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Introduction: Evidence summaries on the benefits and harms of treatment options support informed decisions under controlled conditions. However, few studies have investigated how such formats support decision-making across different social groups. There is a risk that only disadvantaged people will be able to make informed health decisions-possibly increasing the health equity gap. It is also unclear whether they support decision-making in the field at all. The aim of our study is to assess whether evidence summaries based on the fact box format can help people from different social groups make informed decisions about COVID-19 and influenza vaccinations, and thus reduce inequity in health communication., Methods and Analysis: In a multi-centre, cluster-randomised, controlled trial, health educators from usual care and outreach work in Germany will be randomised in a 1:1 ratio to provide either usual health communication plus an evidence summary ('fact box') or usual health communication. Health educators provide a flyer about COVID-19 or influenza vaccination which contains a link to an online study either with (intervention) or without (control) fact box on the reverse side. Flyer and online study will be available in Arabic, German, Turkish and Russian language. The primary outcome is informed vaccination intention, based on vaccination knowledge, attitudes, intentions and behaviour. Secondary outcomes include risk perception, decisional conflict and shared decision-making. We will use linear mixed models to analyse the influence of both individual (eg, education status) and cluster level factors and account for the expected cluster variability in realising usual health communication or the intervention. The statistical analysis plan includes the selection of appropriate measures of effect size and power calculation, assuming a sample size of 800 patients., Ethics and Dissemination: The trial has been approved by the Ethics Committee of the University of Potsdam, Germany (application numbers: 34/2021 and 57/2022).Results will be disseminated through peer-reviewed journals, conferences and to relevant stakeholders., Protocol Version: Version 6 (4 October 2024); Preprint available on Research Square: https://doi.org/10.21203/rs.3.rs-3401234/v3 TRIAL REGISTRATION NUMBER: NCT06076421., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Doubts regarding vaccine effectiveness may prompt people to decide against a seasonal influenza vaccination. While fact boxes show the effectiveness in terms of cases prevented, people often lack knowledge about important contextual factors, for example, why the vaccine formulation needs to be updated annually, the vaccine mechanism and relevance of the antigen-virus match. Adding such contextual information could improve effectiveness perceptions., Objective: In a preregistered online experiment, we tested whether explaining the seasonality's relevance and mechanisms behind influenza vaccine effectiveness affects people's perceptions of influenza vaccination. We compared two means of explanation (an additional expository text vs. a narrative offering an analogy to improve understanding of vaccine effectiveness) with a control condition simply providing effectiveness information., Design: Unvaccinated participants (N = 1554) were assigned to one of three conditions: (1) fact box only (providing the influenza vaccine's benefit-risk profile; control group), (2) fact box plus informational expository text or (3) fact box plus narrative analogy., Methods: After the experimental manipulations, participants rated the vaccine's effectiveness in preventing influenza disease and answered knowledge questions. Effects on perceived risk of vaccination and intention to get vaccinated were also explored., Results: Reading the expository text increased the perceived vaccine effectiveness and overall knowledge, while reading the narrative analogy only increased the perceived vaccine effectiveness compared with the control condition. All other dependent variables were similar in both text conditions., Conclusions: Extended explanations of vaccine effectiveness can increase perceived vaccine effectiveness. The text format chosen can affect outcomes, such as vaccine-related perceptions or knowledge., (© 2024 The Author(s). British Journal of Health Psychology published by John Wiley & Sons Ltd on behalf of British Psychological Society.)

Background: Algorithmic decision-making (ADM) utilises algorithms to collect and process data and develop models to make or support decisions. Advances in artificial intelligence (AI) have led to the development of support systems that can be superior to medical professionals without AI support in certain tasks. However, whether patients can benefit from this remains unclear. The aim of this systematic review is to assess the current evidence on patient-relevant benefits and harms, such as improved survival rates and reduced treatment-related complications, when healthcare professionals use ADM systems (developed using or working with AI) compared to healthcare professionals without AI-related ADM (standard care)-regardless of the clinical issues., Methods: Following the PRISMA statement, MEDLINE and PubMed (via PubMed), Embase (via Elsevier) and IEEE Xplore will be searched using English free text terms in title/abstract, Medical Subject Headings (MeSH) terms and Embase Subject Headings (Emtree fields). Additional studies will be identified by contacting authors of included studies and through reference lists of included studies. Grey literature searches will be conducted in Google Scholar. Risk of bias will be assessed by using Cochrane's RoB 2 for randomised trials and ROBINS-I for non-randomised trials. Transparent reporting of the included studies will be assessed using the CONSORT-AI extension statement. Two researchers will screen, assess and extract from the studies independently, with a third in case of conflicts that cannot be resolved by discussion., Discussion: It is expected that there will be a substantial shortage of suitable studies that compare healthcare professionals with and without ADM systems concerning patient-relevant endpoints. This can be attributed to the prioritisation of technical quality criteria and, in some cases, clinical parameters over patient-relevant endpoints in the development of study designs. Furthermore, it is anticipated that a significant portion of the identified studies will exhibit relatively poor methodological quality and provide only limited generalisable results., Systematic Review Registration: This study is registered within PROSPERO (CRD42023412156)., (© 2024. The Author(s).)

