The pivotal problem of comorbidity research lies in the psychometric foundation it rests on, that is, latent variable theory, in which a mental disorder is viewed as a latent variable that causes a constellation of symptoms. From this perspective, comorbidity is a (bi)directional relationship between multiple latent variables. We argue that such a latent variable perspective encounters serious problems in the study of comorbidity, and offer a radically different conceptualization in terms of a network approach, where comorbidity is hypothesized to (...) arise from direct relations between symptoms of multiple disorders. We propose a method to visualize comorbidity networks and, based on an empirical network for major depression and generalized anxiety, we argue that this approach generates realistic hypotheses about pathways to comorbidity, overlapping symptoms, and diagnostic boundaries, that are not naturally accommodated by latent variable models: Some pathways to comorbidity through the symptom space are more likely than others; those pathways generally have the same direction (i.e., from symptoms of one disorder to symptoms of the other); overlapping symptoms play an important role in comorbidity; and boundaries between diagnostic categories are necessarily fuzzy. (shrink)

The majority of commentators agree on one thing: Our network approach might be the prime candidate for offering a new perspective on the origins of mental disorders. In our response, we elaborate on refinements (e.g., cognitive and genetic levels) and extensions (e.g., to Axis II disorders) of the network model, as well as discuss ways to test its validity.

We analyze the cognitive strategies underlying performance in the Number task, a Math game that requires both arithmetic fluency and mathematical creativity. In this game all elements in a set of numbers have to be used precisely once to create a target number with basic arithmetic operations. We argue that some instances of this game are NP complete, by showing its relation to the well-known Partition problem. We propose heuristics based on the distinction in forward and backward reasoning. The Number (...) Game is part of Math Garden, a popular online educational platform for practicing and monitoring math skills using innovations in computerized adaptive testing. These educational games generate enormous amounts of rich data on children's cognitive development. We found converging evidence for the use of forward proximity heuristics in the data of Math Garden, consisting of more than 20 million answers to 1,700 items. Item difficulties and the structure of correct answers were analyzed. (shrink)

The subtitle of this paper could have been, “Big Data meets Education to advance Cognitive Science.” In it, the authors analyze 20 million answers to 1700 simple arithmetic problems in an educational number game to determine “what makes some problems harder than others.” The results contribute to the cognitive science of arithmetic skill acquisition and have the potential to change how math is taught.

The paper is concerned with the psychological relevance of a logical model for deductive reasoning. We propose a new way to analyze logical reasoning in a deductive version of the Mastermind game implemented within a popular Dutch online educational learning system (Math Garden). Our main goal is to derive predictions about the difficulty of Deductive Mastermind tasks. By means of a logical analysis we derive the number of steps needed for solving these tasks (a proxy for working memory load). Our (...) model is based on the analytic tableaux method, known from proof theory. We associate the difficulty of Deductive Mastermind game-items with the size of the corresponding logical trees obtained by the tableaux method. We derive empirical hypotheses from this model. A large group of students (over 37 thousand children, 5–12 years of age) played the Deductive Mastermind game, which gave empirical difficulty ratings of all 321 game-items. The results show that our logical approach predicts these item ratings well, which supports the psychological relevance of our model. (shrink)

After more than 15 years of study, the 1/f noise or complex-systems approach to cognitive science has delivered promises of progress, colorful verbiage, and statistical analyses of phenomena whose relevance for cognition remains unclear. What the complex-systems approach has arguably failed to deliver are concrete insights about how people perceive, think, decide, and act. Without formal models that implement the proposed abstract concepts, the complex-systems approach to cognitive science runs the danger of becoming a philosophical exercise in futility. The complex-systems (...) approach can be informative and innovative, but only if it is implemented as a formal model that allows concrete prediction, falsification, and comparison against more traditional approaches. (shrink)

Three arguments are given to show that neural constructivism lacks an essential ingredient to explain cognitive development. Based on results in the theory of adaptive signal analysis, adaptive biological pattern information and self-organization in nonlinear systems of information processing, it is concluded that neural constructivism should be further extended to accommodate the occurrence of phase transitions generating qualitative development in the sense of Piaget.

