The role of source reliability in belief polarisation

Psychological studies show that the beliefs of two agents in a hypothesis can diverge even if both agents receive the same evidence. This phenomenon of belief polarisation is often explained by invoking biased assimilation of evidence, where the agents’ prior views about the hypothesis affect the way they process the evidence. We suggest, using a Bayesian model, that even if such influence is excluded, belief polarisation can still arise by another mechanism. This alternative mechanism involves differential weighting of the evidence arising when agents have different initial views about the reliability of their sources of evidence. We provide a systematic exploration of the conditions for belief polarisation in Bayesian models which incorporate opinions about source reliability, and we discuss some implications of our findings for the psychological literature.

Evidence for two distinct thalamocortical circuits in retrosplenial cortex

Retrosplenial cortex (RSC) lies at the interface between perceptual and memory networks in the brain and mediates between these, although it is not yet known how. It has two distinct subregions, granular (gRSC) and dysgranular (dRSC). The present study investigated how these subregions differ with respect to their electrophysiology and connections, as a step towards understanding their functions. gRSC is more closely connected to the hippocampal system, in which theta-band local field potential oscillations are prominent. We therefore compared theta-rhythmic single-unit activity between the two RSC subregions and found, mostly in gRSC, a subpopulation of non-directional cells with spiking activity strongly entrained by theta oscillations, suggesting a stronger coupling of gRSC to the hippocampal system. We then used retrograde tracers to examine whether differences in neural coding between RSC subregions might reflect differential inputs from the anterior thalamus, which is a prominent source of RSC afferents. We found that gRSC and dRSC differ in their afferents from two AV subfields: dorsomedial (AVDM) and ventrolateral (AVVL). AVVL targets both gRSC and dRSC, while AVDM provides a selective projection to gRSC. These combined results suggest the existence of two distinct but interacting RSC subcircuits: one connecting AVDM to gRSC that may comprise part of the cognitive hippocampal system, and the other connecting AVVL to both RSC regions that may link hippocampal and perceptual regions. We suggest that these subcircuits are distinct to allow for differential weighting during integration of converging sensory and cognitive computations: an integration that may take place in thalamus, RSC or both.

Aberrant perceptual judgements on speech-relevant acoustic features in hallucination-prone individuals

Hallucinations constitute an intriguing model of how percepts are generated and how perception can fail. Here, we investigate the hypothesis that an altered perceptual weighting of the spectro-temporal modulations that characterize speech contributes to the emergence of auditory verbal hallucinations. Healthy adults (N=168) varying in their predisposition for hallucinations had to choose the ‘more speech-like’ of two presented ambiguous sound textures and give a confidence judgement. Using psychophysical reverse correlation, we quantified the contribution of different acoustic features to a listener’s perceptual decisions. Higher hallucination proneness covaried with perceptual down-weighting of speech-typical, low-frequency acoustic energy while prioritising high frequencies. Remarkably, higher confidence judgements in single trials depended not only on acoustic evidence but also on an individual’s hallucination proneness and schizotypy score. In line with an account of altered perceptual priors and differential weighting of sensory evidence, these results show that hallucination-prone individuals exhibit qualitative and quantitative changes in their perception of the modulations typical for speech.Author summaryHallucinations -- that is, percepts in the absence of an external stimulus -- are prevalent in psychotic disorders such as schizophrenia, but also occur in the general population. To date it is unknown whether the emergence of hallucinations is rooted in an altered perception of sounds. Fusing the psychophysical technique of reverse correlation with concepts from computational psychiatry, this research reveals alterations of sensory processing in hallucination-prone adults. We show that the higher nonclinical adults’ predisposition to hallucinations, the more they prioritise the sound features atypical for speech such as higher frequencies. At the same time, they express higher confidence in their perceptual judgements. The present approach may contribute to improving early diagnosis and prevention strategies in individuals at risk for psychosis.