Scientific findings can be overturned when new evidence arises. This study examines how communicating and explaining uncertainty around scientific findings affect trust in the communicator when findings change. In an online experiment ( N = 800, convenience sample), participants read a fictitious statement from a public health authority announcing that there was no link between a new COVID-19 vaccine and heart muscle inflammation. The authority communicated (1) no uncertainty, (2) uncertainty without giving a reason, (3) uncertainty due to imprecision, or (4) uncertainty due to incomplete accounting of patients. Participants were then informed that the authority's statement was no longer correct as new data showed a link between the vaccine and heart muscle inflammation. Participants rated the authority's trustworthiness before and after the evidence update. Our findings indicate that communicating uncertainty buffers against a loss of trust when evidence changes. Moreover, explaining uncertainty does not appear to harm trust.

Objective. To enable future open-air festivals during a pandemic, model festivals tested restricted access and behavioural rules to prevent SARS-CoV-2 transmissions. However, the uptake of health-protective measures depends on informed acceptance, meaning people are more likely to follow measures if they understand their effectiveness and related disease risks. Design and main outcome measures. With a series of online surveys, we studied risk perceptions of 6,500 festival guests and the association of perceived effectiveness of protective behaviours with reported compliance. In a scenario-based online experiment ( N  = 1,958) among festival guests, we tested the effect of informing transparently about the risk-reducing potential of protective measures at festivals on the intention to attend hypothetical events. Results. We found that guests tended to overestimate infection risks while still perceiving them as low. Self-reported mask wearing and distancing at and around the festivals could not be associated with the understanding of the measures' effectiveness. However, in addition to protective measures themselves, providing transparent information about their absolute risk-reducing effect increased intentions to attend festivals that employ varying protective measures. Conclusion. Our findings suggest that the acceptance of protected festivals can be influenced by transparent information about the effectiveness of protective measures. This calls for further research on evidence-based public health communications to improve their impact.

Objective: For an effective control of the SARS-CoV-2 pandemic with vaccines, most people in a population need to be vaccinated. It is thus important to know how to inform the public with reference to individual preferences-while also acknowledging the societal preference to encourage vaccinations. According to the health care standard of informed decision-making, a comparison of the benefits and harms of (not) having the vaccination would be required to inform undecided and skeptical people. To test evidence-based fact boxes, an established risk communication format, and to inform their development, we investigated their contribution to knowledge and evaluations of COVID-19 vaccines., Methods: We conducted four studies (1, 2, and 4 were population-wide surveys with N = 1,942 to N = 6,056): Study 1 assessed the relationship between vaccination knowledge and intentions in Germany over three months. Study 2 assessed respective information gaps and needs of the population in Germany. In parallel, an experiment (Study 3) with a mixed design (presentation formats; pre-post-comparison) assessed the effect of fact boxes on risk perceptions and fear, using a convenience sample (N = 719). Study 4 examined how effective two fact box formats are for informing vaccination intentions, with a mixed experimental design: between-subjects (presentation formats) and within-subjects (pre-post-comparison)., Results: Study 1 showed that vaccination knowledge and vaccination intentions increased between November 2020 and February 2021. Study 2 revealed objective information requirements and subjective information needs. Study 3 showed that the fact box format is effective in adjusting risk perceptions concerning COVID-19. Based on those results, fact boxes were revised and implemented with the help of a national health authority in Germany. Study 4 showed that simple fact boxes increase vaccination knowledge and positive evaluations in skeptics and undecideds., Conclusion: Fact boxes can inform COVID-19 vaccination intentions of undecided and skeptical people without threatening societal vaccination goals of the population., Competing Interests: The authors have declared that no competing interests exist.