Most models of response time (RT) in elementary cognitive tasks implicitly assume that the speed-accuracy trade-off is continuous: When payoffs or instructions gradually increase the level of speed stress, people are assumed to gradually sacrifice response accuracy in exchange for gradual increases in response speed. This trade-off presumably operates over the entire range from accurate but slow responding to fast but chance-level responding (i.e., guessing). In this article, we challenge the assumption of continuity and propose a phase transition model for (...) RTs and accuracy. Analogous to the fast guess model (Ollman, 1966), our model postulates two modes of processing: a guess mode and a stimulus-controlled mode. From catastrophe theory, we derive two important predictions that allow us to test our model against the fast guess model and against the popular class of sequential sampling models. The first prediction—hysteresis in the transitions between guessing and stimulus-controlled behavior—was confirmed in an experiment that gradually changed the reward for speed versus accuracy. The second prediction—bimodal RT distributions—was confirmed in an experiment that required participants to respond in a way that is intermediate between guessing and accurate responding. (shrink)

Two decades of research on euthanasia in the Netherlands have resulted into clear insights in the frequency and characteristics of euthanasia and other medical end-of-life decisions in the Netherlands. These empirical studies have contributed to the quality of the public debate, and to the regulating and public control of euthanasia and physician-assisted suicide. No slippery slope seems to have occurred. Physicians seem to adhere to the criteria for due care in the large majority of cases. Further, it has been shown (...) that the majority of physicians think that the euthanasia Act has improved their legal certainty and contributes to the carefulness of life-terminating acts. In 2005, eighty percent of the euthanasia cases were reported to the review committees. Thus, the transparency envisaged by the Act still does not extend to all cases. Unreported cases almost all involve the use of opioids, and are not considered to be euthanasia by physicians. More education and debate is needed to disentangle in these situations which acts should be regarded as euthanasia and which should not. Medical end-of-life decision-making is a crucial part of end-of-life care. It should therefore be given continuous attention in health care policy and medical training. Systematic periodic research is crucial for enhancing our understanding of end-of-life care in modern medicine, in which the pursuit of a good quality of dying is nowadays widely recognized as an important goal, in addition to the traditional goals such as curing diseases and prolonging life. (shrink)

Dynamic Epistemic Logic This article tells the story of the rise of dynamic epistemic logic, which began with epistemic logic, the logic of knowledge, in the 1960s. Then, in the late 1980s, came dynamic epistemic logic, the logic of change of knowledge. Much of it was motivated by puzzles and paradoxes. The number … Continue reading Dynamic Epistemic Logic →.

Two decades of research on euthanasia in the Netherlands have resulted into clear insights in the frequency and characteristics of euthanasia and other medical end-of-life decisions in the Netherlands. These empirical studies have contributed to the quality of the public debate, and to the regulating and public control of euthanasia and physician-assisted suicide. No slippery slope seems to have occurred. Physicians seem to adhere to the criteria for due care in the large majority of cases. Further, it has been shown (...) that the majority of physicians think that the euthanasia Act has improved their legal certainty and contributes to the carefulness of life-terminating acts. In 2005, eighty percent of the euthanasia cases were reported to the review committees. Thus, the transparency envisaged by the Act still does not extend to all cases. Unreported cases almost all involve the use of opioids, and are not considered to be euthanasia by physicians. More education and debate is needed to disentangle in these situations which acts should be regarded as euthanasia and which should not. Medical end-of-life decision-making is a crucial part of end-of-life care. It should therefore be given continuous attention in health care policy and medical training. Systematic periodic research is crucial for enhancing our understanding of end-of-life care in modern medicine, in which the pursuit of a good quality of dying is nowadays widely recognized as an important goal, in addition to the traditional goals such as curing diseases and prolonging life. (shrink)

Peer review is a widely accepted instrument for raising the quality of science. Peer review limits the enormous unstructured influx of information and the sheer amount of dubious data, which in its absence would plunge science into chaos. In particular, peer review offers the benefit of eliminating papers that suffer from poor craftsmanship or methodological shortcomings, especially in the experimental sciences. However, we believe that peer review is not always appropriate for the evaluation of controversial hypothetical science. We argue that (...) the process of peer review can be prone to bias towards ideas that affirm the prior convictions of reviewers and against innovation and radical new ideas. Innovative hypotheses are thus highly vulnerable to being “filtered out” or made to accord with conventional wisdom by the peer review process. Consequently, having introduced peer review, the Elsevier journal Medical Hypotheses may be unable to continue its tradition as a radical journal allowing discussion of improbable or unconventional ideas. Hence we conclude by asking the publisher to consider re-introducing the system of editorial review to Medical Hypotheses. (shrink)

