题目类型对加法认知策略选择影响的比较研究

随机选取小学二、三年级数学学习不良组儿童各30名,数学学习正常组儿童各30名,采用实验法、观察法和口语报告法相结合的方式,考察了两类儿童在解决简单加法题目、复杂加法题目和连加加法题目时,问题结构类型对两类儿童加法策略选择的影响。结果发现,在不同类型加法题目中,小学二、三年级儿童的策略使用表现出对题目的适应性,数学学习正常儿童的适应性特点更加明显。     

Ventral and dorsolateral regions of the midbrain periaqueductal gray (PAG) control different stages of defensive behavior: Dorsolateral PAG lesions enhance the defensive freezing produced by massed and immediate shock

Rats that receive nociceptive electric shock in an environment normally show the conditional fear-induced defensive response of freezing when returned to that environment. If several electric shocks are given in a massed manner they will condition less freezing than the same shocks given in a distributed manner. If a single shock is given immediately after placement in the chamber it does not support any conditioning, although the same shock given after a brief delay does. Electrolytic lesions of the dorsolateral periaqueductal gray (PAG), which damaged dorsomedial, dorsolateral, and lateral PAG, enhanced freezing under these conditions. Lesions of the ventral PAG, which caused extensive damage to the central gray below the aqueduct, reduced conditioning under the more optimal parameters (distributed or delayed shock). This was taken to indicate that both of these regions support different modes of defensive behavior and that when activated, the dorsolateral PAG inbits conditional fear-induced defensive behavior. © 1995 Wiley-Liss, Inc.     

Antipredator behavior of Swiss-Webster mice in a visible burrow system

Swiss-Webster mice living in a visible burrow system (VBS) reacted to presentation of a live cat in the surface area of the VBS by retreat to the burrows and reductions in nondefensive behaviors such as eating and drinking. Live eat-exposed subjects remained in the burrows 14 hr or more, while subjects exposed to a toy (plush) cat prior to live cat exposure reemerged almost immediately and made many contacts with the toy cat. However, subjects exposed first to the cat and later to a toy cat showed intermediate surface reemergence times and cat contacts during toy cat tests, indicating strong sensitization effects of prior live cat exposure. Previous studies indicated that rats in this situation show retreat to the burrows, surface avoidance, and reduction in nondefensive behaviors. The mouse pattern was similar, with the notable exception that in the first 5min block after cat presentation, mice rapidly alternated retreat to the burrow chambers with reappearance in the tunnel segment near the surface, to scan the surface visually and sniff. Movement during this time block involved a stretch attend posture characteristic also of risk assessment activities in rats. Such visual and olfactory inspection of the cat is not seen in rats in the VBS. This difference may be related to the finding that rats, but not mice, emit ultrasonic “alarm cries” during and after cat exposure. © 1995 Wiley-Liss, Inc.     

Selection for reduced aggressiveness towards man and dopaminergic activity in Norway rats

The brain dopaminergic system is involved in the process of long-term selection for reduced aggressive reaction towards man in Norway rats. The dopamine levels in the striatum as well as the nucleus accumbens with the tuberculum olfactorium were significantly lower in domesticated rats than in their wild counterparts. A substantial decrease was found in homovanillic acid level in the n. accumbens and tuberculum olfactorium. Specific binding of [³H]spiperone which labels D-2 dopamine receptors was higher in the mesolimbic structure of tame rats, whereas binding of [³H]SCH 23390 (D-1 receptors) was unchanged in this area. No substantial differences were detected in D-1 and D-2 binding in striatum. Apomorphine (0.3 mg/kg) elicited less locomotion in tame animals, reflecting a decrease of sensitivity of postsynaptic dopamine receptors. Tame rats showed fewer aggressive contacts in a foot-shock test than wild rats and the D-2 receptor antagonist sulpiride (25 mg/kg) significantly decreased the foot-shock aggression only in wild rats. Therefore, domestication, which diminishes defensive behavior and emotional reactivity of animals, is associated with decreases of dopamine level in the striatum, changed metabolism of dopamine in mesolimbic system, and an alteration in density and senstivity of D-2 receptors.     

