Development of abbreviated nine-item forms of the Raven's standard progressive matrices test

The Raven's standard progressive matrices (RSPM) is a 60-item test for measuring abstract reasoning, considered a nonverbal estimate of fluid intelligence, and often included in clinical assessment batteries and research on patients with cognitive deficits. The goal was to develop and apply a predictive model approach to reduce the number of items necessary to yield a score equivalent to that derived from the full scale. The approach is based on a Poisson predictive model. A parsimonious subset of items that accurately predicts the total score was sought, as was a second nonoverlapping alternate form for repeated administrations. A split sample was used for model fitting and validation, with cross-validation to verify results. Using nine RSPM items as predictors, correlations of .9836 and .9782 were achieved for the reduced forms and .9063 and .8978 for the validation data. Thus, a 9-item subset of RSPM predicts the total score for the 60-item scale with good accuracy. A comparison of psychometric properties between 9-item forms, a published 30-item form, and the 60-item set is presented. The two 9-item forms provide a 75% administration time savings compared with the 30-item form, while achieving similar item- and test-level characteristics and equal correlations to 60-item based scores.     

Perceptual fade-out occurs in the binocularly viewed Ganzfeld.

The conviction that time-varying signals are essential for normal visual perception was recently challenged by Bolanowski and Doty who observed that no 'blankouts' occurred in the binocularly viewed Ganzfeld. They suggested that monocularly perceived fading is caused by the eye in darkness suppressing the non-Ganzfeld-viewing eye. In the present paper, fade-out perception under monocular and binocular Ganzfeld viewing is compared, and the effect of the free eye on the Ganzfeld-viewing eye is tested directly. Results show that fading takes place under both monocular and binocular viewing. The data reenforce the view that transient inputs are necessary for maintaining visual perception. It is also shown that there are two Ganzfeld-related phenomena--fade-out and blackout. Fade-out, a slow gradual loss of brightness and of saturation perception, is observed by all subjects under both monocular and binocular viewing, and is affected by the light intensity and wavelength. It is probably retinal in origin. Blackout, a brief intermittent loss of all visual sensation, is experienced by some subjects in the monocular Ganzfeld only and is not appreciably affected by the light intensity or wavelength. It may be caused by a central blocking of all input to the perceiving stage.     

Demographers in the service of the nation: Liebmann Hersch, Jacob Lestschinsky, and the early study of Jewish migration

The historiography of Jewish migration began while the mass emigration from eastern Europe was still in progress. The emigration of hundreds of thousands of Jews left a deep impression on Jewish intellectuals and students, who sought to come up with a satisfactory explanation. The present paper has two aims: The first is to trace the beginning of historiography on Jewish migration, with special emphasis on two demographers — Liebman Hersch and Jacob Lestchinsky - and the way each of them tried to understand the phenomenon. The second aim is to understand the relationship between the rise of Jewish nationalism at the turn of the century and scholarly research at the time. How were the political activities and worldviews of Hersch and Lestschinsky manifested in their research into Jewish migration, and how did each of them attempt — through his research-to solve the problems of the Jewish people in his time?