A tribute to Howard Rachlin and his two-parameter discounting model: Reliable and flexible model fitting

Delay discounting reflects the rate at which a reward loses its subjective value as a function of delay to that reward. Many models have been proposed to measure delay discounting, and many comparisons have been made among these models. We highlight the two-parameter delay discounting model popularized by Howard Rachlin by demonstrating two key practical features of the Rachlin model. The first feature is flexibility; the Rachlin model fits empirical discounting data closely. Second, when compared with other available two-parameter discounting models, the Rachlin model has the advantage that unique best estimates for parameters are easy to obtain across a wide variety of potential discounting patterns. We focus this work on this second feature in the context of maximum likelihood, showing the relative ease with which the Rachlin model can be utilized compared with the extreme care that must be used with other models for discounting data, focusing on two illustrative cases that pass checks for data validity. Both of these features are demonstrated via a reanalysis of discounting data the authors have previously used for model selection purposes.     

A rose by any other name: Maintaining the name and highlighting the uniqueness of psychology as a health care profession

In this article, we reply to the comments made by Holden and Levant (preceding articles). While we agree with their goals of expanding the scope of practice of psychology, standardizing training, and educating the public and other health care professionals about the field of clinical psychology, we do not agree that changing the discipline's name to psychological physician is a necessary or sufficient means to these ends. We outline the bases for our disagreement with the name change proposal and provide other proposals for reaching the goals set forth by Holden and Levant.     

Believing the improbable

I would like to thank Brad Armendt, Patrick Maher, Bas Van Fraassen and Joan Weiner for comments on this (and/or earlier versions of this) paper. I have also benefited from conversation and correspondence with Stewart Cohen. Some of the research of which this paper was a product was supported by a grant from the National Science Foundation.     

Behavior as the central outcome in health care

A predominant justification for health psychology and behavioral medicine is that behavior or environmental conditions affect a biological process. Thus, many investigators focus attention on the effects of behavior on cell pathology and blood chemistry. This article argues that behavioral outcomes are the most important consequences in studies of health care and medicine. These outcomes include longevity, health-related quality of life, and symptomatic complaints. Traditional measures in biomedical science often have limited reliability and validity. Their validity is demonstrated only through relationships with longevity, role performance, behavioral functioning, and symptomatic experience, and these correlations are often modest. A model is proposed to guide future investigations. Biological, environmental, and psychological variables are included in the model as predictors or mediators of behavioral health outcomes. Recognizing that health outcomes are behavioral directs intervention toward whatever method produces the most health benefit at the lowest cost.     

Design decisions in a Pascal-based operant conditioning system

FREDL, a Pascal-based system for control of operant experiments, has been implemented on the IBM PC computer. In the foreground, recurring operations, such as decrementing counters that serve as local clocks, are controlled by a dictionary specifying automatic properties of user defined variables, and random logic is implemented by a user-written Pascal overlay. In the background, the remainder of the program controls communication with the user, output of data to disk, and production of cumulative records.     

Effects of flurazepam and triazolam on neuropsychological performance

A double-blind study examined the effects of a single dose of either triazolam or flurazepam on measures of concept formation, attention, concentration, and motor function, the morning following drug ingestion. Subjects were 53 healthy university students, screened for history of neurological or psychiatric illness. In comparison to placebo-treated controls, there was no difference in the effects on neuropsychological performance, although subjects who received flurazepam reported more side effects. It was concluded that although these drugs may produce side effects, single doses do not appear to impair various aspects of neuropsychological ability the morning after ingestion.