Directional Bias Research Articles

Competing Heterogeneities in Vaccine Effectiveness Estimation.

Understanding the waning of vaccine-induced protection is important for both immunology and public health. Population heterogeneities in underlying (pre-vaccination) susceptibility and vaccine response can cause measured vaccine effectiveness (mVE) to change over time, even in the absence of pathogen evolution and any actual waning of immune responses. We use multi-scale agent-based models parameterized using epidemiological and immunological data, to investigate the effect of these heterogeneities on mVE as measured by the hazard ratio. Based on our previous work, we consider the waning of antibodies according to a power law and link it to protection in two ways: (1) motivated by correlates of risk data and (2) using a within-host model of stochastic viral extinction. The effect of the heterogeneities is given by concise and understandable formulas, one of which is essentially a generalization of Fisher's fundamental theorem of natural selection to include higher derivatives. Heterogeneity in underlying susceptibility accelerates apparent waning, whereas heterogeneity in vaccine response slows down apparent waning. Our models suggest that heterogeneity in underlying susceptibility is likely to dominate. However, heterogeneity in vaccine response offsets <10% to >100% (median of 29%) of this effect in our simulations. Our study suggests heterogeneity is more likely to 'bias' mVE downwards towards the faster waning of immunity but a subtle bias in the opposite direction is also plausible.

Outcomes Affect Evaluations of Decision Quality: Replication and Extensions of Baron and Hershey&amp;rsquo;s (1988) Outcome Bias Experiment 1

Outcome bias is the phenomenon whereby decisions which resulted in successful outcomes were rated more favorably than when the same decisions resulted in failures. We conducted a pre-registered replication and extension of Experiment 1 (original’s: N = 20) from the classic Baron and Hershey (1988) with an online Amazon Mechanical Turk sample using CloudResearch (N = 692), switching from a within-participants design in the original experiment to a between-participants design. We tested outcome bias by measuring participants’ ratings of the quality of decisions in medical scenarios. For the replication (pre-registered) part of the study, we successfully replicated signal and direction of the outcome bias (original: dpaired = 0.21 – 0.53; replication: dindependent = 0.77 [0.62, 0.93] to 1.1 [0.94, 1.26]), and even for participants who stated that outcomes should not be taken into consideration when evaluating decisions (d = 0.64 [0.21, 1.08]). For the extension part of the study, we found differences, dependent on outcome types, in evaluations of the perceived importance of considering the outcome, the perceived responsibility of decision-makers, and the perception that others would act similarly given the choice by outcome type. Materials, data, and code are available on Open Science Framework (OSF): https://osf.io/knjhu/.

Traces of early developmental bias in the adult brain

During the first 2 years of life, there is a high prevalence of optical distortions in the human eye, causing vertical blur on the retina (astigmatism), which is naturally resolved by the age of 5; thus, it is not treated. Here we determined the possible long-term effects on visual grouping resulting from optical distortions during the development of visual perception. Our results show a clear directional bias in shape perception for optically corrected astigmatic adults, compared with non-astigmatic ones, with remarkably slow decision times. These effects can be explained by a mismatch between the developmental timescales of different components in the visual system.

Mild Cognitive Impairment, But Not HIV Status, is Related to Reduced Awareness of Level of Cognitive Performance Among Older Adults

