Sleep EEG changes during adolescence: An index of a fundamental brain reorganization

Delta (1–4 Hz) EEG power in non-rapid eye movement (NREM) sleep declines massively during adolescence. This observation stimulated the hypothesis that during adolescence the human brain undergoes an extensive reorganization driven by synaptic elimination. The parallel declines in synaptic density, delta wave amplitude and cortical metabolic rate during adolescence further support this model. These late brain changes probably represent the final ontogenetic manifestation of nature’s strategy for constructing nervous systems: an initial overproduction of neural elements followed by elimination. Errors in adolescent brain reorganization may cause mental illness; this could explain the typical age of onset of schizophrenia. Longitudinal studies of sleep EEG are enhancing our knowledge of adolescent brain maturation. Our longitudinal study of sleep EEG changes in adolescence showed that delta power, which may reflect frontal cortex maturation, begins its decline between ages 11 and 12 years and falls by 65% by age 17 years. In contrast, NREM theta power begins its decline much earlier. Delta and theta EEG frequencies are important to sleep theory because they behave homeostatically. Surprisingly, these brain changes are unrelated to pubertal maturation but are strongly linked to age. In addition to these (and other) maturational EEG changes, sleep schedules in adolescence change in response to a complex interaction of circadian, social and other influences. Our data demonstrate that the daytime sleepiness that emerges in adolescence is related to the decline in NREM delta as well as to altered sleep schedules. These longitudinal sleep data provide guideposts for studying cognitive and behavioral correlates of adolescent brain reorganization.     

Metric and nonmetric plotting models

A problem with standard printer scatterplot routines is that points are not adequately labeled. Four methods of generating printer plots are presented. All four methods allow multi-character point labels, and three of the methods can guarantee that no portion of the labels are hidden. This is accomplished by using varying amounts of metric and nonmetric distance information to locate the points.The author wishes to thank Warren Sarle and Forrest Young who provided many valuable suggestions during the development of PROC IDPLOT.The methods and procedure described in this paper were developed by the author at the University of North Carolina as a part of a software development project funded by SAS Institute Inc.     

Empirical bayes estimates of domain scores under binomial and hypergeometric distributions for test scores

We introduce two simple empirical approximate Bayes estimators (EABEs)— and —for estimating domain scores under binomial and hypergeometric distributions, respectively. Both EABEs (derived from corresponding marginal distributions of observed test scorex without relying on knowledge of prior domain score distributions) have been proven to hold -asymptotic optimality in Robbins' sense of convergence in mean. We found that, where and are the monotonized versions of and under Van Houwelingen's monotonization method, respectively, the convergence rate of the overall expected loss of Bayes risk in either or depends on test length, sample size, and ratio of test length to size of domain items. In terms of conditional Bayes risk, and outperform their maximum likelihood counterparts over the middle range of domain scales. In terms of mean-squared error, we also found that: (a) given a unimodal prior distribution of domain scores, performs better than both and a linear EBE of the beta-binomial model when domain item size is small or when test items reflect a high degree of heterogeneity; (b) performs as well as when prior distribution is bimodal and test items are homogeneous; and (c) the linear EBE is extremely robust when a large pool of homogeneous items plus a unimodal prior distribution exists.The authors are indebted to both anonymous reviewers, especially Reviewer 2, and the Editor for their invaluable comments and suggestions. Thanks are also due to Yuan-Chin Chang and Chin-Fu Hsiao for their help with our simulation and programming work.     

Set-Theoretic Absoluteness and the Revision Theory of Truth

We describe the solution of the Limit Rule Problem of Revision Theory and discuss the philosophical consequences of the fact that the truth set of Revision Theory is a complete 1/2 set.     

Delta图分析方法及其在冲突控制研究中的应用

近年来,反应时分布分析方法被应用于冲突控制研究领域,以弥补只计算平均反应时和错误率的不足。所谓delta指的是不一致条件与一致条件反应时之差,即冲突效应量。冲突效应量随反应时间的变化图称为delta图。与该分析方法相应的理论模型包括双通路模型和激活－抑制模型。本文介绍了delta图分析的具体方法及其与冲突控制理论模型的关系,然后列举了有关的研究例证,并强调了其优缺点与适用范围     

两种估计多维测验合成信度置信区间方法比较

有两种方法可以估计多维测验合成信度的置信区间：Bootstrap法和Delta法.本文用模拟研究比较这两种方法,结果发现,Delta法与Bootstrap法得到结果的差异很小.因为Bootstrap法得到的是实证结果,通常被认为是真值的反映,而Delta法比Bootstrap法简单得多,所以可以用Delta法估计合成信度的置信区间.举例演示如何计算多维测验的合成信度以及用Delta法计算其置信区间.     

Suppressing the truth as a mechanism of deception: Delta plots reveal the role of response inhibition in lying

Lying takes more time than telling the truth. Because lying involves withholding the truth, this “lie effect” has been related to response inhibition. We investigated the response inhibition hypothesis of lying using the delta-plot method: A leveling-off of the standard increase of the lie effect with slower reaction times would be indicative of successful response inhibition. Participants performed a reaction-time task that required them to alternate between lying and truth telling in response to autobiographical questions. In two experiments, we found that the delta plot of the lie effect leveled off with longer response latencies, but only in a group of participants who had better inhibitory skills as indexed by relatively small lie effects. This finding supports the role of response inhibition in lying. We elaborate on repercussions for cognitive models of deception and the data analysis of reaction-time based lie tests.     

Character mediation of story generation via protagonist insertion

The current study set out to examine how the presence or absence of depicted characters in visual narratives influences the degree of character-related content in improvised stories. The experiment consisted of trials of oral storytelling that were prompted by wordless comics. The degree of character content in the storylines was varied from being character-based—showing people engaging in social interactions—to being characterless, for example scenes depicting natural phenomena. An intermediate “character-implied” condition was also investigated, exemplified by the scene of a tornado passing through a town, where no people were depicted but in which their presence was strongly suggested. Linguistic content analysis of 472 stories demonstrated indistinguishable use of third-person pronouns (she/he) between character-implied and character-containing scenarios. An analysis of character presence demonstrated that storytellers inserted protagonists into the character-implied stories as vehicles for the actions taking place. This phenomenon reveals the character-driven nature of story creation.     

Internet Use of Migrant Workers in the Pearl River Delta

The paper is a report on the study of Internet use and migrant workers in the Pearl River Delta (PRD). First, the paper illustrates that educational attainment is a significant factor in determining the type of Internet use that appeals to migrant workers. Second, it points out that both work-oriented and entertainment-oriented uses of the Internet have a positive influence on migrant workers’ jobs and social lives in the PRD. Access to work-related information improves their employment opportunities, while the various means of entertainment provide relaxation. The online chat and the virtual community provide migrant workers with emotional support and a strong sense of their local identity. The Internet café and online games allow migrant workers to relieve the pressures of work and passively challenge the power hierarchy in the modern factory regime. The paper concludes that the Internet use has become the integral part of the city lives of migrant workers in the PRD.

Heuristic method for label placement in scatterplots

Kuhfeld (1986) has proposed several alternative scatterplot routines with labeled points. To this list is added a heuristic routine that repositions labels to eliminate overlap while attempting to maximize the number of labels presented in a metric plot.I would like to thank the reviewer of a previous version of this paper for several excellent suggestions for future modifications of both the label positioning routine and the overall plotting package.