Attenuating memory distrust in a repeated checking task

Repeated checking has been demonstrated to lead to reductions in memory confidence in several previous studies using student and clinical samples. This process of reduced confidence in memory and detail for memory, are thought to arise from the inhibition of perceptual processing that develops during repeated checking. Our research investigated whether reduced memory confidence from repeated checking could be attenuated through the use of novel stimuli during the repeated checking task. Three groups were generated through random assignment of 65 undergraduate students. As seen in previous research, individuals who repeatedly checked a stimulus (a virtual stovetop) showed reduced memory confidence, vividness, and detail, when compared with individuals who repeatedly checked a different stimulus. A third group in which the colour of the repeatedly-checked stovetop changed every five trials showed no significant decline in memory confidence between the pre-test and post-test. Results suggest that increased memory distrust can be ameliorated through the use of stimuli with characteristics that are novel and distinctive. Findings are discussed in the context of the existing model of repeated checking and memory confidence, and implications for treatment methods are presented.     

Reminders supporting spontaneous remembering in prospective memory tasks1

Abstract: The objective of this study was to identify the reminders that facilitate prospective memory. A total of 64 participants were either provided with three types of reminders for a prospective memory task (to circle a question number when prescribed target words appear) during the retention interval, or not reminded of the task. In addition, an articulatory suppression task was imposed halfway through the test phase to examine whether verbal rehearsal is related to the effects of the reminders. The reminders that referred to the intended activity (to circle the number) did not improve prospective memory. However, both of the reminders that notified that there was something to do and the reminders that referred to the target events (the prescribed words) improved prospective memory. Imposing the suppression task abolished the benefit of the former, but not that of the latter. This result suggests that only the effect of the reminders that referred to the existence of intention is mediated by verbal rehearsal. These data imply that there are some differences in the functions of these reminders.     

Mean Comparison: Manifest Variable Versus Latent Variable

Mean comparisons are of great importance in the application of statistics. Procedures for mean comparison with manifest variables have been well studied. However, few rigorous studies have been conducted on mean comparisons with latent variables, although the methodology has been widely used and documented. This paper studies the commonly used statistics in latent variable mean modeling and compares them with parallel manifest variable statistics. Our results indicate that, under certain conditions, the likelihood ratio and Wald statistics used for latent mean comparisons do not always have greater power than the Hotelling T² statistics used for manifest mean comparisons. The noncentrality parameter corresponding to the T² statistic can be much greater than those corresponding to the likelihood ratio and Wald statistics, which we find to be different from those provided in the literature. Under a fixed alternative hypothesis, our results also indicate that the likelihood ratio statistic can be stochastically much greater than the corresponding Wald statistic. The robustness property of each statistic is also explored when the model is misspecified or when data are nonnormally distributed. Recommendations and advice are provided for the use of each statistic. The research was supported by NSF grant DMS-0437167 and Grant DA01070 from the National Institute on Drug Abuse. We would like to thank three referees for suggestions that helped in improving the paper.     

A new puzzle about belief and credence

I present a puzzle about belief and credence, which takes the form of three independently supported views that are mutually inconsistent. The first is the view that S has a modal belief that p (e.g., S believes that probably-p) if and only if S has a corresponding credence that p. The second is the view that S believes that p only if S has some credence that p. The third is the view that, possibly, S believes that p without a modal belief that p. [Word Count: 85]     

Examining the trade‐off between confidence and optimism in future forecasts

Confident business forecasters are seen as more credible and competent (“confidence heuristic”). We explored a boundary condition of this effect by examining how individuals react to the trade‐off between confidence and optimism. Using hypothetical scenarios, we examined this trade‐off from the perspectives of judges (i.e., business owners who hired analysts to make sales predictions) and forecasters (i.e., the analysts hired to make predictions). Participants were assigned to the role of either judges or forecasters and were asked to rate 2 potential forecasts. In the “no trade‐off” condition, the 2 forecasts were aligned in optimism and confidence (the more confident forecast was also more optimistic); in the “trade‐off” condition, the more confident forecast was less optimistic. In Experiment 1, judges were more likely to positively evaluate confident forecasters when confident forecasters were the more (vs. less) optimistic ones. Experiment 2 demonstrated that forecasters were aware of judges' preferences for optimism and strategically relied on methods that resulted in more optimistic (but less reliable) predictions. Experiment 3 directly compared the perspectives of judges and forecasters, revealing that forecasters overestimated judges' preferences for optimism over confidence. The present studies show that forecasters and judges have different views of the trade‐off between confidence and optimism and that forecasters may unnecessarily sacrifice accuracy for optimism.     

