Representing Meta-Knowledge in Poole-Systems

We show how Poole-systems, a simple approach to nonmonotonic reasoning, can be extended to take meta-information into account adequately. The meta-information is used to guide the choice of formulas accepted by the reasoner as premises. Existence of a consistent set of conclusions is guaranteed by a least fixpoint construction. The proposed formalism has useful applications in defeasible reasoning, knowledge base fusion and belief revision.     

The effect of a masked stimulus on the response to the masking stimulus

Four experiments are reported in which the subjects had to respond to a target that masked a preceding prime via metacontrast masking. In one part of Experiment l, the subjects discriminated the target's shape (square or diamond) by a motor-choice reaction, and in another part they had to respond with a simple reaction. The prime was neutral (circular) with respect to the target's shape. The data showed a facilitation effect. In both tasks the reaction time was reduced by the masked prime. However, the reduction was more pronounced with simple reaction than with choice reaction. In the other experiments, additional primes were used with the same angular shapes as the targets. In Experiments 2 and 3, after discriminating the target's shape by a choice reaction, the subjects had to judge the prime's shape in a signal-detection task. While neither the d' value for discriminating the angular primes from the circular ones (Exp. 2) nor the d' value for distinguishing between the angular primes (Exp. 3) was different from zero, the choice-reaction data showed a congruency effect. With a congruent prime (i.e., a prime that had the same shape as the target), the reaction times were reduced. With an incongruent prime, the reaction times grew. In Experiment 4 the errors were investigated. The facilitation effect was present in the RT, but not in the number of errors, whereas the congruency effect was present in the number, but not in the RT of errors.While the facilitation effect can be attributed either to an unspecific activation by the masked prime or to an influence of the prime on attentional processes, the congruency effect can be explained by the assumption that the masked prime directly activates the specific response, which corresponds to the prime's shape.     

Ceteris Paribus Laws: Classification and Deconstruction

It has not been sufficiently considered in philosophical discussions of ceteris paribus (CP) laws that distinct kinds of CP-laws exist in science with rather different meanings. I distinguish between (1.) comparative CP-laws and (2.) exclusive CP-laws. There exist also mixed CP-laws, which contain a comparative and an exclusive CP-clause. Exclusive CP-laws may be either (2.1) definite, (2.2) indefinite or (2.3) normic. While CP-laws of kind (2.1) and (2.2) exhibit deductivistic behaviour, CP-laws of kind (2.3) require a probabilistic or non-monotonic reconstruction. CP-laws of kind (1) may be both deductivistic or probabilistic. All these kinds of CP-laws have empirical content by which they are testable, except CP-laws of kind (2.2) which are almost vacuous. Typically, CP-laws of kind (1) express invariant correlations, CP-laws of kind (2.1) express closed system laws of physical sciences, and CP-laws of kind (2.3) express normic laws of non-physical sciences based on evolution-theoretic stability properties. This revised version was published online in July 2006 with corrections to the Cover Date.     

Vollkommene Syllogismen und reine Vernunftschlüsse: Aristoteles und Kant. Eine Stellungnahme zu Theodor Eberts Gegeneinwänden. Teil 1

In an earlier article (s. J Gen Philos Sci 40:341–355, 2009), I have rejected an interpretation of Aristotle’s syllogistic which (since Patzig) is predominant in the literature on Aristotle, but wrong in my view. According to this interpretation, the distinguishing feature of perfect syllogisms is their being evident. Theodor Ebert has attempted to defend this interpretation by means of objections (s. J Gen Philos Sci 40:357–365, 2009) which I will try to refute in part [1] of the following article. I want to show that (1) according to Aristotle’s Prior Analytics perfect and imperfect syllogisms do not differ by their being evident, but by the reason for their being evident, (2) Aristotle uses the same words to denote proofs of the validity of perfect and imperfect syllogisms („apodeixis“, “deiknusthai” etc.), (3) accordingly, Aristotle defines perfect syllogisms not as being evident, but as “requiring nothing beyond the things taken in order to make the necessity evident“, i.e. as not “requiring one or more things that are necessary because of the terms assumed, but that have not been taken among the propositions” (APr. I. 1), (4) the proofs by which the validity of perfect assertoric syllogisms can be shown according to APr. I. 4 are based on the Dictum de omni et nullo, (5) the fact that Aristotle describes these proofs only in rough outlines corresponds to the fact that his proofs of the validity of other fundamental rules are likewise produced in rough outlines, e.g. his proof of the validity of conversio simplex in APr. I. 2, which usually has been misunderstood (also by Ebert): (6) Aristotle does not prove the convertibility of E-sentences by presupposing the convertibility of I-sentences; only the reverse is true.     

The Perceived Stress Reactivity Scale: measurement invariance, stability, and validity in three countries

There is accumulating evidence that individual differences in stress reactivity contribute to the risk for stress-related disease. However, the assessment of stress reactivity remains challenging, and there is a relative lack of questionnaires reliably assessing this construct. We here present the Perceived Stress Reactivity Scale (PSRS), a 23-item questionnaire with 5 subscales and 1 overall scale, based on an existing German-language instrument. Perceived stress reactivity and related constructs were assessed in N = 2,040 participants from the United Kingdom, the United States, and Germany. The 5-factor structure of the PSRS was found to be similar in the 3 countries. In the U.S. sample the questionnaire was applied using 2 modes of administration (paper-pencil and computerized), and measures were repeated after 4 weeks. Measurement invariance analyses demonstrated full invariance across mode of administration and partial invariance across gender and countries. Scale scores differed between countries and genders, with women scoring higher on most scales. Overall, reliability analysis suggested good stability of PSRS scores over a 4-week period, and validation analysis showed expected associations with related constructs such as self-efficacy, neuroticism, chronic stress, and perceived stress. Perceived stress reactivity was also associated with depressive symptoms and sleep. These associations were particularly strong when individuals scoring high on perceived stress reactivity were exposed to chronic stress. In sum, our findings suggest that the PSRS is a useful and easy-to-administer instrument to assess perceived stress reactivity.     

Quantitative and Qualitative Research: Beyond the Debate

Psychology has been a highly quantitative field since its conception as a science. However, a qualitative approach to psychological research has gained increasing importance in the last decades, and an enduring debate between quantitative and qualitative approaches has arisen. The recently developed Mixed Methods Research (MMR) addresses this debate by aiming to integrate quantitative and qualitative approaches. This article outlines and discusses quantitative, qualitative and mixed methods research approaches with specific reference to their (1) philosophical foundations (i.e. basic sets of beliefs that ground inquiry), (2) methodological assumptions (i.e. principles and formal conditions which guide scientific investigation), and (3) research methods (i.e. concrete procedures for data collection, analysis and interpretation). We conclude that MMR may reasonably overcome the limitation of purely quantitative and purely qualitative approaches at each of these levels, providing a fruitful context for a more comprehensive psychological research.