The use of do not resuscitate (DNR) orders in Dutch hospitals was studied as part of a nationwide study on medical decisions concerning the end of life. DNR decisions are made in 6 per cent of all admissions, and 61 per cent of all in-hospital deaths were preceded by a DNR decision. We found that in only 14 per cent of the cases had the patients been involved in the DNR decision (32 per cent of competent patients). The concept of (...) futility is analysed as these findings are discussed. We conclude that determining the effectiveness of resuscitation is a medical judgement whereas determining the proportionality (burden/benefit ratio) of it requires a discussion between doctor and patient (or his or her surrogates). Since the respondents in the cases without patient involvement gave many reasons for their decision that went beyond determining effectiveness, we conclude that more patient involvement would have been desirable. (shrink)

Introduction: The Dutch Euthanasia Act states that euthanasia is not punishable if the attending physician acts in accordance with the statutory due care criteria. These criteria hold that: there should be a voluntary and well-considered request, the patient’s suffering should be unbearable and hopeless, the patient should be informed about their situation, there are no reasonable alternatives, an independent physician should be consulted, and the method should be medically and technically appropriate. This study investigates whether physicians experience problems with these (...) criteria in medical practice.Methods: In 2006, questionnaires were sent to a random, stratified sample of 2100 Dutch physicians . Physicians were asked about problems in their decision-making related to requests for euthanasia or assisted suicide after enforcement of the 2002 Euthanasia Act.Results: Of all physicians who had received a request for euthanasia or assisted suicide , 25% had experienced problems in the decision-making with regard to at least one of the criteria of due care. Physicians who had experienced problems mostly indicated to have had problems related to evaluating whether or not the patient’s suffering was unbearable and hopeless and whether or not the patient’s request was voluntary or well considered .Discussion: Physicians in The Netherlands most frequently reported problems related to aspects in which they have to evaluate the patient’s subjective perspective. However, it can be questioned whether placing emphasis on these subjective aspects is an adequate fulfilment of the duties imposed on physicians, as laid down in the Dutch Euthanasia Act. (shrink)

OBJECTIVES: To identify the factors that influence the assessment of reported cases of physician-assisted death by members of the public prosecution. DESIGN/SETTING: At the beginning of 1996, during verbal interviews, 12 short case-descriptions were presented to a representative group of 47 members of the public prosecution in the Netherlands. RESULTS: Assessment varied considerably between respondents. Some respondents made more "lenient" assessments than others. Characteristics of the respondents, such as function, personal-life philosophy and age, were not related to the assessment. Case (...) characteristics, i.e. the presence of an explicit request, life expectancy and the type of suffering, strongly influenced the assessment. Of these characteristics, the presence or absence of an explicit request was the most important determinant of the decision whether or not to hold an inquest. CONCLUSIONS: Although the presence of an explicit request, life expectancy and the type of suffering each influenced the assessment, each individual assessment was dependent on the assessor. The resulting danger of legal inequality and legal uncertainty, particularly in complicated cases, should be kept to a minimum by the introduction of some form of protocol and consultation in doubtful or boundary cases. The notification procedure already promotes a certain degree of uniformity in the prosecution policy. (shrink)

BackgroundAn important principle underlying the Dutch Euthanasia Act is physicians' responsibility to alleviate patients' suffering. The Dutch Act states that euthanasia and physician-assisted suicide are not punishable if the attending physician acts in accordance with criteria of due care. These criteria concern the patient's request, the patient's suffering (unbearable and hopeless), the information provided to the patient, the presence of reasonable alternatives, consultation of another physician and the applied method of ending life. To demonstrate their compliance, the Act requires physicians (...) to report euthanasia to a review committee. We studied which arguments Dutch physicians use to substantiate their adherence to the criteria and which aspects attract review committees' attention.MethodsWe examined 158 files of reported euthanasia and physician-assisted suicide cases that were approved by the review committees. We studied the physicians' reports and the verdicts of the review committees by using a checklist.ResultsPhysicians reported that the patient's request had been well-considered because the patient was clear-headed (65%) and/or had repeated the request several times (23%). Unbearable suffering was often substantiated with physical symptoms (62%), function loss (33%), dependency (28%) or deterioration (15%). In 35%, physicians reported that there had been alternatives to relieve patients' suffering which were refused by the majority. The nature of the relationship with the consultant was sometimes unclear: the consultant was reported to have been an unknown colleague (39%), a known colleague (21%), otherwise (25%), or not clearly specified in the report (24%). Review committees relatively often scrutinized the consultation (41%) and the patient's (unbearable) suffering (32%); they had few questions about possible alternatives (1%).ConclusionDutch physicians substantiate their adherence to the criteria in a variable way with an emphasis on physical symptoms. The information they provide is in most cases sufficient to enable adequate review. Review committees' control seems to focus on (unbearable) suffering and on procedural issues. (shrink)

The Remmelink Committee published its report on medical decisions at the end of life in the Netherlands in September 1991. As a result, the Dutch debate about physician aid‐in‐dying has been broadened to include life‐terminating acts that have not been explicitly requested by the patient.

