Correspondence analysis and association models constrained by a conditional independence graph

The manner in which the conditional independence graph of a multiway contingency table effects the fitting and interpretation of the Goodman association model (RC) and of correspondence analysis (CA) is considered.Estimation of the row and column scores is presented in this context by developing a unified framework that includes both models. Incorporation of the conditional independence constraints inherent in the graph may lead to equal or additive scores for the corresponding marginal tables, depending on the topology of the graph. An example of doubly additive scores in the analysis of a Burt subtable is given.Thanks are due to anonymous referees who substantially improved the original draft of this paper.     

Nimodipine Counteracts Corticosterone-Induced Habituation Impairments

Corticosterone or placebo sustained-release pellets (4 pellets of 200 mg each, released over 90 days) were implanted subcutaneously in young Fischer-344 rats, fed with either regular food or with food containing 860 ppm of nimodipine. Following 2 weeks of treatment, the habituation of the rats to a new environment was studied. On the first test day, placebo-implanted rats explored the new environment and exhibited a characteristic habituation. On the second test day, 48 hr later, low activity was measured in the already familiar environment. This habituation was absent in corticosterone-implanted rats fed with regular food. However, corticosterone-implanted rats fed with food containing nimodipine behaved during the second test similarly to the placebo-implanted group. The data indicated that the behavioral deficit, induced in Fischer-344 rats by the high corticosterone levels, was reversed by the nimodipine treatment. Thus, nimodipine may be useful in counteracting certain prolonged stress-related cognitive impairments.     

The second epistemic way revisited: Reply to Professor Beard's, ‘Professor Lucas on omniscience’

International Journal for Philosophy of Religion -     

SLOTE ON RATIONAL DILEMMAS AND RATIONAL SUPEREROGATION

The so-called optimising conception of rationality includes (amongst other things) the following two claims: (i) that it is irrational to choose an option if you know there is a better one, and (ii) there are no situations in which an agent, through no practical fault of her own, cannot avoid acting irrationally. As part of his ongoing attempt to explain why we need to go beyond the optimising conception, Michael Slote discusses a number of examples in which it seems that (i) and (ii) are inconsistent. According to Slote, these situations seem to involve the existence of rational supererogation (a denial of (i)), or rational dilemmas (a denial of (ii)). The purpose of this paper is to examine Slote's arguments for these claims, and to propose an alternative solution to the problem he presents.     

Asymmetry of perception in free viewing of chimeric faces

We have devised a new free-vision task to index functional cerebral asymmetry for processing facial characteristics. Confirming its sensitivity to properties of lateralized hemispheric functions, left- and right-handers were clearly differentiated on this task with respect to several aspects of performance that conform with known differences between handedness groups in hemispheric asymmetry. Additionally, there were highly reliable and stable individual differences in perceptual asymmetries within handedness. Analyses of items in the task revealed that most of the differences between items in the asymmetries they elicited were random.     

Developmental changes in predicting one's own span of short-term memory

Developmental changes in the accuracy of predicting one's own recall were studied, using preschool, third grade, and college subjects in Experiment 1 and third grade and college subjects in Experiment 2. Experiment 1 showed that prediction accuracy increased from the preschool to the college years, subjects were not influenced by a potential “expectancy” bias in the procedure, and only third grade subjects were influenced by the presence of norms about peer performance. Experiment 2 showed that third graders and college subjects lower their predictions in the face of “false” norm information, with college subjects being the only group to under predict actual recall in both experiments. Thus, although adults are significantly more accurate than elementary shool children in estimating short-term recall, their susceptibility to norm information suggests that even they have uncertainty about their exact capabilities.     

Effects of warm and neutral models on the attention of observational learners

The study was conducted to examine observers' attention to adults following warm and neutral interactions with them. Forty-two preschool and 36 third grade girls interacted with a pair of female models in one of three treatment conditions in which models were, respectively, warm and neutral, neutral and neutral, or warm and warm. Subiects then witnessed the models play a picture-preference game and were asked to recall the models' responses. Analyses of the children's overt attention to the models' responses revealed a greater attention to a warm model when in the presence of both a warm and neutral model and less distraction by nonsocial stimuli when at least one warm model was present. A significant positive correlation was obtained between attention to and recall of the models' responses.     

An empirical comparison of theZ-variance and Box-Scheffé tests for homogeneity of variance

This brief report provides a comparison of theZ-variance and Box-Scheffé tests for homogeneity of variance. Both procedures are relatively simple to perform and both may be readily utilized in complex, multifactor designs. TheZ-variance test is not robust against non-normality; the Box-Scheffé test is robust against non-normality but is not nearly as powerful as theZ-variance test.