This study provides the first representative analysis of error estimations and willingness to accept errors in a Western country (Germany) with regards to algorithmic decision-making systems (ADM). We examine people's expectations about the accuracy of algorithms that predict credit default, recidivism of an offender, suitability of a job applicant, and health behavior. Also, we ask whether expectations about algorithm errors vary between these domains and how they differ from expectations about errors made by human experts. In a nationwide representative study (N = 3086) we find that most respondents underestimated the actual errors made by algorithms and are willing to accept even fewer errors than estimated. Error estimates and error acceptance did not differ consistently for predictions made by algorithms or human experts, but people's living conditions (e.g. unemployment, household income) affected domain-specific acceptance (job suitability, credit defaulting) of misses and false alarms. We conclude that people have unwarranted expectations about the performance of ADM systems and evaluate errors in terms of potential personal consequences. Given the general public's low willingness to accept errors, we further conclude that acceptance of ADM appears to be conditional to strict accuracy requirements., (© 2021. The Author(s).)

Numerous health insurers offer bonus programmes that score customers' health behaviour, and car insurers offer telematics tariffs that score driving behaviour. In many countries, however, only a minority of customers participate in these programmes. In a population-representative survey of private households in Germany (N = 2,215), we study the acceptance of the criteria (features) on which the scoring programmes are based: the features for driver scoring (speed, texting while driving, time of driving, area of driving, accelerating and braking behaviour, respectively) and for health scoring (walking distance per day, sleeping hours per night, alcohol consumption, weight, participation in recommended cancer screenings, smoking status). In a second step, we model participants' acceptance of both programmes with regard to the underlying feature acceptance. We find that insurers in Germany rarely use the features which the participants consider to be the most relevant and justifiable, that is, smoking status for health scoring and smartphone use for driver scoring. Heuristic models (fast-and-frugal trees) show that programme acceptance depends on the acceptance of a few features. These models can help to understand customers' preferences and to design scoring programmes that are based on scientific evidence regarding behaviours and factors associated with good health and safe driving and are thus more likely to be accepted., Competing Interests: The authors have declared that no competing interests exist.

In view of the ageing society and the high costs of support and care in private households, the question arises as to what role assistive robots can play. This article focuses on the extent to which robots in nursing are accepted by the adult population in Germany today, as well as the extent to which gender, age, and experience (professional and private) influence this level of acceptance. The analysis carried out for this purpose was based on three representative surveys conducted among a total of over 7000 respondents. Of these surveys two were conducted in the second half of 2017 on behalf of the German Academy of Science and Engineering (acatech) and the life insurance company ERGO, while the third was commissioned by the German Council of Economic Experts (SVRV) in the spring of 2018. An in-depth and cumulative analysis of these surveys and data sets, which the authors helped to design, with respect to assistive robotics has not yet been published. Despite the different application scenarios for assistive care robots, the results of all three surveys are surprisingly consistent: in Germany there is already a significant minority of people who are open to, and would accept nursing care robots as long as they do not replace but rather support traditional human nursing. Roughly one third of the sample differentiated according to age and gender, fundamentally rejected assistance by robots.

An important prerequisite for the success of the digitisation of the healthcare system are risk-literate users. Risk literacy means the ability to weigh potential benefits and harms of digital technologies and information, to use digital services critically, and to understand statistical evidence. How do people find reliable and comprehensible health information on the Internet? How can they better assess the quality of algorithmic decision systems? This narrative contribution describes two approaches that show how the competence to make informed decisions can be promoted.Evidence-based and reliable health information exists on the Internet but must be distinguished from a large amount of unreliable information. Various institutions in the German-speaking world have therefore provided guidance to help laypersons make informed decisions. The Harding Center for Risk Literacy in Potsdam, for example, has developed a decision tree ("fast-and-frugal tree"). When dealing with algorithms, natural frequency trees (NFTs) can help to assess the quality and fairness of an algorithmic decision system.Independent of reliable and comprehensible digital health services, further tools for laypersons to assess information and algorithms should be developed and provided. These tools can also be included in institutional training programmes for the promotion of digital literacy. This would be an important step towards the success of digitisation in prevention and health promotion.

