Initial Opinion Research Articles

The Projection Method for Reaching Consensus in Discrete-time Multiagent Systems

In the coordination problems for multi-agent systems, a well-known condition of achieving consensus is the presence of a spanning arborescence in the communication digraph. The paper deals with the discrete consensus problem in the case where this condition is not satisfied. Let P be a row stochastic influence matrix, whereas TP is the subspace of initial opinions that ensure consensus in DeGroot's iterative pooling model. We propose a method of coordination that consists of: (1) transformation of the vector of initial opinions into the closest vector in TP and (2) subsequent DeGroot process with the matrix P.

How Expert Advice Influences Decision Making

People often use expert advice when making decisions in our society, but how we are influenced by this advice has yet to be understood. To address this, using functional magnetic resonance imaging, we provided expert and novice advice to participants during an estimation task. Participants reported that they valued expert advice more than novice advice, and activity in the ventral striatum correlated with this valuation, even before decisions with the advice were made. When using advice, participants compared their initial opinion to their advisor’s opinion. This comparison, termed the “opinion difference”, influenced advice utilization and was represented in reward-sensitive brain regions. Finally, the left lateral orbitofrontal cortex integrated both the size of the opinion difference and the advisor’s level of expertise, and average activity in this area correlated with mean advice utilization across participants. Taken together, these findings provide neural evidence for how advice engenders behavioral change during the decision-making process.

Experiences of involuntary admission in an approved mental health centre

The aim of this qualitative study was to gain an understanding of what it means to have an involuntary hospital admission. A sample of six people who were detained at an approved Irish mental health centre consented to recount their experiences were interviewed. The interview transcripts were analysed using Interpretative Phenomenological Analysis. Three superordinate themes were identified: 'The early days', 'Experiences of treatment' and 'Moving on?'. 'The early days' represented participants' initial feelings and opinions of the experience of coming into the approved centre. 'Experiences of treatment' refers to participants' experiences of medication and relationships with staff. Finally, the theme 'Moving on?' represented participants' views on how they adjusted to involuntary admission. 'Learning the way' was central to the participants' notion of moving on. The findings suggest that the meaning of detention is a varied one that evokes an array of emotional responses for participants and highlights the need for a renewed way of thinking and doing concerning those subject to involuntary.

When Subcategorization Facilitates Group Cohesion

This paper analyzes the conditions under which groups composed of two opposing factions are able to preserve group cohesion and subgroup opinion divisions simultaneously. Results from two experimental studies conducted with small interactive groups showed that groups with opposing factions were able to preserve subgroup divergence without jeopardizing superordinate group cohesion. A process termed relational regulation of ingroup opinion divisions explains these findings: The more group members perceived the group as promoting good relations, the more they maintained or even radicalized their initial opinions. In contrast, in an experimental context in which opinion divergences were not reinforced by subcategorization, we observed convergence toward a unique group position destined to maintain group cohesion that was independent of the perceived relational norm.

Multi-Level Opinion Dynamics under Bounded Confidence

Opinion dynamics focuses on the opinion evolution in a social community. Recently, some models of continuous opinion dynamics under bounded confidence were proposed by Deffuant and Krause, et al. In the literature, agents were generally assumed to have a homogeneous confidence level. This paper proposes an extended model for a group of agents with heterogeneous confidence levels. First, a social differentiation theory is introduced and a social group is divided into opinion subgroups with distinct confidence levels. Second, a multi-level heterogeneous opinion formation model is formulated under the framework of bounded confidence. Finally, computer simulations are conducted to study the collective opinion evolution, focusing on three key factors: the fractions of heterogeneous agents, the initial opinions, and the group size. The simulation results demonstrate that the number of final opinions depends on the fraction of close-minded agents when the group size and the initial opinions are fixed; the final opinions converge more easily when the initial opinions are closer; and the number of final opinions can be approximately modeled by a linear increasing function of the group size and the increasing rate is the fraction of close-minded agents.

