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Search Results: 1 - 10 of 34520 matches for " Niels Van Quaquebeke "
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Jumping to Conclusions Is Associated with Paranoia but Not General Suspiciousness: A Comparison of Two Versions of the Probabilistic Reasoning Paradigm
Steffen Moritz,Niels Van Quaquebeke,Tania M. Lincoln
Schizophrenia Research and Treatment , 2012, DOI: 10.1155/2012/384039
Abstract: Theoretical models ascribe jumping to conclusions (JTCs) a prominent role in the pathogenesis of paranoia. While many earlier studies corroborated this account, some newer investigations have found no or only small associations of the JTC bias with paranoid symptoms. The present study examined whether these inconsistencies in part reflect methodological differences across studies. The study was built upon the psychometric high-risk paradigm. A total of 1899 subjects from the general population took part in an online survey and were administered the Paranoia Checklist as well as one of two different variants of the probabilistic reasoning task: one variant with a traditional instruction (a) and one novel variant that combines probability estimates with decision judgments (b). Factor analysis of the Paranoia Checklist yielded an unspecific suspiciousness factor and a psychotic paranoia factor. The latter was significantly associated with scores indicating hasty decision making. Subjects scoring two standard deviations above the mean of the Paranoia Checklist showed an abnormal data-gathering style relative to subjects with normal scores. Findings suggest that the so-called decision threshold parameter is more sensitive than the conventional JTC index. For future research the specific contents of paranoid beliefs deserve more consideration in the investigation of decision making in schizophrenia as JTC seems to be associated with core psychosis-prone features of paranoia only.
Jumping to Conclusions Is Associated with Paranoia but Not General Suspiciousness: A Comparison of Two Versions of the Probabilistic Reasoning Paradigm
Steffen Moritz,Niels Van Quaquebeke,Tania M. Lincoln
Schizophrenia Research and Treatment , 2012, DOI: 10.1155/2012/384039
Abstract: Theoretical models ascribe jumping to conclusions (JTCs) a prominent role in the pathogenesis of paranoia. While many earlier studies corroborated this account, some newer investigations have found no or only small associations of the JTC bias with paranoid symptoms. The present study examined whether these inconsistencies in part reflect methodological differences across studies. The study was built upon the psychometric high-risk paradigm. A total of 1899 subjects from the general population took part in an online survey and were administered the Paranoia Checklist as well as one of two different variants of the probabilistic reasoning task: one variant with a traditional instruction (a) and one novel variant that combines probability estimates with decision judgments (b). Factor analysis of the Paranoia Checklist yielded an unspecific suspiciousness factor and a psychotic paranoia factor. The latter was significantly associated with scores indicating hasty decision making. Subjects scoring two standard deviations above the mean of the Paranoia Checklist showed an abnormal data-gathering style relative to subjects with normal scores. Findings suggest that the so-called decision threshold parameter is more sensitive than the conventional JTC index. For future research the specific contents of paranoid beliefs deserve more consideration in the investigation of decision making in schizophrenia as JTC seems to be associated with core psychosis-prone features of paranoia only. 1. Introduction Research on neuropsychological dysfunctions in schizophrenia (e.g., memory and executive dysfunction) has been increasingly extended by studies on cognitive biases [1–3]. Cognitive biases represent preferences, subtle distortions, and styles of information processing rather than neural deficits or mere inaccuracy [1]. An emerging literature has elucidated that persons with delusions tend to jump to conclusions [3, 4], are over-confident in their incorrect decisions [5–9], and show attributional biases [10–12], for example, a preference for monocausal inferences [13], and a bias against disconfirmatory evidence [14–18]. Some of these biases have been found to correlate with positive symptoms (i.e., delusions and hallucinations), which according to many clinicians represent the core of the disorder. Cognitive training programs such as the Social Cognition and Interaction Training (SCIT) [19, 20], the Maudsley Review Training Program [21] or the Metacognitive Training for Psychosis (MCT) [22, 23] have begun to translate these insights into practice: patients learn to
Can We Trust the Internet to Measure Psychotic Symptoms?
