Use of true-score theory to predict moments of univariate and bivariate observed-score distributions

Formulas are derived for using the available item statistics and score statistics on a test to estimate the moments of the score distribution of a lengthened (or shortened) form of the same test. Other formulas are derived for estimating the bivariate moments of the scatterplot between two parallel test forms using only the data available on either form alone. An empirical study is made showing in each case satisfactory agreement between the theoretical values predicted from the formulas and the values actually observed. These results suggest the utility of the true-score model used in deriving the formulas.This work was supported by contract Nonr-2752(00) between the Office of Naval Research and Educational Testing Service. Reproduction in whole or in part for any purpose of the United States Government is permitted.     

Binocular vision with two stabilized retinal images

Experiments are described in which each eye is presented with a target whose image remains on the same part of the retina when the eye moves. The patterns presented to each eye may be similar and may be placed on corresponding parts of the retina or may be placed in non-corresponding positions: alternatively, different targets may be presented to the two eyes. Each pattern fades intermittently. Sometimes both are seen together and sometimes both fields are dark at once. There is a small negative correlation between the times of clear vision with the two eyes. When corresponding areas of the two retinas are illuminated with red and green light respectively, the composite colour (yellow) is never perceived with steady illumination. When two similar patterns are in nearly corresponding positions there may be subjective fusion. With two different targets there is sometimes a subjective impression that the two patterns move with respect to one another even though their positions on the retina are fixed.     

Reasoning in the hooded rat

A problem situation was devised to test Deutsch's (1956) theory of reasoning. In this situation various problems can be set the rat and these problems admit of various equally rational solutions. Predictions from the theory were made, not only that the animals would solve the problems, but also which particular solution they would adopt. These predictions are confirmed. The rats were trained to run to two goal-boxes, one near, the other more distant. The near one had two paths of equal length leading to it, the more distant goal only one. After training, the animals chose the near goal-box on the first trial of the day. On the test trials the near goal-box was left empty, or the chosen path blocked, or a mesh placed across the goal-box, with the food accessible via the other short path.