Task bias and the accuracy of judgment: Setting a baseline for expected group performance

When a judgment task evokes unbiased estimates (i.e. the errors in individual judgments are distributed randomly around the true value), mathematical aggregation of individual estimates, even by a simple arithmetic mean, often will outperform all group members. However, when a task evokes biased estimates, mathematical aggregation does not perform so well. In this study, simulated data were accumulated to specify the expected' accuracy of mathematical aggregation relative to the accuracy of observed judgment of individual group members under varying conditions of task bias. Three types of judgment tasks were employed: (1) single-estimate, holistic tasks, (2) multiple-estimate, ranking tasks, and (3) multi-cue, decomposed tasks. Findings indicated across all task types that a large percentage of judgment-making group estimates formed strictly by computing the arithmetic mean of individual estimates performed better than their most capable members when a judgment task evoked little or no bias, a result particularly pronounced for ranking tasks. When the task was more greatly bias-evoking, a large percentage of parallel groups performed more poorly than average (or median) members, again a pattern more starkly evident for ranking tasks. These results suggest that the extent to which a judgment task evokes bias in a population of prospective group members is an important explanatory variable deserving much greater attention in the study of group performance. For example, an assertion about the efficacy of a particular group intervention based on a reliable demonstration of group performance as accurate as the most capable members may be unfounded when a task evokes no bias, since the baseline standard under such conditions should be much higher. By selecting tasks and populations that jointly produced highly biased estimates, researchers can lower the performance floor enough to detect (with reasonably small samples of groups) experimental effects should they occur.     

La classification des exemples d'après Aristote (Rhétorique 2,20)

Aristotle considers all examples, as far as they are used as rhetorical arguments, to be inductions (Rhetoric 1, 2, 8). On the other hand, he finds it worthwhile to distinguish different kinds of examples (viz., historical example, comparison, and fable). Moreover, comparisons and fables are said to be made by the orator, whereas historical examples are not (Rhetoric 2, 20, 2s). The present article attempts to explain this opposition.A close examination of what can be meant by induction reveals that this term applies differently to historical examples and to comparisons and fables. In a broader sense, all examples can be called inductions, insofar as a certain logical relation, different from the syllogistic one, obtains between conclusion and premises. This relation, however, is unable to explain why examples can serve as arguments. Applied to historical examples only, the term induction preserves its original meaning of checking samples in a number sufficient to yield generalization. In its narrow sense, induction gives a satisfactory account of how historical examples work. As for comparisons and fables — to which induction applies in a broader sense only — Aristotle fails to explain what makes them arguments. The explanation, missing in Rhetoric 2, 20, can, however, be given according to the general lines of Aristotelian dialectics and rhetorics. The main task of comparison and fable is to elaborate a so far unconsidered middle term (M) meeting the following conditions: the hearer is prepared to agree that M applies to the subject of the conclusion and that the predicate of the conclusion applies to M. All examples make use of a general proposition from which their conclusion can be inferred. Historical examples (like real inductions) produce instances, in order to confirm a proposition previously admitted as suitable premise, provided that its truth can be proved. Comparison and fables, by introducing a new middle term, try to form a premise susceptible of being admitted without proof.

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La classification des exemples d'après Aristote (Rhétorique 2,20)

     

Relevance reviewed: The case of argumentum ad hominem

This article aims tt providing some conceptual tools for dealing adequately with relevance in argumentative discourse. For this purpose, argumentative relevance is defined as a functional interactional relation between certain elements in the discourse. In addition to the distinction between interpretive and evaluative relevance that can be traced in the literature, analytic relevance is introduced as an intermediary concept. In order to classify the various problems of relevance arising in interpreting, analyzing and evaluating argumentative discourse, a taxonomy is proposed in which the concept of relevance is differentiated along three co-ordinate dimensions: object, domain and aspect. With the help of this taxonomy, it can be shown that the problems of evaluative relevance with which the standard approach to fallacies cannot satisfactory deal can be more systematically approached within a pragma-dialectical framework. This is demonstrated for the argumentum and hominem, which is erroneously treated as a homogenous type of relevance fallacy in logico-centric analyses, so that cases where this is not justified must be treated as ad hoc exceptions.     

Components of phonemic processing and the beginning reader

This study primarily investigated various aspects of phonemic processing and memory in relation to reading in 74 5- and 6-year-old British children. A principal components analysis revealed a major connection between reading and aspects of phonemic processing for both age groups. For the 5-year-olds the processing of the initial phoneme was important for reading, whereas for the 6-year-olds processing of initial and final phonemes appeared to be equally related on this factor. A second factor for both groups was intelligence, which was related to reading only for the 6-year-olds; but this intelligence factor was more associated with phonemic processing for the 5-year-olds. An analysis involving clustering individual readers with similar patterns across the experimental variables showed some consistent profiles for disabled readers across the two age groups. These profiles suggested potential areas for remediation according to subgroup membership.     

Heart rate--QT relationships during baroreceptor stimulation with diminished autonomic influence on the ventricles. Ventricular autonomic tone and QT interval.

The shortening of the QT interval of the electrocardiogram coincident with acceleration of heart rate and vice versa has been accepted for many years as evidence that the action potential duration and hence QT are necessarily dependent on heart rate. Exceptions to this rule have been attributed to the intervention of counteracting autonomic effects. In order to test this assumption, 26 conscious dogs divided into three groups were tested during baroreceptor stimulation by a bolus injection of phenylephrine. Seventeen dogs had been used in earlier studies in which they had undergone an experimental anterior myocardial infarction with apparent full recovery. A group of those dogs underwent beta-adrenergic blockade by intravenous atenolol 30 min prior to the baroreceptor activation. To test the intactness of the baroreceptor responses in the previously infarcted dogs, a third group of nine dogs that had had no prior myocardial infarction was included. All dogs were adapted to the laboratory environment and were not sedated during experiments. Simultaneous recordings of RR, QT interval, and phasic arterial pressure were made in all dogs before and during baroreceptor stimulation. In the normal group, and the previously infarcted group that received no atenolol, baroreceptor stimulation elicited a small (8/msec), but significant prolongation of the QT associated with a nearly 50% reduction in heart rate. The QT interval of the atenolol-treated dogs, although significantly more prolonged before stimulation, remained unchanged during the reflex. The data indicate that withdrawal of ventricular sympathetic tone may prolong the QT interval, thereby confirming the role of sympathetic innervation in the control of QT.(ABSTRACT TRUNCATED AT 250 WORDS)