Discriminative stimuli that follow the absence of reinforcement are preferred by pigeons over those that follow reinforcement

Clement, Feltus, Kaiser, and Zentall (2000) found that when pigeons have to work to obtain a discriminative stimulus that is followed by reinforcement, they prefer a discriminative stimulus that requires greater effort over one that requires less effort. The authors suggested that such a preference results from the greater change in hedonic value that occurs between the more aversive event and the onset of the stimulus that signals reinforcement, a contrast effect. It was hypothesized that any stimulus that follows a relatively more aversive event would be preferred over a stimulus that follows a relatively less aversive event. In the present experiment, the authors tested the counterintuitive prediction of that theory, that pigeons should prefer a discriminative stimulus that follows the absence of reinforcement over a discriminative stimulus that follows reinforcement. Results supported the theory.     

学生分组实验教学中应注意的几个环节

学生实验是培养学生观察、动手、思维能力的重要手段，是完成教学活动必不可少的环节。在进行物理分组实验教学时应该注意认真备课，精心设计，引导学生预习实验，加强实验的基本训练；在教学中应充分发挥教师的主导作用；学生分组实验时切忌教师先演示。     

温家宝强调:要把发展职业教育放在更加重要更加突出的位置来抓

日前，中共中央政治局常委、国务院总理温家宝在主持召开教育工作座谈会时强调，要把教育摆在优先发展的战略地位，普及和巩固义务教育，加快发展职业教育，提高高等教育质量。要着力深化教育改革，提高教学质量，培养德智体美全面发展的各级各类人才。我们有一流的教育，才能有一流的国家实力，才能真正成为世界上一流的国家。     

谈书写作文评语应注意的问题

好的作文评语能激发学生的写作兴趣，是提高学生写作水平的重要手段。因此，教师在书写作文评语时应注意以下几个问题：①不写空话，评到实处。②少用挖苦，谐趣指正。③摒弃雷同，富有变化。     

The overshadowing of instrumental conditioning by a stimulus that predicts reinforcement better than the response

In an experiment designed to demonstrate the overshadowing of appetitive instrumental conditioning, three groups of rats were given 10 sessions of RI (random interval) training in which reinforcement was delivered 450 msec following the response. The correlated group experienced a stimulus during the response-reinforcer delay interval, while an uncorrelated control group experienced a similar brief stimulus occasionally following responses, but these were not responses that typically produced reinforcement. A no-stimulus control group did not experience the brief response-produced stimulus. The experiment was run in two replications. The first employed a light as the critical stimulus, the second a tone. Over the 10 RI sessions, subjects in the two control conditions increased their rate of responding significantly faster than subjects in the correlated condition in both replications. This finding was interpreted as an instance of the overshadowing of the acquisition of signal value by a response because of the presence of the stimulus, which, in the correlated condition, was a more reliable predictor of reinforcement than the response. A subsequent conditioned reinforcement test confirmed that, in the correlated condition, the stimulus had, indeed, become a signal for reinforcement as a function of RI training.     

Backward associations: Differential learning about stimuli that follow the presence versus the absence of food in pigeons

During training intended to establish positive and negative backward associations, pigeons received periodic 3-sec illuminations of a grain magazine, with food simultaneously available on 50% of the illuminations. For backward-positive subjects, a red keylight followed food trials only; for backward-negative subjects, it followed no-food trials only. During this training, the birds hardly ever pecked the red stimulus (no evidence of backward conditioning). However, when the red stimulus subsequently preceded and signaled grain for all birds, the backward-positive subjects pecked sooner and more often than did the backward-negative subjects, and control subjects performed at an intermediate level. Increases in the amount of original training did not significantly change the facilitatory effects of the backward-positive stimulus, but seemed to enhance the retarding effects of the backward-negative stimulus. These group differences cannot be attributed to what happened after the backward stimuli during original training. The features of the present technique that could possibly have produced strong and long-lasting positive and negative backward associations are discussed in comparison to prior research that has indicated weak or transitory evidence of true backward conditioning.     

