Handling Locally Stratified Inconsistent Knowledge Bases

This paper investigates the idea of reasoning, in a local (or contextual) way, under prioritized and possibly inconsistent knowledge bases. Priorities are not supposed to be given globally between all the beliefs in the knowledge base, but locally inside sets of pieces of information responsible for inconsistencies. This local stratification offers more flexibility for representing priorities between beliefs. Given this local ordering, we discuss five basic definitions of influence relations between conflicts. These elementary notions of influence between two conflicts A and B exhaustively explore the situations where solving A leads to solve B. Then we propose natural approaches to restore the coherence of a knowledge base on the basis of influence relations between locally-stratified conflicts.     

The effects of perceived competence and sociability on electoral outcomes

Previous research demonstrated that inferences of competence from the face are good predictors of electoral outcomes [Todorov, A., Mandisoza, A. N., Gore, A., & Hall, C. C. (2005). Inferences of competence from faces predict election outcomes. Science, 308, 1623-1626]. In the current work we examined the role of another key dimension in social perception, namely perceived sociability. Results showed that people considered both competence and sociability, as inferred from the face, as related to higher chances of winning the elections. A different pattern emerged in relation to the actual electoral outcomes. Indeed, perceived competence was related to higher chances of winning, whereas perceived sociability was negatively related to electoral success. It is thus shown that these two fundamental dimensions in social perception exert opposite effects on voting behaviors.     

Conditional Reinforcers and Informative Stimuli in A Constant Environment

Five pigeons responded on steady-state concurrent variable-interval variable-interval schedules of food presentation in which half of the foods were removed and replaced with nonfood stimuli. Across conditions, the stimuli were either paired or unpaired with food, and the correlation between the ratio of food deliveries on the two alternatives and the ratio of nonfood stimuli was either −1, 0, or +1. Neither the pairing of stimuli with food, nor the correlation between stimuli and food, affected generalized-matching performance, but paired stimuli had a demonstrable effect at a local level of analysis. This effect was independent of the food–stimulus correlation. These results differ from results previously obtained in a frequently changing environment. We attribute this difference in results to differences in the information value of response-contingent stimuli in frequently changing versus relatively constant environments, as well as to differences between forward pairing and simultaneous pairing of the stimuli with food.     

汉字内隐记忆的实验研究（Ⅰ）──内隐记忆存在的条件

通过四个２×２×２方差设计实验,将直接测量（再认任务）和间接测量（偏好判断任务）在形式上进行匹配,考察了汉字的注意因素,测量任务因素和时程因素经过不同组合构成的１０种情况,其中测量任务因素的间接测量根据汉字的局部加工（字形、字义、字音）和整体加工（整体特征）分为四种子任务,试图寻找汉字认知范畴里内隐记忆存在的条件。实验分学习和测验两个阶段。学习阶段的处理对所有被试都相同。测验阶段的不同指导语形成不同的测量任务。结果发现了内隐记忆存在的三个必要条件是非注意（目标）汉字,汉字的整体加工和偏好判断任务后阶段。匹配方法的使用是发现内隐记忆的保证。汉字的整体加工和局部加工具有不同的特点。     

A multidimensional item response model: Constrained latent class analysis using the gibbs sampler and posterior predictive checks

In this paper it will be shown that a certain class of constrained latent class models may be interpreted as a special case of nonparametric multidimensional item response models. The parameters of this latent class model will be estimated using an application of the Gibbs sampler. It will be illustrated that the Gibbs sampler is an excellent tool if inequality constraints have to be taken into consideration when making inferences. Model fit will be investigated using posterior predictive checks. Checks for manifest monotonicity, the agreement between the observed and expected conditional association structure, marginal local homogeneity, and the number of latent classes will be presented.This paper is supported by grant S40-645 of the Dutch Organization for Scientific Research (NWO).     

Cluster differences scaling with a within-clusters loss component and a fuzzy successive approximation strategy to avoid local minima

Cluster differences scaling is a method for partitioning a set of objects into classes and simultaneously finding a low-dimensional spatial representation ofK cluster points, to model a given square table of dissimilarities amongn stimuli or objects. The least squares loss function of cluster differences scaling, originally defined only on the residuals of pairs of objects that are allocated to different clusters, is extended with a loss component for pairs that are allocated to the same cluster. It is shown that this extension makes the method equivalent to multidimensional scaling with cluster constraints on the coordinates. A decomposition of the sum of squared dissimilarities into contributions from several sources of variation is described, including the appropriate degrees of freedom for each source. After developing a convergent algorithm for fitting the cluster differences model, it is argued that the individual objects and the cluster locations can be jointly displayed in a configuration obtained as a by-product of the optimization. Finally, the paper introduces a fuzzy version of the loss function, which can be used in a successive approximation strategy for avoiding local minima. A simulation study demonstrates that this strategy significantly outperforms two other well-known initialization strategies, and that it has a success rate of 92 out of 100 in attaining the global minimum.     