The Research of Polarization Phenomenon in Blogosphere

Opinion polarization in blogosphere is an special and important group behavior which often foreshow the emergence of some significant public social events. In this paper, we first analyze the original blog dissemination characteristics include dissemination networked, free agenda-setting and against the spiral of silence phenomenon. Then, we construct a opinion dissemination dynamic model with the method of reductionism and holism. We decompose the blogosphere into different subnets according to the degree distribution, and build the basic dynamic equations with the k-degree subnet, then extended to the whole network to study the polarization phenomenon. After that , we point out the weakness of scale free network to depict the blogosphere in brief and give a new novel model and simulate the process of the opinion dissemination influenced by the composition of the initial opinion, the fixed opinion groups and subjective mental preference of interactive groups. Empirical research shows that polarization will surely happen, consensus is impossible in blogosphere.

The potential of host community compensation in facility siting

Overcoming local public opposition is a major challenge for the siting of carbon capture and storage (CCS) facilities, not in the least because CCS facilities are perceived by the public as potentially imposing harm on the host community, while their benefits are mostly non-local. Host community compensation may help to adjust this imbalance and to increase local public acceptance of CCS facilities. To date, however, there is no empirical research that has examined the effectiveness of host community compensation in a CCS context. This article reviews the broader literature on compensation as a first step towards understanding why and when host community compensation may or may not work in CCS settings. We identify several factors that may codetermine how members of the local public respond to compensation offers (e.g. the type of compensation offered; the perceived riskiness of a proposed facility; initial local opinion) and provide suggestions for future research in this field. Furthermore, we explore how some of the insights into the effectiveness of compensation as reported in the facility siting literature may apply to CCS. We conclude that while host community compensation is no panacea, it has the potential to help prevent or solve (CCS) facility siting controversies.

Opinion Dynamics Under Conformity

We present a model of opinion formation where individuals repeatedly engage in discussion and update their opinion in a social network similarly to the DeGroot model. Abstracting from the standard assumption that individuals always report their opinion truthfully, agents in our model interact strategically in the discussion such that their stated opinion can differ from their true opinion. The incentive to do so is induced by agents' preferences for conformity. Highly conforming agents will state an opinion which is close to their neighbors' while agents with low level of conformity may be honest or even overstate their opinion. We model opinion formation as a dynamic process and identify conditions for convergence to consensus. Studying the consensus in detail, we show that an agent's social influence on the consensus opinion is increasing in network centrality and decreasing in the level of conformity. Thus, lower conformity fosters opinion leadership. Moreover, assuming that the initial opinion is a noisy signal about some true state of the world, we consider the mean squared error of the consensus as an estimator for the true state of the world. We show that a society is wise, i.e. the mean squared error is smaller, if players who are well informed are less conform, while uninformed players conform more with their neighbors.

Diachronic Framing Effects in Competitive Opinion Environments

Although theoretical models understand framing as a process that evolves over time, most prior studies were designed to measure the immediate effects of news frames. We theorize that framing effects are diachronic in nature; that is, framing effects at some given point in time can be diminished or reversed at a later point in time. It is argued that the longevity of framing effects depends on how certain people are when they form their initial opinions. If the effects of frames lead to opinions that are held with low certainty, future exposure to competing frames can alter opinions in directions opposite to the original frame. In contrast, when people hold rather strong opinions as a result of initial frame exposure, these framing effects are likely to persist over time. Two studies support the claim that the longevity of framing effects is conditional on opinion certainty.

A 31 day old with head injury – developmental ‘milestones’ do not apply to everyone

