Generalization of cross-modal stimulus equivalence classes: operant processes as components in human category formation.

This study employed a stimulus-class rating procedure to explore whether stimulus equivalence and stimulus generalization can combine to promote the formation of open-ended categories incorporating cross-modal stimuli. A pretest of simple auditory discrimination indicated that subjects (college students) could discriminate among a range of tones used in the main study. Before beginning the main study, 10 subjects learned to use a rating procedure for categorizing sets of stimuli as class consistent or class inconsistent. After completing conditional discrimination training with new stimuli (shapes and tones), the subjects demonstrated the formation of cross-modal equivalence classes. Subsequently, the class-inclusion rating procedure was reinstituted, this time with cross-modal sets of stimuli drawn from the equivalence classes. On some occasions, the tones of the equivalence classes were replaced by novel tones. The probability that these novel sets would be rated as class consistent was generally a function of the auditory distance between the novel tone and the tone that was explicitly included in the equivalence class. These data extend prior work on generalization of equivalence classes, and support the role of operant processes in human category formation.     

Medical Ethics Research Between Theory and Practice

The main object of criticism of present-day medical ethics is the standard view of the relationship between theory and practice. Medical ethics is more than the application of moral theories and principles, and health care is more than the domain of application of moral theories. Moral theories and principles are necessarily abstract, and therefore fail to take account of the sometimes idiosyncratic reality of clinical work and the actual experiences of practitioners. Suggestions to remedy the illnesses of contemporary medical ethics focus on re-establishing the connection between the internal and external morality of medicine. This article discusses the question how to develop a theoretical perspective on medical ethical issues that connects philosophical reflection with the everyday realities of medical practice. Four steps in a comprehensive approach of medical ethics research are distinguished: (1) examine health care contexts in order to obtain a better understanding of the internal morality of these practices; this requires empirical research; (2) analyze and interpret the external morality governing health care practices; sociological study of prevalent values, norms, and attitudes concerning medical-ethical issues is required; (3) creation of new theoretical perspectives on health care practices; Jensen's theory of healthcare practices will be useful here; (4) develop a new conception of bioethics that illuminates and clarifies the complex interaction between the internal and external morality of health care practices. Hermeneutical ethics can be helpful for integrating the experiences disclosed in the empirical ethical studies, as well as utilizing the insights gained from describing the value-contexts of health care practices. For a critical and normative perspective, hermeneutical ethics has to examine and explain the moral experiences uncovered, in order to understand what they tell us.     

Basic research needed for stimulating the development of behavioral technologies

The costs of disconnection between the basic and applied sectors of behavior analysis are reviewed, and some solutions to these problems are proposed. Central to these solutions are collaborations between basic and applied behavioral scientists in programmatic research that addresses the behavioral basis and solution of human behavior problems. This kind of collaboration parallels the deliberate interactions between basic and applied researchers that have proven to be so profitable in other scientific fields, such as medicine. Basic research questions of particular relevance to the development of behavioral technologies are posed in the following areas: response allocation, resistance to change, countercontrol, formation and differentiation/discrimination of stimulus and response classes, analysis of low-rate behavior, and rule-governed behavior. Three interrelated strategies to build connections between the basic and applied analysis of behavior are identified: (a) the development of nonhuman animal models of human behavior problems using operations that parallel plausible human circumstances, (b) replication of the modeled relations with human subjects in the operant laboratory, and (c) tests of the generality of the model with actual human problems in natural settings.     

Empirical bayes estimates of domain scores under binomial and hypergeometric distributions for test scores

We introduce two simple empirical approximate Bayes estimators (EABEs)— and —for estimating domain scores under binomial and hypergeometric distributions, respectively. Both EABEs (derived from corresponding marginal distributions of observed test scorex without relying on knowledge of prior domain score distributions) have been proven to hold -asymptotic optimality in Robbins' sense of convergence in mean. We found that, where and are the monotonized versions of and under Van Houwelingen's monotonization method, respectively, the convergence rate of the overall expected loss of Bayes risk in either or depends on test length, sample size, and ratio of test length to size of domain items. In terms of conditional Bayes risk, and outperform their maximum likelihood counterparts over the middle range of domain scales. In terms of mean-squared error, we also found that: (a) given a unimodal prior distribution of domain scores, performs better than both and a linear EBE of the beta-binomial model when domain item size is small or when test items reflect a high degree of heterogeneity; (b) performs as well as when prior distribution is bimodal and test items are homogeneous; and (c) the linear EBE is extremely robust when a large pool of homogeneous items plus a unimodal prior distribution exists.The authors are indebted to both anonymous reviewers, especially Reviewer 2, and the Editor for their invaluable comments and suggestions. Thanks are also due to Yuan-Chin Chang and Chin-Fu Hsiao for their help with our simulation and programming work.     

