Conditional discrimination and equivalence relations: Control by negative stimuli

Three adult subjects were taught the following two-sample, two-comparison conditional discriminations (each sample is shown with its positive and negative comparison, in that order): A1-B1B2, A2-B2B1; B1-C1C2, B2-C2C1; and C1-D1D2, C2-D2D1. A teaching procedure was designed to encourage control by negative comparisons. Subjects were then tested for emergent performances that would indicate whether the baseline conditional discriminations were reflexive, symmetric, and transitive. The tests documented the emergence of two classes of equivalent stimuli: A1, B2, C1, D2 and A2, B1, C2, D1. These were the classes to be expected if the negative comparisons were the controlling comparisons in the baseline conditional discriminations. The negative comparisons, however, were not the comparisons that subjects were recorded as having chosen in the baseline conditional discriminations. Differential test results confirmed predictions arising from a stimulus-control analysis: In reflexivity tests (AA, BB, CC, DD), subjects chose comparisons that differed from the sample; one-node transitivity (AC, BD) and "equivalence" (CA, DB) tests also yielded results that were the opposite of those to be expected from control by positive comparisons; symmetry tests (BA, CB, DC), two-node transitivity (AD) tests, and two-node "equivalence" (DA) tests yielded results that were to be expected from control by either positive or negative comparisons.     

Observing behavior in a computer game.

Contingencies studied in lever-pressing procedures were incorporated into a popular computer game, "Star Trek," played by college students. One putative reinforcer, the opportunity to destroy Klingon invaders, was scheduled independently of responding according to a variable-time schedule that alternated unpredictably with equal periods of Klingon unavailability (mixed variable time, extinction schedule of reinforcement). Two commands ("observing responses") each produced stimuli that were either correlated or uncorrelated with the two components. In several variations of the basic game, an S-, or bad news, was not as reinforcing as an S+, or good news. In addition, in other conditions for the same subjects observing responses were not maintained better by bad news than by an uninformative stimulus. In both choices, more observing tended to be maintained by an S- for response-independent Klingons when its information could be (and was) used to advantage with respect to other types of reinforcement in the situation (Parts 1 and 2) than when the information could not be so used (Part 3). The findings favor the conditioned reinforcement hypothesis of observing behavior over the uncertainty-reduction hypothesis. This extends research to a more natural setting and to multialternative concurrent schedules of events of seemingly intrinsic value.     

RNAi的曲折经历与发展

RNAi是当今分子生物学研究领域内最引人注目的技术之一.已经在植物、线虫、果蝇、锥虫甚至哺乳动物细胞中发现RNAi现象. RNAi同时也是体内抵御病毒入侵、抵抗外在感染和抑制转座子活动的一种重要保护机制.通过介绍RNAi 技术富有传奇色彩的诞生和发展过程以及它对分子生物学乃至整个生命科学界产生的巨大作用,认识到RNAi是多学科联合发展的结果.我们应该加强各学科之间的整合.     

How Important Is the Digital Divide? The Relation of Computer and Videogame Usage to Gender Differences in Mental Rotation Ability

Researchers interested in the associations of gender with spatial experience and spatial ability have not yet focused on several activities that have become common in the modern digital age. In this study, using a new questionnaire called the Survey of Spatial Representation and Activities (SSRA), we examined spatial experiences with computers and videogames in a sample of nearly 1,300 undergraduate students. Large gender differences, which favored men, were found in computer experience. Although men and women also differed on SAT scores, gender differences in computer experience were still apparent with SAT factored out. Furthermore, men and women with high and low levels of computer experience, who were selected for more intensive study, were found to differ significantly on the Mental Rotations Test (MRT). Path analyses showed that computer experience substantially mediates the gender difference in spatial ability observed on the MRT. These results collectively suggest that the “Digital Divide” is an important phenomenon and that encouraging women and girls to gain spatial experiences, such as computer usage, might help to bridge the gap in spatial ability between the sexes.     

Opinion leadership in a computer‐mediated environment

This paper investigates the characteristics of opinion leaders within the computer‐mediated environment, analyses the differences between online opinion leaders and online non‐leaders and examines the implications of opinion leadership theory for e‐commerce. This study finds that opinion leaders in computer‐mediated environments possess significantly higher levels of enduring involvement, innovativeness, exploratory behaviour and self‐perceived knowledge than non‐leaders. Online opinion leaders also possess greater computer skills, have used the internet for a longer period of time and use the internet more frequently for longer sessions than non‐leaders. Copyright © 2005 John Wiley & Sons, Ltd.     

论中医的辨证论治与肿瘤的分子靶向治疗

辨证论治是中医认识和治疗疾病的基本原则,“同病异治”和“异病同治”是辨证论治的精神实质。恶性肿瘤的分子靶向治疗在很多方面都贯彻了“辨证论治”观念,将所辨的证候落实到受体、基因和各种调控系统上。尽管两者理论基础完全不同,但都强调以患者为中心的综合治疗和个体化治疗理念,对建立正确的临床思维非常重要。     

EQUIVALENCE CLASS FORMATION: A METHOD FOR TEACHING STATISTICAL INTERACTIONS

Many students struggle with statistical concepts such as interaction. In an experimental group, participants took a paper‐and‐pencil test and then were given training to establish equivalent classes containing four different statistical interactions. All participants formed the equivalence classes and showed maintenance when probes contained novel negative exemplars. Thereafter, participants took a second paper‐and‐pencil test. Participants in the control group received two versions of the paper‐and‐pencil test without equivalence‐based instruction. All participants in the experimental group showed increased paper‐and‐pencil test scores after forming the interaction‐indicative equivalence classes. Class‐indicative responding also generalized to novel exemplars and the novel question format used in the paper‐and‐pencil test. Test scores did not change with repetition for control group participants. Implications for behavioral diagnostics and teaching technology are discussed.     

基于计算机仿真的颜色认知实验方法研究

近年来计算机仿真的实验研究方法逐渐成为颜色认知研究的主流方法,该方法克服了传统方法的诸多缺陷。本研究在现有技术的基础上构建了颜色研究仿真系统,并改进了CIE规定的有关CRT显示器颜色标定的方法。笔者通过颜色匹配实验考察了人对CRT显示器上仿真照明体颜色外观的辨别精度,结果表明上述颜色仿真系统在颜色认知实验中具有良好的适用性,并发现被试在计算机模拟颜色刺激的条件下,可进行精确的颜色匹配;不同照明条件下的色差有所不同。这些结果也为建立颜色认知模型提供了人的基准匹配数据。     

有性Penna模型:进化心理学的新工具

进化心理学家以进化论为基础,使用了许多不同的方法来研究人类的心灵。这些方法都有共同的缺陷,即无法直接对提出的假设进行验证,对复杂的系统进行研究难度很大,计算机模拟的方法可在一定程度上修补该问题。有性Penna模型能反映有性生殖种群的进化特点,能反映环境对生物进化的影响,通过该模型来模拟人类进化历程,则可以检验某一心理机制是否是适应的,它是研究生物进化的有力工具。本文在综述已有研究成果的基础上提出用有性Penna模型对进化心理学关于进化轨迹的假设进行验证的构想,并在此基础之上提出了用该模型进行研究的基本框架。