Aggregation of opinions based on correlated cues and advisors

We study the process by which decision makers (DMs) aggregate probabilistic opinions from multiple, correlated sources with a special emphasis on the determinants of the DM's confidence, which is a predictor of the DM's willingness to accept the implications of the aggregation process. Our model assumes that (a) DM combines the advisors' opinions by weighting them according to the amount of information underlying them, and (b) the DM's confidence increases as a function of a variety of factors that reduce the variance of the aggregate. We report results of three studies that manipulate the predictive validity of the cues and their inter‐correlations. Most of the models' predictions are supported but, contrary to the model's prediction, the DMs' confidence is not sensitive to the inter‐cue correlation. The best predictors of the DMs' confidence are the perceived predictability of the event, the level of agreement among the advisors, and the advisors' self‐reports of confidence. This pattern of results is explained by the ‘system neglect’ hypothesis. Copyright © 2006 John Wiley & Sons, Ltd.     

Confidence in aggregation of expert opinions

We investigate the case of a single decision maker (DM) who obtains probabilistic forecasts regarding the occurrence of a unique target event from J distinct, symmetric, and equally diagnostic expert advisors (judges). The paper begins with a mathematical model of DM's aggregation process of expert opinions, in which confidence in the final aggregate is shown to be inversely related to its perceived variance. As such, confidence is expected to vary as a function of factors such as the number of experts, the total number of cues, the fraction of cues available to each expert, the level of inter-expert overlap in information, and the range of experts' opinions. In the second part of the paper, we present results from two experiments that support the main (ordinal) predictions of the model.     

The effects of intergroup comparison on the polarization of opinions

This study investigates the expression of attitudes by individuals within the context of groups. A link is made between two theoretical areas: that of intergroup relations and that of the effects of group interaction on the expression of opinions. It is argued that individuals in groups adopt more polarized attitudes to achieve a more positively distinct group identity, and to afford themselves identification with that group. Subjects individually expressed their opinion on an issue, while the salience of group membership was varied by evoking the identity of an alternative group which held opposed opinions on the issue. When their own group identity was more salient, subjects tended to express their opinions in a more polarized manner, and in a manner more in keeping with the presumed view of their group. Also, they attributed to the other group attitudes that were more polarized and more in keeping with their presumed view of the issue.     

Selective exposure among advisors: the impact of impression motivation

Audience confirmation bias (ACB) refers to the extent to which people prefer information supporting (vs. conflicting with) their audience's views. In two studies, we showed that advisors shifted their ACB toward the needs of their advisees (i.e., audience): When advisors were led to believe that their advisees wanted to defend their views, the ACB was higher compared with when advisees were open minded for critique. Study 2 indicated that this pattern occurred because advisors wanted to have a pleasant interaction with their advisees (impression motivation): Whereas impression‐motivated advisors exhibited a stronger ACB when they were asked to give advice to a defensive (vs. open‐minded) advisee, accuracy‐motivated advisors showed a balanced ACB, regardless of their advisee's needs.     

Motivational effects in the social comparison of opinions

Four experiments were executed to test the effects of different epistemic motivations on subjects' tendency to compare with agreeing or disagreeing others. We found that under high (vs. low) fear of invalidity, subjects tend more to compare with disagreeing (vs. agreeing) others. By contrast, under high (vs. low) need for self-confirmation or a high (vs. low) need for cognitive structure, subjects tended more to compare with agreeing others. These results are discussed in reference to social comparison formulations (Festinger, 1954; Goethals & Darley, 1977) and the theory of lay epistemology (Kruglanski & Ajzen, 1983; Kruglanski & Freund, 1983).     

Biases and their impact on opinions of transgender bathroom usage

The relationship between personality traits and biased assimilation, evaluating arguments, and persuasive messages more favorably if supporting pre-existing attitudes, lacks adequate research. Research suggests that higher narcissistic traits are associated with biased reactions. Additionally, research suggests that people with greater scientific reasoning abilities have more biased reactions to information that challenges their attitude, as they more easily locate flaws on topics that oppose their beliefs. Participants (N = 260) completed measures to identify their views on trans bathroom use, as well as other personality and attitude measures. They were randomly assigned to read one of the two articles using fake scientific data that either supported trans people using a bathroom reflecting their gender identity or that they should use a bathroom matching their sex-assigned at birth. Participants rated the quality of the article significantly higher when their opinion on bathroom use was congruent with the article than when it was incongruent. We used regression analyses with participants' perceptions of the quality of the article as the outcome variable and scientific reasoning scores, narcissism personality index scores, open-mindedness scores as predictor variables. In the mismatch group, the higher the scores on scientific reasoning, the lower the ratings of the quality of the opinion incongruent article. In the match group, the higher the scores on open-mindedness, the lower the ratings of the quality of the opinion congruent article. This research suggests that bias reduction is necessary to function in a world where scientific facts are called into question on a consistent basis.     