Self-assessment of cognitive abilities can be an important predictor of clinical outcomes. This study examined impairments in self-assessments of cognitive performance, assessed with traditional neuropsychological assessments and novel virtual reality tests among older persons with and without human immunodeficiency virus (HIV) and mild cognitive impairment (MCI). One hundred twenty-two participants (82 persons with HIV; 79 MCI+) completed a traditional neuropsychological battery, DETECT virtual reality cognitive battery, and self-reported their general cognitive complaints, depressive symptoms, and perceptions of DETECT performance. Relationships between DETECT performance and self-assessments of performance were examined as were the correlations between general cognitive complaints and performance. These relations were evaluated across HIV and MCI status, considering the associations of depressive symptoms, performance, and self-assessment. We found no effect of HIV status on objective performance or self-assessment of DETECT performance. However, MCI+ participants performed worse on DETECT and traditional cognitive tests, while also showing a directional bias towards overestimation of their performance. MCI- participants showed a bias toward underestimation. Cognitive complaints were reduced compared to objective performance in MCI+ participants. Correlations between self-reported depressive symptoms and cognitive performance or self-assessment of performance were nonsignificant. MCI+ participants underperformed on neuropsychological testing, while overestimating performance. Interestingly, MCI- participants underestimated performance to approximately the same extent as MCI+ participants overestimated. Practical implications include providing support for persons with MCI regarding awareness of limitations and consideration that self-assessments of cognitive performance may be overestimated. Similarly, supporting older persons without MCI to realistically appraise their abilities may have clinical importance.

Implicit Sensorimotor Adaptation Proceeds in Absence of Movement Execution.

In implicit sensorimotor adaptation, a mismatch between the predicted and actual sensory feedback results in a sensory prediction error (SPE). Sensory predictions have long been thought to be linked to descending motor commands, implying a necessary contribution of movement execution to adaptation. However, recent work has shown that mere motor imagery (MI) also engages predictive mechanisms, opening up the possibility that MI might be sufficient to drive implicit adaptation. In a within-subject design in humans (n = 30), implicit adaptation was assessed in a center-out reaching task, following a single exposure to a visuomotor rotation. It was hypothesized that performing MI of a reaching movement while being provided with an animation of rotated visual feedback (MI condition) would lead to postrotation biases (PRBs) similar to those observed when the movement is executed (Execution condition). Results revealed that both the MI and Execution conditions led to significant directional biases following rotated trials. Yet the magnitude of these biases was significantly larger in the Execution condition. To further probe the contribution of MI to adaptation, a Control condition was conducted in which participants were presented with the same rotated visual animation as in the MI condition, but in which they were prevented from performing MI. Surprisingly, significant biases were also observed in the Control condition, suggesting that MI per se may not have accounted for adaptation. Overall, these results suggest that implicit adaptation can be partially supported by processes other than those that strictly pertain to generating motor commands, although movement execution does potentiate it.

Just as I expected? Hindsight bias for the outcome of a national referendum is moderated by outcome valence and surprise

AbstractWhen people learn that an event has occurred, they often report that they expected it all along. The present study explored this “hindsight bias” for the outcome of a national referendum on abortion. Participants rated the probability of the referendum passing one week before polling day, and then recalled their original estimates one week and one year post‐referendum. The magnitude and direction of bias was predicted by voting choice: People on the losing side exhibited a classic hindsight bias, and remembered believing the outcome to be roughly 16% more likely than they originally reported. In contrast, people on the winning side exhibited a weak reversal of the typical bias. Hindsight bias was moderated by feelings of surprise in both groups. This study suggests that individuals on the losing side of political campaigns may be especially likely to misremember their prior expectations if the outcome is disappointing but not unexpected.

Retraction of Keum et al. (2021).

