–Planck equation (IFPE type-I) is introduced from the microscopic equation of motion of opinions by extending the Hegselmann–Krause (HK) model in discrete time to the HK model in continuum time. We find that a steady solution of the opinion distribution function obtained using the IFPE type-I depends only on initial conservative variables. A steady solution of the opinion distribution function obtained using the IFPE type-I, however, deviates from that obtained using the isothermal HK model, which is solved using the direct simulation Monte Carlo (DSMC) method, when the time interval, which is used to solve the isothermal HK model, becomes large. Afterwards, we consider another type of the IFPE (IFPE type-II) from the inelastic Boltzmann equation with the cut-off opinions, which is equivalent to the microscopic model by Deffuant et al (2000 Adv. Complex Syst. 3 87). A steady solution of the opinion distribution function obtained using the IFPE type-II depends on the initial state of opinions. Such a dependency of the steady solution on the initial opinion distribution function is exclusively caused by the dependency of the propagation speed of the opinion on the value of the opinion in the IFPE type-II.

Evolution of public opinions in closed societies influenced by broadcast media

Studies on opinion evolution in a closed society can help people design strategies to emancipate from the control of public opinions and prevent the diffusion of extremism. In this work, the social judgment based opinion (SJBO) dynamics model is extended to explore the collective debates in a closed system that consists of a social network and a broadcast network. The broadcast network is a group of channels through which the so-called broadcast media or mainstream media transmit the same opinion to social agents. Numerical experiments show that the broadcast media can assimilate most of the agents when contrarians are absent. Including agents’ diverse attitudes toward the broadcast media, although downsizes the supporters of broadcast media, fails to make contrarians outnumber the supporters. The dominance of broadcast media in a closed system can be overturned by introducing a small number of inflexible contrarians. Influenced by the competition between contrarians and broadcast media, few centrists survive the collective debates. The scale of supporters is maximized when agents neither have their own initial opinions nor have access to the contrarians, whereas the development of contrarians can be boosted when agents start with non-zero opinions and the repulsion to broadcast media is taken into consideration.

Effects of the Interaction Between Ideological Affinity and Psychological Reaction of Agents on the Opinion Dynamics in a Relative Agreement Model

Ideology is one of the defining elements of opinion dynamics. In this paper, we report the effects of the nonlinear interaction of ideological affinity with the psychological reaction of agents in the frame of a multiparametric mathematical model of opinion dynamics. Computer simulations of artificial networked societies composed of agents of two psychological types were used for studying opinion formation; the simulations showed a phenomenon of preferential self-organization into groups of ideological affinity at the first stages of opinion evolution. The separation into ideologically akin opinion groups (ideological affinity) was more notable in societies composed mostly of concord agents; a larger opinion polarization was associated with the increase of agents’ initial average opinion uncertainty. We also observed a sensibility of opinion dynamics to the initial conditions of opinion and uncertainty, indicating potential instabilities. A measure of convergence was introduced to facilitate the analysis of transitions between the opinion states of networked societies and to detect social instability events. We found that the average of opinion uncertainty distribution reaches a steady state with values lower than the initial average value, sometimes nearing zero, which points at socially apathetic agents. Our analyses showed that the model can be utilized for further investigation on opinion dynamics and can be extended to other social phenomena.

Evaluation of pathological manifestations in concrete structural floor destined to the operation of vehicles in garage: case study of residential building located in the federal district

The origin of pathological problems in the structure indicates in general the existence of faults during the execution of a phase of construction, it also indicates faults in the quality control system of one or more activities. The polished concrete floor is a surface subjected to daily traffic of vehicles and the action of chemical substances, in this way should have as main attributes the durability, hardness and strength. This research has the intention to study the case of pathological changes found by polished concrete floor of the garage of the Condominio Via Parque da Cidade, Setor Sudoeste-Brasilia/DF. In addition, the project presents proposals for corrective action identified these pathologies. The same were mainly identified by visual inspection, but is made necessary the building’s historical analysis and finally percussion tests, extraction and rupture of the test piece of sample, proving the initial opinion. It could be sure that the observed cracks are due to poor adhesion between layers on the garage floor, as the exacerbation of such problems can be blamed on construction execution addictions. As corrective action is recommended the demolition of the current floor and execution of the entire reconstruction process of the polished concrete floor, according to a new project that has the necessary guidelines to prevent the return of pathology and so there is the performance of recovery the same.

Opinion formation in social networks: a time-variant and non-linear model

This paper develops a discrete-time, non-linear, and time-variant model of opinion formation in a social network with global interactions to investigate the relationship between the final consensus belief and the set of agents’ initial opinions. The model uses a novel and considerably intuitive updating rule, according to which the weight placed by an agent on another one’s opinion in each period decreases continuously with the distance between their beliefs in the previous period. In this context, the first part of our analysis proves that agents’ beliefs converge and reach a consensus over time (under a fairly general set of conditions). For the two-agent case, it is then shown that the consensus belief is the simple arithmetic mean of the initial opinions. When there are three agents in the network, the combined use of computational and analytical methods reveals a relatively more complex polynomial relationship between long-run and initial beliefs. In particular, our results for the three-agent case imply that the deviation of the limiting belief from the corresponding average of the initial beliefs can be expressed as a third degree polynomial function incorporating the pairwise differences of agents’ starting beliefs.

