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排序方式: 共有305条查询结果,搜索用时 46 毫秒
71.
医管、医患双重博弈研究 总被引:1,自引:0,他引:1
在中国,老百姓"看病难,看病贵"问题已饱受各方诟病多时,政府不断出台的政策却收效甚微。通过分析医疗机构、管制者和患者所面临的风险与收益、行为与选择、医疗机构与管制者之间的重复博弈,医疗机构与患者之间的一次性博弈,提出医疗机构与管制者、医疗机构与患者的双重博弈假说。指出了"药价虚高"的根源以及解决的可能途径。 相似文献
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Small deviations from bilateral symmetry (fluctuating asymmetries) are cues to fitness differences in some animals. Therefore, researchers have considered whether animals use these small asymmetries as visual cues to determine appropriate behavioral responses (e.g., mate preferences). However, there have been few systematic studies of animals' abilities to visually discriminate such minor asymmetries. If the asymmetries cannot be discriminated, fluctuating asymmetry can not be a visual cue. Here, we report an investigation of European starlings' (Sturnus vulgaris) abilities to discriminate small size asymmetries. We trained starlings, through operant conditioning in a free-flight aviary, to discriminate achromatic, symmetric paired stimuli from size-matched asymmetric stimuli. By starting the learning process with a large asymmetry and progressing through sequential trials of decreasing asymmetry, we elucidated a behavioral limit to asymmetry discrimination. We found that starlings are capable of discriminating a 10% size asymmetry. There was weaker evidence for discrimination of 5% asymmetry but no evidence for signal discrimination at 2.5% size asymmetry. This level of asymmetry discrimination suggests that many size asymmetry cues in nature can be discriminated by birds. At each level of asymmetry discrimination, we also tested whether starlings could generalize their learned symmetry preference to unreinforced novel images. Consistent with previous findings, we found that starlings could generalize their symmetry preferences. 相似文献
74.
Frontal and parietal electroencephalographic (EEG) asymmetries mark vulnerability to depression and anxiety. Drawing on cognitive theories of vulnerability, we hypothesise that cortical asymmetries predict attention to threat. Participants completed a dot-probe task in which bilateral face displays were followed by lateralised targets at either short (300 ms) or long (1050 ms) SOA. We also measured N2pc to face onset as an index of early attentional capture. At long SOA only, frontal and parietal asymmetry interacted to predict attentional bias to angry faces. Those with leftward frontal asymmetry showed no attentional bias. Among those with rightward frontal asymmetry those with low right parietal activity showed vigilance for threat, and those with high right parietal activity showed avoidance. Asymmetry was not related to the N2pc or to attentional bias at the short SOA. Findings suggest that trait asymmetries reflect function in a fronto-parietal network that controls attention to threat. 相似文献
75.
An emerging theory proposes that visual attention operates in parallel at two distinct time scales – a shorter one (<1 s) associated with moment-to-moment orienting of selective visuospatial attention, and a longer one (>10 s) associated with more global aspects of attention-to-task. Given their parallel nature, here we examined whether these comparatively slower fluctuations in task-related attention show the same visual field asymmetry – namely, a right visual field bias – as often reported for selective visual–spatial attention. Participants performed a target detection task at fixation while event-related potentials (ERP) time-locked to task-irrelevant visual probes presented in the left and right visual fields were recorded. At random intervals, participants were asked to report whether they were “on-task” or “mind wandering”. Our results demonstrated that sensory attenuation during periods of “mind wandering” relative to “on-task”, as measured by the visual P1 ERP component at electrodes sites contralateral to the stimulus, was only observed for probes presented in the left visual field. In contrast, the magnitude of sensory gain in the right visual field was insensitive to whether participants were “on-task” or “mind wandering”. Taken together, our results support the notion that task-related attention at longer time scales and spatial attention at shorter time scales affect the same underlying mechanism in visual cortex. 相似文献
76.