Reports the retraction of "Do therapists improve in their ability to assess clients' satisfaction? A truth and bias model" by Brian TaeHyuk Keum, Katherine Morales Dixon, Dennis M. Kivlighan Jr., Clara E. Hill and Charles J. Gelso (Journal of Counseling Psychology, 2021[Oct], Vol 68[5], 608-620). The following article (https://doi.org/10.1037/cou0000525) is being retracted. This retraction is at the request of coauthors Kivlighan, Hill, and Gelso after the results of an investigation by the University of Maryland Institutional Review Board (IRB). The IRB found that the study included data from between one and four therapy clients of the Maryland Psychotherapy Clinic and Research Laboratory (MPCRL) who either had not been asked to provide consent or had withdrawn consent for their data to be included in the research. Keum and Dixon were not responsible for obtaining and verifying participant consent but agreed to the retraction of this article. (The following abstract of the original article appeared in record 2020-51285-001.) We used the truth and bias model to examine changes in tracking accuracy and under/overestimation (directional bias) on therapists' judgments about clients' satisfaction. We examined 3 factors of clinical experience that could moderate accuracy: (a) overall level of acquaintanceship with a client, operationalized as treatment length (i.e., less or more time seeing a client), (b) time point in therapy with a specific client, operationalized as session number (i.e., earlier or later in treatment with a client), and (c) order (1st client seen, 2nd client seen . . . last client seen across two years of training in a psychology clinic) in which clients were seen. We conducted a three-level hierarchical linear modeling using data on 6054 sessions, nested in 284 adult clients, nested in 41 doctoral student therapists providing open-ended psychodynamic individual psychotherapy. We found that therapists were able to accurately track client-rated session evaluations with less underestimation (i.e., lower tendency to estimate that clients were less satisfied than they actually were) as they gained experience (both treatment length and client order). Furthermore, therapists exhibited greater tracking accuracy gains over the span of shorter treatments and when working with clients earlier in their clinical training. In longer treatments and with clients seen later in training, tracking accuracy was stable and consistent. Implications for research and practice are discussed. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Practical machine learning: Forecasting daily financial markets directions

Financial time series prediction has many applications in economics, but producing profitable strategies certainly has a special place among them, a daunting challenge. Statistical and machine learning techniques are intensively researched in the search for a holy grail of stock markets forecasting. However, it is not clear to prospecting researchers how good those popular models are regarding useful predictions on a real scenario. This paper contributes to that discussion, providing decisive evidences contrary to the use of basic out-of-the-box models, specifically Artificial Neural Networks (ANN), Support Vector Machines (SVM), Random Forest (RF) and Naive-Bayes (NB). Results consider optimistic and unreal variables often found in literature, as well as a more close-to-real simulation of the models usage. Specifically, current day closing prices direction forecasting results are contrasted with those on next day forecasts. As expected, when forecasting the current day, accuracy is almost perfect. However, when used to forecast next day closing direction, with a strict data separation policy and without direction or snooping bias, ANN, SVM, RF and NB produce results essentially equal to random guessing. The main achieved result is the demonstration of how a machine learning approach would fare in a support decision system for forecasting short-term future market direction, regardless of the level of market development, considering more than 100 securities in a 10 years period. Consequences for algorithmic trading relate to discouraging usage of the considered models as implemented here. On a more abstract sense, this paper presents more evidence to the Efficient Market Hypothesis (EMH).

Directivity‐enhanced planar slot antenna backed by substrate integrated waveguide cavity

AbstractIn this paper, a directivity‐enhanced planar slot antenna (PSA) backed by substrate integrated waveguide (SIW) cavity is proposed to solve the problem of maximum gain direction bias. According to the radiation principle of slot antenna, the reason for maximum gain direction bias is explained and the solution has been given. Ulteriorly, the problem of frequency bias caused by changing the directivity is also explained by resonance modes and solved by introducing the metal via. An example with 5.8 GHz which has the maximum gain of 5.28 dBi and the total thickness less than λ/4 is given. After structural optimization and measurement, the maximum radiation direction of improved antenna is 0° from the normal direction of antenna surface, and it maintains the good radiation performance and small size of the traditional PSA backed by SIW cavity.

A Higher-Order Defect Correction Method Over an Adaptive Bakhvalov–Shishkin Mesh for Advection–Diffusion Equations

The paper presents a defect correction method based on finite difference discretizations over a Bakhvalov–Shishkin mesh for a class of convection-diffusion equations. The technique combines a stable, low-order accurate, computationally inexpensive upwind difference scheme with a higher-order less stable modified central difference operator at several grid points. We prove that the method is second-order uniformly convergent at all mesh points. We do not use asymptotic expansions of discretization errors in our analysis. The method has no directional bias, and it can be used in an adaptive procedure to refine the mesh in the non-smooth parts. Numerical results are presented, which indicate that defect correction on layer-adapted meshes is an excellent method to achieve higher-order accuracy for singular perturbation problems.

