Environmental risks: Scientific concepts and social perception

Using the example of air pollution, I criticize a restricted utilitarian view of environmental risks. It is likely that damage to health due to environmental pollution in Western countries is relatively modest in quantitative terms (especially when considering cancer and comparing such damage to the effects of some life-style exposures). However, a strictly quantitative approach, which ranks priorities according to the burden of disease attributable to single causes, is questionable because it does not consider such aspects as inequalities in the distribution of risks. Secondly, the ability of epidemiological research to identify some health effects is limited. Third, the environment has symbolic and aesthetic components that overcome a strict evaluation of damage based on the impairment of human health. It is not acceptable that priorities be set just balancing the burden of disease caused by pollution in the environment against economic constraints. As an example of a computation that inherently includes economic analysis, I refer to the proposal of an estimator of mortality in coal mining, i.e., a rate which puts deaths in the numerator and tons of coal extracted in the denominator. According to this estimator, mortality due to accidents decreased from 1.15 to 0.42 in the period 1950–1970 in the United States, for each million tons of coal extracted. However, considering the steep decline in the workforce in the same period, the traditional mortality rate (deaths over persons-time) actually increased. The proposal of a measure of mortality based on the amount of coal extracted is just one example of the attempts to influence decisions by including an economic element (productivity) in risk assessment. This paper has three purposes: One, to describe empirical research concerning the health effects of environmental pollutants; two, to discuss the scientific principles and methods used in the identification of environmental hazards; and three, to critically discuss some of the ethical principles which are applied in medicine and in the assessment and management of risk.     

Proof-Theoretic Modal PA-Completeness II: The Syntactic Countermodel

This paper is the second part of the syntactic demonstration of the Arithmetical Completeness of the modal system G, the first part of which is presented in [9]. Given a sequent S so that ⊢_GL-LIN S, ⊬_G S, and given its characteristic formula H = char(S), which expresses the non G-provability of S, we construct a canonical proof-tree T of ~ H in GL-LIN, the height of which is the distance d(S, G) of S from G. T is the syntactic countermodel of S with respect to Gand is a tool of general interest in Provability Logic, that allows some classification in the set of the arithmetical interpretations. This revised version was published online in June 2006 with corrections to the Cover Date.     

The influence of affective factors on time perception

Several studies have suggested that both affective valence and arousal affect the perception of time. However, in previous experiments, the two affective dimensions have not been systematically controlled. In this study, standardized photographic slides rated for emotional valence and arousal were projected to two groups of subjects for 2, 4, and 6 sec. One group of subjects estimated the projection duration on an analog scale, whereas the second group of subjects reproduced the intervals by pushing a button. Heart rate and skin conductance responses were also recorded during stimulus presentation as indices of attention and arousal. Time estimation results showed neither a main effect of valence nor a main effect of arousal. A highly significant valence × arousal interaction affected duration judgments. For low-arousal stimuli, the duration of negative slides was judged relatively shorter than the duration of positive slides. For high-arousal stimuli, the duration of negative slides was judged longer than the duration of positive slides. The same interaction pattern was observed across judgment modalities. These results are interpreted in terms of a model of action tendency, in which the level of arousal controls two different motivational mechanisms, one emotional and the other attentional.     

Lightness, equivalent backgrounds, and anchoring

Observers compared two center/surround configurations haploscopically. One configuration consisted of a standard surface surrounded by two, three, or four surfaces, each with a different luminance. The other configuration consisted of a comparison surface surrounded by a single annulus that varied in luminance. Center surfaces always had the same luminance but only appeared to have the same lightness with certain annuli (equivalent backgrounds). For most displays, the luminance needed to obtain an equivalent background was close to the highest luminance in the standard surround configuration. Models based on the space-average luminance or the space-average contrast of the standard surround configuration yielded poorer fits. Implications for computational models of lightness and for candidate solutions to the anchoring problem are discussed.     

Definition and classification of cancer: Monothetic or polythetic?

