Logical Features Research Articles

The Development of Selective Attention: From Perceptual Exploration to Logical Search

Publisher Summary There is a major developmental shift in the nature of the stimulus variables that control attending behavior. This shift is proposed as an important contributor to the development of systematic information processing in children. This chapter proposes a distinction between exploration and search as distinctive modes of information-getting behavior. These two patterns are discriminable in their own right in terms of measurable response properties; they are further discriminable in terms of the stimulus and task features that control them; and they are observed to have a different course of development and period of acquisition. It is argued that exploration is a simpler process that develops earlier than search, it is maintained by different types of motivation, and it provides the germinal perceptual experiences out of which logical, systematic search can evolve when the appropriate cognitive structures for its organization become available. Parallel with the developmental evolution of exploratory schemas into search routines, the evidence reviewed suggests a shift from the control of attention by salient features of stimuli toward its control by logical features of the task and a shift from passively tracked to actively sequenced attending.

Some Features of Navya-Nyaya Logic

Some Features of Navya-Nyaya Logic

Narrative Explanation and Redescription

Over the past decade numerous philosophers have devoted considerable effort to explicating and defending the claim that narrative can be a satisfactory form of explanation. Much of this interest in narrative has taken the form of a reaction against the covering-law model of explanation-particularly against the claim that that model is applicable to history and to what W. B. Gallie has called “the genetic sciences.” What has been lacking from most of this discussion of narrative is any very clear indication of just what narrative is or any extended attempt to delineate its logical features. The philosophical yield of introducing the concept “narrative” into discussions of explanation has frequently appeared to be very small.In a recent paper Michael Ruse has argued that the logical structure of explanations relating to the theory of evolution can be examined more helpfully by using the covering-law model than by using a narrative model of explanation.

Concepts of disease: logical features and social implications.

Concepts of disease: logical features and social implications.

A study of space-time clustering in Hodgkin's disease in the Manchester region.

MacMahon (1966), in a comprehensive review of the epidemiology of Hodgkin's disease, provided evi dence for the hypothesis that Hodgkin's disease may consist of several separate entities. Cole, MacMahon, and Aisenberg (1968) supported this hypothesis by analysis of regional and age variation in mortality within the United States. Smithers (1970) has reviewed the epidemiological and clinical evidence and he concludes that it is unlikely that Hodgkin's disease is two distinct conditions. Families with more than one affected member have been reported, in which the disease occurred at the same time among relatives of different ages (DeVore and Doan, 1957; Razis, Diamond, and Craver, 1959). On the basis of this, together with the clinical and patho logical features of Hodgkin's disease, MacMahon (1966) suggested that one variety may be triggered off by infections. Fraumeni and Li (1969) and Cridland (1961) have shown that an excess of cases presents in the winter months. Clemmesen, Busk, and Nielsen (1952), who used a crude mapping tech nique, reported microclusters of the disease. Fraumeni and Li (1969) looked for time and space clustering in 314 affected children; they were unable to identify any evidence of clustering of cases using the procedure developed by Ederer, Myers, and Mantel (1964). Alderson and Nayak (1971) carried out a pre liminary analysis of incidence data for 370 patients presenting with Hodgkin's disease over a period of four years in the Manchester area; they showed a trimodal age distribution and variation in the preponderance of males at different ages, as re ported by other authors (MacMahon, 1966; Clem mesen, 1965). There was no appreciable variation in the social class or marital status of the patients compared with the population from which they were drawn, but analysis of the date of first attend ance at hospital revealed a significant peak of patients first attending in the second quarter of the year. There was an excess of patients close to gether in space and time, the clustering being signi

Logique Et Psychologie De L'apprentissage Des Concepts

Abstract In the field of concept learning, there are very few studies in which logical conditions are used as independent variables. A logical analysis of concept learning phenomena is presented: it is an application of some elementary theoremas of logics and set theory. To learn a concept means to identify relevant attributes of the phenomena observed; the theoretical analysis of the situation shows that concept learning can be seen as a problem, the solution of which depends on a precise algorithm. Numerous experiments have been carried out on the basis of such an analysis, some of which are described here. Results provide evidence that time and quality of performance depend on the length and logical structure of the set of successive stimuli presented to subjects. So logical features of the situation influence concept learning; but, there are various other factors which control subject's performance: for instance, number of redundant examples, and subject's memory and perceptual-motor activity. Current...