NbS2/MoSi2P4 van der Waals Heterojunction: Flexibly tunable electrical contact properties and potential applications for Schottky junction devices

To obtain miniaturized and high-performance nanoelectronic devices, it is still crucially technical problem to realize ohmic contact at metal–semiconductor interface. Here, we construct H-, T-NbS2/MoSi2P4 van der Waals heterojunctions (vdWHs) and theoretically explore their mechanic and electronic behaviors, focusing on electrical contact features and tunability as well as Schottky junction device properties. The suitable Poisson’s ratio and sufficient rigidity suggest that such vdWHs are highly favorable to act as electrode or channel materials. The quasi-ohmic contact for H-NbS2/MSP occurs in the intrinsic equilibrium state (ES), and its entire ohmic contact emerges only by a very small interlayer spacing compression. For both H- and T-NbS2/MSP, entire ohmic contacts can be realized by applied appropriate electric field. Based on these studies, we design 5 nm gate-controlled Schottky junction devices. The calculated energy-resolved currents show that the thermal emission transmission plays an important role in rectification, making the rectification ratio exceeding 105, enhanced further by positive gate voltage applied. These behaviors can be identified by the calculated PLDOS, which shows that the highly asymmetric device potential barrier with respect to bias polarity and tuned flexibly by gate voltage results in a highly asymmetric electron transport under different directional biases. Our study provide a new possibility for designing high-performance Schottky junction devices.

INTRAOPERATIVE BLEB BEHAVIOR IN SUBRETINAL GENE AUGMENTATION THERAPY FOR INHERITED RETINAL DISEASES.

In subretinal gene therapy for inherited retinal diseases (IRDs), blebs may not propagate predictably in the direction of the injection cannula. We evaluated factors that influenced bleb propagation among various IRDs. Retrospective review of all subretinal gene therapy procedures performed by a single surgeon between September 2018 and March 2020 for various IRDs. Main outcome measures were directional bias of bleb propagation and intraoperative foveal detachment. Desired injection volumes and/or foveal treatment were successfully achieved in all 70 eyes of 46 patients with IRD regardless of IRD indication. Bullous foveal detachment was associated with retinotomy closer to the fovea, posterior bleb bias, and greater bleb volumes ( P < 0.01). Blebs biased anteriorly or posteriorly based on disease indication ( P = 0.04) and age ( P < 0.001). Retinotomy location ≤ 3.7 mm (approximately two disk diameters) from the fovea favored foveal detachment ( P < 0.001). Multiple retinotomies and blebs allowed greater surface area coverage in some eyes, but intersecting blebs did not propagate further. Bleb formation and propagation are predictable based on patient age, retinotomy location, disease indication, and how tangentially fluid is directed into the subretinal space.

Failure analysis of high-performance woven fabrics during quasistatic stabbing

In recent years, stab protection is getting increasing attention from the researchers and practitioners. Most of the stab protective vests are made of high-performance fibre based woven fabrics. However, unlike ballistic protection, the roles of fibre material, fabric structure, and test parameters on the failure mechanism during stabbing are still not well-understood. This study systematically examines the effects of fibre type, weave architecture and stabbing direction on the quasistatic stab resistance of woven fabrics. P-aramid (Kevlar®), aromatic polyester (Vectran®), and ultra-high molecular weight polyethylene (Spectra®) fibres were used to weave plain, 3/1 twill, and 2/2 twill fabrics of same areal density. All the fabrics were tested in warp, weft and bias directions using a P1 knife (NIJ 0115.0 standard). Among the fibres, Spectra® demonstrated the highest stab resistance followed by Vectran®. Plain woven fabric showed higher stab resistance than the other two weaves in bias direction. For all weaves, stab resistance was also found to be higher in bias direction followed by weft and warp. Statistical analysis (three-way ANOVA) revealed that fibre type, weave architecture and stabbing direction have significant roles (p < 0.05) in determining the stab resistance of woven fabrics. The outcome of this research will be useful for designing stab resistant vest using high-performance woven fabrics.