Comparison of initial and tertiary centre second opinion reads of multiparametric magnetic resonance imaging of the prostate prior to repeat biopsy

ObjectivesTo investigate the value of second-opinion evaluation of multiparametric prostate magnetic resonance imaging (MRI) by subspecialised uroradiologists at a tertiary centre for the detection of significant cancer in transperineal fusion prostate biopsy.MethodsEvaluation of prospectively acquired initial and second-opinion radiology reports of 158 patients who underwent MRI at regional hospitals prior to transperineal MR/untrasound fusion biopsy at a tertiary referral centre over a 3-year period. Gleason score (GS) 7-10 cancer, positive predictive value (PPV) and negative (NPV) predictive value (±95 % confidence intervals) were calculated and compared by Fisher’s exact test.ResultsDisagreement between initial and tertiary centre second-opinion reports was observed in 54 % of cases (86/158). MRIs had a higher NPV for GS 7-10 in tertiary centre reads compared to initial reports (0.89 ± 0.08 vs 0.72 ± 0.16; p = 0.04), and a higher PPV in the target area for all cancer (0.61 ± 0.12 vs 0.28 ± 0.10; p = 0.01) and GS 7-10 cancer (0.43 ± 0.12 vs 0.2 3 ± 0.09; p = 0.02). For equivocal suspicion, the PPV for GS 7-10 was 0.12 ± 0.11 for tertiary centre and 0.11 ± 0.09 for initial reads; p = 1.00.ConclusionsSecond readings of prostate MRI by subspecialised uroradiologists at a tertiary centre significantly improved both NPV and PPV. Reporter experience may help to reduce overcalling and avoid overtargeting of lesions.Key Points• Multiparametric MRIs were more often called negative in subspecialist reads (41 % vs 20 %).• Second readings of prostate mpMRIs by subspecialist uroradiologists significantly improved NPV and PPV.• Reporter experience may reduce overcalling and avoid overtargeting of lesions.• Greater education and training of radiologists in prostate MRI interpretation is advised.

Political opinion formation: Initial opinion distribution and individual heterogeneity of tolerance

Abstract Opinion dynamics on networks have received serious attention for its profound prospects in social behaviours and self-organized systems. However, political opinion formation, as one typical and significant case, remains lacking in discussion. Previous agent-based simulations propose various models that are based on different mechanisms like the coevolution between network topology and status transition. Nonetheless, even under the same network topology and with the same simple mechanism, forming opinions can still be uncertain. In this work, we propose two features, the initial distribution of opinions and the individual heterogeneity of tolerances on opinion changing, in political opinion formation. These two features are imbedded in the network construction phase of a classical model. By comparing multi simple-party systems, along with a detailed analysis on the two-party system, we capture the critical phenomenon of fragmentation, polarization and consensus both in the persistent stable stage and in-process. We further introduce the average ratio of nearest neighbours to characterize the stage of opinion formation. The results show that the initial distribution of opinions leads to different evolution results on similar random networks. In addition, the existence of stubborn nodes plays a special role: only nodes that are extremely stubborn can cause the change of final opinion distribution while in other cases they only delay the time to reach stability. If stubborn nodes are small in number, their effects are confined within a small range. This theoretical work goes deeper on an existing model, it is an early exploration on qualitative and quantitative simulation of party competition.

Opinion Consensus with Delay When the Zero Eigenvalue of the Connection Matrix is Semi-simple

Two or more groups with different initial opinions can develop into a consensus with appropriate inter- and intra group interactions and communication delay. Here we consider the case when zero is a semi-simple eigenvalue of the normalized connection matrix, and we expand the concept of consensus where opinions of all individual agents must converge to the common (consensus) value to the weak consensus where opinions are clustered and the consensus value is no longer a scalar constant but a vector in a certain consensus subspace. The linearity of the system enables us to adopt an argument of Atay, using the phase space decomposition in terms of the standard bilinear form for functional differential equations, to derive sharp conditions for the system to reach a weak consensus, and to calculate the consensus vector. This calculation also informs how the consensus value of the coupled systems depends on the consensus of the subgroups, initial conditions and communication delay. We also point out the challenge of extending these results to nonlinear versions of the opinion dynamical systems with delay.