<h3>Case history</h3> FD, a 36 week gestation well baby, presented from home after a head injury. During a nappy change, he had been positioned on a changing mat on top of a chest of drawers, one metre above a carpeted floor. He fell off the mat and was found lying on the floor, not losing consciousness. Developmentally, FD was reported to be a very active baby and parents believed he had ‘wriggled’ off the changing mat. They mentioned that FD had rolled from front to back previously. There was a boggy swelling 5 cm×8 cm in the left parieto-occipital region with no other bruising, injury or abnormality. He was not witnessed to be able to roll during initial assessment. Safeguarding protocols were followed as the mechanism of injury was not fully explained in a non-mobile infant. CT head revealed a left-sided parietal skull fracture associated with a subdural haematoma. No other parenchymal injury or stigmata of previous traumatic brain injury was seen. There were no retinal haemorrhages, other skeletal survey findings or blood test abnormalities. During his stay in hospital, the nursing and medical team witnessed (and digitally recorded) FD rolling from back to front: this is available for presentation and corroborated the parents9 history. <h3>Discussion</h3> Evidence shows that abusive and non-abusive skull fractures are commoner in younger infants and a recent meta-analysis calculated the overall probability that a skull fracture is due to abuse is 29%. Initial consensus opinion in FD9s case was that accidental head injury was very unlikely given his developmental age. This case highlights that normal developmental milestones do not apply to every child. The Denver II developmental screening test, constructed from 2,000 subjects, shows that a baby would not roll before two months. It is crucial in all cases to keep a non-judgemental attitude and be open to mechanisms of injury that seem unusual, particularly if there are Safeguarding concerns.

When guessing what another person would say is better than giving your own opinion: Using perspective-taking to improve advice-taking

We investigated how perspective-taking might be used to overcome bias and improve advice-based judgments. Decision makers often tend to underweight the opinions of others relative to their own, and thus fail to exploit the wisdom of others. We tested the idea that decision makers taking the perspective of another person engage a less egocentric mode of processing of advisory opinions and thereby improve their accuracy. In Studies 1–2, participants gave their initial opinions and then considered a sample of advisory opinions in two conditions. In one condition (self-perspective), they were asked to give their best advice-based estimates. In the second (other-perspective), they were asked to give advice-based estimates from the perspective of another judge. The dependent variables were the participants' accuracy and indices that traced their judgment policy. In the self-perspective condition participants adhered to their initial opinions, whereas in the other-perspective condition they were far less egocentric, weighted the available opinions more equally and produced more accurate estimates. In Study 3, initial estimates were not elicited, yet the data patterns were consistent with these conclusions. All the studies suggest that switching perspectives allows decision makers to generate advice-based judgments that are superior to those they would otherwise have produced. We discuss the merits of perspective-taking as a procedure for correcting bias, suggesting that it is theoretically justifiable, practicable, and effective.

The projection method for reaching consensus and the regularized power limit of a stochastic matrix

In the coordination/consensus problem for multi-agent systems, a well-known condition of achieving consensus is the presence of a spanning arborescence in the communication digraph. The paper deals with the discrete consensus problem in the case where this condition is not satisfied. A characterization of the subspace T P of initial opinions (where P is the influence matrix) that ensure consensus in the DeGroot model is given. We propose a method of coordination that consists of: (1) the transformation of the vector of initial opinions into a vector belonging to T P by orthogonal projection and (2) subsequent iterations of the transformation P. The properties of this method are studied. It is shown that for any non-periodic stochastic matrix P, the resulting matrix of the orthogonal projection method can be treated as a regularized power limit of P.

Prospective diagnostic performance evaluation of single‐voxel 1H MRS for typing and grading of brain tumours

The purpose of this study was to evaluate whether single-voxel (1)H MRS could add useful information to conventional MRI in the preoperative characterisation of the type and grade of brain tumours. MRI and MRS examinations from a prospective cohort of 40 consecutive patients were analysed double blind by radiologists and spectroscopists before the histological diagnosis was known. The spectroscopists had only the MR spectra, whereas the radiologists had both the MR images and basic clinical details (age, sex and presenting symptoms). Then, the radiologists and spectroscopists exchanged their predictions and re-evaluated their initial opinions, taking into account the new evidence. Spectroscopists used four different systems of analysis for (1)H MRS data, and the efficacy of each of these methods was also evaluated. Information extracted from (1)H MRS significantly improved the radiologists' MRI-based characterisation of grade IV tumours (glioblastomas, metastases, medulloblastomas and lymphomas) in the cohort [area under the curve (AUC) in the MRI re-evaluation 0.93 versus AUC in the MRI evaluation 0.85], and also of the less malignant glial tumours (AUC in the MRI re-evaluation 0.93 versus AUC in the MRI evaluation 0.81). One of the MRS analysis systems used, the INTERPRET (International Network for Pattern Recognition of Tumours Using Magnetic Resonance) decision support system, outperformed the others, as well as being better than the MRI evaluation for the characterisation of grade III astrocytomas. Thus, preoperative MRS data improve the radiologists' performance in diagnosing grade IV tumours and, for those of grade II-III, MRS data help them to recognise the glial lineage. Even in cases in which their diagnoses were not improved, the provision of MRS data to the radiologists had no negative influence on their predictions.