The participation of vulnerable patients in clinical research poses apparent ethical dilemmas. Depending on the nature of the vulnerability, their participation may challenge the ethical principles of autonomy, non-maleficence, or justice. On the other hand, non-participation may preclude the building of a knowledge base that is a prerequisite for defining the optimal clinical management of vulnerable patients. Such clinical uncertainty may also incur substantial economic costs. We present the participation of pre-menopausal women with atrial fibrillation in trials of novel oral (...) anticoagulant drugs as a case study. Due to their non-participation in pivotal trials, it is uncertain whether for them, the risks that are associated with these drugs are outweighed by the advantages compared with conventional treatment. We addressed the question whether research of this new class of drugs in this subgroup would be appropriate from both, an ethical as well an economic perspective. We used the method of specifying norms as a wider framework to resolve the apparent ethical dilemma, while incorporating the question whether research of oral anticoagulants in premenopausal women with atrial fibrillation can be justified on economic grounds. For the latter, the results of a value-of-information analysis were used. Further clinical research on NOACs in premenopausal women with atrial fibrillation can be justified on both, ethical and economic grounds. Addressing apparent ethical dilemmas by invoking a method such as specifying norms can improve the quality of public practical reasoning. As such, the method should also prove valuable to committees that have formally been granted the authority to review trial protocols and proposals for scientific research. (shrink)

Dynamic Epistemic Logic This article tells the story of the rise of dynamic epistemic logic, which began with epistemic logic, the logic of knowledge, in the 1960s. Then, in the late 1980s, came dynamic epistemic logic, the logic of change of knowledge. Much of it was motivated by puzzles and paradoxes. The number … Continue reading Dynamic Epistemic Logic →.

Although agreement on the positive sign of the relationship between corporate social and financial performance is observed in the literature, the mechanisms that constitute this relationship are not yet well-known. We address this issue by extending management’s stakeholder theory by adding insights from psychology’s prospect decision theory and sociology’s resource dependence theory. Empirically, we analyze an extensive panel dataset, including information on disaggregated measures of social performance for the S&P 500 in the 1997–2002 period. In so doing, we enrich the (...) extant literature by focusing on stakeholder heterogeneity, perceptional framing, and disaggregated measures of corporate social performance. (shrink)

There is a claim that clinical ethics support services (CESS) improve healthcare quality within healthcare organisations. However, there is lack of strong evidence supporting this claim. Rather, the current focus is on the quality of CESS themselves or on individual learning outcomes. In response, this article proposes a theoretical framework leading to empirical hypotheses that describe the relationship between a specific type of CESS, moral case deliberation and the quality of care at the organisational level. We combine insights from the (...) literature on CESS, organisational learning and quality improvement and argue that moral case deliberation causes healthcare professionals to acquire practical wisdom. At the organisational level, where improving quality is a continuous and collective endeavour, this practical wisdom can be aggregated into morisprudence, which is an ongoing formulation of moral judgements across cases encountered within the organisation. Focusing on the development of morisprudence enables refined scrutinisation of CESS-related quality claims. (shrink)

Dynamic Epistemic Logic is the logic of knowledge change. This book provides various logics to support such formal specifications, including proof systems. Concrete examples and epistemic puzzles enliven the exposition. The book also offers exercises with answers. It is suitable for graduate courses in logic. Many examples, exercises, and thorough completeness proofs and expressivity results are included. A companion web page offers slides for lecturers and exams for further practice.

Two decades of research on euthanasia in the Netherlands have resulted into clear insights in the frequency and characteristics of euthanasia and other medical end-of-life decisions in the Netherlands. These empirical studies have contributed to the quality of the public debate, and to the regulating and public control of euthanasia and physician-assisted suicide. No slippery slope seems to have occurred. Physicians seem to adhere to the criteria for due care in the large majority of cases. Further, it has been shown (...) that the majority of physicians think that the euthanasia Act has improved their legal certainty and contributes to the carefulness of life-terminating acts. In 2005, eighty percent of the euthanasia cases were reported to the review committees. Thus, the transparency envisaged by the Act still does not extend to all cases. Unreported cases almost all involve the use of opioids, and are not considered to be euthanasia by physicians. More education and debate is needed to disentangle in these situations which acts should be regarded as euthanasia and which should not. Medical end-of-life decision-making is a crucial part of end-of-life care. It should therefore be given continuous attention in health care policy and medical training. Systematic periodic research is crucial for enhancing our understanding of end-of-life care in modern medicine, in which the pursuit of a good quality of dying is nowadays widely recognized as an important goal, in addition to the traditional goals such as curing diseases and prolonging life. (shrink)