Opinion evolution influenced by informed agents

Abstract Guiding public opinions toward a pre-set target by informed agents can be a strategy adopted in some practical applications. The informed agents are common agents who are employed or chosen to spread the pre-set opinion. In this work, we propose a social judgment based opinion (SJBO) dynamics model to explore the opinion evolution under the influence of informed agents. The SJBO model distinguishes between inner opinions and observable choices, and incorporates both the compromise between similar opinions and the repulsion between dissimilar opinions. Three choices (support, opposition, and remaining undecided) are considered in the SJBO model. Using the SJBO model, both the inner opinions and the observable choices can be tracked during the opinion evolution process. The simulation results indicate that if the exchanges of inner opinions among agents are not available, the effect of informed agents is mainly dependent on the characteristics of regular agents, including the assimilation threshold, decay threshold, and initial opinions. Increasing the assimilation threshold and decay threshold can improve the guiding effectiveness of informed agents. Moreover, if the initial opinions of regular agents are close to null, the full and unanimous consensus at the pre-set opinion can be realized, indicating that, to maximize the influence of informed agents, the guidance should be started when regular agents have little knowledge about a subject under consideration. If the regular agents have had clear opinions, the full and unanimous consensus at the pre-set opinion cannot be achieved. However, the introduction of informed agents can make the majority of agents choose the pre-set opinion.

Considering the Reach of Phelps

As the Court in Quanta recently confirms, patent and copyright owners have limited rights following voluntary transfers of protected goods. Moreover, as discussed at length by the Second Circuit in Platt & Munk Co. v. Republic Graphics, Inc., patent owners' rights have long been similarly affected by involuntary transfers. Platt & Munk finds lack of equivalent copyright rulings remarkable but does not allow lack of direct precedent to stand in the way of finding that involuntary transferees of copyright-protected goods have the same rights as voluntary transferees. This comment considers the Fourth Circuit's opinions in Christopher Phelps & Assoc., LLC v. Galloway. Initiallly, that court went one step further, holding, under the first sale doctrine, an infringer is entitled to sell, or otherwise dispose of any copy that the court does not order destroyed or otherwise disposed of, without further obligation, once he satisfies the judgment that remedied the infringement, even if the copy was originally pirated. Those remarks were undoubtaibly colored by the subject of the dispute, however, Defendant's million-dollar house had been constructed according to unauthorized copies of plans that initially sold for only $20,000. The initial opinion was withdrawn, along with most references to the first-sale doctrine, and more emphasis was placed on eBay's limitations on the availability of injunctions. It is unclear whether the eBay opinion, more than concern about encumbering real estate unrelated to the infringement motivated refusal to enjoin sale or lease of a house as a remedy for unauthorized use of plans used for its construction.

Optimal Influence Strategies in Social Networks

This paper suggests a modeling framework to investigate the optimal strategy followed by a monopolistic firm aiming to manipulate the process of opinion formation in a social network. The monopolist and a set of consumers communicate to form their beliefs about the underlying product quality. Since the firm's associated optimization problem can be analytically solved only under specific assumptions, we rely on the sequential quadratic programming computational approach to characterize the equilibrium. When consumers' initial beliefs are uniform, the firm's optimal influence strategy always involves targeting the most influential consumer. For the case of non-uniform initial beliefs, the monopolist might target the less influential consumer if the latter's initial opinion is low enough. The probability of investing more in the consumer with the lower influence increases with the distance between consumers' initial beliefs and with the degree of trust attributed on consumers by the firm. The firm's profit is minimized when consumers' influences become equal, implying that the firm benefits from the presence of consumers with divergent strategic locations in the network. In the absence of a binding constraint on total investment, the monopolist's incentives to manipulate the network decrease with consumers' initial beliefs and might either increase or decrease with the trust put in consumers' opinion by the firm. Finally, the firm's strategic motivation to communicate persistently high beliefs during the opinion formation process is positively associated with the market size, with the available budget and with the direct influence of the most influential consumer on the other but negatively associated with consumers' initial valuation of the good.

Opinion Dynamics and Stubbornness Via Multi-Population Mean-Field Games

This paper studies opinion dynamics for a set of heterogeneous populations of individuals pursuing two conflicting goals: to seek consensus and to be coherent with their initial opinions. The multi-population game under investigation is characterized by (i) rational agents who behave strategically, (ii) heterogeneous populations, and (iii) opinions evolving in response to local interactions. The main contribution of this paper is to encompass all of these aspects under the unified framework of mean-field game theory. We show that, assuming initial Gaussian density functions and affine control policies, the Fokker---Planck---Kolmogorov equation preserves Gaussianity over time. This fact is then used to explicitly derive expressions for the optimal control strategies when the players are myopic. We then explore consensus formation depending on the stubbornness of the involved populations: We identify conditions that lead to some elementary patterns, such as consensus, polarization, or plurality of opinions. Finally, under the baseline example of the presence of a stubborn population and a most gregarious one, we study the behavior of the model with a finite number of players, describing the dynamics of the average opinion, which is now a stochastic process. We also provide numerical simulations to show how the parameters impact the equilibrium formation.