Estimating true score in the compound binomial error model

Several procedures have been proposed in the statistical literature for estimating simultaneously the mean of each ofk binomial populations. In terms of mental test theory, however, it is not clear that these procedures should be used when an item sampling model applies since the binomial error model is usually viewed as an oversimplification of the true situation. In this study we compare empirically several of these estimation techniques. Particular attention is given to situations where observations are generated according to a two-term approximation to the compound binomial distribution.The author would like to thank Shelley Niwa for writing the computer programs used in this study.The work upon which this publication is based was performed pursuant to Grant # NIE-G-76-0083 with the National Institute of Education, Department of Health, Education and Welfare. Points of view or opinions stated do not necessarily represent official NIE position or policy.     

AUDITORY SUCCESSIVE CONDITIONAL DISCRIMINATION AND AUDITORY STIMULUS EQUIVALENCE CLASSES

This paper describes an experimental demonstration of stimulus equivalence classes consisting entirely of auditory stimuli. Stimuli were digitized arbitrary syllables (e.g., “cug,” “vek”) presented via microcomputer. Training and testing were conducted with a two-choice auditory successive conditional discrimination procedure. On each trial, auditory samples and comparisons were presented successively. As each comparison was presented, a response location (a rectangle) appeared on the computer screen. After all stimuli for a trial were presented, subjects selected one of the response locations. Six subjects acquired the conditional discrimination baseline, 4 subjects demonstrated the formation of three-member auditory equivalence classes resulting from sample-S+ relations, and 1 subject demonstrated equivalence classes resulting from sample-S— relations. Four subjects received additional training and subsequently demonstrated expansion of the three-member classes to four members each.     

The transfer of specific and general consequential functions through simple and conditional equivalence relations

The purpose of this study was to examine the transfer of consequential (reinforcement and punishment) functions through equivalence relations. In Experiment 1, 9 subjects acquired three three-member equivalence classes through matching-to-sample training using arbitrary visual forms. Comparison stimuli were then given conditioned reinforcement or punishment functions by pairing them with verbal feedback during a sorting task. For 8 of the 9 subjects, trained consequential functions transferred through their respective equivalence classes without additional training. In Experiment 2, transfer of function was initially tested before equivalence testing per se. Three of 4 subjects showed the transfer without a formal equivalence test. In Experiment 3, 3 subjects were given training that gave rise to six new three-member conditional equivalence classes. For 2 of the subjects, the same stimulus could have either a reinforcement or punishment function on the basis of contextual cues that defined its class membership. Experiment 4 assessed whether equivalence training had established general or specific consequential functions primarily by adding novel stimuli in the transfer test. Subjects treated even novel feedback stimuli in the transfer test as consequences, but the direction of consequential effects depended upon the transfer of specific consequential functions through equivalence relations.     

STIMULUS GENERALIZATION AND EQUIVALENCE CLASSES: A MODEL FOR NATURAL CATEGORIES

Two three-member classes were formed by training AB and BC using a conditional discrimination procedure. The A and B stimuli were nonsense syllables, and the C stimuli were sets of “short” or “long” lines. To test for equivalence, C1 or C2 was presented as a sample with A1 and A2 as comparisons. Once the class-related comparison was chosen consistently, different line lengths were substituted for the training lines in the CA tests. In general, the likelihood of choosing a given comparison was an inverse function of the difference in the length of the test line from the training line. Stimuli in an equivalence class became functionally related not only to each other but also to novel stimuli that resembled a member of the equivalence class. The combination of primary generalization and equivalence class formation, then, can serve as a model to account for the development of naturally occurring categories.     

Evaluating Multiple-Attribute Decision Support Systems

Differences in the perceived usefulness of five multiple-attribute decision support systems versus a basic spreadsheet are empirically assessed. Twenty-four college faculty members participated in a repeated measures experiment in which they used decision support software for personal computers to analyse semistructured multiple-attribute problems. The software packages employed were Criterium, Expert Choice, Logical Decision, VIMDA, VISA and the spreadsheet package Quattro Pro. A questionnaire was developed to assess user-friendliness of the software, confidence in the procedure implemented by the software, and users’ confidence in their results when employing the decision aids. Time to reach a decision was also measured. Significant differences were fund in the overall way users ranked these aids, in the perceived user-friendliness and the confidence in procedure among aids, and in the time it took to arrive at a result. Comments from users are also reported. © 1997 John Wiley & Sons, Ltd.     

Reading comprehension with the Go/No-Go procedure with compound stimuli

The present study investigated whether the Go/No-Go procedure with compound stimuli produces emergent relations among dictated words (A), pictures (B), and printed words (C) and the emergence of textual behavior (CD) using a multiple probe design across word sets. Three preschool children were exposed to 4 phases: (1) pretests for BC, CB, and CD relations, (2) pretraining with known stimuli, (3) AB and AC training, and (4) posttests for BC, CB, and CD relations. During AB and AC training, responses to A1B1, A2B2, A1C1, and A2C2 compound stimuli, but not to A1B2, A2B1, A1C2, and A2C1, were reinforced. The results showed that all participants met the learning criterion and demonstrated emergence of BC and CB relations (i.e., relations between pictures and printed words), and CD relations (i.e., textual behavior) after training. These results suggest that the Go/No-Go procedure with compound stimuli is an effective alternative for establishing reading comprehension.