A fast numerical algorithm for the estimation of diffusion model parameters

In this paper, we describe a new algorithmic approach for parameter estimation in Ratcliff's [(1978). A theory of memory retrieval. Psychological Review, 85 (2), 59-108] diffusion model. This problem, especially if inter-trial variabilities of parameters are included in the model, is computationally very expensive; the parameter estimation procedure often takes a long time even with today's high-speed computers. The algorithm described here makes the calculation of the cumulative distribution functions for predicted process durations computationally much less expensive. This improvement is achieved by solving the Kolmogorov backward equation numerically instead of employing the previously used closed form solution. Additionally, the algorithm can determine the optimum fit for one of the model parameters (the starting point z) directly, thereby reducing the dimension of the parameter search space by one. The resulting method is shown to be notably faster than the standard (closed-form solution) method for parameter estimation.     

元代疫灾述论

元代疫灾严重程度难以想象,为害甚重。据史实考察可以发现：元代疫灾虽是由自然界的破坏力及人与人之间社会关系失调共同作用而引发的,但作用主体是有变化的,且时段划分比较明显。疫灾的时间分布密集,空间分布也较为平衡。元政府在防疫方面也有许多积极举措。     

The being-with of being-there

In Being and Time, Heidegger affirms that being-with or Mitsein is an essential constitution of Dasein but he does not submit this existential to the same rigorous analyses as other existentials. In this essay, Jean-Luc Nancy points to the different places where Heidegger erased the possibility of thinking an essential with that he himself opened. This erasure is due, according to Nancy, to the subordination of Mitsein to a thinking of the proper and the improper. The polarization of Being-with between an improper face, the Anyone, and a proper one, the people, which is also, as Nancy shows, a polarization between everydayness and historicity, between a being-together in exteriority (indifference and anonymity) and a being-together in interiority (union through destiny), between a solitary dying and the sacrificial death in combat, leaves the essential with unthought. This essay shows not only the tensions that arise out of Heidegger’s own analyses of Mitsein and affect the whole of Being and Time but also underlines in the end a “shortfall in thinking” inherent not only to Heidegger’s work but, as Nancy claims, to our Western tradition, a shortfall which Nancy has attempted to remedy in his Being Singular Plural. A slightly different version has been published under the title “L’être-avec de l’être-là” in Lieu-Dit 19 “Communauté” (Spring 2003). All additions in square brackets are the translators’ unless otherwise indicated. The German words in parentheses are Nancy’s additions. For the translation of citations from Being and Time, we have used the Macquarrie & Robinson’s translation which we have modified only when constrained by Nancy himself. Overall, we have tried to be faithful to the Heideggerian tone of Nancy’s text by using the accepted English translation of the central concepts of Being and Time. When we depart from the accepted translations, it is to remain true to Nancy’s paraphrases, emphases, and displacements. For example, we refrain from using “authentic” and “inauthentic.” Translated by Marie-Eve Morin Department of Philosophy, 4-97 Humanities Centre, University of Alberta, Edmonton, AB, Canada T6G 2E5 e-mail: mmorin1@ualberta.ca

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Avoidance of timeout from response-independent food: effects of delivery rate and quality

In three experiments, a rat's lever presses could postpone timeouts from food pellets delivered on response-independent schedules. In Experiment 1, the pellets were delivered at variable-time (VT) rates ranging from VT 0.5 to VT 8 min. Experiment 2 replicated the VT 1 min and VT 8 min conditions of Experiment 1 with new subjects. Finally, subjects in Experiment 3 could postpone timeouts from delivery of pellets that differed in quality rather than quantity (unsweetened versus sweetened pellets). In general, response rates and success in avoiding increased as a function of the rate and quality of the pellets. Also, performance efficiency increased as the experiments progressed, that is, the avoidance response occurred later and later in the response-timeout interval. The results support the conclusion that timeout from reinforcement has functional properties similar to those of more commonly studied aversive stimuli (e.g., shock).     

Limited information estimation and testing of discretized multivariate normal structural models

Discretized multivariate normal structural models are often estimated using multistage estimation procedures. The asymptotic properties of parameter estimates, standard errors, and tests of structural restrictions on thresholds and polychoric correlations are well known. It was not clear how to assess the overall discrepancy between the contingency table and the model for these estimators. It is shown that the overall discrepancy can be decomposed into a distributional discrepancy and a structural discrepancy. A test of the overall model specification is proposed, as well as a test of the distributional specification (i.e., discretized multivariate normality). Also, the small sample performance of overall, distributional, and structural tests, as well as of parameter estimates and standard errors is investigated under conditions of correct model specification and also under mild structural and/or distributional misspecification. It is found that relatively small samples are needed for parameter estimates, standard errors, and structural tests. Larger samples are needed for the distributional and overall tests. Furthermore, parameter estimates, standard errors, and structural tests are surprisingly robust to distributional misspecification. This research was supported by the Department of Universities, Research and Information Society (DURSI) of the Catalan Government, and by grants BSO2000-0661 and BSO2003-08507 of the Spanish Ministry of Science and Technology.     

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.     

How to, and how not to, bridge computational cognitive neuroscience and Husserlian phenomenology of time consciousness

A number of recent attempts to bridge Husserlian phenomenology of time consciousness and contemporary tools and results from cognitive science or computational neuroscience are described and critiqued. An alternate proposal is outlined that lacks the weaknesses of existing accounts.     

Quantification over Sets of Possible Worlds in Branching-Time Semantics

Temporal logic is one of the many areas in which a possible world semantics is adopted. Prior's Ockhamist and Peircean semantics for branching-time, though, depart from the genuine Kripke semantics in that they involve a quantification over histories, which is a second-order quantification over sets of possible worlds. In the paper, variants of the original Prior's semantics will be considered and it will be shown that all of them can be viewed as first-order counterparts of the original semantics.     

Are unsupervised neural networks ignorant? Sizing the effect of environmental distributions on unsupervised learning

Learning environmental biases is a rational behavior: by using prior odds, Bayesian networks rapidly became a benchmark in machine learning. Moreover, a growing body of evidence now suggests that humans are using base rate information. Unsupervised connectionist networks are used in computer science for machine learning and in psychology to model human cognition, but it is unclear whether they are sensitive to prior odds. In this paper, we show that hard competitive learners are unable to use environmental biases while recurrent associative memories use frequency of exemplars and categories independently. Hence, it is concluded that recurrent associative memories are more useful than hard competitive networks to model human cognition and have a higher potential in machine learning.     

应当关注时间心理无意识的研究

随着心理无意识研究在记忆、学习和思维等领域的兴起,内隐时间认知也逐步成为时间心理学中的一个研究热点。本文分析了探究内隐时间认知的四种方法:分离范式、序列学习范式、表征动量范式和计时分布相关范式,指出内隐时间认知实验范式在无意识时间人格与社会心理学中的研究也是有相当前景的。