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11.
Two visual half-field experiments tested Moscovitch’s (1979) proposition that cerebral asymmetry does not concern the earliest perceptual stages but only later processing. Subjects were briefly shown displays that included one (Experiment 1) or two (Experiment 2) types of forms differing in size and which, according to previous evidence, might lead to opposite laterality effects. Laterality effects were assessed for correct detections and for illusory conjunctions, both in terms of raw detection scores and in terms of perceptual discriminability (dr scores). In Experiment 1, displays included either rectangles or triangles. In the first case, the target was a cross; in the second case, it was a Star of David. A hemifield x size interaction was observed both on correct detections and on associated discriminability. Yet, no such interaction was obtained for illusory conjunctions or for associated d’ scores. In Experiment 2, the two types of forms were presented simultaneously, with the small ones either inside or outside the large ones. No laterality effects were observed. Some implications of these data for both hemispheric asymmetry and feature integration issues are discussed. The results suggest that early preattentive processes of feature extraction are not lateralized, whereas some integrative mechanisms, such as Treisman’s (1988) focal attention, may operate differently in the two hemispheres. 相似文献
12.
The processing dominance of global and local levels of visual patterns was studied using two tasks: speeded classification and identification. Stimuli were presented with spatial certainty and controlled eccentricity. The results with both procedures showed global advantage: RTs to global level were faster than those to local level. In the same way, the interference effect was bidirectional between the global and local levels, the amount of interference being larger from the global level to the local one than vice versa. 相似文献
13.
Medical expertise asa function of task difficulty 总被引:4,自引:0,他引:4
This paper is concerned with factors that disrupt the pattern of forward reasoning characteristic of experts with accurate performance. Two experiments are described. In the first, the performances of cardiologists, psychiatrists, and surgeons in diagnostic explanation of a clinical problem in cardiology were examined. In the second, the performances of cardiologists and endocrinologists in diagnostic explanation of clinical problems within and outside their domains of expertise were examined. The performances of researchers and practicing physicians are also compared. The results of Experiment 1 replicated earlier results regarding the relationship between forward reasoning and accurate diagnosis. There were no differences in recall as a function of expertise. Experts did not show any bias toward using specific knowledge from their own areas of expertise. The results of Experiment 2 showed that the breakdown of forward reasoning was related to the structure of the task. In particular, nonsalient cues induced some backward reasoning even in subjects with accurate diagnoses. Some differences were also found between the types of explanation used by researchers and practitioners. The practitioners referred more to clinical components in their explanations, whereas the researchers focused more on the biomedical components. 相似文献
14.
Recently, several studies have addressed the question of whether depression affects priming in implicit memory tasks. The main aim of this experiment was to assess the presence of a bias for negative information in explicit memory (free recall) and implicit memory (word-stem completion) tasks among subclinically depressed subjects compared to nondepressed subjects, using the typical levels of processing manipulation. The results of this study show the existence of a mood-congruent memory bias for both implicit and explicit memory in depressed subjects. The theoretical implications of these findings for implicit and explicit memory biases associated with depressed mood are discussed. 相似文献
15.
The present paper introduces theP system as a scheme for organizing Pavlovian procedures in an orderly and comprehensive manner. The system is defined by three temporal variables and three restrictions on their possible values. It can be used to define all standard temporal variables—namely, stimulus duration, interstimulus interval, trace interval, and intertrial interval—as well as variables C and T of scalar expectancy theory. The system also permits the definition of new independent variables through combinations of the basic temporal parameters. We exemplify this possibility by defining two ratios of temporal intervals. These ratios lead to a space where traditional Pavlovian arrangements (viz., simultaneous, forward-trace, forward-delay, backward) become points on a continuum, and optimal conditions across different experimental preparations become equivalent. Finally, the system can be used to define contingency variables such asp(US/CS),p(US/~CS), and the phi coefficient (φ). In this manner, an organization of different kinds of Pavlovian procedures is achieved on the basis of a single parametric scheme. Such an organization facilitates establishing procedural and theoretical relationships between temporal and contingency variables. The paper concludes with a discussion of certain limitations of the system and other related issues 相似文献
16.