Objective: BRCA1/2-mutation carriers are at high risk of developing cancer. Since they must weigh clinical recommendations and decide on risk-reducing measures, the correct understanding of their 10-year cancer risks is essential. This study focused on the accuracy of women's subjective estimates of developing breast and ovarian cancer within ten years as prerequisite to reduce unnecessary prevention., Methods: 59 and 52 BRCA1/2-mutation carriers provided their individual risks of developing breast or ovarian cancer in the next 10 years, along with self-reported sociodemographic and psychosocial variables. Women's risk estimates were compared with their objective cancer risks that had been communicated before., Results: 22.6% of counselees under- and 53.2% of the counselees overestimated their 10-year risk of developing breast cancer. As for ovarian cancer, 5.6% under- whereas 51.9% overestimated their risk. Neither demographic factors such as education, parenthood and age, nor a prior diagnosis of breast cancer or prophylactic surgery accounted for these variations in risk accuracy., Conclusion: Currently, risk communication during genetic counseling does not guarantee accurate risk estimation in BRCA-mutation carriers., Practice Implications: Counselors must be prepared to prevent overestimation. Counselees' risk estimates need to be assessed and corrected to enable informed decision-making and reduce risks of unnecessary preventive efforts., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Background: Personal cancer risk assessments enable stratified care, for example, offering preventive surgical measures such as risk-reducing mastectomy (RRM) to women at high risk for breast cancer. In scenario-based experiments, we investigated whether different benefit-harm ratios of RRM influence women's consideration of this, whether this consideration is influenced by women's perception of and desire to know their personal cancer risk, or by their intention to take a novel cancer risk-predictive test, and whether consideration varies across different countries., Method: In January 2017, 1,675 women 40 to 75 years of age from five European countries-Czech Republic, Germany, UK, Italy, and Sweden-took part in an online scenario-based experiment. Six different scenarios of hypothetical benefit-harm ratios of RRM were presented in accessible fact box formats: Baseline risk/risk reduction pairings were 20/16, 20/4, 10/8, 10/2, 5/4, and 5/1 out of 1,000 women dying from breast cancer., Results: Varying the baseline risk of dying from breast cancer and the extent of risk reduction influenced the decision to consider RRM for 23% of women. Decisions varied by country, risk perception, and the intention to take a cancer risk-predictive test. Women who expressed a stronger intention to take such a test were more likely to consider having RRM. The desire to know one's risk of developing any female cancer in general moderated women's decisions, whereas the specific desire to know the risk of breast cancer did not., Conclusions: In this hypothetical scenario-based study, only for a minority of women did the change in benefit-harm ratio inform their consideration of RRM. Because this consideration is influenced by risk perception and the intention to learn one's cancer risks via a cancer risk-predictive test, careful disclosure of different potential preventive measures and their benefit-harm ratios is necessary before testing for individual risk. Furthermore, information on risk testing should acknowledge country-specific sensitivities for benefit-harm ratios., Competing Interests: The authors have declared that no competing interests exist.

Background: Epigenetic markers might be used for risk-stratifying cancer screening and prevention programs in the future. Although the clinical utility of consequent epigenetic tests for risk stratification is yet to be proven, successful adoption into clinical practice also requires the public's acceptance of such tests. This cross-sectional online survey study sought to learn for the first time about European women's perceptions, attitudes, and intended behavior regarding a predictive epigenetic test for female cancer (breast, ovarian, cervical, and endometrial) risks., Methods: 1675 women (40-75 years) from five European countries (Czech Republic, Germany, United Kingdom, Italy, Sweden), drawn from online panels by the survey sampling company Harris Interactive (Germany), participated in an online survey where they first received online leaflet information on a predictive epigenetic test for female cancer risks and were subsequently queried by an online questionnaire on their desire to know their female cancer risks, their perception of the benefit-to-harm ratio of an epigenetic test predicting female cancer risks, reasons in favor and disfavor of taking such a test, and their intention to take a predictive epigenetic test for female cancer risks., Results: Most women desired information on each of their female cancer risks, 56.6% (95% CI: 54.2-59.0) thought the potential benefits outweighed potential harms, and 75% (72.0-77.8) intended to take a predictive epigenetic test for female cancer risks if freely available. Results varied considerably by country with women from Germany and the Czech Republic being more reserved about this new form of testing than women from the other three European countries. The main reason cited in favor of a predictive epigenetic test for female cancer risks was its potential to guide healthcare strategies and lifestyle changes in the future, and in its disfavor was that it may increase cancer worry and coerce unintended lifestyle changes and healthcare interventions., Conclusions: A successful introduction of predictive epigenetic tests for cancer risks will require a balanced and transparent communication of the benefit-to-harm ratio of healthcare pathways resulting from such tests in order to curb unjustified expectations and at the same time to prevent unjustified concerns.