Some Philosophic Comments on Cultural History

Philosophy abstracts and generalizes and, au fond, it is normative. Philosophy of history, as a branch of philosophy, thus quite rightly attempts to find out of what logical stuff history is made and to make explicit the criteria by which the adequacy of historical work is to be measured. Still, it makes a difference from what vantage point a philosopher chooses to look at history, for the laws of perspective hold for concepts and logical features as much as they do for shapes and colors. There are advantages to being up close: while one take in little, what one sees appears in great detail. But there are at least two dangers in proximity, and not enough analytic philosophy of history has succeeded in avoiding either of them. If one's nose is too close, one may take the molehill for a mountain and mistake a peculiar local feature for a characteristic of the whole landscape. Some philosophers of history are too impressed by the very words historians use and are thus prevented from penetrating fully to the conceptual structure that lies beneath the verbal surface. And lack of scope gives rise to a second type of error. One forgets to look around to see what else might be examined and too readily concludes that what holds for the particular specimen that has been subjected to analysis holds for everything else as well. I want to make a small contribution toward the correction of this second consequence of myopia in the philosophy of history. Without enlarging the gap from great distances many things have a tendency to look alike I want to recommend that philosophic reflection about history consider more and different kinds of historical writing than it generally does. I shall do so by actually taking up some examples of historical work. History embraces more than writers about history sometimes appear to think more than the telling of stories about what happened, together with explanations of why the events in question occurred. Much else besides narratives so conceived is to be found in historical work that is produced by members of academic departments of history; and when one looks at history that is often done outside history departments or at least outside the tradi-

An Expository Note on Estimation of Simultaneous Structural Equations

In a recent article appearing in this journal Turner and Stevens [1959] have presented an excellent discussion of regression analysis of causal paths based on the early work of Sewall Wright and others. authors note that considerable work on the treatment of multiple equations has also been done by econometricians. (See the papers by Haavelmo [1943, 1944], Koopmans and Reiers0l 1950].) purpose of the present note is to make known to biologists and biometricians several methods of genieralized linear estimation of structural parameters not yet widely known outside of econometrics, in particular the leastvariance difference method. latter method, in two different forms, has been introduced into the econometric literature by Theil [1953] and the present author [1957]; but the principle on which it is based and, indeed, the mathematical technique itself have been known for some considerable time in the Theory of Errors, the principle having been laid down and the technique fully adumbrated by Gauss [182123j. This principle, in Gauss's words, asserts that The most plausible value of a quantity that is a given function of the unknown quantities (i.e. the parameters) of the problem is found by one's substituting for the latter their most plausible values as determined by the Method of Least Squares. (Gauss [1823], pp. 34ff., pp. 102-3.) This principle foreshadows the well-known modern theorem about the invariance of maximum-likelihood estimators. technique of least-variance difference estimation can be formulated exactly as Aitken's [1935] generalization of Gauss's method of treating independent observations of unequal precision (Gauss [1809], p. 214) to the case of interdependent observations. plan of this note is as follows: Section 2 contains a discussion of some logical features of causal

Some Remarks on the Logic of Explanation

These considerations on Carl G. Hempel's and Paul Oppenheim's lucid article “Studies in the Logic of Explanation'”—LE for short—are an attempt to exploit some of the considerable advances made there. I wish to show how these advances may be incorporated into a technique for the investigation of problems of the philosophy of science, which has been called discourse-analytic. This discipline consists essentially in a technique of examining actual texts provided by specialists, such as physicists, psychologists, historians, etc., the task being to discover fundamental logical and semantical features in the discourses under investigation. I am preparing a book on historical explanation, which will contain such case studies of historical texts.