Perceptual estimates of action-relevant space have been reported to vary dependent on postural stability and concomitant changes in arousal. These findings contribute to current theories proposing that perception may be embodied. However, systematic manipulations to postural stability have not been tested, and a causal relationship between postural stability and perceptual estimates remains to be proven. We manipulated postural stability by asking participants to stand in three differently stable postures on a force plate measuring postural sway. Participants looked at and imagined traversing wooden beams of different widths and then provided perceptual estimates of the beams’ widths. They also rated their level of arousal. Manipulation checks revealed that the different postures resulted in systematic differences in body sway. This systematic variation in postural stability was accompanied by significant differences in self-reported arousal. Yet, despite systematic differences in postural stability and levels of arousal perceptual estimates of the beams’ widths remained invariant. 相似文献
77.
Chris Westbury Jeff Keith Benny B. Briesemeister Markus J. Hofmann Arthur M. Jacobs 《Quarterly journal of experimental psychology (2006)》2015,68(8):1599-1622
Ever since Aristotle discussed the issue in Book II of his Rhetoric, humans have attempted to identify a set of “basic emotion labels”. In this paper we propose an algorithmic method for evaluating sets of basic emotion labels that relies upon computed co-occurrence distances between words in a 12.7-billion-word corpus of unselected text from USENET discussion groups. Our method uses the relationship between human arousal and valence ratings collected for a large list of words, and the co-occurrence similarity between each word and emotion labels. We assess how well the words in each of 12 emotion label sets—proposed by various researchers over the past 118 years—predict the arousal and valence ratings on a test and validation dataset, each consisting of over 5970 items. We also assess how well these emotion labels predict lexical decision residuals (LDRTs), after co-varying out the effects attributable to basic lexical predictors. We then demonstrate a generalization of our method to determine the most predictive “basic” emotion labels from among all of the putative models of basic emotion that we considered. As well as contributing empirical data towards the development of a more rigorous definition of basic emotions, our method makes it possible to derive principled computational estimates of emotionality—specifically, of arousal and valence—for all words in the language. 相似文献
78.
Hemispheric specialization for motor control influences how individuals perform and adapt to goal-directed movements. In contrast to adaptation, motor skill learning involves a process wherein one learns to synthesize novel movement capabilities in absence of perturbation such that they are performed with greater accuracy, consistency and efficiency. Here, we investigated manual asymmetry in acquisition and retention of a complex motor skill that requires speed and accuracy for optimal performance in right-handed and left-handed individuals. We further determined if degree of handedness influences motor skill learning. Ten right-handed (RH) and 10 left-handed (LH) adults practiced two distinct motor skills with their dominant or nondominant arms during separate sessions two–four weeks apart. Learning was quantified by changes in the speed–accuracy tradeoff function measured at baseline and one-day retention. Manual asymmetry was evident in the RH group but not the LH group. RH group demonstrated significantly greater skill improvement for their dominant-right hand than their nondominant-left hand. In contrast, for the LH group, both dominant and nondominant hands demonstrated comparable learning. Less strongly-LH individuals (lower EHI scores) exhibited more learning of their dominant hand. These results suggest that while hemispheric specialization influences motor skill learning, these effects may be influenced by handedness. 相似文献
79.
Philip Hyland Mark Shevlin Maj Hansen Frédérique Vallières Jamie Murphy Ask Elklit 《Journal of Loss and Trauma》2016,21(6):492-506
This prospective study assessed the temporal relationships between the symptom clusters of PTSD in two nonprobability samples of treatment-seeking victims of sexual abuse: rape victims and adult survivors of childhood sexual abuse. Both groups were assessed at three time periods using self-report measures of PTSD symptomology. Findings from two cross-lagged panel analyses indicated weak temporal relationships between the symptom clusters of PTSD; however, avoidance and emotional numbing symptoms were found to exert the strongest cross-lagged effects. Avoidance and emotional numbing symptoms were also found to be the strongest predictor of subsequently meeting caseness for PTSD in both samples. Results suggest that there are minimal cross-lagged effects between the PTSD symptom clusters after three months from traumatic exposure. 相似文献
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