Pigeon and human performance in a multi-armed bandit task in response to changes in variable interval schedules

The tension between exploitation of the best options and exploration of alternatives is a ubiquitous problem that all organisms face. To examine this trade-off across species, pigeons and people were trained on an eight-armed bandit task in which the options were rewarded on a variable interval (VI) schedule. At regular intervals, each option’s VI changed, thus encouraging dynamic increases in exploration in response to these anticipated changes. Both species showed sensitivity to the payoffs that was often well modeled by Luce’s (1963) decision rule. For pigeons, exploration of alternative options was driven by experienced changes in the payoff schedules, not the beginning of a new session, even though each session signaled a new schedule. In contrast, people quickly learned to explore in response to signaled changes in the payoffs.     

含时滞不确定线性系统的输出鲁棒镇定

研究了含时滞的不确定系统的输出反馈鲁棒镇定问题，该系统同时含有时变状态时滞和时变控制时滞，所构造的控制器增益矩阵包含在两个Hamiltonina矩阵中。所给镇定的充分条件易于检测，控制器有易于设计的特点。     

An IRT modeling of change over time for repeated measures item response data using a random weights linear logistic test model approach

In this study, repeated measures item response data from an English language proficiency (ELP) test administered over 2?years were analyzed by item response theory-based approaches to model change over time. First, change over time was modeled by an item side change approach where change was parameterized at the item level. Second, more importantly, this study introduced and demonstrated an application of an interaction model for change, which overcomes a limitation of the item side change approach by allowing interaction effects between persons and item side change parameters. The results showed that student changes in the ELP data used in this study should be modeled for the three sub-content areas and that modeling interaction for change was necessary.     

The effect of a retention interval on habituation of the neophobic response

In three experiments, water-deprived rats were preexposed to a novel saccharin solution. The neophobic response to this flavor was then assessed in a choice test involving saccharin and water, administered either immediately or 24 h after preexposure. Subjects displayed a significantly greater preference for saccharin at the 24-h test than at the immediate test (Experiments 2 and 3). This “incubation” effect was eliminated if the subjects were more water-deprived at the delayed test than at the immediate test (Experiment 1), and enhanced if the amount of saccharin consumed during preexposure was increased (Experiment 3). Possible ways in which current theories of habituation might be amended in order to accommodate this finding are discussed.     

Differential effects of a retention interval on latent inhibition and the habituation of an orienting response

In Experiment 1, rats experienced presentations of a discrete visual stimulus (Stage 1) until habituation of the orienting response (OR) occurred. On a test session given after an interval of 16 days (Stage 2) the OR reappeared. For control subjects that received no Stage 1 training but presentations of the light in Stage 2, habituation persisted during the test. All subjects then received conditioning trials on which the light preceded the delivery of food. They showed latent inhibition, acquiring the conditioned response less readily than control subjects that had not previously experienced the light. Experiment 2 confirmed that the latent inhibition effect survived the retention interval for subjects that received no habituation test session. This pattern of results implies that habituation of the OR and latent inhibition are determined by different mechanisms.     

Influence of surface treatments on fatigue life of a two-stroke free piston linear engine component using random loading

INTRODUCTION Fatigue durability has long been important issues in the design of a two-stroke free piston linear engine structure (Torres and Voorwald, 2002; Rahman et al., 2005a; 2005b). Durability assessment is traditionally done in the later part of the product development stage when prototypes are available, and heavily re- lied on in confirming ground durability tests. This process is very time consuming and often results in over-design with weight penalties, which is the major obsta…     

半无界奇异边值问题Laguerre谱配置方法

以Laguerre-Gauss-Radau节点为配置点,利用广义Laguerre谱配置方法求数值解,逼近半无界常微分方程奇异边值问题的正确解.给出算法格式和相应的数值例子,表明所提算法格式的有效性和高精度.这里所用方法也可用于求解其他奇异问题.     

基于状态方程法的钢筋混凝土梁桥随机地震反应概率分析

钢筋混凝土梁桥在地震作用下结构可简化为一多自由度体系，基于状态方程法的一般原理，推导了钢筋混凝土梁桥的自由振动解和强迫振动解，并对结构在平稳白噪声激励下进行了随机地震反应分析。     

捕食者具有反馈控制的Leslie-Gower捕食-食饵模型的稳定性研究

研究一类捕食者具有反馈控制的Leslie-Gower捕食食饵模型,通过构造Lyapunov函数方法,可以得到系统的唯一正平衡点是全局稳定的结论.这表明反馈控制变量只改变平衡点的位置-捕食者密度增加而食饵密度降低,但不会改变系统的稳定性态.     

Fostering achievement and motivation with bug-related tutoring feedback in a computer-based training for written subtraction

Most studies on feedback compare elaborated feedback types presenting knowledge on the correct response (KCR) immediately together with further information to simple feedback types providing knowledge of result (KR) or KCR. This study uses bug-related tutoring feedback (BRT-feedback) offering strategic information for error correction, but no immediate KCR. In a computer-based learning experiment with 50 fourth-grade pupils having learning difficulties in written subtraction, cognitive and motivational effects of this BRT-feedback algorithm were compared to the effects of a traditional KR–KCR-feedback algorithm. Results show that BRT-feedback is significantly more beneficial for achievement and motivation than KR–KCR-feedback.     

