A representation theorem for languages with generalized quantifiers through back-and-forth methods

We obtain in this paper a representation of the formulae of extensions ofL by generalized quantifiers through functors between categories of first-order structures and partial isomorphisms. The main tool in the proofs is the back-and-forth technique. As a corollary we obtain the Caicedo's version of Fraïssés theorem characterizing elementary equivalence for such languages. We also discuss informally some geometrical interpretations of our results.     

Problem structure and the use of base-rate information from experience

This article is concerned with the use of base-rate information that is derived from experience in classifying examples of a category. The basic task involved simulated medical decision making in which participants learned to diagnose hypothetical diseases on the basis of symptom information. Alternative diseases differed in their relative frequency or base rates of occurrence. In five experiments initial learning was followed by a series of transfer tests designed to index the use of base-rate information. On these tests, patterns of symptoms were presented that suggested more than one disease and were therefore ambiguous. The alternative or candidate diseases on such tests could differ in their relative frequency of occurrence during learning. For example, a symptom might be presented that had appeared with both a relatively common and a relatively rare disease. If participants are using base-rate information appropriately (according to Bayes' theorem), then they should be more likely to predict that the common disease is present than that the rare disease is present on such ambiguous tests. Current classification models differ in their predictions concerning the use of base-rate information. For example, most prototype models imply an insensitivity to base-rate information, whereas many exemplar-based classification models predict appropriate use of base-rate information. The results reveal a consistent but complex pattern. Depending on the category structure and the nature of the ambiguous tests, participants use base-rate information appropriately, ignore base-rate information, or use base-rate information inappropriately (predict that the rare disease is more likely to be present). To our knowledge, no current categorization model predicts this pattern of results. To account for these results, a new model is described incorporating the ideas of property or symptom competition and context-sensitive retrieval.     

Understanding the central processing limit in consistent-mapping visual search tasks

Effects of load (i.e., the number of stimuli in the display) have been observed in multiple-frame studies using a consistent mapping of stimuli to responses (e.g., Fisher, 1982, 1984). In a series of four experiments, it is shown that these effects are not the consequence of differences across the high- and low-load conditions in either decision noise or peripheral masking. Additionally, it is shown that of two modes of limited capacity (a limited-channel and divided-capacity model) considered as possible explanations of load effects in tasks where subjects are required to locate a target, only one--the limited-channel model--is consistent with the results from all three location tasks. Finally, it is argued that the limited-channel model predicts not only the behavior observed in the four consistent-mapping experiments reported in this article but also the behavior observed in several related consistent-mapping tasks (Kleiss & Lane, 1986; Shiffrin & Gardner, 1972).     

The Values of Counseling: Three Domains

This article examines how values, as orienting beliefs about what is good for a client, group of clients, or a nation, affect the delivery of counseling services. Specifically, this article explores the role of value assumptions within such areas as counselor-client interactions, psychometrics, career services, and the transportability of counseling theories across national boundaries.     

A developmental-genetic analysis of aggressive behavior in mice (Mus musculus): III. Behavioral mediation by heightened reactivity or immobility?

This research was designed to investigate development and behavioral mediation in lines of ICR mice that have been selectively bred for aggressive behavior. General behavioral reactivity and behavioral immobility have been implicated as potential mediators by prior analyses of preattack interactions. To evaluate the separate roles of these dispositions, the emergence of attacks in genetically selected lines was tracked for 11 years by three levels of analysis: over successive generations, over development, and over dyadic interactions. Convergent outcomes were observed in all three levels with respect to two findings: (a) Robust line differences were obtained in attack behaviors, and (b) strong associations were found between line differences in attacks and line differences in behavioral immobility. Conversely, all three levels of analysis indicated a weak and inconsistent association between line differences in attacks and measures of social and nonsocial reactivity.     

Ambiguity and rationality

Recently, several theories of decision making and probability judgment have been proposed that take into account ambiguity (Einhorn and Hogarth, 1985; Gardenfors and Sahlin, 1982). However, none of these theories explains exactly what the psychological causes of ambiguity are or addresses the issue of whether ambiguity effects are rational. In this paper, we define ambiguity as the subjective experience of missing information relevant to a prediction. We show how this definition can explain why ambiguity affects decisions in the ways it does. We argue that there are a variety of rational reasons ambiguity affects probability judgments and choices in the ways it does. However, we argue that the ambiguity effect does not cast doubt on the claim that utility theory is a standard of rational choice. Rather, we suggest that the effect of ambiguity on decisions highlights the fact that utility theory, like any normative model of decision making only prescribes the optimal decision, given what one knows.     

Computerized Career Information and Guidance Systems: Caveat Emptor

Computerized career information and guidance systems, although now commonplace, have received little psychometric scrutiny. The authors argue for examining these systems in the same way in which paper and pencil instruments are assessed. Consideration is also given to issues related to programming, technical-service problems, and staffing.     

Evaluation of a mutual help network for the elderly residents of planned housing

We set up a mutual help network among the elderly residents of a government-subsidized apartment building and evaluated its impact on their social ties, social support satisfaction, and depression. A quasi-experimental design was used, with the residents of a similar building located in the same neighborhood serving as the control group. A total of 230 individual services were exchanged, and 28 group activities were organized during the study period. There was almost no difference between experimental and control groups with respect to the change over the study period in the number of social ties with other residents of the building. Support satisfaction decreased in both groups, but the decrease was larger in the experimental group. The control group had a slight decrease in the frequency of their depressive symptoms, whereas the experimental group had a moderate increase. More research is needed on the ability of social support interventions to produce beneficial effects on mental health among individuals who are not experiencing a particular life stress.     

Personal Versus Vocational Focus in Career Counseling: A Retrospective Outcome Study

In this archival study the authors sought to determine the relationship, if any, between counseling outcomes and the topical focus in career counseling. Twenty-two counselors saw 46 adult clients at a community-based clinic for an average of eight sessions. Counseling outcome and topical focus (the extent to which the actual content of counseling sessions reflected relatively more vocationally or personally focused topics) were assessed from follow-up questionnaires to former career clients and from trained raters' evaluations of the counselors' written progress notes. Results showed that, from the counselors' perspective, outcomes were better when the focus of the sessions was relatively more vocational than personal and when relatively more interviews were held. Client satisfaction, on the other hand, was predictable only from the counselor's level of experience. Satisfaction with occupational status was not associated with any of the client, counselor, or treatment factors. Discussion focuses on the contribution of the results to career counseling practice and on the feasibility and validity of retrospective, archival research.     

Predicting diagnosis performance with measures of cognitive style

This study examines the relationship between performance on a context-independent fault diagnosis task and two dimensions of cognitive style: field dependence/independence (D-I) and focusing/scanning (F-S). The effects on diagnosis performance of training and the ability of both dimensions of style jointly to predict fault-finding ability were considered. The results showed that field independents and focusers were superior fault diagnosticians. Training, in the form of verbal feedback messages, was uniformly effective for the D-I dimension although field independents maintained a superior level of performance, over field dependents. In general, for the F-S dimension, training had little effect on either the focusers or scanners. A combination of scores on the F-S and D-I dimensions significantly enhanced the proportion of the variance in testing efficiency that could be accounted for during fault-finding. Finally it is argued that the F-S and D-I dimensions should be recognized as measures of ability, not style. Future research should be directed at identifying between subject differences on fault diagnosis tasks with reference to theories of information processing.