A note on the system of propositional calculus with primitive rule of extensionality

Summary The present paper deals with a systemS of propositional calculus, conjunction, equivalence and falsum being its primitive terms. The only primitive rule inS is the rule of extensionality defined by the scheme:      

Correspondence Results for Relational Proof Systems with Application to the Lambek Calculus

We present a general framework for proof systems for relational theories. We discuss principles of the construction of deduction rules and correspondences reflecting relationships between semantics of relational logics and the rules of the respective proof systems. We illustrate the methods developed in the paper with examples relevant for the Lambek calculus and some of its extensions.     

Word length effects are not due to proactive interference.

In immediate serial recall short words are better recalled than long words. The word length effect has become pivotal in the development of short-term memory models. The current research tests one explanation of the word length effect; that it is related to proactive interference (PI). We report two experiments in which the relationship is directly tested. In the first experiment we show that word length effects can be observed over the first few trials in an experiment and that the effect shows itself primarily in the number of omissions made. In the second experiment we simultaneously test for PI and word length effects. Strong word length effects were present but there was little evidence for PI influencing either overall levels of recall or the word length effect. In short, no empirical support was found for PI as an explanation of the word length effect.     

The Case for Psychologism in Default and Inheritance Reasoning

Default reasoning occurs whenever the truth of the evidence available to the reasoner does not guarantee the truth of the conclusion being drawn. Despite this, one is entitled to draw the conclusion “by default” on the grounds that we have no information which would make us doubt that the inference should be drawn. It is the type of conclusion we draw in the ordinary world and ordinary situations in which we find ourselves. Formally speaking, ‘nonmonotonic reasoning’ refers to argumentation in which one uses certain information to reach a conclusion, but where it is possible that adding some further information to those very same premises could make one want to retract the original conclusion. It is easily seen that the informal notion of default reasoning manifests a type of nonmonotonic reasoning. Generally speaking, default statements are said to be true about the class of objects they describe, despite the acknowledged existence of “exceptional instances” of the class. In the absence of explicit information that an object is one of the exceptions we are enjoined to apply the default statement to the object. But further information may later tell us that the object is in fact one of the exceptions. So this is one of the points where nonmonotonicity resides in default reasoning. The informal notion has been seen as central to a number of areas of scholarly investigation, and we canvass some of them before turning our attention to its role in AI. It is because ordinary people so cleverly and effortlessly use default reasoning to solve interesting cognitive tasks that nonmonotonic formalisms were introduced into AI, and we argue that this is a form of psychologism, despite the fact that it is not usually recognized as such in AI. We close by mentioning some of the results from our empirical investigations that we believe should be incorporated into nonmonotonic formalisms.     

Nikolai Mikhailovskii and Konstantin Leont'ev. On the Political Implication of Herbert Spencer's Sociology

I present a fragment from thehistory of the Russian reception of HerbertSpencer's sociology. The discussion concernstwo diametrically opposed but exceptionallyimportant figures in the history of Russianthought, Nikolai Mikhajlovskij (1842–1904) andKonstantin Leont'ev (1831–1891). As one of thechief ideologues of the Populist movementMikhajlovskij turned Spencer's ideas into anegative frame of reference for his own`romantic socialist utopia'. In turn, Leont'evformulated his extremely conservative politicalviews on the basis of Spencer's organicistsociology. Though at the opposite ends of thespectrum both standpoints succeeded inexhibiting the political implications of thepositivist and naturalist style of thinking.     

A domain‐specific risk‐attitude scale: measuring risk perceptions and risk behaviors

We present a psychometric scale that assesses risk taking in five content domains: financial decisions (separately for investing versus gambling), health/safety, recreational, ethical, and social decisions. Respondents rate the likelihood that they would engage in domain‐specific risky activities (Part I). An optional Part II assesses respondents' perceptions of the magnitude of the risks and expected benefits of the activities judged in Part I. The scale's construct validity and consistency is evaluated for a sample of American undergraduate students. As expected, respondents' degree of risk taking was highly domain‐specific, i.e. not consistently risk‐averse or consistently risk‐seeking across all content domains. Women appeared to be more risk‐averse in all domains except social risk. A regression of risk taking (likelihood of engaging in the risky activity) on expected benefits and perceived risks suggests that gender and content domain differences in apparent risk taking are associated with differences in the perception of the activities' benefits and risk, rather than with differences in attitude towards perceived risk. Copyright © 2002 John Wiley & Sons, Ltd.     

Age-related changes of phasic heart rate responses to affective pictures

This study examined age differences in phasic heart rate in response to neutral, negative and positive pictures. Heart rate changes and subjective ratings were analyzed in 22 middle-aged (40-55 years) and 30 older (56-78 years) participants. The effects of valence on the HR pattern across time were similar to that obtained by Bradley and co-workers. Conversely to previous studies, we did not report any age-related reduction in cardiac reactivity. Instead, when viewing positive pictures, the triphasic wave form appeared in the group of older adults, but for younger participants, it was replaced by a sustained deceleration. These results were interpreted in the light of the socioemotional selectivity theory.     

Initial examination of the validity and reliability of the female photographic figure rating scale for body image assessment

The present study reports on the reliability and validity of an improved body image assessment scale, namely the female Photographic Figure Rating Scale (PFRS). This scale consists of ten photographic images of real women varying in body mass index (BMI) from emaciated to obese. The PFRS was designed to overcome many of the limitations associated with line-drawn figures that are currently in use, including a lack of realism and poor ecological validity. Based on a sample of 208 adult women, the results of the present study showed that the PFRS had good validity in that all images were correctly rank-ordered by BMI. In addition, construct validity was supported by the finding that current self-ratings of body size based on the PFRS were significantly correlated with participants’ BMI and that body dissatisfaction was negatively correlated with positive body image. Finally, test–retest reliabilities showed that the PFRS remained stable after a three-week interval. The discussion focuses on the strengths and limitations of the PFRS in relation to existing scales used in body image assessment.     

Modeling distributions of immediate memory effects: no strategies needed?

Many models of immediate memory predict the presence or absence of various effects, but none have been tested to see whether they predict an appropriate distribution of effect sizes. The authors show that the feature model (J. S. Nairne, 1990) produces appropriate distributions of effect sizes for both the phonological confusion effect and the word-length effect. The model produces the appropriate number of reversals, when participants are more accurate with similar items or long items, and also correctly predicts that participants performing less well overall demonstrate smaller and less reliable phonological similarity and word-length effects and are more likely to show reversals. These patterns appear within the model without the need to assume a change in encoding or rehearsal strategy or the deployment of a different storage buffer. The implications of these results and the wider applicability of the distributionmodeling approach are discussed.