Background: Cancer risk assessment should stratify screening and enable preventive health interventions based on individuals' risk of developing cancer. Studies are underway to develop epigenetic tests, including trials investigating women's risk of female-specific cancers., Objective: Given potential consequences for quality of life and care, women considering such assessment need to be able to make a fully informed choice. It is currently unknown what information they require., Method: We conducted 4 focus groups with 25 women (aged 30-65 years) to explore what they want to know about epigenetic cancer risk assessment, how they evaluate its usefulness, and how they would like to be informed about their risk. Independent coders categorised paraphrases based on transcribed recordings of the group discussions to enable a summarising text analysis., Results: The women in the study wanted to understand how the epigenetic approach is different from established genomic tests, how epigenetic changes relate to cancer, and whether the test enables monitoring of one's cancer risk (n = 11). Furthermore, they desired information about their basic cancer risks (n = 11), about the quality of the assessment (n = 9), and about measures to deal with a risk result (n = 11)., Conclusions: Informed consent in epigenetic cancer risk assessments depends on whether basic cancer risks, uncertainties of testing, and effects of tests on care management are transparently communicated prior to testing. These requirements are not limited to epigenetic testing. Accordingly, physicians and health authorities will have to provide multi-layered information when counselling women on cancer risk assessment., (© 2019 S. Karger AG, Basel.)

Background: Fact boxes employ evidence-based guidelines on risk communication to present benefits and harms of health interventions in a balanced and transparent format. However, little is known about their short- and long-term efficacy and whether designing fact boxes to present multiple outcomes with icon arrays would increase their efficacy., Method: In study 1, 120 men (30-75 y) completed a lab study. Participants were randomly assigned to 1 of 3 fact box formats on prostate cancer screening: a tabular fact box with numbers, a fact box with numbers and icon array, and a fact box with numbers, separate icon arrays, and text to describe each benefit and harm. Comprehension of information (while materials were present) and short-term knowledge recall were assessed. Study 2 recruited an online sample of 244 German men (40-75 y). Participants were randomly assigned to 1 of the 3 fact box formats or widely distributed health information, and knowledge was assessed at baseline, shortly after presentation, and at 6-mo follow-up, along with comprehension while materials were present., Results: In both studies, comprehension and knowledge-recall scores were similar when comparing tabular and icon fact boxes. In the 6-mo follow-up, this positive effect on knowledge recall disappeared. Fact boxes increased knowledge relative to baseline but did not affect decision intentions or perceptions of having complete information to make decisions., Conclusions: This study shows that fact boxes with and without icon arrays are equally effective at improving comprehension and knowledge recall over the short-term and are simple formats that can improve on current health information. Specifically, if fact boxes are used at the time or immediately before a decision is made, they promote informed decisions about prostate cancer screening.

Objectives: Informed decisions about cancer screening require accurate knowledge regarding cancer risks and screening. This study investigates: (1) European women's knowledge of their risk of developing breast, ovarian, cervical or endometrial cancer, (2) their knowledge about mammography screening and (3) whether an evidence-based leaflet improves their knowledge., Design: Cross-sectional online intervention survey., Setting: National samples from five European countries (Czech Republic, Germany, UK, Italy and Sweden)-drawn from the Harris Interactive and the Toluna panel, respectively, in January 2017-were queried on their knowledge of age-specific risks of developing breast, cervical, ovarian or endometrial cancer within the next 10 years and of mammography screening before and after intervention., Participants: Of 3629 women (inclusion criteria: age 40-75 years) invited, 2092 responded and 1675 completed the survey (response rate: 61.4%)., Intervention: Evidence-based leaflet summarising information on age-adjusted female cancer risks, mammography and aspects of cancer prevention., Primary Outcome Measures: Proportion of women (1) accurately estimating their risk of four female cancers, (2) holding correct assumptions of mammography screening and (3) changing their estimations and assumptions after exposure to leaflet., Findings: Across countries, 59.2% (95% CI 56.8% to 61.6%) to 91.8% (95% CI 90.3% to 93.0%) overestimated their female cancer risks 7-33 fold (medians across tumours : 50.0 to 200.0). 26.5% (95% CI 24.4% to 28.7%) were aware that mammography screening has both benefits and harms. Women who accurately estimated their breast cancer risk were less likely to believe that mammography prevents cancer (p<0.001). After leaflet intervention, knowledge of cancer risks improved by 27.0 (95% CI 24.9 to 29.2) to 37.1 (95% CI 34.8 to 39.4) percentage points and of mammography by 23.0 (95% CI 21.0 to 25.1) percentage points., Conclusion: A considerable number of women in five European countries may not possess the prerequisites for an informed choice on cancer screening. Evidence-based information in patient leaflets can improve this situation., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2018. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

