A Simple Simulation Technique for Nonnormal Data with Prespecified Skewness,Kurtosis, and Covariance Matrix

We present and investigate a simple way to generate nonnormal data using linear combinations of independent generator (IG) variables. The simulated data have prespecified univariate skewness and kurtosis and a given covariance matrix. In contrast to the widely used Vale-Maurelli (VM) transform, the obtained data are shown to have a non-Gaussian copula. We analytically obtain asymptotic robustness conditions for the IG distribution. We show empirically that popular test statistics in covariance analysis tend to reject true models more often under the IG transform than under the VM transform. This implies that overly optimistic evaluations of estimators and fit statistics in covariance structure analysis may be tempered by including the IG transform for nonnormal data generation. We provide an implementation of the IG transform in the R environment.     

Can We Trust Our Memories? C. I. Lewis's Coherence Argument

In this paper we examine C. I. Lewis's view on the roleof coherence – what he calls 'congruence' – in thejustification of beliefs based on memory ortestimony. Lewis has two main theses on the subject. His negativethesis states that coherence of independent items ofevidence has no impact on the probability of a conclusionunless each item has some credibility of its own. Thepositive thesis says, roughly speaking, that coherenceof independently obtained items of evidence – such asconverging memories or testimonies – raises the probabilityof a conclusion to the extent sufficient for epistemicjustification, or, to use Lewis's expression, 'rationaland practical reliance'.It turns out that, while thenegative thesis is essentially correct (apart from aslight flaw in Lewis's account of independence), astrong positive connection between congruence andprobability – a connection of the kind Lewis ultimatelyneeds in his validation of memory – is contingent on thePrinciple of Indifference. In the final section we assess therepercussions of the latter fact for Lewis's theory in particularand for coherence justification in general.     

Internal imagery training in active high jumpers

The main purpose of this study was to examine whether the use of internal imagery would affect high jumping performance for active high jumping athletes. Over a period of six weeks, a group of active high jumpers were trained with an internal imagery program for a total of 72 minutes. This group was compared to a control group consisting of active high jumpers that only maintained their regular work-outs during the same time period. Four variables were measured; jumping height, number of failed attempts, take-off angle, and bar clearance. There was a significant improvement on bar clearance for the group that trained imagery (p < 0.05) but not for the control group. No other differences were found. The results suggest that internal imagery training may be used to improve a component of a complex motor skill. Possible explanations and future recommendations are discussed.     

ON THE ROLE OF THE RESEARCH AGENDA IN EPISTEMIC CHANGE

The standard way of representing an epistemic state in formal philosophy is in terms of a set of sentences, corresponding to the agent’s beliefs, and an ordering of those sentences, reflecting how well entrenched they are in the agent’s epistemic state. We argue that this wide-spread representational view – a view that we identify as a “Quinean dogma” – is incapable of making certain crucial distinctions. We propose, as a remedy, that any adequate representation of epistemic states must also include the agent’s research agenda, i.e., the list of question that are open or closed at any given point in time. If the argument of the paper is sound, a person’s questions and practical interests, on the one hand, and her beliefs and theoretical values, on the other, are more tightly interwoven than has previously been assumed to be the case in formal epistemology.     

Fear Extinction to an Out-Group Face: The Role of Target Gender

ABSTRACT— Conditioning studies on humans and other primates show that fear responses acquired toward danger-relevant stimuli, such as snakes, resist extinction, whereas responses toward danger-irrelevant stimuli, such as birds, are more readily extinguished. Similar evolved biases may extend to human groups, as recent research demonstrates that a conditioned fear response to faces of persons of a social out-group resists extinction, whereas fear toward a social in-group is more readily extinguished. Here, we provide an important extension to previous work by demonstrating that this fear-extinction bias occurs solely when the exemplars are male. These results underscore the importance of considering how gender of the target stimulus affects psychological and physiological responses to out-group threat.     

TEACHING CONSERVATION OF WEIGHT BY MEANS OF VERBAL INSTRUCTIONS

Three groups of preschool children were given verbal instructions as to the invariance of weight in spite of transformations of shape. Instructions were phrased according to the principles of reversibility, decentering, and addition-subtraction, respectively. A fourth group received no verbal information but only external reinforcement. Verbally instructed groups were superior to control and nonverbal groups on a posttest. On transfer and counter-suggestion items the addition-subtraction group had a tendency towards superior performance.     

Visual perception of dynamic properties: cue heuristics versus direct-perceptual competence

Constructivist and Gibsonian approaches disagree over the possibility of direct perceptual use of advanced information. A trenchant instance concerns visual perception of underlying dynamic properties as specified by kinematic patterns of events. For the paradigmatic task of discrimination of relative mass in observed collisions, 2 mathematical models are developed, 1 model representing a direct, invariant-based approach, and 1 representing a cue-heuristic approach. The models enable a critical experimental design with distinct predictions concerning performance data and confidence ratings. Although pretraining results were mixed, the invariant-based model was empirically confirmed after a minimal amount of training: Competence entails the use of advanced kinematic information in a direct-perceptual ("sensory") mode of apprehension, in contrast to beginners' use of simpler cues in an inferential ("cognitive") mode.     

Naive empiricism and dogmatism in confidence research: a critical examination of the hard-easy effect

Two robust phenomena in research on confidence in one's general knowledge are the overconfidence phenomenon and the hard-easy effect. In this article, the authors propose that the hard-easy effect has been interpreted with insufficient attention to the scale-end effects, the linear dependency, and the regression effects in data and that the continued adherence to the idea of a "cognitive overconfidence bias" is mediated by selective attention to particular data sets. A quantitative review of studies with 2-alternative general knowledge items demonstrates that, contrary to widespread belief, there is (a) very little support for a cognitive-processing bias in these data; (b) a difference between representative and selected item samples that is not reducible to the difference in difficulty; and (c) near elimination of the hard-easy effect when there is control for scale-end effects and linear dependency.