当今医学科技的发展趋势及我国的发展战略

作为生命科学最重要组成部分的医学科学走向科技发展的新时代。在下个世纪,科研重点将向生命科学和生命医学转移。充分认识医学科学技术的地位和作用,及当代医学科技发展的主要趋势和特点,制定我国医学科学的发展战略,加强医学高技术的发展,对我国的医学科技发展将具有十分重要的意义。     

作文前构思时间分配及其对写作成绩影响的研究

通过3个分实验考察了优差生的作文前构思时间分配及其不同的构思时间分配策略对作文成绩的影响。实验1发现“优生”和“差生”在无时限写作情况下,前者花在构思上的时间更多,并运用了较好的构思策略;实验2发现“优生”和“差生在限时写作情况下,在构思时间上没有显著的差异,但他们在构思策略上仍表现出差异;实验3发现长时限构思比短时限构思能够带来更好的文本质量。作者对写作前构思的计划和管理,可能是提高作文质量的自我调控策略之一。     

不同条件下拟合指数的表现及临界值的选择

在本模拟研究中设计了6种样本容量,6种因子载荷,和4种评分等级,并考察了正态和非正态分布两种情况。采用的错误模型为参数误置（真模型中每个因子各由5个题目来测量,错误模型中则是第一个因子由6个题测量,另两个因子各由4个和5个题来测量,即有一个因子载荷被误置）模型。结果发现（1）样本量、载荷量、评分等级数和分布形态都对GOF的取值确有影响。其中分布形态的影响最大。NNFI、IFI在不同条件下的平均值是最稳定的,其次是CFI、RMSEA和SRMR。它们都算是值得推荐的GOF,尤其是NNFI和IFI。（2）在正态分布中,当样本量≥1000时,根据NNFI、IFI、CFI、RMSEA、SRMR对模型是否拟合做出判断时有很低的两类错误率,在样本量<1000时则不理想。在偏态条件下无论选择哪个GOF两类错误率都很高。（3）采用2指数策略在很多情况下也不能显著降低两类错误率。（4）由于在数据分布非正态,或正态但样本量<1000时是难判断模型是否拟合的。因此我们提出了2界值策略。即为每个GOF确定上下两个界值。低于下界值时可判断模型是不正确的,而高于上界值时则可判断模型是正确的。GOF取值处于上下界值之间时难以判断模型是否拟合,只能说越高拟合的可能性越大。这时就要通过跨样本验证和增加样本量来确定模型是否正确     

自我表现理论概述

人们把自觉的印象控制过程称作自我表现,它是人与人之间相互作用的一个方面。从Goffman1959年提出自我表现的概念以来,有关问题一直为研究者所关注。因为大部分社会交往活动可以基于自我表现的分析,只有少部分行为可以被认为是没有自我表现的意图。但已有研究主要集中于分析自我表现的类型、自我表现的影响因素、自我表现的策略等问题。而自我表现问题的研究,对于丰富社会心理学的理论,推动相关问题的进一步研究都将具有重要的价值。     

知识教学中认知策略与原有知识间关系的实验研究

模拟课堂教学情境,探讨知识教学中学习者的认知策略与原有知识间的相互关系。研究表明,二者存在明显的相互作用,策略学习只有在学习者具备适当原有知识的基础上才能有效地促进学习;当原有知识缺乏时,策略教学对学习成绩没有显著性影响;原有知识水平的高低可直接影响学生的学习成绩。该结论对于实际教学工作具有一定的指导意义。     

成年人现实生活问题解决的年龄差异

采用自行编制的十个与现实生活有关的问题,对２０至８５岁的成年人,分成青年至老老年四个年龄组进行测验,试图探讨成年人现实生活问题解决的年龄差异;并同时进行２０个问题（简称猜图）作业的实验,以期对比研究。结果看到：（１）两组主试对现实生活问题解决的评分一致率合格（ｒ值均在０．７４以上）。（２）对现实生活问题解决提出方案的数量（Ｎ）,三个较年轻组比老老年组答案多些;解决问题有效最高分（Ｈ）和各方案的平均