Roles of magnetic coupling and spin-orbit torque in the electrical manipulation of exchange bias in a Pt/Co/IrMn heterostructure

Heavy-metal/ferromagnet/antiferromagnet heterostructures have attracted significant attention in manipulating antiferromagnetic ordering electrically. We report electric control of the exchange bias field along both the out-of-plane and in-plane directions in Pt/Co/IrMn with assist magnetic fields. Experiments with different directions and amplitudes of the assist magnetic field show the role of magnetic coupling between ferromagnet and antiferromagnet spins. Furthermore, we find that the magnitude and direction of the exchange bias can be manipulated by the magnitude of the current pulse. The observed results can be explained based on a numerical macrospin model; the antiferromagnetic spins are excited and precessed from their ground state via the spin-orbit torque-driven oscillation and are reoriented, being mediated by magnetic coupling with the ferromagnet. Our results provide an approach to achieve electrical omnidirectional exchange bias manipulation and an understanding of the spin dynamics at the antiferromagnet-ferromagnet interface.

Misclassification Bias in the Assessment of Gene-by-Environment Interactions.

Misclassification bias is a common concern in epidemiologic studies. Despite strong bias on main effects, gene-environment interactions have been shown to be biased towards the null under gene-environment independence. In the context of a recent article examining the interaction between nerve agent exposure and paraoxonase-1 gene on Gulf War Illness, we aimed to assess the impact of recall bias-a common misclassfication bias-on the identification of gene-environment interactions when the independence assumption is violated. We derive equations to quantify the bias of the interaction, and numerically illustrate these results by simulating a case-control study of 1000 cases and 1000 controls. Simulation input parameters included exposure prevalence, strength of gene-environment dependence, strength of the main effect, exposure specificity among cases, and strength of the gene-environment interaction. We show that, even if gene-environment independence is violated, we can bound possible gene-environment interactions by knowing the strength and direction of the gene-environment dependence ( ) and the observed gene-environment interaction ( )-thus often still allowing for the identification of such interactions. Depending on whether is larger or smaller than the inverse of , is a lower (if ) or upper (if ) bound for the true interaction. In addition, the bias magnitude is somewhat predictable by examining other characteristics such as exposure prevalence, the strength of the exposure main effect, and directions of the recall bias and gene-environment dependence. Even if gene-environment dependence exists, we may still be able to identify gene-environment interactions even when misclassification bias is present.

Half Empty and Half Full? Biased Perceptions of Compassionate Love and Effects of Dyadic Complementarity.

The prevailing theory on relationship judgments for interaction attributes suggests individuals tend to underestimate a romantic partner's expressions of compassionate love and that such underestimation is beneficial for the relationship. Yet, limited research has incorporated dyadic perspectives to assess how biased perceptions are associated with both partners' outcomes. In two daily studies of couples, we used distinct analytical approaches (Truth and Bias Model; Dyadic Response Surface Analysis) to inform perspectives on how biased perceptions are interrelated and predict relationship satisfaction. Consistent with prior research, people demonstrated an underestimation bias. However, there were differential effects of biased perceptions for actors versus partners: Underestimation predicted lower actor satisfaction but generally higher satisfaction for partners. Furthermore, we find evidence for complementarity effects: partners' directional biases were inversely related, and couples were more satisfied when partners had opposing patterns of directional bias. Findings help integrate theoretical perspectives on the adaptive role of biased relationship perceptions.

Shifts in mutation spectra enhance access to beneficial mutations

Biased mutation spectra are pervasive, with wide variation in the magnitude of mutational biases that influence genome evolution and adaptation. How do such diverse biases evolve? Our experiments show that changing the mutation spectrum allows populations to sample previously undersampled mutational space, including beneficial mutations. The resulting shift in the distribution of fitness effects is advantageous: Beneficial mutation supply and beneficial pleiotropy both increase, while deleterious load reduces. More broadly, simulations indicate that reducing or reversing the direction of a long-term bias is always selectively favored. Such changes in mutation bias can occur easily via altered function of DNA repair genes. A phylogenetic analysis shows that these genes are repeatedly gained and lost in bacterial lineages, leading to frequent bias shifts in opposite directions. Thus, shifts in mutation spectra may evolve under selection and can directly alter the outcome of adaptive evolution by facilitating access to beneficial mutations.

