Une hypothèse sur l'extension des relations finies et sa vérification dans certaines classes particulières

Sans résumé     

Agricultural policy and strategic investment in information technology

In this article the perspective shifts to the “upstream” end of the agricultural knowledge and information system (AKIS). Because knowledge policy and strategic decision-making are not the prerogative of the public sector, organizations such as cooperative unions and multinational companies are included. After considering the influence of the changing environment on the nature of the AKIS, the role of knowledge management and policy in the emerging knowledge and information market is examined. Special attention is given to public and private R&D. The article then looks where information technology (IT) fits in and what considerations determine strategic investment in IT projects and sustained services. Some of the European experiences with this strategic investment are evaluated.     

Parent and child perceptions of Boszormenyi-Nagy's ethical dimensions of the parent-child relationship

The parent-child relationship plays an important role in Boszormenyi-Nagy's contextual therapy. This article presents the results of four interview studies of the opinions of parents and children about their ethical relationship.The children in these studies were five-to-seven-year-olds, 10-to-12 year olds and 15-year-olds. In one study only the mothers were interviewed, in the other three both parents participated. In all 73 children, 62 mothers, and 43 fathers were interviewed. The majority of parents and children agreed with most aspects of Nagy's theory about the parent-child relation, but there were some notable exceptions. Very few shared Nagy's ideas about entitlement. The age of the child had a clear effect on the opinions of the children on the dimensions of trust/reliability, loyalty and shifting of the balance with age of the child and on the opinions of the parents on the dimensions of childrens' rights, parents' rights, and balance of fairness. The sex of the interviewee had some effect: Mothers and fathers differ on the dimension of parents' rights and adolescent girls and boys differ on the dimensions of childrens' rights and parents' duties.     

Some reflections on the notion of hypotyposis in Kant

In the Critique of Judgement, Kant, despite his strong condemnation of rhetoric, introduces the figure of hypotyposis at the very moment he sets out to tackle the philosophical problem of presentation as such. This study holds that this choice of the rhetorical term is not fortuitous. Its connotations of vivid illustration, synopsis, and moral grandeur serve Kant in arguing that, on a transcendental level, presentation secures the mind's life, unity, and self-affection. Although of rhetorical origin, hypotyposis is thus shown to link up with a specifically philosophical meaning of the term in the writings of Aristotle.     

场依存性与独立性认知方式对视动错觉的影响

为探讨认知方式对视动性错觉的影响,对100名男性军校学员进行了棒框测验,15名高分者和15名低分者分别作为场依存组和场独立组。每名被试随机给予一系列视动阶跃刺激(5,10,15,20,30,40,60,80,100,120度/秒),每个刺激持续20秒。记录被试视动错觉出现的潜伏期和错觉模糊量。研究结果表明:1.场依存组被试的错觉潜伏期短于场独立组,它与刺激速度呈幂函数关系,而场独立组潜伏期随刺激速度的增加呈直线下降;2.在5—120度/秒的范围内,两组被试错觉量回归成两条直线,两直线回归系数无显著性差异,而截距差别十分显著。因此,场依存性/独立性认知方式是视动错觉个体差异性的一种重要影响因素,它对军事飞行员的心理学选拔和训练有着重要的意义。     

Stereo-motion cooperation and the use ofmotion disparity in the visual perception of 3-D structure

When an observer views a moving scene binocularly, both motion parallax and binocular disparity provide depth information. In Experiments lA-1C, we measured sensitivity to surface curvature when these depth cues were available either individually or simultaneously. When the depth cues yielded comparable sensitivity to surface curvature, we found that curvature detection was easier with the cues present simultaneously, rather than individually. For 2 of the 6 subjects, this effect was stronger when the component of frontal translation of the surface was vertical, rather than horizontal. No such anisotropy was found for the 4 other subjects. If a moving object is observed binocularly, the patterns of optic flow are different on the left and right retinae. We have suggested elsewhere (Cornilleau-Pérès & Droulez, in press) that this motion disparity might be used as avisual cue for the perception of a 3-D structure. Our model consisted in deriving binocular disparity from the left and right distributions of vertical velocities, rather than from luminous intensities, as has been done in classical studies on stereoscopic vision. The model led to some predictions concerning the detection of surface curvature from motion disparity in the presence or absence of intensity-based disparity (classically termedbinocular disparity). In a second set of experiments, we attempted to test these predictions, and we failed to validate our theoretical scheme from a physiological point of view.     

Illusory conjunctions and the cerebral hemispheres

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.     

The role of position in object selection in vision

Summary Within contemporary visual-information-processing psychology, two classes of selective-attention theories can be distinguished: position-not-special theories and position-special theories. The position-not-special theories postulate that attentional selection by colour, by form, and by position are equivalent selective operations. The position-special theories assume that selection by position is more basic or direct than selection by colour or by form. Examples of both types of theory are briefly described, and irrelevant and relevant evidence is critically discussed. It is concluded that the relevant evidence is directly compatible with the position-special views and that the position-not-special theories require additional extraneous assumptions. The position-special model presented in Van der Heijden (1992) is elaborated in further detail. It is shown that this model is compatible with two important and often substantiated assumptions of the position-not-special theories: the assumption that pre-attentive analysers organize the visual scene in objects against a background, and the assumption that visual-selective attention can be directed at objects isolated in this way. This position-special theory is a parsimonious theory because it can identify the mentalistic conceptselective attention with the materialistic conceptspatial position.     

Auditory accessory effects on visual processing

A series of experiments on intersensory facilitation demonstrates that non-informative sound of low to moderate intensity (30/80 dB) facilitates the reaction to a visual stimulus. By manipulating the preprocessing and perceptual stages of the visual signals, it appears that auditory intensity reduces choice reaction time independently from the positive influence of the intensity and duration of the visual imperative signal, but interacts with the effect of stimulus degradation. Degraded stimuli take more profit of the sound than intact stimuli. Besides a short-term activation effect, originated by accessories of the auditory modality, on the motor adjustment stage (cf. Sanders 1983), the results suggest that the accessory influences the stage of feature extraction.