The incidence of cancer is continuing to rise and risk-tailored early diagnostic and/or primary prevention strategies are urgently required. The ideal risk-predictive test should: integrate the effects of both genetic and nongenetic factors and aim to capture these effects using an approach that is both biologically stable and technically reproducible; derive a score from easily accessible biological samples that acts as a surrogate for the organ in question; and enable the effectiveness of risk-reducing measures to be monitored. Substantial evidence has accumulated suggesting that the epigenome and, in particular, DNA methylation-based tests meet all of these requirements. However, the development and implementation of DNA methylation-based risk-prediction tests poses considerable challenges. In particular, the cell type specificity of DNA methylation and the extensive cellular heterogeneity of the easily accessible surrogate cells that might contain information relevant to less accessible tissues necessitates the use of novel methods in order to account for these confounding issues. Furthermore, the engagement of the scientific community with health-care professionals, policymakers and the public is required in order to identify and address the organizational, ethical, legal, social and economic challenges associated with the routine use of epigenetic testing.

One of the major hurdles to promoting informed decision making in health is the continued use of poor risk presentation formats. This article offers a guide to develop a Fact Box, a simple decision tool to present data about the benefits and harms of treatments that has been demonstrated to improve understanding of health risks, an important part of risk literacy. The article offers guidance about how to determine the evidence basis for a health topic, select outcomes to report, extract and present numbers or outcomes, and design the layout. The guide also addresses potential challenges for summarizing evidence and provides alternatives for addressing issues related to missing, insufficient, imprecise, or conflicting evidence and for dealing with issues related to statistical and clinical significance. The guide concludes with details on how to document the development of the Fact Box for the purpose of transparency and reproducibility. Fact Boxes are an efficient tool to promote risk literacy and should be available in every physician's office.

Diagnostic reasoning draws on knowledge about effects and their potential causes. The causal-diversity effect in diagnostic reasoning normatively depends on the distribution of effects in causal structures, and thus, a psychological diversity effect could indicate whether causally structured knowledge is used in evaluating the probability of a diagnosis, if the effect were to covary with manipulations of causal structures. In four experiments, participants dealt with a quasi-medical scenario presenting symptom sets (effects) that consistently suggested a specified diagnosis (cause). The probability that the diagnosis was correct had to be rated for two opposed symptom sets that differed with regard to the symptoms' positions (proximal or diverse) in the causal structure that was initially acquired. The causal structure linking the diagnosis to the symptoms and the base rate of the diagnosis were manipulated to explore whether the diagnosis was rated as more probable for diverse than for proximal symptoms when alternative causations were more plausible (e.g., because of a lower base rate of the diagnosis in question). The results replicated the causal diversity effect in diagnostic reasoning across these conditions, but no consistent effects of structure and base rate variations were observed. Diversity effects computed in causal Bayesian networks are presented, illustrating the consequences of the structure manipulations and corroborating that a diversity effect across the different experimental manipulations is normatively justified. The observed diversity effects presumably resulted from shortcut reasoning about the possibilities of alternative causation.

In sequential diagnostic reasoning, observed pieces of evidence activate hypotheses in memory and are integrated to reach a final diagnosis. The order of evidence can influence diagnostic reasoning. This article examines the processing of ambiguous evidence underlying order effects if multiple hypotheses are activated. In five experiments with a quasi-medical scenario, participants dealt with symptom sequences supporting multiple diagnoses. The symptom order, the response mode (end-of-sequence, step-by-step), and the consistency of evidence were manipulated. A primacy order effect occurred with both response modes suggesting that ambiguous pieces of evidence were distorted toward the hypothesis that strongly corresponded with the first piece. The primacy effect was partially counteracted by stepwise belief ratings, which strengthened the weight of recent evidence and promoted switching to an alternative diagnosis. We conclude that once hypotheses are generated, the interplay of coherence-oriented information distortion and memory-dependent analytic processes propagates into distinct order effects in diagnoses.