Effects of rate of reinforcement-time upon concurrent operant performance

Three experiments were conducted to investigate the theoretical reduction of rate and duration of reinforcement to their product, rate of reinforcement-time, under concurrent chain schedules. In Exp. I, rate of reinforcement-time was varied by varying rate of reinforcement delivery, holding duration of reinforcement availability constant; in Exp. II, rate of reinforcement-time was varied by holding rate of reinforcement delivery constant and varying duration of reinforcement availability; in Exp. III, rate of reinforcement-time was held constant by varying both rate and duration of reinforcement simultaneously and inversely. For all three experiments, both relative rate of responding and relative time spent in the initial link were found to match approximately the relative rate of reinforcement-time arranged in the terminal link. These data were interpreted as support for the notion that rate and duration of reinforcement may be functionally equivalent and reducible to a single variable, rate of reinforcement-time.     

Auditory spatial alternation transforms auditory time (again): Comments on Lakatos (1993), “Temporal constraints on apparent motion in auditory space”

Lakatos (1993) reported interesting data that indeed support “the hypothesis that the extent of spatial separation between successive sound events directly affects the perception of time intervals between these events” (p. 139). The present comment is an attempt to show that, as far as the horizontal plane is concerned, Lakatos’s hypothesis was already answered qualitatively by Axelrod and coworkers (Axelrod & Guzy, 1968; Axelrod, Guzy, & Diamond, 1968) in their studies of attention shifting, and by ten Hoopen and coworkers, who quantified the amount of “interaural time dilation” (Akerboom, ten Hoopen, Olierook, & van der Schaaf, 1983; ten Hoopen, 1982; ten Hoopen, Vos, & Dispa, 1982). Nonetheless, Lakatos’s study is very worthwhile. It originated from the realm of “apparent motion paradigms,” but I will argue that the study rather used an “auditory streaming paradigm,” and that the data is a welcome contribution to elucidate how the perceptual processes of auditory stream formation and interaural time dilation interact.     

Philosophy of medicine in the Netherlands

This report explores the relationship between philosophy and medicine in the Netherlands. In Section 1 we outline the ups and downs of medico-philosophical research in our country: pre-war flourishing, post-war decline, and modern renaissance. In Section 2 we review recent Dutch literature in the philosophy of medicine. The topics dealt with include methodology of medical science, alternative medicine, the basic concepts of medicine, anthropological medicine, medicalization, medicine and culture, and health care ethics.     

Attention switching is not a fatigable process: methodological comments on Axelrod and Guzy (1972)

Guzy and Axelrod investigated auditory attention switching by means of the click-counting paradigm and concluded that attention switching is a fatigable process. In the present comment it is shown that this conclusion is based on a faulty analysis of the data: The scores subjected to the analysis of variance were transformed such that they were no longer linear combinations of the factorial effects. Reanalyzing the data in the correct way renders perfectly linear conting functions that deviate from theoretical fatigue functions. It is concluded that the attention-switching mechanism is not fatigable.     

A generalization of Kristof's theorem on the trace of certain matrix products

Kristof has derived a theorem on the maximum and minimum of the trace of matrix products of the form \(X_1 \hat \Gamma _1 X_2 \hat \Gamma _2 \cdots X_n \hat \Gamma _n\) where the matrices \(\hat \Gamma _i\) are diagonal and fixed and theX _i vary unrestrictedly and independently over the set of orthonormal matrices. The theorem is a useful tool in deriving maxima and minima of matrix trace functions subject to orthogonality constraints. The present paper contains a generalization of Kristof's theorem to the case where theX _i are merely required to be submatrices of orthonormal matrices and to have a specified maximum rank. The generalized theorem contains the Schwarz inequality as a special case. Various examples from the psychometric literature, illustrating the practical use of the generalized theorem, are discussed.