Task-dependent compensatory responses to perturbations applied during rhythmic movements in humans

Modulation of the responses to perturbation applied during different phases of three rhythmic movements in humans-running, cycling, and hopping-was studied. The perturbation was an electrical stimulus. The results showed gating and modulation of the responses in both ipsi- and contralateral limb muscles. The responses during running and cycling were only excitatory in nature, while during hopping an inhibitory response was observed. These responses were not correlated with the normal activity during the movement. The latency of the response in general was not altered for different stimulation phases. The alterations in the step cycle demonstrated overt behavioral changes due to the responses. There were differences between the responses observed during these movements and walking. In running, the major adaptation to perturbations appears to be in the contralateral side as seen in the changes in the step cycle. During cycling (except for one phase) and hopping, the same set of muscles was activated in response to perturbation. This represents a simplifying strategy in response organization. The dependency of the response on the task characteristics, postural stability requirement, and external constraints imposed on the subject is discussed. These studies provide insights into task-dependent strategies adopted by the nervous system to meet unexpected perturbation during rhythmic movements in humans.     

Variable-interval schedules of timeout from avoidance

Rats were trained on concurrent schedules in which pressing one lever postponed shock and pressing the other occasionally produced a 2-min timeout during which the shock-postponement schedule was suspended and its correlated stimuli were removed. Throughout, the shock-postponement schedule maintained proficient levels of avoidance. Nevertheless, in Experiment 1 responding on the timeout lever was established rapidly, was maintained at stable levels on variable-interval schedules, was extinguished by withholding timeout, was reestablished when timeout was reintroduced, and was brought under discriminative control with a multiple variable-interval extinction schedule of timeout. These results are in contrast with Verhave's (1962) conclusion that timeout is an ineffective reinforcer when presented to rats on intermittent schedules. In Experiment 2 the consequence of responding on the timeout lever was altered so that the shock-postponement schedule remained in effect even though the stimulus conditions associated with timeout were produced for 2 min. Responding extinguished, indicating that suspension of the shock-postponement schedule, not stimulus change, was the source of reinforcement. By establishing the reinforcing efficacy of timeout with standard variable-interval schedules, these experiments illustrate a procedure for studying negative reinforcement in the same way as positive reinforcement.     

攻击的社会性认知学习的调节

这项研究探索了小学儿童的攻击与影响儿童是否采取攻击行为的社会认知的两个等级的联系.给攻击性和非攻击性的儿童(平均年龄为11.3岁)提供二个调查表,让他们进行回答.一个调查表是测量儿童对自己进行攻击的能力及相应的行为的认识(即自我实力的认识),而另一个调查表则测量儿童对攻击性行为会得到的奖励和惩罚的后果的认识.     

《物性论》

罗素说过,“几乎没有任何别的大诗人要等待这么久的时间才为人所认识到,但是到了近代,他的优异性差不多已是普遍公认的。”这位大诗人便是卢克莱修(约公元前99年—55年)。他的哲学巨著《物性论》在写成之后,整整湮没了一千余年,直到1473年才被发掘出来。而且在中世纪,它仅仅存下了一份手稿。该书用诗歌体裁著成,共六卷,七千余行。马克思曾据之称赞卢克莱修是“真正罗马的史诗诗人”,是“朝气蓬勃的,大胆的、富有诗意的世界主宰者”。     

四十三周年生日皈依三宝赋呈正果老法师

(一)孽海生涯四十春,风花雪月枉哦吟。欺名交负诗文债,居室常牵儿女情。五蕴焉能空浊体,六如未必了凡心。无边佛法人间有,处处随缘证夙因。 (二)自是尘心终未泯,杨枝洒落指迷津。收将狂慧板三宝,证得因缘学五乘。名利场中鄙俗客,菩提树下仰高僧。借来南海半瓶水,化作东山一片云。四十三周年生日皈依三宝赋呈正果老法师@德纯~~     

悖论,类型论以及解救悖论的其它方法(续)

罗素的观点看来是主张,类型论提供了避免一切悖论的方法,此外类型论在本质上还是这种方法的理论基础。让我们依次来考虑这两点。晚近的作者在所谓“语义悖论”和集合论悖论之间作出了区分,而罗素没有这样做。埃匹曼尼德悖论被称为语义悖论,因为它在本质上涉及到真的概念(谎话是不真的);并且“真”被称作一种语义关系,因为它是     

运动心理学的历史和当前的研究课题

一、历史运动心理学的基础在于运动学习和动作操作。1920年之前,就有少数人单独地进行一些零星分散的调查。这些调查推动了各种心理变量影响动作操作的研究。首先在美国发表的是观众对自行车比赛的影响。在1918年,伊利诺斯大学的心理学家C·R·格里菲斯对足球运动员和篮球运动员的反应时进行了比较,这仅仅为以后的研究播下了一些种子。在此期间,其它国家(苏联、德国和日本)也有类似的研究。 1920—1940年间,有些人对运动心理学的研究发生了特殊的兴趣。美国的运动心理学之父 C·R·     

欧州关于领导问题的研究

欧洲学者对于领导问题始终保持着兴趣。现代的有关研究有别于美国,更注重理论探讨,所考查的因素也更为广泛。英国伦敦塔维斯托克人类关系所的研究将组织看作为“社会-技术”系统,而领导就负责管理系统内各子系统间以及与环境间边界关系的过程。英国阿斯顿大学则认为是组织的整体结构而不是个别管理者的领导行为方式决定了组织的运行。斯图亚特的学说介乎两者之间,它将领导分为必须完成的、自愿完成的任务和限制完成任务的因素三种成分,这样领导既是被决定的,又是可作出选择的。在欧洲对领导问题中参与过程的研究很流行。几项大规模的调查表明参与性决策具有差异性和阶段性,因而海勒-维尔波特提出权变理论。领导问题的研究应朝着能够对在某一具体情景下领导者应如何行动作出预测的方向进行。     

模态逻辑的某些认知解释

Ⅰ我们的信念(至少)在两方面是模糊的:所相信的命题是模糊的(含有模糊的概念),相信与不相信的界限是模糊的,就是说相信这个概念本身是模糊的。通过下面的语句我们来说明后一种类型的模糊性。(1)光比声音传播的速度快。(2)大量的维生素 C 预防流感。(3)奥尔弗·帕尔梅将在1980年出任瑞典总理。(4)大卫·休谟身高五英尺六英寸。