Effects of reinforcer delays on choice as a function of income level

Three rats earned their daily food ration by responding during individual trials either on a lever that delivered one food pellet immediately or on a second lever that delivered three pellets after a delay that was continuously adjusted to ensure substantial responding to both alternatives. Choice of the delayed reinforcer increased when the number of trials per session was reduced. This result suggests that models seeking closure on choice effects must include a parameter reflecting how preference changes with sessionwide income. Moreover, models positing that reinforcer probability and immediacy (1/delay) function equivalently in choice are called into question by the finding that probability and immediacy produce opposing effects when income level is changed.     

Cultural practices of Hispanics: implications for the prevention of AIDS

Hispanic Americans have one of the highest rates of HIV seroprevalence among all ethnics groups in the US, with high rates being especially noticeable among women and children. Were it known which cultural factors have the most influence on whether Hispanics engage in high-risk behavior for HIV transmission, prevention interventions could be targeted accordingly. To that end, this study was mounted to identify which Hispanic cultural factors relate to condom use. 117 males and 73 females aged 17-56 years of mean age 25.67 were surveyed in Washoe county, Nevada. These mostly young adults had recently immigrated to the western US. It was initially posited that fate orientation, male- female relationships, family relationships, machismo behavior, and religion would have equal influence with respect to condom use. Analysis found that condom use was largely associated with and determined by men who are the principal buyers of condoms. A machismo attitude toward protecting women by using condoms was also associated with condom use. Neither fate orientation with respect to AIDS, nor religion were important determinants of condom use, even though 86.5% of the respondents were Catholic. The degree to which respondents adhered to traditional Hispanic cultural values was influenced by the degree of education and acculturation. On the basis of these findings, the authors suggest targeting AIDS prevention messages to males, while emphasizing the protection of women through condom use. They also suggest that both education and acculturation levels be assessed before implementing prevention programs.     

The legal consensus about foregoing life-sustaining treatment: its status and its prospects

The legal consensus that has evolved through adjudication and legislation since the Karen Quinlan case in 1976 is founded on the premise that there is a bright line between passive euthanasia and active euthanasia. Indeed, the term passive euthanasia is often eschewed in favor of less emotionally-laden terminology such as "forgoing life-sustaining treatment" or "terminating life support" so as to further sever any possible connection with active euthanasia. Legal approval has been bestowed upon passive euthanasia under certain circumstances while active euthanasia is routinely condemned. This consensus was put to a test in 1990 when the United States Supreme Court ruled on the Cruzan case. However, the Court's narrow decision did not upset the consensus, and in the most significant appellate decisions handed down by state courts since Cruzan, there has been a reaffirmation--and possibly even an extension--of the consensus. Two other threats to the legal consensus about forgoing life-sustaining treatment have begun to manifest themselves: the increasing pressure for mercy killing and "futility" cases. Both of these challenge the fundamental premises on which the consensus is grounded.     

库恩的可否证性模式

库恩和拉卡托斯都不同意把理论的评价看作是理论的可证实性或理论的可否证性这一传统观点。他们的批判分为两个题目:首先,一种科学理论并非只能凭经验的结果来检验;其次,人们不会在没有现成可替代的理论时就摈弃一种理论。在拉卡托斯的术语里,要么被接受,要么被摈弃的是理论的研究纲领而不仅仅是理论本身。进一步说,某一特定的范式或研究纲领的摈弃并不就是简单地被取代,一种替代范式在另一种范式或研究纲领被摈弃之前必须发生效用。最近,人们对拉卡托斯夸大第二点进行了批判。F.M.亚克罗德认为,在科学史上有一些情况是,一项研究被简单地摈弃了,而且的确是被合理地摈弃了,尽管还没有替代者。在本文中,我     

《主体·客体·认识》中译本序言

B·A·列克托尔斯基是苏联著名的马克思主义哲学家,现任苏联《哲学问题》杂志主编、科学院哲学所认识论研究室主任。《主体·客体·认识》一书是他的一本有相当高学术价值、享有国际盛名的力作,已被翻译为七种文字。本文系他为该书中译本写的前言,其中谈了对认识论发展的重要看法。该书中译本由贾泽林等人译,将由中国人民大学出版社出版。     

判断和选择中的认知错觉

人类的错误为研究人类智能的结构和功能提供了有价值的资料。对于记忆的研究多是建立在遗忘的基础上,对知觉的研究常常基于识别力衰退,对于语言和思维的研究已经揭示了失言。关于人类错误的研究格外重要,因为它表明了人类智力的某些局限,它时常暴露出隐藏在人们行为之下的规律和机制,它常常提示出可以改善人们表现的方式。错觉是一种特殊的错误,它特别令人困惑,因为人们造成的这种错误始终具有迷惑力,甚至当人们已彻底认识到这是一种错误时亦然。例如,我们会感到在图1中右边的线     

系统剪影:作为哲学的一般系统

我对介绍一般系统论有为难和讨厌之感。显然,在我看来,一般系统论者所关注的中心问题即“系统的本质是什么?”基本上是一个哲学问题。然而,我所接触的一般系统论者不仅没提及哲学,而且似乎把哲学看作废弃的和缺乏时代性的东西(哲学的某些问题很久以前就被逻辑实证主义者取消     

Qualitative dynamics of disordered human locomotion: a preliminary investigation

A qualitative approach to the evaluation of disordered locomotion is introduced within the framework of dynamical systems theory. Exemplar phase plane and angle-angle plots of knee and ankle movements were constructed from limb trajectories of neurologically impaired individuals and qualitatively compared with similar plots, reflecting normal locomotion. In phase plane trajectories of normal locomotion, characteristics of spring-like dynamics dominated the loading and unloading phases whereas those of ballistic pendular dynamics were seen during swing. The overall squareness of the normal phase plane trajectories suggested precisely timed and narrowly focused controls. in contrast, phase plane records from hemiparetic subjects had markedly reduced segmental velocities, pronounced velocity reversals in both stance and swing, and a loss of overall squareness. Knee-ankle plots of normal locomotion revealed important features of intersegmental coordination such as coupled out-of-phase coordination in loading and unloading, a decoupled phase offset in early swing, and a kind of active partitioning in late swing in which one segment moved while the other remained constant. These intersegmental relations were absent or distorted in the hemiparetic angle-angle plots. It is suggested that this qualitative approach, together with electromyography and force dynamics, may allow the characterization of the movement disorders associated with given neuropathologies.     

生态哲学

生态学是一门研究生物体和它们的环境之间的相互关系的科学。它基本上属于生物科学。众所周知,科学哲学是哲学研究项目中最重要的门类之一,例如,我们现在有数学哲学、物理学哲学和其他自然科学的哲学,以及各门社会科学的哲学。有许多根本的问题处于科学和哲学二者的边缘交接点,如时空、能量、物质、生命、心理、演化等等的性质既是科学家考虑的问题又是哲学家考虑的问题。宇宙起源和宇宙论的问题更是科学和哲学的一