基于区间数据加速寿命试验参数估计的EM算法

主要讨论了在步进应力加速寿命试验中,如果寿命分布服从对数正态分布,寿命数据为区间数据,且试验产品满足Nelson提出的累积失效模型的情况下,可以通过推导出的时间折算公式及EM算法给出参数估计。同时举例说明了在样本数据较多的情况下该估计方法的有效性。     

具有反馈控制和时滞的两企业竞争与合作离散模型的持久性

研究一类具有反馈控制和时滞的两企业竞争与合作的离散模型.运用差分不等式的有关理论,得到保证该系统持久的充分性条件.所得结论表明在适当条件下,反馈控制变量对该系统的持久性没有影响.     

具无穷时滞反馈控制竞争模型的全局吸引性的注记

研究了两种群具有无穷时滞反馈控制竞争模型的正平衡点的全局吸引性，通过构造单调递归序列的方法得到该模型存在全局吸引正平衡点的充分性条件．     

具无穷时滞反馈控制竞争模型的全局吸引性的注记

研究了两种群具有无穷时滞反馈控制竞争模型的正平衡点的全局吸引性,通过构造单调递归序列的方法得到该模型存在全局吸引正平衡点的充分性条件.     

Early science learning with a virtual tutor through multimedia explanations and feedback on spoken questions

The purpose of this pilot study with a within-subject design was to gain a deeper understanding about the promise and restrictions of a virtual tutoring system designed to teach science to first grade students in Finland. Participants were 61 students who received six tutoring science sessions of approximately 20 min each. Sessions consisted of a sequence of narrated multimedia science presentations during which a virtual tutor explained science phenomena displayed in pictures. Narrated science explanations were followed by one or more multiple choice questions with immediate feedback about students’ choices and a possible second attempt, during which students reached 97% accuracy. A pretest and posttest was administered to assess students’ ability to reason about the science and to transfer knowledge to new contexts. Results indicated significantly greater improvement in the understanding of the science concepts taught during the tutoring sessions, relative to the concepts that were not taught. Results from the surveys administered to teachers and students indicated that the program was well received. Detailed analysis of student error responses provided a deeper understanding about the complex interplay between students’ prior knowledge, the way topics were taught in the multimedia lessons, and the way learning was assessed. Findings from the quantitative and qualitative analyses are discussed in the context of designing high quality lessons delivered through a virtual tutoring system.     

Instrumental responding by rats on free-operant schedules with components that schedule response-dependent reinforcer omission: Implications for optimization theories

In two experiments, we assessed whether rats optimize the number of reinforcers per response. In Experiment 1, one group of rats was trained to leverpress for food reinforcement on a simple variable-interval (VI) 60-sec schedule. For another group, a negative fixed-ratio component was imposed on the VI schedule to produce a conjoint contingency in which reinforcement became available on the VI schedule but was omitted when the ratio criterion was satisfied. In Experiment 2, one group of rats responded on a VI schedule and also received response-independent food. For another group, responding above a certain rate canceled the response-independent food. Despite the negative contingency experienced by the groups in Experiments 1 and 2, responding was maintained at a level at which the number of obtained reinforcers was reduced substantially below the maximum number possible. In addition, in both experiments, the groups that experienced the negative contingency responded at a lower rate than did a yoked control group that experienced the same frequency of reinforcement but lacked the negative component. These results demonstrate that although rats do not optimize their behavior with respect to reinforcement, they are nevertheless sensitive to some aspect of the instrumental contingency in operation.     

Longitudinal perspectives on students’ experiences of feedback: a need for teacher–student partnerships

ABSTRACT

How students react to and use feedback is an important element of their higher education experience. Within the constraints of mass higher education, effective feedback processes are, however, difficult to manage. The aim of this longitudinal qualitative inquiry is to investigate through repeated interviews and related documentary analysis how four case study learners experienced feedback processes over the duration of their undergraduate studies. The analysis is guided by a social constructivist perspective on feedback research. The findings highlight students’ development of more sophisticated orientations to feedback over time; how they experienced and used feedback over the shorter and longer term; their varied affective responses; and how their perspectives evolved. The novel aspects of the findings lie in detailing the individual nature of students’ responses to feedback and documenting the different ways these changed during their undergraduate studies. The role of grades and projected honours classification was a significant element of the performative nature of the students’ experience, and impacted on the extent to which they engaged with feedback. Students often felt that there were dissonances between feedback that teachers were providing and what would be useful or palatable to them. The implications propose that the concept of students as partners can support the reframing of feedback processes as a partnership between students and teachers. Partnership approaches resonate with the need for social constructivist approaches to feedback where knowledge and understanding are co-constructed. Feedback partnerships also carry potential to enable the mutual development of staff and student feedback literacy.     

Maltreatment of children with disabilities: training needs for a collaborative response

PROBLEM STATEMENT: There is a dearth of research on how to respond to children with disabilities who have been maltreated. The literature that does exist recommends a collaborative team approach, with each team member possessing a broad understanding of the special considerations of working with children with disabilities. The literature does not define current understanding levels of response team members in comparison to essential knowledge levels. METHOD: The current study used a needs assessment instrument tailored to each of three key groups: parents, educators, and investigators. Respondents were asked about their knowledge level, experience with, and training interests on maltreatment of children with disabilities. RESULTS: While respondents seemed to have a cursory awareness in some of the topic areas, their knowledge levels were not extensive in most of the survey areas. A majority of respondents were willing to attend training, and all three groups ranked the recognition of maltreatment of children with disabilities as a top training priority. CONCLUSIONS: It was concluded that these integral players in the response to maltreatment of children with disabilities are receptive to becoming more effective partners, by attending training to bridge the knowledge gaps they possess. The current study helps document the nature of those knowledge gaps and, thereby informs the development of training programs for building a more coordinated and informed response to maltreatment of children with disabilities.