Reproduction of bacterial chemotaxis by a non-living self-propelled object

Taxic behavior as a response to an external stimulus is a fundamental function of living organisms. Some bacteria successfully implement chemotaxis without directly controlling the direction of movement. They periodically alternate between run and tumble, i.e., straight movement and change in direction, respectively. They tune their running period depending on the concentration gradient of attractants around them. Consequently, they respond to a gentle concentration gradient stochastically, which is called “bacterial chemotaxis.” In this study, such a stochastic response was reproduced by a non-living self-propelled object. We used a phenanthroline disk floating on an aqueous solution of Fe^{2+}. The disk spontaneously alternated between rapid motion and rest, similar to the run-and-tumble motion of bacteria. The movement direction of the disk was isotropic independent of the concentration gradient. However, the existing probability of the self-propelled object was higher at the low-concentration region, where the run length was longer. To explain the mechanism underlying this phenomenon, we proposed a simple mathematical model that considers random walkers whose run length depends on the local concentration and direction of movement against the gradient. Our model adopts deterministic functions to reproduce the both effects, which is instead of stochastic tuning the period of operation used in the previous reports. This allows us to analyze the proposed model mathematically, which indicated that our model reproduces both positive and negative chemotaxis depending on the competition between the local concentration effect and it’s gradient effect. Owing to the newly introduced directional bias, the experimental observations were reproduced numerically and analytically. The results indicate that the directional bias response to the concentration gradient is an essential parameter for determining bacterial chemotaxis. This rule might be universal for the stochastic response of self-propelled particles in living and non-living systems.

A continuum damage model of fatigue and failure in whole bone

Predicting the fatigue failure of whole bone may provide insight into the etiology of stress fractures and lead to new methods for preventing and rehabilitating these injuries. Although finite element (FE) models of whole bone have been used to predict fatigue failure, they often do not consider the cumulative and nonlinear effect of fatigue damage, which causes stress redistribution over many loading cycles. The purpose of this study was to develop and validate a continuum damage mechanics FE model for the prediction of fatigue damage and failure. Sixteen whole rabbit-tibiae were imaged using computed tomography (CT) and then cyclically loaded in uniaxial compression until failure. CT images were used to generate specimen-specific FE models and a custom program was developed to iteratively simulate cyclic loading and progressive modulus degradation associated with mechanical fatigue. Four tibiae from the experimental tests were used to develop a suitable damage model and define a failure criterion; the remaining twelve tibiae were used to test the validity of the continuum damage mechanics model. Fatigue-life predictions explained 71% of the variation in experimental fatigue-life measurements with a directional bias towards over-predicting fatigue-life in the low-cycle regime. These findings demonstrate the efficacy of using FE modeling with continuum damage mechanics to predict damage evolution and fatigue failure of whole bone. Through further refinement and validation, this model may be used to investigate different mechanical factors that influence the risk of stress fractures in humans.

Retinal waves align the concentric orientation map in mouse superior colliculus to the center of vision

Neurons in the mouse superior colliculus (SC) are arranged in a concentric orientation map, which is aligned to the center of vision and the optic flow experienced by the mouse. The origin of this map remains unclear. Here, we propose that spontaneous retinal waves during development provide a scaffold to establish the concentric orientation map within the SC and its alignment to the optic flow. We test this hypothesis by modeling the orientation-tuned SC neurons that receive ON/OFF retinal inputs. Our model suggests that the propagation direction bias of stage III retinal waves, together with OFF-delayed responses, shapes the spatial organization of the orientation map. The OFF delay establishes orientation-tuned neurons by segregating their ON/OFF receptive subfields, the wave-like activities form the concentric pattern, and the direction biases align the map to the center of vision. Together, retinal waves may play an instructive role in establishing functional properties of single SC neurons and their spatial organization within maps.