Framing, Motivated Reasoning, and Opinions About Emergent Technologies

How do individuals form opinions about new technologies? What role does factual information play in that process? We address these questions by incorporating two critical dynamics, typically ignored in extant work: competition between information and over-time processes. We present results from experiments on two technologies: carbon-nanotubes and genetically modified foods. We find that factual information is of limited utility—it does not have a greater impact than other background factors (e.g. values), it adds little power to newly provided arguments/frames (e.g., compared to arguments that lack factual information), and it is perceived in biased ways once individuals form clear initial opinions (e.g., there is motivated reasoning). Not only do our results provide insight into how individuals form opinions, over time, when presented with novel technologies, but they also bring together various distinct literatures including work on information, framing and motivated reasoning.

Dynamics of bounded confidence opinion in heterogeneous social networks: Concord against partial antagonism

Bounded confidence models of opinion dynamics in social networks have been actively studied in recent years, in particular, opinion formation and extremism propagation along with other aspects of social dynamics. In this work, after an analysis of limitations of the Deffuant–Weisbuch (DW) bounded confidence, relative agreement model, we propose the mixed model that takes into account two psychological types of individuals. Concord agents (C-agents) are friendly people; they interact in a way that their opinions always get closer. Agents of the other psychological type show partial antagonism in their interaction (PA-agents). Opinion dynamics in heterogeneous social groups, consisting of agents of the two types, was studied on different social networks: Erdös–Rényi random graphs, small-world networks and complete graphs. Limit cases of the mixed model, pure C- and PA-societies, were also studied. We found that group opinion formation is, qualitatively, almost independent of the topology of networks used in this work. Opinion fragmentation, polarization and consensus are observed in the mixed model at different proportions of PA- and C-agents, depending on the value of initial opinion tolerance of agents. As for the opinion formation and arising of “dissidents”, the opinion dynamics of the C-agents society was found to be similar to that of the DW model, except for the rate of opinion convergence. Nevertheless, mixed societies showed dynamics and bifurcation patterns notably different to those of the DW model. The influence of biased initial conditions over opinion formation in heterogeneous social groups was also studied versus the initial value of opinion uncertainty, varying the proportion of the PA- to C-agents. Bifurcation diagrams showed an impressive evolution of collective opinion, in particular, radical changes of left to right consensus or vice versa at an opinion uncertainty value equal to 0.7 in the model with the PA/C mixture of population near 50/50.

Why do people place lower weight on advice far from their own initial opinion?

Experimental studies find that the weight put on advice is negatively related to the distance between the advice and the decision-maker’s initial opinion. We show that this can be rational if the decision-maker has imperfect knowledge about the advisor’s competence.

Opinion Word Expansion and Target Extraction through Double Propagation

Analysis of opinions, known as opinion mining or sentiment analysis, has attracted a great deal of attention recently due to many practical applications and challenging research problems. In this article, we study two important problems, namely, opinion lexicon expansion and opinion target extraction. Opinion targets (targets, for short) are entities and their attributes on which opinions have been expressed. To perform the tasks, we found that there are several syntactic relations that link opinion words and targets. These relations can be identified using a dependency parser and then utilized to expand the initial opinion lexicon and to extract targets. This proposed method is based on bootstrapping. We call it double propagation as it propagates information between opinion words and targets. A key advantage of the proposed method is that it only needs an initial opinion lexicon to start the bootstrapping process. Thus, the method is semi-supervised due to the use of opinion word seeds. In evaluation, we compare the proposed method with several state-of-the-art methods using a standard product review test collection. The results show that our approach outperforms these existing methods significantly.

