Bug distribution and statistical pattern classification

A model (called the rule space model) which permits measuring cognitive skill acquisition, diagnosing cognitive errors, detecting the weaknesses and strengths of knowledge possessed by individuals was introduced earlier. This study further discusses the theoretical foundation of the model by introducing bug distribution and hypothesis testing (Bayes' decision rules for minimum errors) for classifying subjects into their most plausible latent state of knowledge. The model is illustrated with the domain of fraction arithmetic and compared with the results obtained from a conventional artificial intelligence approach.The authors would like to acknowledge Mr. Robert Baillie for developing several computer programs used for this research.This research was sponsored by the Personnel and Training Research Program, Psychological Sciences Division, Office of Naval Research.Some of the analyses presented in this report were performed on the PLATO® system. The PLATO® system is a development of the University of Illinois and PLATO® is a service mark of the Control Data Corporation.     

An examination of procedures for determining the number of clusters in a data set

A Monte Carlo evaluation of 30 procedures for determining the number of clusters was conducted on artificial data sets which contained either 2, 3, 4, or 5 distinct nonoverlapping clusters. To provide a variety of clustering solutions, the data sets were analyzed by four hierarchical clustering methods. External criterion measures indicated excellent recovery of the true cluster structure by the methods at the correct hierarchy level. Thus, the clustering present in the data was quite strong. The simulation results for the stopping rules revealed a wide range in their ability to determine the correct number of clusters in the data. Several procedures worked fairly well, whereas others performed rather poorly. Thus, the latter group of rules would appear to have little validity, particularly for data sets containing distinct clusters. Applied researchers are urged to select one or more of the better criteria. However, users are cautioned that the performance of some of the criteria may be data dependent.The authors would like to express their appreciation to a number of individuals who provided assistance during the conduct of this research. Those who deserve recognition include Roger Blashfield, John Crawford, John Gower, James Lingoes, Wansoo Rhee, F. James Rohlf, Warren Sarle, and Tom Soon.     

Effects of the discriminability of alternatives in three-alternative concurrent-schedule performance

Six pigeons were trained on two- and three-alternative concurrent schedules in which the alternatives were signaled by different wavelengths of light on the main pecking key. The schedules were arranged according to a switching-key procedure in which pecks on a white side key produced a 3-s blackout and, intermittently, a change in the variable-interval schedule of food programmed on the main (center) key after the blackout. In Part 1, a two-alternative concurrent variable-interval schedule was arranged in which the alternatives were signaled by 560 nm and 630 nm. Parts 2 and 3 arranged three-alternative concurrent variable-interval schedules with the alternatives signaled by 560 nm, 600 nm, and 630 nm (Part 2) and 560 nm, 623 nm, and 630 nm (Part 3). Within each part, the relative rate of food reinforcers available on the alternatives was varied across a wide range. In all parts of the experiment, the ratios of responses emitted between pairs of alternatives were more extreme than the ratios of reinforcers obtained on the pairs of alternatives, a result termed overmatching. In Parts 2 and 3, generalized matching sensitivities between pairs of alternatives were found to be higher when the reinforcer rate on the third alternative was low than when it was high—an apparent failure of the constant-ratio rule. The data were well described by an extension of the Davison and Jenkins (1985) model, which assumes differing discriminabilities between concurrent-schedule alternatives in combination with a punishing effect of blackout following changeovers.     

Apocalyptic relevance

In their book, Relevance, Sperber and Wilson make an important contribution towards constructing a credible theory of this unforthcoming notion. All is not clear sailing, however. If it is accepted as a condition on the adequacy of any account of relevance that it not be derivable either that nothing is relevant to anything or that everything is relevant to everything, it can be shown that Sperber and Wilson come close to violating the condition.     

Protoalgebraic Gentzen Systems and the Cut Rule

In this paper we show that, in Gentzen systems, there is a close relation between two of the main characters in algebraic logic and proof theory respectively: protoalgebraicity and the cut rule. We give certain conditions under which a Gentzen system is protoalgebraic if and only if it possesses the cut rule. To obtain this equivalence, we limit our discussion to what we call regular sequent calculi, which are those comprising some of the structural rules and some logical rules, in a sense we make precise. We note that this restricted set of rules includes all the usual rules in the literature. We also stress the difference between the case of two-sided sequents and the case of many-sided sequents, in which more conditions are needed.     

小学儿童亲社会价值取向发展的实验研究

本研究采用问卷法对小学二年级、四年级和六年级学生共337人进行研究.结果表明,小学二、四、六年级儿童的亲社会价值取向在某些情境中存在差异.男女儿童的价值取向存在显著差异,女性比男性更加明确自己的价值取向,更愿意对受难者给予直接的关怀和帮助.不同价值取向的儿童在教师评价中表现出显著的亲社会行为差异.     

公民情感的法律确认:立法伦理的应有视域

公民情感的法律确认是基于公民行为选择中两难困境的应对之策。这一立法实践有其学理和历史的依据。将公民情感的法律确认纳入立法伦理的视域,将不仅有助于良法的创制,而且还因其逻辑地排除了司法活动的情感障碍和为公民奠定了守法的情感基础而有利于良法的有效实现。     

决策过程中的记忆可提取性效用

记忆的可提取性效用是人们在评估过往事件时所感受到的愉悦或满意程度, 这种评估建立在人们从记忆中提取出的信息基础上。研究发现, 人们对过往事件进行评估时会出现违反效用最大化原则的决策, 主要表现在三个实验现象上：峰终律、时长忽视和违背单调叠加性。研究者多从原型判断的角度去理解这些现象, 但可提取性效用是否还有其他内在机制仍然有待进一步研究。