An advantage of the concealed information polygraph test (CIT) is that its false positive rate is determined on statistical grounds, and can be set a priori at arbitrary low levels (i.e., few innocents declared guilty). This criterion, however, inevitably leads to a loss of sensitivity (i.e., more guilty suspects declared innocent). We explored whether the sensitivity of a CIT procedure could be increased by adding an independent measure that is based on an entirely different psychological mechanism. In two experiments, we explored whether the accuracy of a CIT procedure could be increased by adding Symptom Validity Testing (SVT), a relatively simple, forced-choice, self-report procedure that has previously been used to detect malingering in various contexts. Results of a feigned amnesia experiment but not from a mock crime experiment showed that a combination measure of both tests yielded better detection than either test alone.
Studies comparing the cognitive status of the sciences have long sought to identify the distinguishing features of `hard' and `soft' science. Attempts by philosophers of science to ground such distinctions in abstract principles and by sociologists of science to detect relevant differences (for example, in consensus levels) have met with limited success. However, recent investigations of scientists' concrete practices of data representation provide new leads on this problem. In particular, Bruno Latour has argued that graphs are essential to science due to their ability to render phenomena into compact, transportable and persuasive form. Applying Latour's notion of `graphism' to the hierarchy of sciences, we found that the use of graphs across seven scientific disciplines correlated almost perfectly with their hardness, and that the same pattern held up across ten specialty fields in psychology.
Summary Arnold, M. L., Kentner, E. K., Johnston, J. A., Cornman, S. & Bouck, A. C.: Natural hybridisation and fitness. – Taxon 50: 93–104. 2001. – ISSN 0040‐0262. There are several inferences that can be made from studies of the fitness of hybrid plants and animals. First, the fitness of hybrids varies. However, it is not possible to make a priori predictions concerning the relative fitness of a given hybrid genotype, or a series of genotypes. For example, plant hybrids are not more likely to have elevated fitness than animal hybrids. The variation in fitness for hybrids ranges from the highest fitness relative to parental genotypes to the lowest. The variation can be due to different environments or age classes. Furthermore, notwithstanding the paradigm that derived from the Neo‐Darwinian synthesis, some hybrid genotypes demonstrate elevated fitness relative to their parents. To test the evolutionary importance of hybridisation in a given species complex, it is critical that findings from greenhouse/population cage experiments be tested in the field. This latter statement is easier for a botanist to argue, but even with plants, the field experimentation needed for a rigorous test of fitness (i.e., reciprocal transplants) is at the best risky, and costly in time and resources. Yet, these are the types of studies needed to test predictions concerning the likeliest circumstances under which hybridisation will be promoted. The scientific literature over the past decade has seen a change in the tenor of papers describing natural hybridisation. Ten years ago, papers more often than not reported the use of natural hybridisation as a tool to understand divergent evolution. More recently, a majority of studies have discussed the evolutionary impact of natural hybridisation. We look forward to a continued increase in the frequency of studies that assume this process to have evolutionary importance per se.
Although phenotypic plasticity is demonstrably adaptive in a range of settings, organisms are not perfectly plastic. Costs of plasticity comprise one factor predicted to counter the evolution of this adaptive strategy, yet evidence of costs is rare. Here, we test the fitness effects of plastic life-history and morphological responses to density and costs of this plasticity in recombinant inbred lines of Arabidopsis thaliana. Several costs of plasticity and homeostasis were detected. Of particular relevance, there was a significant cost of plasticity to active stem-elongation responses, an adaptive trait in many species. There was also a cost of plasticity to apical branch production at both high and low density, which resulted from the greater suppression of basal branching in genotypes with plastic apical branch production relative to genotypes with fixed apical branch production. The presence of a cost in multiple environments (i.e., a global cost) is predicted to counter the evolution of plasticity. Experimental segregating progenies such as the one used here are expected to have higher genetic costs of plasticity than arrays of genotypes sampled from natural populations because selection should remove genotypes with costs resulting from linkage disequilibrium or epistasis. The use of experimental progeny arrays therefore increases the ability to evaluate genetic costs.
Several models of hybrid zone evolution predict the same spatial patterns of genotypic distribution whether or not structuring is due to environment-dependent or -independent selection. In this study, we tested for evidence of environment-dependent selection in an Iris fulva x Iris brevicaulis hybrid population by examining the distribution of genotypes in relation to environmental gradients. We selected 201 Louisiana Iris plants from within a known hybrid population (80 m x 80 m) and placed them in four different genotypic classes (I. fulva, I. fulva-like hybrid, I. brevicaulis-like hybrid and I. brevicaulis) based on seven species-specific random amplified polymorphic DNA (RAPD) markers and two chloroplast DNA haplotypes. Environmental variables were then measured. These variables included percentage cover by tree canopy, elevation from the high water mark, soil pH and percentage soil organic matter. Each variable was sampled for all 201 plants. Canonical discriminant analysis (CDA) was used to infer the environmental factors most strongly associated with the different genotypic groups. Slight differences in elevation (-0.5 m to +0.4 m) were important for distinguishing habitat distributions described by CDA, even though there were no statistical differences between mean elevations alone. I. brevicaulis occurred in a broad range of habitats, while I. fulva had a narrower distribution. Of all the possible combinations, I. fulva-like hybrids and I. brevicaulis-like hybrids occurred in the most distinct habitat types relative to one another. Each hybrid class was not significantly different from its closest parent with regard to habitat occupied, but was statistically unique from its more distant parental species. Within the hybrid genotypes, most, but not all, RAPD loci were individually correlated with environmental variables. This study suggests that, at a very fine spatial scale, environment-dependent selection contributed to the genetic structuring of this hybrid zone.
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