Single and multidimensional same-different judgments

A probabilistic, multidimensional Thurstonian model for treating same-different judgments was tested in an experiment in which subjects made single-dimensional and two-dimensional same-different judgments. Strong asymmetries in the data required adding temporal bias parameters to the model. The model, with bias parameters, accounted for the single- and two-dimensional judgments reasonably well, but the parameters were not invariant between the different solutions. The two-dimensional judgments were more variable than expected on the basis of the single-dimensional judgments.     

Eine neue Wahrnehmungstäuschung

Zusammenfassung Die Grenze des durch beide Arme bestimmten menschlichen Doppelgreifraumes hat die Gestalt einer Kugeldoppelhaube. Alle Punkte dieser Grenzfläche sind durch Greifbewegung gleich bequem (noch) erreichbar, wobei der Doppelarm als einheitliches Greif organ aufzufassen ist. Es besteht für diese Fläche nach allen Richtungen Gleichheit der Greifentfernung. Durch Spiegel-Hand-Versuche kann man nunmehr zeigen, daß alle Punkte dieser Grenzfläche bei visueller Wahrnehmung auch vom Auge aus gleichweit entfernt erscheinen, obwohl dies geometrisch schon wegen der exzentrischen Lage des Auges keineswegs der Fall ist. Die Grenze des Doppelgreifraumes nimmt beim Aufbau des menschlichen Sehraumes eine Schlüsselstellung ein.Man kann an dem beschriebenen Phänomen mit Aussicht auf Erfolg neue psychische Grundgesetze aufspüren. Versuche mit sogenannten Contergankindern können hierzu neue Aufschlüsse liefern.

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Summary The periphery delimiting the space circumscribed by the motional range of both human arms takes the shape of a double truncated sphere. All points of this periphery may still be reached with equal ease by a mere gripping motion (regarding, for the purposes of this study, the two arms as a single prehensile organ), and peripheral equidistance of reach exists in all directions. By means of tests in which the outstretched hand is expediently reflected in a mirror it can now be demonstrated that in visual perception (due to the above-mentioned motional equidistance) the entire double-spherical periphery appears equidistant also from the vantage-point of the eye, even though geometrically this is by no means the case. The periphery of the bilateral space of prehension, therefore, assumes a key position in the configuration of space as perceived by the human eye.The phenomenon opens views fowards new basic psychic laws. Also experiments with thalidomide children may provide new insights.

     

On the existence and uniqueness of maximum-likelihood estimates in the Rasch model

Necessary and sufficient conditions for the existence and uniqueness of a solution of the so-called unconditional (UML) and the conditional (CML) maximum-likelihood estimation equations in the dichotomous Rasch model are given. The basic critical condition is essentially the same for UML and CML estimation. For complete data matricesA, it is formulated both as a structural property ofA and in terms of the sufficient marginal sums. In case of incomplete data, the condition is equivalent to complete connectedness of a certain directed graph. It is shown how to apply the results in practical uses of the Rasch model.Paper read at the European Meeting of the Psychometric Society, Groningen, June 19–21, 1980.Part of the research reported herein was done while the author was staying at the Pulmologisches Zentrum der Stadt Wien; he is indebted to Professor Dr. F. Muhar and Dr. R. Mutschlechner for providing excellent working conditions.     

POLITICAL OBLIGATION,FAIRNESS, AND INDEPENDENCE

In the first section the problem of political obligation is motivated, and in Section 2 the core structure of the problem is laid bare. A recognition of this structure prompts reflection that the problem will appear very different to different thinkers, depending on their moral theories. It also invites the speculation that the problem will be incapable of solution on some moral theories while trivial on others. This polarity does reflect the state of much of the literature until fairly recently. However this picture is seen to be too crude, and in the third section it is shown how an interesting solution has been proposed by advocates of the ‘theory of fairness’. In Section 4 this theory is evaluated, concentrating particularly on George Klosko's version, which is, in part, rejected. However it is argued that no version of the theory is able to guarantee universal political obligations. In Section 5 it is argued that this is an unnoticed advantage of the theory, for it may well be that, morally at least, we should allow those who do not benefit from the existence of the state to escape political obligations. The consequences of this view are examined and found not to be as threatening as they might first have appeared.     

Nondirectiveness and genetic counseling

Nondirectiveness is the generally required and professed standard for genetic counseling. However, studies are lacking in the field of human genetics and in other disciplines which address either the theory or practice of this type of therapeutic procedure in the context of genetic counseling. Moreover, there is no indication the further development this concept has undergone in client-centered therapy has been acknowledged in human genetics. This could be due tot he historical development of genetic counseling, its inherent conflicts and often undefined goals, and the latent need of human geneticists to defend themselves against being accused of eugenic tendencies. Nondirectiveness and directiveness, however, can neither adequately describe what takes place in genetic counseling, nor can they — according to their original meaning — be used to define an ethical standard of genetic counseling. Starting with the writings by Carl Rogers (1942), an experiential approach is described, in which counseling is seen as a process of influence, which is wished by all the persons involved, during which activities are oriented toward the experience of the client, and which allows the counselor to communicate openly and directly with the client. The present study illustrates the use of the experiential approach in genetic counseling and shows that it can uphold the principle of ethics, which nondirectiveness demands and, at the same time, prevent the inevitable and unresolvable contradictions. This means that in their training genetic counselors must learn to recognize and constantly reflect on the influence they can and want to exert. In order to be able to use this influence in a responsible manner, genetic counselors must also learn to have a certain degree of flexibility so that they are able to check at any time how their client responds to this influence.     

A Bayesian approach to nonlinear latent variable models using the Gibbs sampler and the metropolis-hastings algorithm

Nonlinear latent variable models are specified that include quadratic forms and interactions of latent regressor variables as special cases. To estimate the parameters, the models are put in a Bayesian framework with conjugate priors for the parameters. The posterior distributions of the parameters and the latent variables are estimated using Markov chain Monte Carlo methods such as the Gibbs sampler and the Metropolis-Hastings algorithm. The proposed estimation methods are illustrated by two simulation studies and by the estimation of a non-linear model for the dependence of performance on task complexity and goal specificity using empirical data.     

Dynamics of oralrespiratory coordination in full-term and preterm infants: I. Comparisons at 38-40 weeks postconceptional age

This study compares the coordination of pacifier sucking and breathing between healthy full-term, low risk preterm, and high risk preterm infants at 38–40 weeks postconceptional age. High and low risk preterm infants did not differ in overall score on a neurobehavioral examination (NAPI), but infants in the high risk group differed from the others in breathing frequency and in the coordination of breathing and sucking rhythms. For infants in the high risk group, sucking had less influence on respiratory frequency and patterns of coordination between the frequencies of sucking and breathing were simpler. Oral–respiratory coordination may be a useful marker of infants at risk for later speech problems.