Adaptation in the constancy of visual direction measured by a one-trial method

Adaptation to field displacement during head movements in the direction with the head rotation and in the direction against it was produced under otherwise identical conditions and compared; the field displacement rate was also varied. A rapid training procedure was used, and a novel one-trial test was employed that could measure the adaptation well enough to compare the effects of various training conditions. The one-trial test measured the magnitude of one of the manifestations of adaptation, the apparent displacement of a stationary target during head movements. This apparent horizontal target displacement was transformed into an oblique one by having the head movements that brought forth the apparent target displacement simultaneously cause an objective vertical target displacement. The slant of the resultant apparent motion path varied with the magnitude of the apparent horizontal target displacement. It was measured by having S reproduce its slant angle. It was found that adaptation to field displacement in the direction with the head rotation was consistently greater than adaptation to the opposite displacement conditions. An explanation for this result is offered.     

The effect of abnormal displacement of the retinal image during eye movements

The displacement of the images on the retina that results from a turning of the eye does not lead to an apparent motion of what is seen, It has been generally assumed that this is due to a compensating process which takes eye movement into account and serves to discount those image displacements that result from eye movements, It follows from this view that an abnormal image displacement, that is, an image displacement that is larger or smaller than the causing eye movement would warrant, should lead to an experienced displacement of the target. Abnormal image displacement was produced by placing the eye in the converging or diverging bundle of rays from a point source that form behind a strong positive lens; this arrangement yielded a disc-shaped image, the projection of the pupil onto the retina, which displaced abnormally during eye movements. By changing the position of the eye along the axis of the lens in relation to the crossing point of the bundle, the degree to which the displacement was abnormal could be varied, For various displacement rates ranging from 25% to 120 and 400% of normal, abnormal displacements produced by incidental eye movements remained unnoticed, Only where eye movements were intentional did some of our Ss report shifts of the perceived image. It is suggested that the organism copes with the image displacement resulting from the ever-present incidental eye movements not by compensation but by ignoring them.     

Hemispheric involvement in shadowing vs. interpretation: a time-sharing study of simultaneous interpreters with matched bilingual and monolingual controls

A time-sharing study used shadowing and interpretation/paraphrasing tasks to evaluate lateralization in professional interpreters individually matched to bilingual and monolingual controls. A two-step multivariate general linear model procedure was used to determine lateralized effects and extent of disruption produced by the tasks. Results revealed the monolingual group to be left lateralized for both tasks, but the two bilingual groups were lateralized in the LH only for shadowing. The monolingual group was significantly different from the bilingual groups in the pattern of hand asymmetry for interpretation/paraphrasing. The findings replicate outcomes of prior repeated measures analysis of variance procedures on percentage of change scores. However, new information is added by the more refined analysis. The findings are also discussed in terms of previous laterality studies using similar tasks and subject samples.     

“This project is mad”: Descartes,Derrida, and the notion of philosophical crisis

In “Cogito and the History of Madness,” Derrida maintains that crisis is endemic to philosophy rather than being, as Husserl forcefully argued, a temporary condition that can and must be overcome through the resources of reason. A reflection on the place of madness in Descartes's Meditations serves as the point of departure for demonstrating that Derrida has done an injustice to philosophy; and a comparison of Derrida's views with the thought of Husserl, Heidegger, and Nietzsche reveals that Derrida's position in “Cogito and the History of Madness” entails a sacrifice of the notion of responsibility that lies at the center of meaningful historical action.     

An extension of the concept of specific objectivity

Comparisons of subjects are specifically objective if they do not depend on the items involved. Such comparisons are not restricted to the 1-parameter logistic latent trait model, but may also be defined within ordinal independence models and even within the 2-parameter logistic model.     

How valid is the psychoticism scale? A comment on the Van Kampen critique

Van Kampen (1993) has published a paper in which he criticizes the concept of psychoticism and the use of the P scale as a measuring device, and advances measures for his own S scale and its validity. This reply attempts to clarify the notion of ‘validity’, and to demonstrate that there is a considerable body of experimental evidence to show that P has a high degree of construct validity, whereas the Van Kampen S scale lacks completely any degree of construct validity. Several examples are given of how the experimental evidence legitimates both the P scale, and the theory (nomological network) on which it is based.     

A compensatory approach to optimal selection with mastery scores

A Bayesian approach for simultaneous optimization of test-based decisions is presented using the example of a selection decision for a treatment followed by a mastery decision. A distinction is made between weak and strong rules where, as opposed to strong rules, weak rules use prior test scores as collateral data. Conditions for monotonicity of optimal weak and strong rules are presented. It is shown that under mild conditions on the test score distributions and utility functions, weak rules are always compensatory by nature. The authors are indebted to Wilbert Kallenberg for his valuable comments and to Jan Gulmans for providing the data for the empirical example. The names of the authors are alphabetical; they are equally responsible for the contents of this paper.     

Validation of a full body 3-D dynamic linked segment model

In studies related to human movement, linked segment models (LSM's) are often used to quantify forces and torques, generated in body joints. Some LSM's represent only a few body segments. Others, for instance used in studies on the control of whole body movements, include all body segments. As a consequence of the complexity of 3-dimensional (3-D) analyses, most LSM's are restricted to one plane of motion. However, in asymmetric movements this may result in a loss of relevant information. The aim of the current study was to develop and validate a 3-D LSM including all body segments. Braces with markers, attached to all body segments, were used to record the body movements. The validation of the model was accomplished by comparing the measured with the estimated ground reaction force and by comparing the torques at the lumbo-sacral joint that resulted from a bottom-up and a top-down mechanical analysis. For both comparisons, reasonable to good agreement was found. Sources of error that could not be analysed this way, were subjected to an additional sensitivity analysis. It was concluded that the internal validity of the current model is quite satisfactory.     

Competing interests: The need to control conflict of interests in biomedical research

Individual and institutional conflict of interests in biomedical research have becomes matters of increasing concern in recent years. In the United States, the growth in relationships — sponsored research agreements, consultancies, memberships on boards, licensing agreements, and equity ownership — between for-profit corporations and research universities and their scientists has made the problem of conflicts, particularly financial conflicts, more acute. Conflicts can interfere with or compromise important principles and obligations of researchers and their institutions, e.g., adherence to accepted research norms, duty of care to patients, and open exchange of information. Disclosure is a key component of a successful conflict policy. Commitments which conflict with a faculty member's primary obligations to teaching, research, administrative responsibilities, or patient care also need attention. Institutional conflict of interests present different problems, some of which are discussed in an analysis of an actual problem posed by two proposed clinical trials. This paper is adapted from a lecture presented to a Symposium on Scientific Integrity, Warsaw, Poland, 23 November 1995. Daniel Steiner was Vice-President and General Counsel of Harvard University (1972–92) and in that capacity became familiar with conflict of interest issues. He is currently Counsel to the Boston law firm. Ropes and Gray, and is Adjunct Lecturer in Public Policy at the John F. Kennedy School of Government. Harvard University.