Iterated N-player prisoner's dilemma games

Philosophical Studies -     

Representational guidance of action production in observational learning: a causal analysis

This experiment tested the hypothesis that the number of model presentations and verbal coding of modeled actions affect reproduction accuracy through their effect on cognitive representation. Subjects viewed a complex action pattern either two or eight times with or without verbal coding to highlight the dynamic structure of the component actions and their temporal sequencing. They then received, in order, a recognition test and a pictorial-arrangement test to assess the accuracy of their cognitive representations of the modeled actions. Subsequently, all subjects were tested for their ability to reproduce the action pattern from memory. Results showed that increased exposure to modeled actions enhanced the accuracy of both the cognitive representation and the behavioral reproduction. Verbal coding also increased cognitive and reproduction accuracy, but only when combined with multiple opportunities to observe the modeled actions. A causal analysis confirmed that the effects of multiple exposures and verbal coding were entirely mediated by changes produced in the accuracy of cognitive representation.     

A psychiatrist's reflections on the workers' compensation system

In the ‘looking-glass land’ of workers' compensation psychiatry, symptoms are not always what they seem, treatments may have little or no positive effect, and workers' claims of continued disability may puzzle and perplex. Disability is in part a social role, and a simple medical model cannot explain the complex interactions of sociology, psychology, anthropology, medicine, economics, and law characteristic of the workers' compensation system. Psychiatrists functioning within and reciprocally shaped by this semi-adversarial system will rarely encounter an ‘ideal’ patient. Factors in all areas of workers' lives, including those integral to the workers' compensation system, influence their movement along a health-illness, ableddisabled axis. This paper identifies a number of interacting factors that may prolong, or even subvert, the recovery process following a work-incurred injury or illness.     

Simple software for impedance cardiography

Simple software techniques for the digital analysis of impedance cardiography data are described. The software digitizes simultaneous impedance and ECG signals, averages these signals over time on a beat-by-beat basis, processes the averaged signals to locate relevant features, and computes heart rate, stroke volume, and cardiac output for the averaged period. The source and executable code, written in Pascal for a PDP-11 with standard peripheral addressing and a VT125 graphics terminal, is available from the authors.     

Predictive Genetic Testing and Alternatives to Face to Face Results Disclosure: A Retrospective Review of Patients Preference for Alternative Modes of BRCA 1 and 2 Results Disclosure in the Republic of Ireland

The traditional model of providing cancer predictive testing services is changing. Many genetic centres are now offering a choice to patients in how they receive their results instead of the typical face-to-face disclosure. In view of this shift in practice and the increasing demand on the ROI cancer predictive testing service, a 2 year retrospective study on patient preference in how to receive a Breast Cancer (BRCA) predictive result was carried out. Results showed that 71.7 % of respondents would have liked to have the option of obtaining their results by telephone or by letter. However, when asked about their actual experience of BRCA predictive results disclosure 40.6 % did still value the face-to-face contact, while 44.9 % would still have preferred to receive results by either post or telephone. No significant difference was found between males and females (p?>?0.05) and those who tested negative or positive for the BRCA mutation (p?>?0.05) in wanting a choice in how their results were disclosed. While the majority expressed a wish to have a choice in how to receive their results, it is important not to underestimate the value of a face-to-face encounter in these circumstances.     

The Impact of Breast Cancer and Its Treatment on Marital Functioning

This article reviews the research that has examined the impact of breast cancer and its treatment on the patient's marital relationship. Breast cancer and its treatment affect not only the patient, but also her intimate partner and their relationship, including their communication, sexual relationship, and role identities. Both positive and negative effects of the experience have been identified. Predictors of marital adjustment following breast cancer are also reviewed, including demographic factors, illness factors, and characteristics of the couple. The strongest predictor of the impact of the cancer experience appears to be the premorbid quality of the relationship. A methodological critique identifies limitations of past research, and suggestions for future research are addressed. Finally, two theoretical paradigms that may account for the impact of breast cancer on relationships are discussed.     

The dependency of schema formation on type of verbal material: Linear orderings and set inclusions

Two paragraph structures, linear orderings (Potts, 1972) and set inclusions (Frase, 1969), were equated on relevant independent variables to examine recognition memory for relationships between pairs of terms. Experiment 1 replicated Potts' findings: Proportion correct was greater on remote than on adjacent linear pairs. For set pairs, however, there was an interaction between remoteness and truth, giving better performance on remote false and adjacent true pairs. It was suggested that the memory representation (schema) for linear structure was predicted by Potts' end-term anchoring and rating-scale strategies, while set structure performance reflected logical errors in processing. Experiment 2, an "open book" test, confirmed this view: In the nonmemory task, there was no evidence of schema formation for linear structure, whereas set performance still merely reflected logical errors in processing.     

Learning on a response continuum: Comparison of a linear change and a functional learning model

Two reinforcement schedules were used to compare the predictive validity of a linear change model with a functional learning model. In one schedule, termed “convergent,” the linear change model predicts convergence to the optimum response, while in the other, termed “divergent,” this model predicts that a subject's response will not converge. The functional learning model predicts convergence in both cases. Another factor that was varied was presence or absence of random error or “noise” in the relationship between response and outcome. In the “noiseless” condition, in which no noise is added, a subject could discover the optimum response by chance, so that some subjects could appear to have converged fortuitously. In the “noisy” conditions such chance apparent convergence could not occur.The results did not unequivocally favor either model. While the linear change model's prediction of nonconvergence in the divergent conditions (particularly the “noisy” divergent condition) was not sustained, there was a clear difference in speed of convergence, counter to the prediction inferred from the functional learning model. Evidence that at least some subjects were utilizing a functional learning strategy was adduced from the fact that subjects were able to “map out” the relation between response and outcome quite accurately in a follow-up task. Almost all subjects in the “noisy” conditions had evidently “learned” a strong linear relation, with slope closely matching the veridical one.The data were consistent with a hybrid model assuming a “hierarchy of cognitive strategies” in which more complex strategies (e.g., functional learning) are utilized only when the simpler ones (e.g., a linear change strategy) fail to solve the problem.     

Spatial,non-spatial and hybrid models for scaling

In this paper, hierarchical and non-hierarchical tree structures are proposed as models of similarity data. Trees are viewed as intermediate between multidimensional scaling and simple clustering. Procedures are discussed for fitting both types of trees to data. The concept of multiple tree structures shows great promise for analyzing more complex data. Hybrid models in which multiple trees and other discrete structures are combined with continuous dimensions are discussed. Examples of the use of multiple tree structures and hybrid models are given. Extensions to the analysis of individual differences are suggested.1976 Psychometric Society Presidential Address.While people too numerous to list here have contributed ideas, inspiration, and other help, I particularly wish to acknowledge the contributions of Sandra Pruzansky, without whom this paper could not have been written. I would also like to acknowledge the past contributions of my long-time colleague Jih-Jie Chang, without whose help I probably would not have beenasked to write it.