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The aim of this paper is to introduce a new approach to the modal operators of necessity and possibility. This approach is based on the existence of two negations in certain lattices that we call bi-Heyting algebras. Modal operators are obtained by iterating certain combinations of these negations and going to the limit. Examples of these operators are given by means of graphs. 相似文献
73.
Enrique Gracia Fernando García Gonzalo Musitu 《Journal of community & applied social psychology》1995,5(2):105-119
Theory and research on social support have paid little attention to the existence of important macrosocial variables determining level and content of social relationships. This study examines variations in social integration as a function of social class and residential area characteristics. Results for 234 subjects living in high and low risk neighbourhoods indicated that differences between higher and lower social class groups follow different patterns in different residential areas. Also, same social class position appeared to have different significance as a function of residential area characteristics. The levels of three social integration measures—community integration and satisfaction, community association and participation, and contribution in community organizations—were significantly higher for lower class in low risk neighbourhoods than in high risk ones. However, significant differences were found in only one measure for higher social class groups, with higher levels of community association and participation in high risk neighbourhoods than in low risk ones. The discussion examines a ‘social impoverishment’ hypothesis for high risk environments, and proposes possible protective factors for higher status residents. Relations between formal and informal sources of support, and implications for social intervention strategies are also considered. 相似文献
74.
Many antipredator adaptations are induced by the prey’s ability to recognize chemical cues from predators. However, predator
recognition often requires learning by prey individuals. Iberian green frog tadpoles (Pelophylax perezi) have the ability to learn new potential predators. Here, we tested the memory capabilities of Iberian green frog tadpoles.
We conditioned tadpoles with chemicals cues from a non-predatory fish in conjunction with conspecific alarm cues, and examined
whether tadpoles retained their conditioned response (reduction of activity level). We found that conditioned tadpoles reduced
their activity levels in subsequent exposures to the non-predatory fish cues alone. Tadpoles were able to remember this association
and reduced movement rate at least for 9 days after. The ability to learn and memorize potential predators may be especially
important for the survivorship of prey species that are likely to find a high variety of predators. However, after those 9 days,
there was a lack of response to the non-predatory fish cues alone in the absence of reinforcement. This could be explained
if tadpoles behave according to the threat-sensitive predator avoidance hypothesis, and the perceived risk to the learning
cue diminished over time, or it could be due to an apparent forgetting process to avoid non-adaptative responses to chemical
cues of non-dangerous species that were randomly paired with alarm cues. Thus, this study demonstrates that green frog tadpoles
in the absence of reinforcement remember the chemical cues of a learned predator only for a limited time that may be adaptative
in a threat-sensitive context. 相似文献
75.
Cuesta Izquierdo M de Iscar Pérez MJ Begega Losa MA Mendez López M Alvarez Pérez L Solís G Fernández Colomer B Arias Pérez JL 《Psicothema》2007,19(4):706-710
The psychometric properties of the d2 Selective Attention Test are analyzed in two samples of premature ( n = 63) and born-at-term ( n = 78) children. The reliability coefficients (internal consistency) reached values of around .90. Principal components analysis revealed a three-factor structure, which accounts for 58% of the variance, and thus coincides with the number of factors presented in the manual of the Spanish adaptation of the test but not with their composition. Results suggest that the d2 test has adequate psychometric properties both for the global sample and for each sub-sample. 相似文献
76.
This article analyzes the evolution of Philosophy of Educationin Spain and its situation at the dawn of the 21st century. Spain'speculiar socio-historical circumstances have largely conditioned thedirection this discipline has taken over the last several decades. So,although during a period there was some approximation towards themethods of analytic philosophy, Philosophy of Education has never fullyrelinquished its normative vocation. To do so would have meant spurningthe hopes and fears that had filled Spanish society by the mid 1970supon the reinstatement of civil liberties and democracy. Indeed,attention to the circumstances and that normative orientation have foundtheir best fit in a practical Aristotelian-based philosophy meant toendow Philosophy of Education with a normative character that do notshun the educator's need for reflection, practical decision-making, andresponsibility. Since the 1990s, new directions have been marked by thechallenge of postmodernism, inasmuch as it affects not only thetechnological positivist model but also the reflective educator's modelof a practical Philosophy of Education. The new directions spread out invarious ways, yet they all fall into a common denominator of narrativetrends. The problem posed by these new languages lies in the extent towhich they are consistent with pedagogic intent. In turn, the answerstake on different profiles depending on whether the stance leans moretowards the philosophical or the pedagogical point of view withinPhilosophy of Education. The complementary nature of both perspectivescharacterizes the current state of the field in Spain. 相似文献
77.
Modal Realism and Metaphysical Nihilism 总被引:1,自引:0,他引:1
78.
Urcelay GP Miller RR 《Journal of experimental psychology. Animal behavior processes》2006,32(1):21-32
Four experiments using rats in a Pavlovian lick-suppression preparation investigated the effects of combining 2 treatments known for their response-decrementing effects, namely, overshadowing and degraded contingency. Contrary to most contemporary learning theories, the extended comparator hypothesis predicts that these 2 treatments will counteract each other, and therefore, less of a decrement in conditioned responding should be observed than with either treatment alone. Experiments 1 and 2 confirmed this prediction in first-order conditioning and sensory preconditioning preparations, respectively. Experiment 3 demonstrated that posttraining extinction of the training context resulted in a recovery from degraded contingency and reversed the counteractive effect on overshadowing. Finally, Experiment 4 demonstrated that posttraining extinction of the overshadowing stimulus resulted in recovery from simple overshadowing and also reversed the counteractive effect on degraded contingency. These results are consistent with the extended comparator hypothesis but not traditional or recent acquisition-focused models. 相似文献
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80.
The aim of this study was to analyse the prevalence of victimization through mobile phone and internet. The differences of gender and academic year in the type of electronic aggression were also examined. The sample comprised 2001 adolescents of both genders and ages between 11 and 17 years. Results indicated that 24.6% of the adolescents had been bullied by mobile phone during the last year, and 29% through internet. In most of the electronic aggressions, girls were more bullied than boys. It was also observed that students attending the first two years of secondary education tended to be more victimized. 相似文献