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151.
In this paper we examine young Germans’ occupational aspirations and the significance of neighborhoods and schools in explaining these aspirations. We aim to show (i) which of the two contexts is more significant in this regard and (ii) by which mechanisms characteristics of these contexts become relevant for youths’ actions or, more precisely, anticipated actions. We conduct our analyses by means of multilevel models. Merging data from Germany’s National Educational Panel Study on 9th grade students with micro-geographic data on residential quarters allows us to consider characteristics of the micro- as well as the meso- and macro-levels. The results show that the school context is considerably more influential on young people’s aspirations than the neighborhoods where they live. This probably reflects the selection of young people into different school types that is characteristic of Germany, a country with a highly stratified school system. Schools do not only shape youths’ career expectations; they are also important places of secondary socialization in that they have an impact on youths’ preferences for particular occupations. Furthermore, we found evidence that the social pressure to aspire high status occupations varies by social composition of the school as well as of the neighborhood context; the effect of neighborhoods, however, is rather weak.  相似文献   
152.
Abstract

Fluorescence transitions in LiNdP4O12: 4 F3/24I9/2 (0·90μm), 4F3/24I11/2 (1·05μm), 4F3/24I13/2 (1·32μm), 4F3/24I15/2 (1·77μm), and in LiErYP4O12: 4S3/24I11/2 (1·3μm), 4I13/24I15/2 (1·53μm), have been obtained at room temperature. The positions of the energy levels related to the excitation, nonradiative and radiative processes have been established from complementary absorption measurements. The fluorescence lifetimes of the above-mentioned transitions have been determined from single exponential decays.  相似文献   
153.
Two experiments examined pigeons' generalization to intermediate forms following training of concept discriminations. In Experiment 1, the training stimuli were sets of images of dogs and cats, and the transfer stimuli were head/body chimeras, which humans tend to categorize more readily in terms of the head part rather than the body part. In Experiment 2, the training stimuli were sets of images of heads of dogs and cats, and the intermediate stimuli were computer-generated morphs. In both experiments, pigeons learned the concept discrimination quickly and generalized with some decrement to novel instances of the categories. In both experiments, transfer tests were carried out with intermediate forms generated from both familiar and novel exemplars of the training sets. In Experiment 1, the pigeons' transfer performance, unlike that of human infants exposed to similar stimuli, was best predicted by the body part of the stimulus when the chimeras were formed from familiar exemplars. Spatial frequency analysis of the stimuli showed that the body parts were richer in high spatial frequencies than the head parts, so these data are consistent with the hypothesis that categorization is more dependent on local stimulus features in pigeons than in humans. There was no corresponding trend when the chimeras were formed from novel exemplars. In Experiment 2, when morphs of training stimuli were used, response rates declined smoothly as the proportion of the morph contributed by the positive stimulus fell, although results with morphs of novel stimuli were again less orderly.  相似文献   
154.
We investigated the effects that sequences of reinforcers obtained from the same response key have on local preference in concurrent variable-interval schedules with pigeons as subjects. With an overall reinforcer rate of one every 27 s, on average, reinforcers were scheduled dependently, and the probability that a reinforcer would be arranged on the same alternative as the previous reinforcer was manipulated. Throughout the experiment, the overall reinforcer ratio was 1:1, but across conditions we varied the average lengths of same-key reinforcer sequences by varying this conditional probability from 0 to 1. Thus, in some conditions, reinforcer locations changed frequently, whereas in others there tended to be very long sequences of same-key reinforcers. Although there was a general tendency to stay at the just-reinforced alternative, this tendency was considerably decreased in conditions where same-key reinforcer sequences were short. Some effects of reinforcers are at least partly to be accounted for by their signaling subsequent reinforcer locations.  相似文献   
155.
Recent literature has pointed out that the basic local independence model (BLIM) when applied to some specific instances of knowledge structures presents identifiability issues. Furthermore, it has been shown that for such instances the model presents a stronger form of unidentifiability named empirical indistinguishability, which leads to the fact that the existence of certain knowledge states in such structures cannot be empirically tested. In this article the notion of indistinguishability is extended to skill maps and, more generally, to the competence-based knowledge space theory. Theoretical results are provided showing that skill maps can be empirically indistinguishable from one another. The most relevant consequence of this is that for some skills there is no empirical evidence to establish their existence. This result is strictly related to the type of probabilistic model investigated, which is essentially the BLIM. Alternative models may exist or can be developed in knowledge space theory for which this indistinguishability problem disappears.  相似文献   
156.