The impact of information from similar or different advisors on judgment

People rely on others’ advice to make judgments on a daily basis. In three studies, we examine the differential impacts of similarity between the source of that advice and the person making the judgment in two settings: judging others’ behavior and judging one’s own actions. We find that similarity interacts with the target of the judgment. In particular, information received from a different advisor is more heavily weighed than from a similar advisor in judging others’ actions, but information from a similar advisor is more heavily weighed than from a different advisor in judging one’s own. We provide two potential explanations for this interaction, difficulty of the judgment and informativeness of the advice. Our analyses show a moderated mediating role of informativeness and difficulty in the relationship between the advisor’s similarity by judgment type interaction and advice use.     

The effects of social influence on children's memory reports: the omission and commission error asymmetry

Children in two age groups (7 vs. 12 yrs, N= 174) individually interacted with a stranger and were later interviewed about this event. Right before the interview, each child encountered the stranger once again and he engaged in a conversation where he either suggested that a (central or peripheral) detail originally present in the event had actually not been there or that an originally non-present (central or peripheral) detail had in fact been there. It was hypothesized that the two types of misinformation would result in omission and commission errors respectively. The results showed that the social influence resulted in an asymmetric effect (i.e., more commission than omission errors). Importantly, we also found that the children made more errors with respect to the peripheral detail (a suitcase), compared to the central detail (a passenger). Younger children did not make more errors (neither omission nor commission errors) than older children.     

Variations in patterns of lateral asymmetry among dextrals

Evidence supporting individual variations in patterns of hemispheric involvement in the recognition of visuo-spatial and verbal stimuli among dextrals is reported. In Experiment 1, subjects' asymmetry scores on a task that was nonlateralized for the group as a whole were significantly correlated with their asymmetry scores on right-hemisphere-specialized tasks, including face recognition. In Experiment 2, subjects' asymmetry scores on a task that was nonlateralized for the group as a whole were significantly correlated with their asymmetry scores on a left-hemisphere-specialized word recognition task. These results suggest that individual dextrals' asymmetry scores on lateralized tasks are a joint function of a subject's underlying hemispheric specialization for that task and stable individual variations in asymmetric hemispheric reliance.     

The modulation of stimulus structure on visual field asymmetry effects: The case of Chinese character recognition

Recent research suggests that visual field (VF) asymmetry effects in visual recognition may be influenced by information distribution within the stimuli for the recognition task in addition to hemispheric processing differences: Stimuli with more information on the left have a right VF (RVF) advantage because the left part is closer to the centre, where the highest visual acuity is obtained. It remains unclear whether visual complexity distribution of the stimuli also has similar modulation effects. Here we used Chinese characters with contrasting structures—left-heavy, symmetric, and right-heavy, in terms of either visual complexity of components or information distribution defined by location of the phonetic component—and examined participants' naming performance. We found that left-heavy characters had the largest RVF advantage, followed by symmetric and right-heavy characters; this effect was only observed in characters that contrasted in information distribution, in which information for pronunciation was skewed to the phonetic component, but not in those that contrasted only in visual complexity distribution and had no phonetic component. This result provides strong evidence for the influence of information distribution within the stimuli on VF asymmetry effects; in contrast, visual complexity distribution within the stimuli does not have similar modulation effects.     

