Temporal discrimination as a function of marker duration.

In a series of three experiments, the effect of marker duration on temporal discrimination was evaluated with empty auditory intervals bounded by markers ranging from 3 to 300 msec or presented as a gap within a continuous tone. As a measure of performance, difference thresholds in relation to a base duration of 50 msec were computed. Performance on temporal discrimination was significantly better with markers ranging from 3 to 150 msec than with markers ranging from 225 to 300 msec or under the gap condition. However, within each range of marker duration (3-150 msec; 225-300 msec or gap) performance did not differ significantly. A fourth experiment provided evidence that the effect of marker duration cannot be explained in terms of marker-induced masking. A good approximation of the relationship between marker duration and temporal discrimination performance in the present experiments is a smooth step function, which can account for 99.3% of the variance of mean discrimination performance. Thus, the findings of the present study point to the conclusion that two different mechanisms are used in the processing of temporal information, depending on the duration of the auditory markers. The tradeoff point for the hypothetical shift from one timing mechanism to the other may be found at a marker duration of approximately 200 msec.

[RADIOLIS. A radiologic instruction and training system for systematic evaluation of roentgen images exemplified by focal bone lesions]. / RADIOLIS. Ein radiologisches Instruktions- und Trainingssystem zur systematischen Befundung von Röntgenbildern am Beispiel fokaler Knochenläsionen.

RADIOLIS is an instructional software system for radiological training that guides the user through a systematic analysis of an image. The backbone of the analysis is a detailed and structured questionnaire which, as applied to our example, includes all relevant differential-diagnostic criteria for focal bone lesions. The variation range of the radiomorphologic characteristics in the questionnaire is introduced to the user with digitized X-ray images, making the simulation of an image analysis possible. In preparation, diverse teaching/learning methods reinforced by instructional psychology were incorporated during the system's development. At the core of the training system are an expandable image database and a database containing descriptions of image material formulated by radiology experts. The field of focal bone lesions, for instance, has already been integrated into RADIOLIS. A graphic user interface and an interactive dialogue enable both comfortable and simple use of the system and the user-specific structuring of the learning process.

Seasonal allergic rhinitis and antihistamine effects on children's learning.

Children suffering from seasonal allergic rhinitis and matched normals were instructed on the use of a didactic computer simulation in a realistic classroom situation. Groups of atopic children received different treatments before instruction; ie, sedating (diphenylhydramine HCl) or nonsedating (loratadine) antihistamines or placebo. All returned after 2 weeks for an examination measuring factual and conceptual knowledge and the application of a learned strategy. Examination results showed large and consistent impairing effects of the allergic reaction on prior learning. Both the placebo and diphenhydramine groups learned significantly less than normal controls. The loratadine group's learning performance was superior to either of the other atopic groups' but still inferior to the normals'. Our conclusions are that the allergic reaction reduces learning ability in children and that this effect is partially counteracted by treatment with loratadine and aggravated by diphenhydramine.

The Structure of Student Interest in Computers and Information Technology: An Application of Facet Theory and Multidimensional Scaling.

The present study addressed the question of whether computers and information technology constitute a uniform attitude object which can influence the study interests of students. Based on a facet design, an interest questionnaire with 72 university course descriptions was constructed in which computers and information technology was embedded as one of four item-design facets (Weinsier & Leutner, 1988). One hundred students from each of two universities responded to the questionnaire. The multidimensional interest structures of the two samples were nearly identical. The design facets constituted uniform attitude objects and the multidimensional scaling solution of the inter-item correlation matrix could be partitioned almost perfectly according to regional hypotheses derived from the facet design. Next to the discipline facet (i.e., academic discipline), computers and information technology constituted the most relevant facet of student interest. An analysis of variance supported the conclusions drawn from the multidimensional scalings.

Measuring the Similarity of MDS Configurations.

The similarity of multidimensional scaling configurations can be assessed by either correlating over corresponding point coordinates, after Procrustean similarity transformations, or by directly assessing the similarity of corresponding distances. The product-moment correlation is, however, an inadmissible measure in the latter case, and hence the statistical norms reported by Poor and Wherry (1976) are worthless. What can be used is the congruence coefficient. Norms are derived for this coefficient under a wide range of parameters. We thus have two measures of configurational similarity, but even though they are both admissible, it is shown that they are not related in a simple way. Moreover, their statistical evaluation with respect to the question whether two configurations are "significantly similar" is likely to lead to different conclusions. Alternative ways to assess configurational similarity are discussed.