Tests of the conditioned reinforcement value of sequential stimuli in pigeons

Egger and Miller (1962) hypothesized that the conditioned reinforcing value of stimuli depends on their information value. Egger and Miller and others have tested this hypothesis by comparing the conditioned reinforcing value of S1 and S2 following S1-S2-reward training. However, none of these experiments have controlled for differential generalization of conditioned reinforcement value from training to comparison tests. That is, the S1 cue pattern during the conditioned reinforcement tests has been very similar to the S1 cue pattern of training, while the training and test S2 cue patterns have been quite dissimilar. In Experiment 1, pigeons in a procedure unconfounded by differential generalization produced S2 reliably more frequently than S1, and pigeons in a confounded procedure produced S1 somewhat more frequently than S2. A significant groups × stimuli interaction was attributed to differential stimulus generalization from training to test for S1 and S2 in the confounded condition. In Experiment 2, pigeons in an unconfounded procedure again produced S2 reliably more frequently under a different testing procedure. The results are interpreted as demonstrating that, following S1-S2-food training trials, S2 is the more effective conditioned reinforcer in unconfounded conditions. A reconceptualization of the information hypothesis is shown to be consistent with these results.     

Some grammatical rules are more difficult than others: The case of the generic interpretation of the masculine

In this paper we argue that the generic use of the masculine represents a grammatical rule that might be easy to learn but difficult to apply when understanding texts. This argument is substantiated by reviewing the relevant literature as well as the recent work conducted by the GREL Group (Gender Representation in Language) on the interaction between stereotypical and grammatical information in the construction of a representation of gender when reading role names. The studies presented in this paper show that the masculine form used as a generic to refer to persons of both sexes, or to persons of indefinite sex or whose sex is irrelevant, in gender marked languages is likely to be associated with its specific meaning (i.e., masculine refers only to men). This is true even though the generic nature of the masculine is a very common grammatical rule learnt at school. People may have learned this rule and may understand it, but may not readily apply it.     

物理教学中使用课件应注意的几个问题

多媒体教学是一种立体式的教学，它信息量大，直观性强，节奏快，密度高，集中了图形、文字、动画、声效等多媒体的技术，将抽象的物理概念和物理过程，以直观的形式展现在学生面前，活化了教学内容．多媒体技术和物理教学的结合，为激发学生的学习兴趣，提高教学质量提供了理想的平台。正因如此，现在越来越多的     

深圳市产业结构调整要学会两条腿走路———高新技术产业与重化工产业并重

产业结构调整是目前深圳市经济发展迫切需要解决的问题。高新技术产业是深圳市国民经济发展的支柱产业, 但是高新技术产业大多属于生产最终消费品的产业, 前后向关联作用不强。深圳需要辐射和带动能力更强的重化工工业。从国外发展重化工工业的历史启示和深圳产业结构的现状上看, 深圳未来产业的发展方向应是高新技术产业与重化工工业并重, 双极发展是未来产业结构调整的一个模式。     

Tonic immobility in chickens: Is a stimulus that signals shock more aversive than the receipt of shock?

Three experiments were conducted on the effect of shock and aversive conditioning on tonic immobility. In the first study, increasing the intensity of preinduction shock was shown to produce reliable increases in the duration of immobility. Using classical conditioning procedures in the second experiment, a significant effect of UCS intensity was obtained. In the third experiment, brief confrontation with a conditioned fear stimulus was found more effective than shock for enhancing immobility duration. The data were discussed in terms of the fear hypothesis of animal hypnosis and as supporting a more general notion that the anticipation of shock may be more aversive than the receipt of shock.     

