Inference and Explanation: Assessing the Likelihood of Conjunctive Events

This study examined the effect of increasing the salience of alternatives in the use of inference and explanation sets when evaluating the likelihood of conjunctive events. Response mode (ranking or rating of events) was used to manipulate the salience of alternatives in a professional judgment context using a standard conjunction task. Participants were 196 experienced professionals and 192 undergraduate students. There was a significant interaction for attribution set x response mode. The different in conjunction effects between an inference and an explanation set was not observed when subjects were asked to rank events rather than to rate their likelihood. This finding provides evidence that a model of causal reasoning should include evaluating the strength of alternatives as well as the necessity and sufficiency of a possible cause.

Physicians' use of medical knowledge resources: preliminary theoretical framework and findings

The recurring decision of selecting among potential knowledge resources was modeled as a cost-benefit tradeoff, with associated observable features. Internal medicine and community family practice physicians (n = 228) completed a self-administered questionnaire designed to elicit reported use and cost-benefit features of nine knowledge resources. The subjects reported most frequent use of clinical colleagues, intermediate use of textbooks and journals, and least use of indexing systems. Resources' benefit-related qualities (extensiveness and credibility) were not related to reported use. In contrast, the model's access cost variables (availability, searchability, understandability, and clinical applicability) were significantly related to use. Results were generally favorable to the model's framework of knowledge resource selection. Multiple linear regression analysis suggested that physicians' use of clinical knowledge resources could be described by the physician's level of training, availability, applicability, and the resource medium (colleague, index, or text/journal).

Effects of Goal Specificity and Goal Difficulty upon Skill Acquisition of a Selected Shooting Task

This study investigated the effect of goal specificity and goal difficulty upon skill acquisition of a selected shooting task Utilizing a two-stage sampling technique, nine classes (90 subjects) were randomly assigned to one of three conditions: specific difficult goals, specific moderate goals, and generalized “do your best” goals. Following a pretest trial under a “do your best” condition, subjects performed five skill acquisition trials on a kneeling task under their assigned conditions. A 3×2×5 (Goal Groups × Sex × Trials) multivariate analysis of covariance with repeated measures on the last factor and pretest performance as the covariate indicated that the group with a specific difficult goal was significantly superior to the “do your best” group. There was also a significant main effect for trials, however, none of interactions were significant. The results are discussed as they relate to existing investigations in industrial, laboratory, and physical education situations.

Tracing the footsteps of Sherlock Holmes: cognitive representations of hypothesis testing

A well-documented phenomenon in opinion-revision literature is subjects' failure to revise probability estimates for an exhaustive set of mutually exclusive hypotheses in a complementary manner. However, prior research has not addressed the question of whether such behavior simply represents a misunderstanding of mathematical rules, or whether it is a consequence of a cognitive representation of hypotheses that is at odds with the Bayesian notion of a set relationship. Two alternatives to the Bayesian representation, a belief system (Shafer, 1976) and a system of independent hypotheses, were proposed, and three experiments were conducted to examine cognitive representations of hypothesis sets in the testing of multiple competing hypotheses. Subjects were given brief murder mysteries to solve and allowed to request various types of information about the suspects; after having received each new piece of information, subjects rated each suspect's probability of being the murderer. Presence and timing of suspect eliminations were varied in the first two experiments; the final experiment involved the varying of percentages of clues that referred to more than one suspect (for example, all of the female suspects). The noncomplementarity of opinion revisions remained a strong phenomenon in all conditions. Information-search data refuted the idea that subjects represented hypotheses as a Bayesian set; further study of the independent hypotheses theory and Shaferian belief functions as descriptive models is encouraged.

Gaining Power and Viability in Management Development Programmes

The history of a management development programme in the Israel Defence Forces (IDF) is presented. The programme was developed in response to two problems which handicapped internal consultants in the IDF, their low power position and the inappropriateness of organisation development as a paradigm for applying behavioural sciences in this organisation. Both problems were alleviated by institutionalising a management development programme in the curriculum of two officer schools of the IDF, and by changing behavioural scientists′ roles from consultants to instructors.

Stress and the Part-Time Student: Work Factors Associated with Failure Rate

The purpose of this study was to determine the relationship between four variables, namely, role ambiguity, role conflict, the resultant stress, and failure rate of the working part-time student. All variables were significantly and positively intercorrelated, with highest correlations between failure rate, stress and ambiguity. The positive correlation between role conflict and failure rate lost significance when stress and role ambiguity were partialled out. Results suggest that a higher failure rate is associated with high work stress and high role ambiguity.