Three experiments investigated face processing in children with Williams syndrome (WS). In Experiment 1, the ability to discriminate different aspects of faces was compared between WS subjects and a group of children individually matched for chronological age (CA-matches) and another group matched for mental age (MA-matches). In Experiments 2 and 3, the ability to process the local and configural aspects of geometrical patterns and faces was assessed within the same groups of subjects. The results indicated that the WSs' overall performance on face recognition was below that of the CA-matches, but similar to that of the MA-matches. This study revealed in addition that the CA- and MA-matches showed a bias toward a configural mode of face and geometrical shape processing, whereas children with WS did not show any bias. These findings suggest that face processing undergoes an abnormal developmental course in WS.  相似文献   
157.
本文研究当封闭性作为被试分辨的图形性质时,空间位置不确定性和视野位置对大范围优先性有何影响。实验发现:(1)无论复合刺激呈现在视野的中央或外周.分辨复合刺激的整体性质的反应时(RT)比分辨局部性质的RT短,整体性质对分辨局部性质的反应有较强的干扰作用。相反,局部性质对分辨整体性质的反应的影响较小;(2)刺激位置的不确定对大范围优先性没有显著影响;(3)与周边刺激相比,分辨视野中央的复合刺激的RT较短,但整体性质的RT优势和对局部性质的干扰作用,不受刺激在视野中的位置的影响。这些实验结果揭示了封闭性知觉在大范围优先性中的特殊性。  相似文献   
158.
知觉整体优先性的研究及其进展   总被引:2,自引:0,他引:2  
知觉的性质是整体的还是分析的 ?这是心理学家们长期争论不休的问题。本世纪 70年代以来 ,一些认知心理学家提出知觉加工的整体优先性假设 ,强调整体在知觉加工中的优先地位。这一假设激发了大量整体 /局部范例的研究。本文综述了这方面的研究 ,分析了它们的理论假设 ,指出了这方面研究的局限以及替代的探讨。  相似文献   
159.
Measurement invariance (lack of bias) of a manifest variableY with respect to a latent variableW is defined as invariance of the conditional distribution ofY givenW over selected subpopulations. Invariance is commonly assessed by studying subpopulation differences in the conditional distribution ofY given a manifest variableZ, chosen to substitute forW. A unified treatment of conditions that may allow the detection of measurement bias using statistical procedures involving only observed or manifest variables is presented. Theorems are provided that give conditions for measurement invariance, and for invariance of the conditional distribution ofY givenZ. Additional theorems and examples explore the Bayes sufficiency ofZ, stochastic ordering inW, local independence ofY andZ, exponential families, and the reliability ofZ. It is shown that when Bayes sufficiency ofZ fails, the two forms of invariance will often not be equivalent in practice. Bayes sufficiency holds under Rasch model assumptions, and in long tests under certain conditions. It is concluded that bias detection procedures that rely strictly on observed variables are not in general diagnostic of measurement bias, or the lack of bias.Preparation of this article was supported in part by PSC-CUNY grant #661282 to Roger E. Millsap.  相似文献   
160.
Two experiments examined the effects of number and similarity of stimuli on local contrast. In the first experiment, local contrast effects differed in magnitude as a function of the similarity among stimuli; greater positive local contrast appeared when stimuli were less similar, though this effect sometimes reversed for very dissimilar stimuli. In the second experiment, both positive and negative local contrast appeared transiently during the course of training a discrimination including two quite dissimilar stimuli. When two new stimuli were added, both effects reappeared in several cases. The effects remained when the discrimination was rendered more difficult by substituting a new stimulus very similar to one of the original pair. These and other data suggest that local contrast depends on the same factors that produce Pavlovian induction; in the absence of an alternative account, Pavlov's interpretation may be useful in suggesting further research that will help identify the mechanisms involved in both classical and operant discrimination learning.  相似文献   
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