Routine second-opinion cytopathology review of thyroid fine needle aspiration biopsies reduces diagnostic thyroidectomy

Follicular thyroid carcinoma cannot be distinguished reliably from benign follicular neoplasia by fine needle aspiration (FNA) biopsy. Given an estimated 20% risk of malignancy, many patients with indeterminate FNA biopsies require thyroidectomy for diagnosis. Some centers have shown significant discordance when a second pathologist evaluates the same FNA biopsy. We sought to determine whether routine second-opinion cytopathology reduces the need for diagnostic thyroidectomy, especially in patients with indeterminate FNA biopsies. In all, 331 thyroid FNA biopsy specimens obtained from outside centers from 2004 to 2009 were reviewed at our institution. The FNA biopsy results were categorized into nondiagnostic (Bethesda I), benign (Bethesda II), indeterminate (follicular/Hurthle cell neoplasm, follicular/Hurthle cell lesion; Bethesda III & IV), and malignant (papillary or suspicious for papillary or other malignancy; Bethesda V and VI). Second-opinion cytology was compared with the initial opinion in 331 cases and with final operative pathology in the 250 patients who progressed to thyroidectomy. The average patient age was 51 with a predominant number of female (79%) participants. The overall cytology concordance for all 331 FNA biopsies was 66% (218/331). Concordance was highest at 86% (74/86) with malignant FNA biopsies. Concordance in the 129 patients with indeterminate FNA biopsies was only 37% (48/129). Indeterminate FNA biopsies were reread as nondiagnostic in 21% (27/129) of patients and as benign in 42% (54/129) of patients. Twenty-two patients with an indeterminate FNA biopsy reread as benign progressed to operative therapy for reasons other than cytology (eg, symptomatic nodule and radiation exposure/high risk) and were found to be benign in 95% (21/22) of patients on operative pathology for a 95% negative predictive value. An additional 11 patients with an indeterminate FNA reread as benign had follow-up FNA biopsies, each of which was benign. Indeterminate FNA biopsies on initial cytology had a malignancy rate of 13% (17/129) on operative pathology compared with 29% (14/48) for indeterminate FNA biopsies from second opinion. A second opinion improved FNA biopsy accuracy from 60% to 74%. Overall, second-opinion cytology of indeterminate FNA biopsies avoided diagnostic operation in 25% (32/129). Routine second opinion review of indeterminate thyroid FNA biopsies can potentially obviate the need for diagnostic thyroidectomy in 25% of patients without increases in false negatives.

POI10 Using atypical symptoms to predict nondemyelinating disease in patients as “query multiple sclerosis”

Using atypical symptoms at presentation as red flags to indicate an alternative diagnosis to MS has not been formally assessed. The purpose of this study was to assess the utility...

Patient preferences and urologist recommendations among local-stage prostate cancer patients who present for initial consultation and second opinions

This study describes urologist recommendations for treatment among local-stage prostate cancer patients presenting for initial management consultations versus second opinions. We hypothesized that urologists present a wider range of management recommendations and are less likely to consider the patient preference during the initial consultation. Newly diagnosed local-stage prostate cancer patients and their urologists participated in a survey at urology practices in three states. The urologist's survey included questions about the patient's clinical status, treatments discussed and recommended, and factors that influenced the urologist's recommendations. Of the 238 eligible patients, 95 men presented for an initial consultation, and 143 men presented for a second opinion. In multivariate analysis, urologists recommended 0.52 more treatments (standard error 0.19, P<0.001) during an initial consultation as opposed to a second opinion. The proportion recommending surgery increased from 71-91% (initial consultation versus second opinion setting). Among initial consultations, 59% had low-risk disease, and urologists' recommendations included surgery (80%), external radiation (38%), brachytherapy (seeds) (52%), and active surveillance (25%). Of the 54% with low-risk disease in a second opinion consultation, urologists' recommendations included surgery (90%), external radiation (16%), brachytherapy (14%), and active surveillance (16%). In second opinion settings urologists discussed fewer treatment options and recommended surgery more often. These findings also applied to men with low-risk prostate cancer.