Steffen Moritz,Niels Van Quaquebeke,Tania M. Lincoln,Ulf K?ther,Christina Andreou
Schizophrenia Research and Treatment , 2013, DOI: 10.1155/2013/457010
Abstract: Online studies are increasingly utilized in applied research. However, lack of external diagnostic verification in many of these investigations is seen as a threat to the reliability of the data. The present study examined the robustness of internet studies on psychosis against simulation. We compared the psychometric properties of the Community Assessment of Psychic Experiences scale (CAPE), a self-report instrument measuring psychotic symptoms, across three independent samples: (1) participants with a confirmed diagnosis of schizophrenia, (2) participants with self-reported schizophrenia who were recruited over the internet, and (3) clinical experts on schizophrenia as well as students who were asked to simulate a person with schizophrenia when completing the CAPE. The CAPE was complemented by a newly developed 4-item psychosis lie scale. Results demonstrate that experts asked to simulate schizophrenia symptoms could be distinguished from real patients: simulators overreported positive symptoms and showed elevated scores on the psychosis lie scale. The present study suggests that simulated answers in online studies on psychosis can be distinguished from authentic responses. Researchers conducting clinical online studies are advised to adopt a number of methodological precautions and to compare the psychometric properties of online studies to established clinical indices to assert the validity of their results. 1. Introduction Traditionally, psychological assessments administered by an interviewer are preferred over nonpersonal assessments such as questionnaires. Face-to-face (FTF) assessment may in some cases unveil hidden symptoms and/or partly compensate for a lack of reliable information provided by a patient alone [1]. To illustrate, a patient with psychosis may deny hearing voices upon direct questioning but at the same time be observed talking to voices without overt source. This may persuade the clinician to discard the patient's response and suspect the presence of auditory hallucinations. On the other hand, research assessing the correspondence between self- and observer ratings indicates that self-report of psychotic symptoms is more reliable than commonly thought. Studies have generally found satisfactory associations between self- and observer-based ratings for overall pathology [2], negative symptoms [3], and positive symptoms [4–8]. Despite the aforementioned merits, clinical assessment is not without weaknesses. The presence of an assessor may induce important biases [9, 10], especially underreporting, that are often smaller with
Charge regulation and ionic screening of patchy surfaces
Niels Boon,René van Roij
Physics , 2010, DOI: 10.1063/1.3533279
Abstract: The properties of surfaces with charge-regulated patches are studied using non-linear Poisson-Boltzmann theory. Using a mode expansion to solve the non-linear problem efficiently, we reveal the charging behaviour of Debye-length sized patches. We find that patches charge up to higher charge densities if their size is relatively small and if the patches are well separated. The numerical results are used to construct a basic analytical model which predicts the average surface charge density on surfaces with patchy chargeable groups.
Perturbation semigroup of matrix algebras
Niels Neumann,Walter D. van Suijlekom
Physics , 2014,
Abstract: In this article we analyze the structure of the semigroup of inner perturbations in noncommutative geometry. This perturbation semigroup is associated to a unital associative *-algebra and extends the group of unitary elements of this *-algebra. We compute the perturbation semigroup for all matrix algebras.
Density-induced reentrant melting of colloidal Wigner crystals
Jeffrey Everts,Niels Boon,René van Roij
Physics , 2015,
Abstract: Electrostatic repulsions can drive crystallization in many-particle systems. For charged colloidal systems, the phase boundaries as well as crystal structure are highly tunable by experimental parameters such as salt concentration and pH. By using projections of the colloid-ion mixture to a system of (soft) repulsive spheres and the one-component plasma (OCP), we study the hitherto unexplained experimentally observed reentrant melting of electrostatically repelling colloids upon increasing the colloid density. Our study shows that the surface chemistry should involve a competition between adsorption of cations and anions to explain the observed density-induced reentrant melting.