认定制作、传播计算机病毒罪的几个问题

在各种计算机犯罪中，制作，传播计算机病毒的行为示出严重的社会危害性，本文主要阐释制作，传播计算机病毒罪认定方面应注意的几个问题。     

我国个体私营经济发展应注意的几个问题

１９７８年以来我国个体私营经济发展很快,社会地位有很大提高,但是继续发展必须注意一些策略问题。否则,会因失去特点而缺乏应有的活力,甚至因之走向衰退,丧失个体私营经济的国民经济发展发挥的重要作用和活力     

Matching-to-sample in pigeons: In the absence of sample memory,sample frequency is a better predictor of comparison choice than the probability of reinforcement for comparison choice

In matching-to-sample, comparison choice should be controlled by the identity of the sample and, when the sample is not available, by the overall probability of reinforcement associated with each of the comparisons. In the present research, pigeons were trained to match a frequent sample (appearing on 80% of the trials) to one comparison (C _fr) and an infrequent sample (appearing on 20% of the trials) to the other (C _inf), with the number of reinforcements associated with each sample equated. In Experiment 1, the task was identity matching; in Experiments 2 and 3, it was symbolic matching. We asked whether, when control of comparison choice by the sample was reduced (by inserting a delay between the sample and the comparisons), pigeons would choose comparisons on the basis of (1) the number of reinforcements per comparison (and thus show no comparison bias), (2) the comparison associated with the more frequent sample during training (and show a preference forC _fr), or (3) the probability of reinforcement given a correct response (and show a preference forC _inf), or (4) inhibition produced by nonreinforced choice of the more frequently correct comparison (and show a preference forC _inf). Pigeons showed a significant tendency to chooseC _fr. In Experiment 3, we showed that this bias did not result from the effects of intertrial facilitation or interference. Thus, it appears that when control of comparison choice by the sample is reduced, pigeons’ choice is controlled not merely by the probability of reinforcement but also by overall sample frequency.     

初中生物学教学中要重视对学生心理健康的教育

在人的生长发育过程中，随着青春期生殖系统的快速发育，相关的激素分泌量的上升，男、女儿童的生理、心理等各方面都发生了重大变化。从生理上看，男性生殖器开始增大，腋毛、阴毛开始增多，喉结开始突出，并出现遗精现象；女性乳房开始发育，腋毛、阴毛开始出现，并有了初潮。从心理上看，突出的变化表现在两方面：一是由于身体迅速生长，新陈代谢旺盛，     

Assessing more than you teach: the difficult case of transfer

We conducted two case studies to evaluate the effectiveness of individualized remedial reading instruction linked to direct measures of student learning and transfer. The participants were two first grade children at serious risk of reading failure. The instruction targeted decoding of one syllable short vowel words and first emphasized onset-rimes and then phoneme manipulation. Forty words organized into 10 rime patterns were targeted for instruction. Probes consisting of all the instructional words were administered before each instructional session to monitor student progress. We also administered transfer probes to determine if the children could apply their knowledge more broadly. Instruction with onset-rime units yielded excellent maintenance and near transfer (novel words containing instructed rimes) but not far transfer (novel words derived from uninstructed rimes). The instructional change to phoneme manipulation yielded better far transfer for one of the two children. We consider the importance of administering measures that assess more than what is taught to get an accurate portrait of children’s responsiveness to instruction.     

苯酚的羟基难被取代而其苯环上的氢原子却易被取代的原因

众所周知 ,乙醇 (ＣＨ3ＣＨ2 ＯＨ)和苯酚 (Ｃ6 Ｈ5ＯＨ )分子中都含有羟基 (—ＯＨ) ,但是羟基的取代活性却大不相同。例如 ,把乙醇与氢溴酸混合加热 ,就能得到一种不溶于水且比水轻的油状液体溴乙烷(ＣＨ3ＣＨ2 ＯＨ +ＨＢｒ △ ＣＨ3ＣＨ2 Ｂｒ +Ｈ2 Ｏ) ,说明在反应中 ,乙醇分子中的碳氧键断裂 ,卤素原子取代了羟基而生成了卤代烃。但是苯酚中的羟基在一般条件下 ,却很难使碳氧键断裂而发生取代反应。这种取代活性的差异可以从两者结构的不同找到原因。在醇分子中。由于碳和氧电负性不同 ,两原子间的电子云偏向电负性较强的氧原子一方 ,…