Aberrant Perceptual Judgments on Speech-Relevant Acoustic Features in Hallucination-Prone Individuals

Hallucinations constitute an intriguing model of how percepts are generated and how perception can fail. Here, we investigate the hypothesis that an altered perceptual weighting of the spectro-temporal modulations that characterize speech contributes to the emergence of auditory verbal hallucinations. Healthy human adults (N = 168) varying in their predisposition to hallucinations had to choose the “more speech-like” of two presented ambiguous sound textures and give a confidence judgment. Using psychophysical reverse correlation, we quantified the contribution of different acoustic features to a listener’s perceptual decisions. Higher hallucination proneness covaried with perceptual down-weighting of speech-typical, low-frequency acoustic energy and prioritizing of high frequencies. Remarkably, higher confidence judgments in single trials depended not only on acoustic evidence but also on an individual’s hallucination proneness and schizotypy score. In line with an account of altered perceptual priors and differential weighting of sensory evidence, these results show that hallucination-prone individuals exhibit qualitative and quantitative changes in their perception of the modulations typical for speech.

Evaluating the Cumulative Impact of Childhood Misfortune: A Structural Equation Modeling Approach

Most studies of the early origins of adult health rely on summing dichotomously measured negative exposures to measure childhood misfortune (CM), neglect, adversity, or trauma. There are several limitations to this approach, including that it assumes each exposure carries the same level of risk for a particular outcome. Further, it often leads researchers to dichotomize continuous measures for the sake of creating an additive variable from similar indicators. We propose an alternative approach within the structural equation modeling (SEM) framework that allows differential weighting of the negative exposures and can incorporate dichotomous and continuous observed variables as well as latent variables. Using the Health and Retirement Study data, our analyses compare the traditional approach (i.e., adding indicators) with alternative models and assess their prognostic validity on adult depressive symptoms. Results reveal that parameter estimates using the conventional model likely underestimate the effects of CM on adult health outcomes. Additionally, while the conventional approach inhibits testing for mediation, our model enables testing mediation of both individual CM variables and the cumulative variable. Further, we test whether cumulative CM is moderated by the accumulation of protective factors, which facilitates theoretical advances in life course and social inequality research. The approach presented here is one way to examine the cumulative effects of early exposures while attending to diversity in the types of exposures experienced. Using the SEM framework, this versatile approach could be used to model the accumulation of risk or reward in many other areas of sociology and the social sciences beyond health.

An Algorithm to Evaluate Methodological Rigor and Risk of Bias in Single-Case Studies

Critical appraisal scales play an important role in evaluating methodological rigor (MR) of between-groups and single-case designs (SCDs). For intervention research this forms an essential basis for ascertaining the strength of evidence. Yet, few such scales provide classifications that take into account the differential weighting of items contributing to internal validity. This study aimed to develop an algorithm derived from the Risk of Bias in N-of-1 Trials (RoBiNT) Scale to classify MR and risk of bias magnitude in SCDs. The algorithm was applied to 46 SCD experiments. Two experiments (4%) were classified as Very High MR, 14 (30%) as High, 5 (11%) as Moderate, 2 (4%) as Fair, 2 (4%) as Low, and 21 (46%) as Very Low. These proportions were comparable to the What Works Clearinghouse classifications: 13 (28%) met standards, 8 (17%) met standards with reservations, and 25 (54%) did not meet standards. There was strong association between the two classification systems.

Salience-driven value construction for adaptive choice under risk

Decisions we face in real life are inherently risky and can result in one of many possible outcomes. However, most of what we know about choice under risk is based on studies that use options with only two possible outcomes (simple gambles), so it remains unclear how the brain constructs reward values for more complex risky options faced in real life. To address this question, we combined experimental and modeling approaches to examine choice between pairs of simple gambles and pairs of three-outcome gambles in male and female human subjects. We found that subjects evaluated individual outcomes of three-outcome gambles by multiplying functions of reward magnitude and probability. To construct the overall value of each gamble, however, most subjects differentially weighted possible outcomes based on either reward magnitude or probability. These results reveal a novel dissociation between how reward information is processed when evaluating complex gambles: valuation of each outcome is based on an integrated value whereas combination of possible outcomes relies on a single piece of reward information. We show that differential weighting of possible outcomes enabled subjects to make decisions more easily and quickly. Together, these findings reveal a plausible mechanism for how salience, in terms of possible reward magnitude or probability, can influence the construction of subjective values for complex gambles. They also point to separable neural mechanisms for how reward value controls choice and attention in order to allow for more adaptive decision making.