Forensic voice discrimination by lay listeners: The effect of speech type and background noise on performance

In forensic settings, lay (nonexpert) listeners may be required to compare voice samples for identity. In two experiments we investigated the effect of background noise and variations in speaking style on performance. In each trial, participants heard two recordings, responded whether the voices belonged to the same person, and provided a confidence rating. In Experiment 1, the first recording featured read speech and the second featured read or spontaneous speech. Both recordings were presented in quiet, or with background noise. Accuracy was highest when recordings featured the same speaking style. In Experiment 2, background noise either occurred in the first or second recording. Accuracy was higher when it occurred in the second. The overall results reveal that both speaking style and background noise can disrupt accuracy. Although there is a relationship between confidence and accuracy in all conditions, it is variable. The forensic implications of these findings are discussed.     

Professional Autonomy in Belgium

The Belgian health care system has a few features that may havecontributed to the rising costs of health care: patients' freechoice of physicians, large clinical freedom of physicians, essentiallya fee-for-service remuneration for medical specialists in which the feesare agreed between insurance funds and physicians. The increased medicalconsumption and costs have prompted the state and insurance companies totake measures that limit the professional autonomy of the physicians.Access to medical education, free until 1997, is now restricted. Themedical profession is organized in the Order of Physicians that hasestablished a code of professional ethics that has moral but not legalforce. So far, there is no special legislation for thepatient–physician relationship, though laws on specific issueslike organ transplantation contain duties for physicians. In recentyears a debate is taking place on patients' rights, of which informedconsent is central and gaining importance in medico-legal publications.An analysis of (ethical and legal) regulations concerning thewithholding or withdrawal of treatment by physicians demonstrate thatthe profession still enjoys a large clinical autonomy, though duediscussion with the patient has become more explicitly required. Therespect for professional autonomy is not primarily due to any formalpower that the Order of Physicians would have, but is rather grounded inthe generally high quality of the patient–physician relationshipthat in ethical terms is considered essentially as a confidencerelationship rather than a contractual relationship.     

Exact distributions of intraclass correlation and Cronbach's alpha with Gaussian data and general covariance

Intraclass correlation and Cronbach's alpha are widely used to describe reliability of tests and measurements. Even with Gaussian data, exact distributions are known only for compound symmetric covariance (equal variances and equal correlations). Recently, large sample Gaussian approximations were derived for the distribution functions. New exact results allow calculating the exact distribution function and other properties of intraclass correlation and Cronbach's alpha, for Gaussian data with any covariance pattern, not just compound symmetry. Probabilities are computed in terms of the distribution function of a weighted sum of independent chi-square random variables. NewF approximations for the distribution functions of intraclass correlation and Cronbach's alpha are much simpler and faster to compute than the exact forms. Assuming the covariance matrix is known, the approximations typically provide sufficient accuracy, even with as few as ten observations. Either the exact or approximate distributions may be used to create confidence intervals around an estimate of reliability. Monte Carlo simulations led to a number of conclusions. Correctly assuming that the covariance matrix is compound symmetric leads to accurate confidence intervals, as was expected from previously known results. However, assuming and estimating a general covariance matrix produces somewhat optimistically narrow confidence intervals with 10 observations. Increasing sample size to 100 gives essentially unbiased coverage. Incorrectly assuming compound symmetry leads to pessimistically large confidence intervals, with pessimism increasing with sample size. In contrast, incorrectly assuming general covariance introduces only a modest optimistic bias in small samples. Hence the new methods seem preferable for creating confidence intervals, except when compound symmetry definitely holds. An earlier version of this paper was submitted in partial fulfillment of the requirements for the M.S. in Biostatistics, and also summarized in a presentation at the meetings of the Eastern North American Region of the International Biometric Society in March, 2001. Kistner's work was supported in part by NIEHS training grant ES07018-24 and NCI program project grant P01 CA47 982-04. She gratefully acknowledges the inspiration of A. Calandra's “Scoring formulas and probability considerations” (Psychometrika, 6, 1–9). Muller's work supported in part by NCI program project grant P01 CA47 982-04.     

Detecting Differential Item Functioning Using Multiple-Group Cognitive Diagnosis Models

This study proposes a multiple-group cognitive diagnosis model to account for the fact that students in different groups may use distinct attributes or use the same attributes but in different manners (e.g., conjunctive, disjunctive, and compensatory) to solve problems. Based on the proposed model, this study systematically investigates the performance of the likelihood ratio (LR) test and Wald test in detecting differential item functioning (DIF). A forward anchor item search procedure was also proposed to identify a set of anchor items with invariant item parameters across groups. Results showed that the LR and Wald tests with the forward anchor item search algorithm produced better calibrated Type I error rates than the ordinary LR and Wald tests, especially when items were of low quality. A set of real data were also analyzed to illustrate the use of these DIF detection procedures.