Fixed-ratio performance with and without a postreinforcement timeout

Pigeons pecked a key, producing food reinforcement on fixed-ratio (FR) schedules requiring 50, 100, or 150 responses. In each session, 30-second timeouts were inserted before a random half of the FR trials, whereas the other trials began immediately after reinforcement. In general, preratio pauses were shorter on trials preceded by timeouts. On these trials, the probability of a first response tended to be highest in the first 20 seconds of the trials, suggesting that the shorter pauses were the result of transient behavioral contrast. Direct observations and analyses of interresponse times (IRTs) after the preratio pause indicated that IRTs could be grouped into three categories: (1) IRTs of about .1 second, which were produced by small head movements in the vicinity of the key; (2) IRTs of about .3 second, which were produced by distinct pecking motions; and (3) IRTs greater than .5 second, which were accompanied by pausing or movements away from the key. At all ratio sizes, as a subject progressed through a trial, the probability of a long IRT decreased, whereas the probability of an intermediate IRT usually increased at first and then decreased. The probability of a short IRT increased monotonically across a trial. The results show that responding changes systematically as a subject progresses through a ratio on an FR schedule. Some characteristics of performance varied as functions of the absolute size of the response requirement, whereas others appeared to depend on the relative location within a ratio (i.e., the proportion of the ratio completed at a given moment).     

Local rates of responding and reinforcement during concurrent schedules

The literature was searched for information about the local rates of responding and reinforcement during concurrent schedules. The local rates of reinforcement obtained from the two components of a concurrent schedule were equal when a long-duration changeover delay was used and when many sessions were conducted, except when the two components provided different simple schedules. The local rates of responding were equal under some conditions, but they differed when one component provided a ratio and the other an interval schedule. Across schedules, local rates of reinforcement changed with changes in the schedule of reinforcement. Local rates of responding did not change with changes in change-over-delay duration but did with changes in the changeover ratio and with changes in the programmed rates of reinforcement. The results generally conform to the Equalizing and Melioration Principles and help to clarify current statements of the Matching Law. The results also suggest that changes in the local rates of responding and reinforcement may be orderly across schedules.     

Effects of variations in local reinforcement rate on local response rate in variable interval schedules

Rats trained to lever press for sucrose were exposed to variable-interval schedules in which (i) the probability of reinforcement in each unit of time was a constant, (ii) the probability was high in the first ten seconds after reinforcement and low thereafter, (iii) the probability was low for ten seconds and high thereafter, (iv) the probability increased with time since reinforcement, or (v) the probability was initially zero and then increased with time since reinforcement. All schedules generated similar overall reinforcement rates. A peak in local response rate occurred several seconds after reinforcement under those schedules where reinforcement rate at this time was moderate or high ([i], [ii], and [iv]). Later in the inter-reinforcement interval, local response rate was roughly constant under those schedules with a constant local reinforcement rate ([i], [ii], and [iii]), but increased steadily when local reinforcement rate increased with time since reinforcement ([iv] and [v]). Postreinforcement pauses occurred on all schedules, but were much longer when local reinforcement rate was very low in the ten seconds after reinforcement ([iii]). The interresponse time distribution was highly correlated with the distribution of reinforced interresponse times, and the distribution of postreinforcement pauses was highly correlated with the distribution of reinforced postreinforcement pauses on some schedules. However, there was no direct evidence that these correlations resulted from selective reinforcement of classes of interresponse times and pauses.     

Undermatching and contrast within components of multiple schedules

Six multiple variable-interval schedules each comprised one variable-interval sixty second component and an alternated component which was varied. Four pigeons' responses were recorded in five successive subintervals of each component. Response rate changes across subintervals revealed instances of local contrast and small local induction effects in the changed component. In the constant component, smaller local contrast and larger local induction effects obtained. Accordingly, the magnitude of behavioral contrast, defined as an inverse relation between response rate in the constant component and reinforcement rate in the changed component, did not change reliably across subintervals of the constant component. Ratios of response rates in initial subintervals were highly sensitive to reinforcement ratios. Sensitivity decreased sharply over the first two-fifths of the components and remained constant for the remainder. The results demonstrated that changes in multiple schedule sensitivity are a function of time since the alternation of successive components.