What Eye Movements Can Tell about Theory of Mind in a Strategic Game
Ben Meijering, Hedderik van Rijn, Niels A. Taatgen, Rineke Verbrugge
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0045961
Abstract: This study investigates strategies in reasoning about mental states of others, a process that requires theory of mind. It is a first step in studying the cognitive basis of such reasoning, as strategies affect tradeoffs between cognitive resources. Participants were presented with a two-player game that required reasoning about the mental states of the opponent. Game theory literature discerns two candidate strategies that participants could use in this game: either forward reasoning or backward reasoning. Forward reasoning proceeds from the first decision point to the last, whereas backward reasoning proceeds in the opposite direction. Backward reasoning is the only optimal strategy, because the optimal outcome is known at each decision point. Nevertheless, we argue that participants prefer forward reasoning because it is similar to causal reasoning. Causal reasoning, in turn, is prevalent in human reasoning. Eye movements were measured to discern between forward and backward progressions of fixations. The observed fixation sequences corresponded best with forward reasoning. Early in games, the probability of observing a forward progression of fixations is higher than the probability of observing a backward progression. Later in games, the probabilities of forward and backward progressions are similar, which seems to imply that participants were either applying backward reasoning or jumping back to previous decision points while applying forward reasoning. Thus, the game-theoretical favorite strategy, backward reasoning, does seem to exist in human reasoning. However, participants preferred the more familiar, practiced, and prevalent strategy: forward reasoning.
A New Myohaptic Instrument to Assess Wrist Motion Dynamically
Mario Manto,Niels Van Den Braber,Giuliana Grimaldi,Piet Lammertse
Sensors , 2010, DOI: 10.3390/s100403180
Abstract: The pathophysiological assessment of joint properties and voluntary motion in neurological patients remains a challenge. This is typically the case in cerebellar patients, who exhibit dysmetric movements due to the dysfunction of cerebellar circuitry. Several tools have been developed, but so far most of these tools have remained confined to laboratories, with a lack of standardization. We report on a new device which combines the use of electromyographic (EMG) sensors with haptic technology for the dynamic investigation of wrist properties. The instrument is composed of a drivetrain, a haptic controller and a signal acquisition unit. Angular accuracy is 0.00611 rad, nominal torque is 6 N·m, maximal rotation velocity is 34.907 rad/sec, with a range of motion of –1.0472 to +1.0472 rad. The inertia of the motor and handgrip is 0.004 kg·m2. This is the first standardized myohaptic instrument allowing the dynamic characterization of wrist properties, including under the condition of artificial damping. We show that cerebellar patients are unable to adapt EMG activities when faced with an increase in damping while performing fast reversal movements. The instrument allows the extraction of an electrophysiological signature of a cerebellar deficit.
Delaying information search
Yaniv Shani,Niels van de Ven,Marcel Zeelenberg
Judgment and Decision Making , 2012,
Abstract: In three studies, we examined factors that may temporarily attenuate information search. People are generally curious and dislike uncertainty, which typically encourages them to look for relevant information. Despite these strong forces that promote information search, people sometimes deliberately delay obtaining valuable information. We find they may do so when they are concerned that the information might interfere with future pleasurable activities. Interestingly, the decision to search or to postpone searching for information is influenced not only by the value and importance of the information itself but also by well-being maintenance goals related to possible detrimental effects that negative knowledge may have on unrelated future plans.
Electrostatic Interactions between Janus Particles
Joost de Graaf,Niels Boon,Marjolein Dijkstra,René van Roij
Physics , 2012, DOI: 10.1063/1.4751482
Abstract: In this paper we study the electrostatic properties of `Janus' spheres with unequal charge densities on both hemispheres. We introduce a method to compare primitive-model Monte Carlo simulations of the ionic double layer with predictions of (mean-field) nonlinear Poisson-Boltzmann theory. We also derive practical DLVO-like expressions that describe the Janus-particle pair interactions by mean-field theory. Using a large set of parameters, we are able to probe the range of validity of the Poisson-Boltzmann approximation, and thus of DLVO-like theories, for such particles. For homogeneously charged spheres this range corresponds well to the range that was predicted by field-theoretical studies of homogeneously charged flat surfaces. Moreover, we find similar ranges for colloids with a Janus-type charge distribution. The techniques and parameters we introduce show promise for future studies of an even wider class of charged-patterned particles.
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