Eduardo R. Cruz 《Zygon》1995,30(4):591-612
Abstract. Ralph Burhoe developed his proposals for a social reformation at a time when the “two cultures” debate was still active. It is suggested here that Burhoe, sharing with his contemporaries an understanding of culture that was Western and normative in character, overlooked the distinction between the culture of the elites and popular culture, and consequently between religion as presented by theologians and church officials and popular religion. Therefore, his proposals for the revitalization of traditional religions, even if implemented, would not work. Some contradictions within his own program are pointed out, and the social role of the sciences after World War II, as well as the ambiguities of their presence in the so-called underdeveloped nations, is analyzed. As a positive conclusion, it is suggested that Burhoe's main contribution should be sought, not in his outline for a social reformation, but in his role as an organizer of the dialogue between religion and science. 相似文献
17.
Summary Two experiments investigated relative spatial coding in the Simon effect. It was hypothesized that relative spatial coding is carried out with reference to the position of the focus of visual attention. The spatial code for an imperative stimulus presented exactly at the position of focal attention should be neutral on the horizontal plane, and therefore no Simon effect should be observed. However, when the imperative stimulus is presented to the left or to the right of the current position of focal attention, the spatial code should not be neutral, thus producing a Simon effect. In both experiments, focal attention was manipulated either by a peripherally presented onset precue (Experiment 1) or by a centrally presented symbolic precue (Experiment 2). Results showed that the Simon effect was substantially reduced in both experiments when a valid precue preceded the imperative stimulus just in time to conclude refocusing of attention to the position of the imperative stimulus before it was presented. However, conditions with neutral precues yielded a normally sized Simon effect. In both experiments, the Simon effect decreased as the SOA grew when the precue was valid. At least for the Simon effect, the results can be interpreted as evidence that relative spatial coding is functionally related to the position of the focus of attention. 相似文献
18.
19.
Zellini (1979, Theorem 3.1) has shown how to decompose an arbitrary symmetric matrix of ordern ×n as a linear combination of 1/2n(n+1) fixed rank one matrices, thus constructing an explicit tensor basis for the set of symmetricn ×n matrices. Zellini's decomposition is based on properties of persymmetric matrices. In the present paper, a simplified tensor basis is given, by showing that a symmetric matrix can also be decomposed in terms of 1/2n(n+1) fixed binary matrices of rank one. The decomposition implies that ann ×n ×p array consisting ofp symmetricn ×n slabs has maximal rank 1/2n(n+1). Likewise, an unconstrained INDSCAL (symmetric CANDECOMP/PARAFAC) decomposition of such an array will yield a perfect fit in 1/2n(n+1) dimensions. When the fitting only pertains to the off-diagonal elements of the symmetric matrices, as is the case in a version of PARAFAC where communalities are involved, the maximal number of dimensions can be further reduced to 1/2n(n–1). However, when the saliences in INDSCAL are constrained to be nonnegative, the tensor basis result does not apply. In fact, it is shown that in this case the number of dimensions needed can be as large asp, the number of matrices analyzed. 相似文献
20.
Jos V. M. Welie 《Theoretical medicine and bioethics》1994,15(3):211-225
Increasingly, contemporary medical ethicists have become aware of the need to explicate a foundation for their various models of applied ethics. Many of these theories are inspired by the apparent incompatibility of patient autonomy and provider beneficence. The principle of patient autonomy derives its current primacy to a large extent from its legal origins. However, this principle seems at odds with the clinical reality. In the bioethical literature, the notion of authenticity has been proposed as an alternative foundational principle to autonomy. This article examines this proposal in reference to various existentialist philosophers (Heidegger, Sartre, Camus and Marcel). It is concluded that the principle of autonomy fails to do what it is commonly supposed to do: provide a criterion of distinction that can be invoked to settle moral controversies between patients and providers. The existentialist concept of authenticity is more promising in at least one crucial respect: It acknowledges that the essence of human life disappears from sight if life's temporal character is reduced to a series of present decisions and actions. This also implies that the very quest for a criterion that allows physicians to distinguish between sudden, unexpected decisions of their patients to be or not to be respected, without recourse to the patient's past or future, is erroneous. 相似文献