Justification logics and hybrid logics

Hybrid logics internalize their own semantics. Members of the newer family of justification logics internalize their own proof methodology. It is an appealing goal to combine these two ideas into a single system, and in this paper we make a start. We present a hybrid/justification version of the modal logic T. We give a semantics, a proof theory, and prove a completeness theorem. In addition, we prove a Realization Theorem, something that plays a central role for justification logics generally. Since justification logics are newer and less well known than hybrid logics, we sketch their background, and give pointers to their range of applicability. We conclude with suggestions for future research. Indeed, the main goal of this paper is to encourage others to continue the investigation begun here.     

PROMOTING SAFETY BELT USE WITH TRAFFIC SIGNS AND PROMPTERS

Two studies were conducted examining the stimulus-control effects of conventional traffic signs as prompts for motor vehicle driver safety belt use. Following pilot research which suggested that a traffic sign reading “Fasten Safety Belt” posted at a parking lot exit was effective in producing small increases in safety belt use, Study I demonstrated the superiority of having human prompters display such signs compared to simply posting the signs. Study II replicated the findings of Study I and found that posted signs became more effective in prompting safety belt use if simple posting was preceded by a period involving human prompters who displayed the signs. The results bear upon the development of more effective use of traffic signs in promoting safety belt use and in viewing such use as an instance of rule-governed behavior.     

Near-death experiences: A neurophysiologic explanatory model

Prior hypotheses as to the etiology of near-death experiences (NDEs) have been limited to psychiatric explanations or brief discussions of endorphins as causative agents. We present a neurophysiological explanation for NDEs based on their similarities with lysergic acid-, ketamine-, and hypercapnia-induced hallucinations. We believe the core NDE is genetically imprinted and triggered by serotonergic mechanisms.     

Judging psychopathology: Expectation and contrast

An experiment was performed to assess the role of expectations in psychosocial contrast effects. Subjects were initially presented with a series of word definitions that were either high or low pathology; their task was to indicate those definitions that had been produced by schizophrenic (vs nonschizophrenic) patients. After this “induction” series, subjects were presented with a common “test” series that included both definitions and handwriting samples; they evaluated the degree of psychopathology that was implied by each item. Some subjects were required to state their expectations in connection with the test items. First they attempted to guess the percentage of schizophrenics in the overall test series; second, before being presented with each test item, they guessed whether the patient in question was (or was not) schizophrenic. Subjects' expectations were consistent with the induction series to which they were assigned; those assigned to the high-pathology induction expected the test series to include more schizophrenic patients than those in the low-pathology group. Nonetheless, despite these expectations, subjects showed a contrast effect in their evaluations of the test definitions (but not in evaluating the handwriting samples). That is, subjects from the low-pathology induction group rated the test definitions as being more pathological than did those in the high-pathology condition. Within-group correlations indicated that the subjects' expectations were directly related to subsequent judgments. A two-path model is discussed, relating (a) the respondents' induction group assignment, (b) his/her expectations, and (c) subsequent test judgments.     

Causal ambiguity and heterosexual affiliation

A male's decision to approach a physically attractive female stranger may be fraught with ambivalence. He is drawn by her beauty but he may fear rejection. The conflict lessens, however, if approach can occur under the guise of a motive other than desire to be with the attractive woman. This is because keeping one's true approach motive ambiguous may make direct personal rejection less likely. The effect of ambiguity on males' tendencies to approach females was explored in two experiments. In the first study, presented to subjects as a movie rating exercise, an excuse to sit with an attractive female confederate (a movie preference) was available to some subjects but not to others. As predicted, males only sat with the confederate when a reason for their affiliative behavior, other than her attractiveness, was available. In the second study, male-female dyads were run through the film rating paradigm with the female subjects in the role played by the confederate in Study I. The results of Study I were replicated for the dyads which included attractive females, as expected. The relationships between fear of failure and attributional ambiguity in social and achievement settings are examined. The tendency to discount a person's physical appearance as a cause of social behavior is discussed.     

Attitude attribution when behavior is constrained

Five experiments were conducted in which subjects were asked to attribute attitudes to target persons on the basis of opinion statements written under high constraints, i.e., the target persons were instructed to prepare the statements but were given no choice concerning the position to be endorsed. In previous studies it had been observed that reader-subjects tended to attribute attitudes in line with the opinion statement even when the writer obviously had no choice. However, in these earlier studies the opinion endorsements were actually standardized statements prepared by the investigators and they may have contained subtle cues indicating attitude strength. In the present experiments the statements were those actually written by other subjects in response to no choice instructions. Even though the subjects as attributors were well aware of these instructions, and had complied to the same instructions as target persons, attitudes in line with expressed opinions were attributed. In the final experiment, constraints were strengthened even further by the provision of specific arguments that had to be included in the opinion statements. Here the “over attribution effect” finally fell below significance. With the exception of such extreme variants of constraint, the results provide further evidence that people tend to make dispositional attributions to “explain” behavior, underestimating the role of environmental constraints.     

Computing the von Neumann-Morgenstern characteristic functionυ(S) for cooperativen-person transferable utility normal form games: LP and saddlepoint solutions

An APL computer program is described for computing the von Neumann-Morgensterncharacteristic function of cooperativen-person transferable utility games in normal form. The program is designed to stand alone, or it can be used in conjunction with other programs for game theoretic computation that will be introduced in future articles.     

Bayesian inference and the classical test theory model: Reliability and true scores

A general one-way analysis of variance components with unequal replication numbers is used to provide unbiased estimates of the true and error score variance of classical test theory. The inadequacy of the ANOVA theory is noted and the foundations for a Bayesian approach are detailed. The choice of prior distribution is discussed and a justification for the Tiao-Tan prior is found in the particular context of the “n-split” technique. The posterior distributions of reliability, error score variance, observed score variance and true score variance are presented with some extensions of the original work of Tiao and Tan. Special attention is given to simple approximations that are available in important cases and also to the problems that arise when the ANOVA estimate of true score variance is negative. Bayesian methods derived by Box and Tiao and by Lindley are studied numerically in relation to the problem of estimating true score. Each is found to be useful and the advantages and disadvantages of each are discussed and related to the classical test-theoretic methods. Finally, some general relationships between Bayesian inference and classical test theory are discussed. Supported in part by the National Institute of Child Health and Human Development under Research Grant 1 PO1 HDO1762. Reproduction, translation, use or disposal by or for the United States Government is permitted.