BackgroundThe interpretation of clinical gait data in children with cerebral palsy (CP) is time-consuming, requires extensive expertise and often lacks transparency. Here we aimed to develop a set of look-up tables to support this process, linking typical gait features as present in CP to their potential underlying impairments.MethodsWe developed an initial core set of gait features and their potential underlying impairments based on biomechanical reasoning, literature and clinical experience. This core set was further specified through a Delphi process in a (...) multidisciplinary group of experts in gait analysis of children with CP and evaluated on 20 patient cases. The likelihood of the listed gait feature–impairment relationships was scored by the expert panel on a five-point scale.ResultsThe final core set included 120 relevant gait feature–impairment relations including likelihood scores. This set was presented in the form of look-up tables in both directions, i.e., sorted by gait features with potential underlying impairment, and sorted by impairments with potential related gait features. The average likelihood score for the relations was 3.5 ± 0.6 (range 2.1–4.6).ConclusionThe developed set of look-up tables linking gait features and impairments, can assist gait analysts and clinicians in standardized biomechanical reasoning, to support treatment decision-making for gait impairments in children with CP. (shrink)

Although agreement on the positive sign of the relationship between corporate social and financial performance is observed in the literature, the mechanisms that constitute this relationship are not yet well-known. We address this issue by extending management’s stakeholder theory by adding insights from psychology’s prospect decision theory and sociology’s resource dependence theory. Empirically, we analyze an extensive panel dataset, including information on disaggregated measures of social performance for the S&P 500 in the 1997–2002 period. In so doing, we enrich the (...) extant literature by focusing on stakeholder heterogeneity, perceptional framing, and disaggregated measures of corporate social performance. (shrink)

While numerous studies show that brain signals contain information about an individual’s current state that are potentially valuable for smoothing man-machine interfaces, this has not yet lead to the use of brain computer interfaces (BCI) in daily life. One of the main challenges is the common requirement of personal data that is correctly labelled concerning the state of interest in order to train a model, where this trained model is not guaranteed to generalize across time and context. Another challenge is (...) the requirement to wear electrodes on the head. We here propose a BCI that can tackle these issues and may be a promising case for BCI research and application in everyday life. The BCI uses EEG signals to predict head rotation in order to improve images presented in a Virtual Reality (VR) headset. When presenting a 360° video to a headset, Field-of-View approaches only stream the content that is in the current field of view and leave out the rest. When the user rotates the head, other content parts need to be made available soon enough to go unnoticed by the user which is problematic given the available bandwidth. By predicting head rotation, the content parts adjacent to the currently viewed part could be retrieved in time for display when the rotation actually takes place. Eleven participants generated left- and rightward head rotations while head movements were recorded using the headsets motion sensing system and EEG sensors. We trained neural network models to distinguish EEG epochs preceding rightward, leftward and no rotation. Applying these models to streaming EEG data that was withheld from the training showed that 400 ms before rotation onset, the probability ‘no rotation’ started to decrease and the probabilities of an upcoming right- or leftward rotation started to diverge in the correct direction. In the proposed BCI scenario, users already wear a device on their head allowing for integrated sensors. Moreover, it is possible to acquire accurately labeled training data on the fly, and continuously monitor and improve the model’s performance. The BCI can be harnessed if it will improve imagery and therewith enhance immersive experience. (shrink)

Research suggests that sedentary behavior is negatively associated with cognitive outcomes. Interrupting prolonged sitting has been shown to improve cognitive functions, including executive functioning, which is important for academic performance. No research has been conducted on the effect of standing on EF in VET students, who make up a large proportion of the adolescent population and who are known to sit more than other students of this age. In this study, we investigated the acute effects of reducing SB by short (...) time standing on EF in vocational education and training students. In a randomized crossover study, 165 VET students were first taught for 15 min in seated position. After this, they performed while seated the Letter Memory Test for updating, and the Color Shape Test for shifting and inhibition. Students were randomly assigned to a sitting or standing condition. All students were taught again for 15 min and then took the same tests in the condition they were allocated to, respectively, standing or seated. After 1 week, the test procedure was repeated, in which students switched conditions. Mixed model analyses showed no significant effect of sitting or standing on updating, shifting, or inhibition. Also, no significant differences were found for the order of condition on updating, shifting, or inhibition. Our results suggest that 40 min of standing does not significantly influence EF among VET students. (shrink)