A New Biomedical Passage Retrieval Framework for Laboratory Medicine: Leveraging Domain-specific Ontology, Multilevel PRF, and Negation Differential Weighting

Clinical decision support (CDS) search is performed to retrieve key medical literature that can assist the practice of medical experts by offering appropriate medical information relevant to the medical case in hand. In this paper, we present a novel CDS search framework designed for passage retrieval from biomedical textbooks in order to support clinical decision-making using laboratory test results. The framework utilizes two unique characteristics of the textual reports derived from the test results, which are syntax variation and negation information. The proposed framework consists of three components: domain ontology, index repository, and query processing engine. We first created a domain ontology to resolve syntax variation by applying the ontology to detect medical concepts from the test results with language translation. We then preprocessed and performed indexing of biomedical textbooks recommended by clinicians for passage retrieval. We finally built the query-processing engine tailored for CDS, including translation, concept detection, query expansion, pseudo-relevance feedback at the local and global levels, and ranking with differential weighting of negation information. To evaluate the effectiveness of the proposed framework, we followed the standard information retrieval evaluation procedure. An evaluation dataset was created, including 28,581 textual reports for 30 laboratory test results and 56,228 passages from widely used biomedical textbooks, recommended by clinicians. Overall, our proposed passage retrieval framework, GPRF-NEG, outperforms the baseline by 36.2, 100.5, and 69.7 percent for MRR,R-precision, and Precision at 5, respectively. Our study results indicate that the proposed CDS search framework specifically designed for passage retrieval of biomedical literature represents a practically viable choice for clinicians as it supports their decision-making processes by providing relevant passages extracted from the sources that they prefer to refer to, with improved performances.

On the flexibility of basic risk attitudes in monkeys

ABSTRACTMonkeys and other animals appear to share with humans two risk attitudes predicted by prospect theory: an inverse-S-shaped probability weighting function and a steeper utility curve for losses than for gains. These findings suggest that such preferences are stable traits with common neural substrates. We hypothesized instead that animals tailor their preferences to subtle changes in task contexts, making risk attitudes flexible. Previous studies used a limited number of outcomes, trial types, and contexts. To gain a broader perspective, we examined two large datasets of male macaques’ risky choices: one from a task with real (juice) gains and another from a token task with gains and losses. In contrast to previous findings, monkeys were risk-seeking for both gains and losses (i.e. lacked a reflection effect) and showed steeper gain than loss curves (loss-seeking). Utility curves for gains were substantially different in the two tasks. Monkeys showed nearly linear probability weightings in one task and S-shaped ones in the other; neither task produced a consistent inverse-S-shaped curve. To account for these observations, we developed and tested various computational models of the processes involved in the construction of reward value. We found that adaptive differential weighting of prospective gamble outcomes could partially account for the observed differences in the utility functions across the two experiments and thus, provide a plausible mechanism underlying flexible risk attitudes. Together, our results support the idea that risky choices are flexibly constructed at the time of elicitation and place important constraints on neural models of economic choice.

The role of intentions and outcomes in the foreign language effect on moral judgements

We explore the origin of the foreign language effect on moral judgements by assessing whether language context alters the weight given to intentions and outcomes during moral judgement. Specifically, we investigated whether foreign language contexts, compared with native ones, may lead people to focus more on the outcomes of an action and less on the intentions behind it. We report two studies in which participants read scenarios in which the actor’s intentions and the resulting consequences were manipulated. As previously shown, people considered both the actor’s intentions and the action’s outcomes when assessing the damage, cause, moral wrongness, responsibility, and punishment deserved. However, although the foreign language context reduced the impact of intentions on damage assessment, the overall effect of intention and outcomes on these variables was mainly the same in the foreign and the native language contexts. We conclude that differential weighting of intentions and outcomes is unlikely to account for the impact of foreign language use on moral judgement.