Optimal Partitioning of Testing Time: Theoretical Properties and Practical Implications

This paper deals with optimal partitioning of limited testing time in order to achieve maximum total test score. Nonlinear optimization theory was used to analyze this problem. A general case using a generic item response model is first presented. A special case that applies a response time model proposed by Wang and Hanson (2005) is also presented. Theoretical properties of the optimal solution are derived. Their practical implications to optimal test-taking strategies are also discussed. The theoretical properties are in general agreement with the conventional advice to the examinees on pacing strategy.     

Right hemispatial neglect: frequency and characterization following acute left hemisphere stroke

The frequency of various types of unilateral spatial neglect and associated areas of neural dysfunction after left hemisphere stroke are not well characterized. Unilateral spatial neglect (USN) in distinct spatial reference frames have been identified after acute right, but not left hemisphere stroke. We studied 47 consecutive right handed patients within 48h of left hemisphere stroke to determine the frequency and distribution of types of right USN using cognitive testing and MRI imaging. The distribution of USN types was different from the previously reported distribution following acute right hemisphere stroke. In this left hemisphere stroke population, allocentric neglect was more frequent than egocentric neglect.     

下腰痛综合征的诊治与人文思想

下腰痛是一种常见的骨科病症,轻者可影响患者生活,重者可使患者丧失劳动力。它的发病原因有很多,治疗方法各有不同。在下腰痛的诊断中要按照适度医疗的原则选择合适的检查;在下腰痛的治疗中须按照最优化医疗的原则选择最佳的治疗方案。在治疗中要注意结合人文思想来提高下腰痛的治疗效果。     

基于性能反馈的PSO算法速度上限调整策略

速度上限是影响微粒群算法性能的一个主要参数。针对现有调节策略存在参数统一设置、与微粒性能无关等缺点,本文提出一种基于性能反馈的调整策略,使得速度上限能随着个体性能的改变而动态调整,从而更加真实有效的模拟了鸟类觅食的群体行为特征。仿真结果表明该算法能较好地提高微粒群算法的计算效率。     

The Problem of local optimality with OSMOD

The possibility of obtaining locally optimal solutions with categorical data is pointed out for the original version of OSMOD development by Saito and Otsu. A revision of the initialization strategy in OSMOD is suggested, and its effectiveness in diminishing this possibility is demonstrated.     

Information on response requirements compared with information on food density as a reinforcer of observing in pigeons

On a variable-interval schedule, pecking the key to the pigeon's right (observing response) produced red or green displays relating to the delivery of grain and its dependence on pecking the key to the left (food key). During various blocks of sessions, mixed (no stimulus change) schedules including the following pairs of components were temporarily converted by the observing response to their corresponding multiple (correlated stimuli) schedules: variable-interval 60-s, extinction; variable-interval 60-s, variable-time (response-independent) 60-s; extinction, variable-time 60-s. Differences in food delivery maintained substantial rates of responding on the observing key, without regard to pecking requirements on the food key. Although stimuli correlated with differences in the response requirement on the food key maintained higher observing rates than those maintained by uncorrelated stimuli, they were much lower than those based on food. The value of predictive stimuli as reinforcers is determined by the value of the events predicted. In particular, the cost of pecking appears to be low, and this may place limitations on the applicability of energy-based and economic models of behavior.     

Clustering with relational constraint

The paper deals with clustering problems where grouping is constrained by a symmetric and reflexive relation. For solving clustering problems with relational constraints two methods are adapted: the standard hierarchical clustering procedure based on the Lance and Williams formula, and local optimization procedure, CLUDIA. To illustrate these procedures, clusterings of the European countries are given based on the developmental indicators where the relation is determined by the geographical neighbourhoods of countries.Extended version of the paper presented at the European meeting of the Psychometric Society, Groningen, June, 19–21, 1980.This work was supported in part by the Boris Kidri Fund, Yugoslavia.     

Applying an exemplar model to the artificial-grammar task: Inferring grammaticality from similarity

We present three artificial-grammar experiments. The first used position constraints, and the second used sequential constraints. The third varied both the amount of training and the degree of sequential constraint. Increasing both the amount of training and the redundancy of the grammar benefited participants' ability to infer grammatical status; nevertheless, they were unable to describe the grammar. We applied a multitrace model of memory to the task. The model used a global measure of similarity to assess the grammatical status of the probe and captured performance both in our experiments and in three classic studies from the literature. The model shows that retrieval is sensitive to structure in memory, even when individual exemplars are encoded sparsely. The work ties an understanding of performance in the artificial-grammar task to the principles used to understand performance in episodic-memory tasks.     

Self-construal priming modulates the scope of visual attention

Although it is well documented that cultures influence basic cognitive processes such as attention, the underlying mechanisms remain unclear. We tested the hypothesis that self-concepts that characterize people from different cultures mediate the variation of visual attention. After being primed with self-construals that emphasize the Eastern interdependent self or the Western independent self, Chinese participants were asked to discriminate a central target letter flanked by compatible or incompatible stimuli (Experiment 1) or global/local letters in a compound stimulus (Experiment 2). Experiment 1 showed that, while responses were slower to the incompatible than to the compatible stimuli, this flanker compatibility effect was increased by the interdependent relative to the independent self-construal priming. Experiment 2 showed that the interdependent-self priming resulted in faster responses to the global than to the local targets in compound letters whereas a reverse pattern was observed in the independent-self priming condition. The results provide evidence for dynamics of the scope of visual attention as a function of self-construal priming that switches self-concept toward the interdependent or independent styles in Chinese.     

Want to block earworms from conscious awareness?B(u)y gum!

In a recent article, Jamieson and Mewhort (2009) proposed a novel account of artificial grammar learning (AGL), which is based on a multitrace model of episodic memory, the Minerva 2 model. According to this account, test performance in AGL is based on an assessment of global similarity of the test strings to the memory traces of the training strings. In this article, simulation studies are presented, showing for three different AGL experiments that the predictions of the Minerva 2 model strikingly deviate from participants' performance. It is argued that participants' test performance is not generally based on general similarity.