Biochemistry in routine neuropathology. II. Determination of hexosamine in chloroform-methanol extracts of brain as a diagnostic procedure with special references to the quantitation of gangliosides.

Neuropathological interest in the gangliosides originates from Klenk's dis­ covery that these lipids are accumulated in the brain in infantile amaurotic idiocy (Tay-Sachs disease) and, to a lesser extent, also in the brain in Niemann Pick disease. Consequently measurement of the ganglioside content of the brain may be an aid either in the diagnosis of incidental cases suspect for these diseases, or speaking more broadly, in answering the question whether a given group of neuropathologic ally similar cases should be classified with the lip­ idoses or not. Thus estimation of gangliosides seemed especially indicated in various types of leucodystrophies (1) which, on the basis of their histopatho­ logical features, ,,,ere often assumed to bear a kinship with amaurotic idiocy. The usual method for the estimation of gangliosides in nervous tissue was devised by Klenk and Langerbeins (2) and is essentially based on colorimetrical determination of one of the characteristic components of the ganglioside molecule (i.e. neuraminic acid, Table 1) in a chloroform-methanol extract. Unfortunately, however, adoption of this method for routine purposes was hampered by the fact that a pure neuraminic acid compound, required for the preparation of standard solutions is not for sale and can be only obtained through a chemical laboratory able and willing to produce it by means of a difficult and time con­ suming isolation method .. Moreover, it was not possible to measure neura­ minic acid accurately in samples of the white matter of the brainl as it was re­ quired in the study of the leucodystrophies (1). Therefore, an attempt was made to replace the neuraminic acid determination by the determination of the quan­ tity of hexosamine present in a chloroform-methanol extract. This substance is another component of the ganglioside molecule (fig. 1), and it was presumed that in a lipid extract hexosamine and neuraminic acid come from the same

Notes on the Logic of Simile, Metaphor and Analogy

THE DISCUSSION of simile, metaphor, and analogy suffers from a number of well-worn clich6s and misleading generalizations. One usually hears that metaphors may be converted into similes and similes into metaphors; this is not always so. Similes are grouped together whether open or closed, though these may behave in quite different ways. Analogies are frequently defined as extensive closed similes, but the fact is that not all analogies are similes and closed similes may be said to include more than analogies. Elementary distinctions, therefore, need still to be made about these concepts. The following remarks, however, are confined to their logical features only, leaving aside their proper rhetorical values. Each of the terms-simile, metaphor, analogy-is actually made to serve for somewhat heterogeneous items. I do not include here obvious errors in labeling, as for example in calling the comparison 'She is as fair as my sister' a simile. But what passes for simile, metaphor, and analogy usually have many important differences which cannot be made clear unless we ask for a translation into literal statements (as far as this is possible) of particular figurative expressions. Let me offer an array of sentences that may lead us into the puzzles: She has a heart of stone; Her heart is like stone; Her heart is as hard as stone; Her hard heart resists pleading just as hard stone resists hammering. The first is a metaphor; the second, an open simile; the third, a closed simile; the fourth, a simile closed in a somewhat different manner from the third. But now, what are their differences? The first makes no explicit comparison but attributes a property explicitly to something. We understand this to be intended figuratively; that is, we understand that the expression taken literally is false. And if we wish to exhibit the meaning and cogency of the metaphor, we supply in effect a corresponding simile for analysis (e.g., 'Her heart is like stone' for 'She has a heart of stone'). Of the simile, we say that two essentially unlike things are explicitly compared. Again our usage is figurative, and we are to understand that, though some likeness is suggested between the two, the likeness is not literally intended. Hence, also, a metaphor is said to entail an implicit simile, and in translating a simile into appropriate literal statements we mean at the same time to translate the corresponding metaphor. So far, similes and their corresponding metaphors may reasonably be viewed

Some features of Professor Anderson's logic

Some features of Professor Anderson's logic