Ethical issues related to the artificial heart

This paper is a general survey of ethical issues related to the artificial heart. It begins by looking at the history of funding of the artificial heart program through the National Institute of Health in 1965. Attention is paid to the problem of the lack of planning related to social, ethical, economic, and legal implications. The paper then deals with three areas of ethical concerns. They are those issues relating to the experimental versus therapeutic benefits, the cost, and public involvement with a private interest.     

Integrating fieldwork into employment counseling for methadone‐treatment patients

An innovative employment counseling model, Customized Employment Supports, was developed for methadone‐treatment patients, a population with historically low employment rates. The effectiveness of a key component of the model, “vocational fieldwork,” the delivery of services in the community rather than only within the clinic, was assessed through a quasi‐experimental study of the first 55 patients receiving the model in 2 clinics. Employment outcomes after 6 months were compared between patients who received vocational fieldwork (n = 18) and those who did not (n = 37). Logistic regression analysis demonstrated that patients receiving vocational fieldwork had significantly better outcomes for competitive work, informal work, and any paid work.     

Style follows content: on the microgenesis of art perception

Despite fruitful research in experimental aesthetics, the dynamics of aesthetics, i.e., the processes involved in art perception, have received little attention. Concerning representational art, two aspects seem most important in this respect: style and content. In two experiments, we examined the dynamics of processing of style and content by means of the microgenetic approach. This approach systematically varies perceptual conditions to find out about the stages involved in the formation of percepts – their microgenesis. Participants gave similarity ratings for pairs of pictures that were fully crossed in style (artist) and content (motif). Presentation times were systematically varied between 10, 50, 202 and 3000 ms (Experiment 1) plus unlimited presentation time (Experiment 2). While effects of content were present at all presentation times, effects of style were traceable from 50 ms onwards. The results show clear differences in the microgenesis of style and content, suggesting that in art perception style follows content.     

Stevens' power law and the problem of meaningfulness

Frequently, it is postulated that the results of a ratio production (resp., ratio estimation) experiment can be summarized by Stevens' power law psi=alphaphi(beta). In the present article, it is argued that the power law parameters depend, among other things, on the standard stimulus presented as a reference point, and the physical stimulus scale by which the physical intensities are measured. To formalize this idea, a new formulation of Stevens' power law is presented. We show that the exponent in Stevens' power law can only be interpreted in a meaningful way if the stimulus scale is a ratio scale. Furthermore, we present empirically testable axioms (termed invertibility and weak multiplicativity) which are both necessary and sufficient for the power law exponent to be invariant under changes of the standard stimulus. Finally, invertibility and weak multiplicativity are evaluated in a ratio production experiment. Ten participants were required to adjust the area of variable circles to prescribed ratio production factors. Both axioms are violated for all participants. The results cast doubts on the well-established practice of comparing power law exponents across different modalities.     

A Bayesian Model For The Estimation Of Latent Interaction And Quadratic Effects When Latent Variables Are Non-Normally Distributed

Structural equation models with interaction and quadratic effects have become a standard tool for testing nonlinear hypotheses in the social sciences. Most of the current approaches assume normally distributed latent predictor variables. In this article, we present a Bayesian model for the estimation of latent nonlinear effects when the latent predictor variables are nonnormally distributed. The nonnormal predictor distribution is approximated by a finite mixture distribution. We conduct a simulation study that demonstrates the advantages of the proposed Bayesian model over contemporary approaches (Latent Moderated Structural Equations [LMS], Quasi-Maximum-Likelihood [QML], and the extended unconstrained approach) when the latent predictor variables follow a nonnormal distribution. The conventional approaches show biased estimates of the nonlinear effects; the proposed Bayesian model provides unbiased estimates. We present an empirical example from work and stress research and provide syntax for substantive researchers. Advantages and limitations of the new model are discussed.     

Extensions of Narens' theory of ratio magnitude estimation

Stevens postulated that the responses of a participant in a ratio scaling experiment can be used directly to construct a psychophysical function. Today, it is generally accepted that the axioms of commutativity and multiplicativity are crucial for the interpretation of the subjects' ratio scaling behaviour. Empirical findings provide evidence that commutativity holds, whereas multiplicativity fails to hold across different sensory modalities. This shows that, in principle, Stevens' direct scaling methods yield measurements on a ratio scale level, but that the numerals occurring in a ratio scaling experiment cannot be taken at face value. Thus, Narens and others introduced a transformation function f, which converts the numerals used in an experiment into the latent mathematical numbers. The aim of the present paper is to specify the (unknown) shape of the transformation function f, by analysing different extensions of the multiplicative property. The results provide evidence that f is either a power function or a logarithmic function.     

Stevens’ Direct Scaling Methods and the Uniqueness Problem

Stevens postulated that we can use the responses of a participant in a ratio scaling experiment directly to construct a psychophysical function representing the participant's sensations. Although Stevens' methods of constructing measurement scales are widely used in the behavioral sciences, the problem of which scale type is appropriate to describe ratio scaling data is still unresolved. To deal with this problem, we develop a theoretical framework to specify the scale type attained by Stevens' direct scaling methods. It is shown, under fairly mild background assumptions, that the behavioral axioms presented in this paper are necessary and sufficient for the psychophysical functions to be ordinal-, interval-, log-interval-, or ratio-scales. Furthermore, suggestions on how to test these behavioral axioms are provided. Requests for reprints should be sent to thomas.     

Empirical evaluation of the axioms of multiplicativity, commutativity, and monotonicity in ratio production of area

Although direct scaling methods have been widely used in the behavioral sciences since the 1950s, theoretical approaches which could clarify the implicit assumptions inherent in Stevens' ratio scaling approach were developed only recently. Today, it is generally accepted that the axioms of commutativity and multiplicativity are fundamental to the subjects' ratio scaling behavior. Therefore, both axioms were evaluated in ratio production of area. Participants were required to adjust the area of a variable circle to prescribed ratio production factors. The results are in accordance with previous empirical findings: commutativity was satisfied, whereas multiplicativity failed to hold. Additionally, the validity of the monotonicity property was analyzed, which postulates that the subjects' adjustments in a ratio production experiment preserve the mathematical order of the ratio production factors. Monotonicity was satisfied empirically, which is consistent with all the current theories of ratio scaling.