The effects of neonatal gonadectomy and prenatal stress on cortical thickness and asymmetry in rats

In Study I measures of cortical thickness were taken in 90-day-old male and female Sprague-Dawley, Wistar, and Long-Evans rats that were born to pregnant females shipped to the laboratory in late pregnancy and that were either gonadectomized at birth or left intact. No evidence for hemispheric differences in cortical thickness was found in any of the groups. Gonadectomy resulted in increased cortical thickness in male Sprague-Dawley and Wistar rats and in small increases in thickness of the left hemisphere in Long-Evans rats, especially males. No effects of gonadectomy were found in females of any strain. The lack of the expected right-over-left difference in cortical thickness in intact males may have been due to prenatal stress caused by housing, handling, and shipping. In Study 2 measures of cortical thickness were taken in 90-day-old male and female Sprague-Dawley rats that were bred in our laboratory, but otherwise similarly treated at birth. In this second study, the expected right-over-left hemispheric difference in cortical thickness was found in intact male rats; none was found in gonadectomized males or in either of the female groups. The lack of asymmetry in gonadectomized males appeared to be due to an increase in thickness in the left hemisphere. Taken together these studies provide support for the idea that hormones of testicular origin suppress cortical enlargement in the perinatal period, particularly in the left hemisphere.     

Cerebral asymmetry for American Sign Language: The effects of moving stimuli

Previous studies of cerebral asymmetry for the perception of American Sign Language (ASL) have used only static representations of signs; in this study we present moving signs. Congenitally deaf, native ASL signers identified moving signs, static representations of signs, and English words. The stimuli were presented rapidly by motion picture to each visual hemifield. Normally hearing English speakers also identified the English words. Consistent with previous findings, both the deaf and the hearing subjects showed a left-hemisphere advantage to the English words; likewise, the deaf subjects showed a right hemisphere advantage to the statically presented signs. With the moving signs, the deaf showed no lateral asymmetry. The shift from right dominance to a more balanced hemispheric involvement with the change from static to moving signs is consistent with Kimura's position that the left hemisphere predominates in the analysis of skilled motor sequencing (Kimura 1976). The results also indicate that ASL may be more bilaterally represented than is English and that the spatial component of language stimuli can greatly influence lateral asymmetries.     

The effects of mortality reminders on posttraumatic growth and finding benefits among patients with life-threatening illness and their caregivers

Individuals confronted with a life-threatening illness often report posttraumatic growth (PTG) or finding benefits in disease. These positive evaluations of personal strength, perceptions of improved personal relations and new possibilities may represent a defensive response (cf Janus-face model). Three studies investigated the effects of mortality reminders on reports of PTG or benefit findings among people living with life-threatening illness or their caregivers. 80 people living with HIV (study 1), 164 breast cancer survivors (study 2) and 50 family caregivers for a patient with huntington disease (study 3) were randomly assigned to the experimental (mortality reminders) or control conditions. Across three studies, those exposed to mortality reminders reported lower PTG or benefit finding, compared to the controls. These effects were moderated by time elapsed since diagnosis: mortality reminders led to lower PTG/benefit finding among those who received the diagnosis more recently. The results provide an insight into the defensive character of PTG/finding benefits in illness and changes in the function of these beliefs over time elapsing since diagnosis.     

The effects of mortality reminders on posttraumatic growth and finding benefits among patients with life-threatening illness and their caregivers

Individuals confronted with a life-threatening illness often report posttraumatic growth (PTG) or finding benefits in disease. These positive evaluations of personal strength, perceptions of improved personal relations and new possibilities may represent a defensive response (cf Janus-face model). Three studies investigated the effects of mortality reminders on reports of PTG or benefit findings among people living with life-threatening illness or their caregivers. 80 people living with HIV (Study 1), 164 breast cancer survivors (Study 2) and 50 family caregivers for a patient with Huntington Disease (Study 3) were randomly assigned to the experimental (mortality reminders) or control conditions. Across three studies, those exposed to mortality reminders reported lower PTG or benefit finding, compared to the controls. These effects were moderated by time elapsed since diagnosis: mortality reminders led to lower PTG/benefit finding among those who received the diagnosis more recently. The results provide an insight into the defensive character of PTG/finding benefits in illness and changes in the function of these beliefs over time elapsing since diagnosis.     

Embodied free will beliefs: Some effects of physical states on metaphysical opinions

The present research suggests that people’s bodily states affect their beliefs about free will. People with epilepsy and people with panic disorder, which are disorders characterized by a lack of control over one’s body, reported less belief in free will compared to people without such disorders (Study 1). The more intensely people felt sexual desire, physical tiredness, and the urge to urinate, the less they believed in free will (Study 2). Among non-dieters, the more intensely they felt hunger, the less they believed in free will. However, dieters showed a trend in the opposite direction (Study 3).