Adaptive influence of long term high altitude residence on spatial working memory: An fMRI study

With an increasing population living at a high altitude (HA), the impact of HA residence on human cognitive function has raised concerns. We recruited two groups of college students with one group born and grew up at HA until early adulthood and the control group born and grew up at near sea level (SL); the two groups were matched at age, gender ratio, educational level, the ancestral lines, and peripheral physiology (especially the hemoglobin concentration). A 2-back spatial working memory task was performed by each subject in the scanner while fMRI data were acquired. Compared to the SL control group, the HA group showed equal response accuracy, with more variance in reaction time and a larger average value. fMRI data indicated that both groups showed common activation patterns in the neural pathway typically associated with working memory. The HA group had greater activation at the left pyramis, the left superior temporal gyrus and less activation at the left middle occipital gyrus. Significant correlations were found within each group between the reaction times and BOLD signal change amplitudes at the frontal cortex and the precentral cortex.     

Perceived racial discrimination as a barrier to college enrollment for African Americans

African Americans trail European Americans in terms of academic achievement, even when accounting for differences in socioeconomic status. One cause of this gap may be racial discrimination. In the current article the authors hypothesized that early perceived racial discrimination (by 5th grade) would predict college enrollment, mediated by changes from 7th grade to 10th grade in academic orientation, college aspirations and expectations, and deviance tolerance. Participants were 750 African Americans from the Family and Community Health Study. A structural equation model that controlled for socioeconomic status and earlier academic performance supported the hypothesis, with the exception that discrimination did not influence aspirations. The effect of discrimination on expectations, however, was moderated: Participants with high future orientation maintained high expectations in spite of discrimination. These results suggest that discrimination discourages some African Americans from pursuing higher education and that increasing future orientation may promote African Americans' college enrollment.     

Predicting changes in teenage drug use: the role of intention-behavior discrepancy

This research investigated the role of intention-behavior discrepancy in predicting changes in drug use by American teenagers. The tested behavior included drinking alcohol, smoking cannabis, and taking hard drugs. Data were collected from 1,177 young adolescents at two time points separated by one year. Two sets of analysis were performed--a multitrait-multimethod latent variable model and longitudinal analyses. The results of longitudinal analyses indicated that, although young adolescents were legally and socially prohibited from engaging in drug-taking activities, some of them intended to use drugs. This discrepancy between behaviors and intentions decreased neither drug-taking behaviors nor intentions to use drugs over time; on the contrary, it increased adolescents' illegal drug use and intention to engage in such behaviors as predicted by Brehm's reactance theory. This discrepancy factor was a better predictor of later drug-taking behavior and positive intentions to use drugs than early intentions alone. The best predictor of later behavior and intentions was prior drug use.     

梨状皮层或苍白球损毁对大鼠空间认知能力的影响

在Ｍｏｒｒｉｓ迷宫中,梨状皮层或苍白球损毁大鼠的空间认知作业成绩较显著低于控制组,搜索目标以趋向式策略为主,与正常大鼠搜索策略的差异提示：①梨状皮层和苍白球参与了空间认知加工;②在图认知系统中梨状皮层和苍白球居辅助层次。     

加工水平及词对类型在新异联系形成中的作用

该研究采用过程分离方法和知觉辨认方法探讨不同加工水平和词对类型在新异联系形成中的作用。结果表明,深加工是形成非相关词对间联想启动的条件之一。另外,具体词对的联想启动没有表现出加工水平效应,出现了内隐和外显记忆的分离现象,提示不同的词对类型与加工水平间存在着交互作用,当联系程度较紧时,并不一定需要语义加工,而联系程度不紧时,语义加工则是必要的。     

荷包牡丹碱对受低强度训练的小鸡的记忆形成的影响

在小鸡一次性被动回避行为中,低强度训练的动物其长时记忆保持不良,而训练前１０或２０分钟注射γ－氨基丁酸能颉颃剂荷包牡丹碱,可明显提高长时记忆的保持水平,这一作用可被激动剂蝇蕈碱反转。记忆保持曲线进一步显示,受低强度训练的动物其记忆仅能保持至训练后２０分钟,而注射荷包牡丹碱可使记忆至少延长至训练后１２０分钟。上述结果提示：小鸡的记忆形成受γ－氨基丁酸能系统的调节;γ－氨基丁酸能系统虽然直接参与中时记忆,但对长时记忆的形成似乎也是必需的。     

Reliabilism and imprecise credences

Philosophical Studies - What is it for an imprecise credence to be justified? It might be thought that this is not a particularly urgent question for friends of imprecise credences to answer. For...     

Recollection reduces unitised familiarity effect

Two types of encoding tasks have been employed in previous research to investigate the beneficial effect of unitisation on familiarity-based associative recognition (unitised familiarity effect), namely the compound task and the interactive imagery task. Here we show how these two tasks could differentially engage subsequent recollection-based associative recognition and consequently lead to the turn-on or turn-off of the unitised familiarity effect. In the compound task, participants studied unrelated word pairs as newly learned compounds. In the interactive imagery task, participants studied the same word pairs as interactive images. An associative recognition task was used in combination with the Remember/Know procedure to measure recollection-based and familiarity-based associative recognition. The results showed that the unitised familiarity effect was present in the compound task but was absent in the interactive imagery task. A comparison of the compound and the interactive imagery task revealed a dramatic increase in recollection-based associative recognition for the interactive imagery task. These results suggest that unitisation could benefit familiarity-based associative recognition; however, this effect will be eliminated when the memory trace formed is easily accessed by strong recollection without the need for a familiarity assessment.     

Minimax d-optimal designs for item response theory models

Various different item response theory (IRT) models can be used in educational and psychological measurement to analyze test data. One of the major drawbacks of these models is that efficient parameter estimation can only be achieved with very large data sets. Therefore, it is often worthwhile to search for designs of the test data that in some way will optimize the parameter estimates. The results from the statistical theory on optimal design can be applied for efficient estimation of the parameters.A major problem in finding an optimal design for IRT models is that the designs are only optimal for a given set of parameters, that is, they are locally optimal. Locally optimal designs can be constructed with a sequential design procedure. In this paper minimax designs are proposed for IRT models to overcome the problem of local optimality. Minimax designs are compared to sequentially constructed designs for the two parameter logistic model and the results show that minimax design can be nearly as efficient as sequentially constructed designs.