Since the microbiological revolution, most infectious diseases have been defined and classified according to an etiologic criterion, i.e. the identification of single, external “necessary” causes (for example, Mycobacterium for tuberculosis). This is not the case with cancer. Not only external “necessary” causes of cancer have not been identified, but also the morphological classification cannot be based on univocal criteria. Although “neoplasia” and “anaplasia” appear to be universal attributes of cancer, these events are only quantitative. Neoplastic growth can be fast or slow (development may take weeks or years), and tissue pathologies are difficult to detect from normal tissue in some cancers but are obvious in others. Common special properties of anaplasia appear to be concealed in the wide range of morphologies. In the absence of a coherent morphological definition, and of external necessary causes (such as bacteria for infectious diseases), a mechanistic definition could be adopted. However, unless molecular biology discovers specific mechanistic steps in carcinogenesis, which indicate the existence of “necessary” events in carcinogenesis, we cannot adopt a univocal (monothetic) definition of cancer. The alternative is to use a polythetic definition, according to Wittgenstein's model of a “long rope twisted together out of many shorter fibres.”     

On the status of proofs by contradiction in the seventeenth century

In this paper I show that proofs by contradiction were a serious problem in seventeenth century mathematics and philosophy. Their status was put into question and positive mathematical developments emerged from such reflections. I analyse how mathematics, logic, and epistemology are intertwined in the issue at hand. The mathematical part describes Cavalieri's and Guldin's mathematical programmes of providing a development of parts of geometry free of proofs by contradiction. The logical part shows how the traditional Aristotelean doctrine that perfect demonstrations are causal demonstrations influenced the reflection on proofs by contradiction. The main protagonist of this part is Wallis. Finally, I analyse some epistemological developments arising from the Cartesian tradition. In particular, I look at Arnauld's programme of providing an epistemologically motivated reformulation of Geometry free of proofs by contradiction. The conclusion explains in which sense these epistemological reflections can be compared with those informing contemporary intuitionism.     

Different WAIS-R short forms and their relation to ethnicity

Potential racial bias on commonly used WAIS-R short forms was examined in a group of 201 African-Americans matched with Caucasians in terms of age, education, gender, and occupational status. Within racial groups, all short form IQs correlated highly with the WAIS-R IQs (all rs 0.87). Although relatively large racial differences emerged on the Block Design, Vocabulary, and Arithmetic subtests, only mild racial discrepancies emerged for three out of the seven short forms investigated. While the magnitude of the results for the short forms was mild, based on these findings it was suggested that certain short forms not be used with African-Americans in order to minimize the potential influence of racial basis.     

Position of the Egocentric Reference and Directional Arm Movements in Right-Brain-Damaged Patients

We asked 12 right-brain-damaged patients (6 with left neglect signs and 6 without left neglect signs) to perform a straight ahead pointing task and a visual detection task with lateralized motor response, in order to investigate the relationship between the position of the egocentric reference and response time and accuracy in producing lateralized arm movements. Results showed that there was no correlation between the position of the egocentric reference and neglect signs, nor between the position of the egocentric reference and the latencies to direct a motor response toward either side of space. These findings were interpreted within the context of egocentric hypotheses of neglect. In particular, it was suggested that attentional or intentional neglect signs cannot be considered as a direct consequence of an ipsilesional deviation of the egocentric reference.     

Principal components analysis of the Psychological Screening Inventory in a sample of substance abusers.

A principal components analysis of responses to the Psychological Screening Inventory from a sample of substance abusers was conducted. Subjects were 153 inpatients admitted to a midwestern program for chemical dependency treatment. Means for age and education were 28.0 yr. (SD = 8.1) and 11.4 (SD = 1.8), respectively. Analysis indicated that a two-factor solution best described these data. Factor 1 reflected over-all maladjustment, while Factor 2 was a measure of extroversion. Clinical utility of the inventory was discussed.     

I know a dog when I see one: dogs (Canis familiaris) recognize dogs from videos

Animal Cognition - Several aspects of dogs’ visual and social cognition have been explored using bi-dimensional representations of other dogs. It remains unclear, however, if dogs do...