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101.
The problem of constructing computational models of space that mimic those found in human spatial reasoning is addressed. This paper extends a formal model that addressed point objects in a 2D world to include the presence of line objects and barriers. The problem consists of determining an appropriate global model for the spatial configuration given a sequence of local views or observations. A formal model is proposed based on constraint network theory. The model leads to the identification of stable regions within which perceptual information about the environment changes slowly, and zones of transition within which the perceptual information changes more quickly. A special case of transition zones is a gateway, which may be viewed as a kind of discontinuity or singularity in the model. It is expected that the model obtained will be used to mimic human mental representations of navigable outdoor environments. 相似文献
102.
103.
Recently, it has been recognized that the commonly used linear structural equation model is inadequate to deal with some complicated substantive theory. A new nonlinear structural equation model with fixed covariates is proposed in this article. A procedure, which utilizes the powerful path sampling for computing the Bayes factor, is developed for model comparison. In the implementation, the required random observations are simulated via a hybrid algorithm that combines the Gibbs sampler and the Metropolis-Hastings algorithm. It is shown that the proposed procedure is efficient and flexible; and it produces Bayesian estimates of the parameters, latent variables, and their highest posterior density intervals as by-products. Empirical performances of the proposed procedure such as sensitivity to prior inputs are illustrated by a simulation study and a real example.This research is fully supported by a grant from the Research Grant Council of the Hong Kong Special Administrative Region, China (Project No. CUHK 4346/01H). The authors are thankful to the Editor, the Associate Editor, and anonymous reviewers for valuable comments which improve the paper significantly, and grateful to ICPSR and the relevant funding agency for allowing use of the data in the example. The assistance of Michael K.H. Leung and Esther L.S. Tam is gratefully acknowledged. 相似文献
104.
A person-fit index for polytomous rasch models,latent class models,and their mixture generalizations
A normally distributed person-fit index is proposed for detecting aberrant response patterns in latent class models and mixture distribution IRT models for dichotomous and polytomous data.This article extends previous work on the null distribution of person-fit indices for the dichotomous Rasch model to a number of models for categorical data. A comparison of two different approaches to handle the skewness of the person-fit index distribution is included.Major parts of this paper were written while the first author worked at the Institute for Science Education, Kiel, Germany. Any opinions expressed in this paper are those of the authors and not necessarily of Educational Testing Service. The results presented in this paper were improved by valuable comments from J. Rost, K. Yamamoto, N.D. Verhelst, E. Bedrick and two anonymous reviewers. 相似文献
105.
This paper concerns items that consist of several item steps to be responded to sequentially. The item scoreX is defined as the number of correct responses until the first failure. Samejima's graded response model states that each steph=1,...,m is characterized by a parameterb
h
, and, for a subject with ability, Pr(Xh; )=F(–b
h
). Tutz's general sequential model associates with each step a parameterdh, and it states that Pr(Xh;)=
r
=1h
G(–d
r
). Tutz's (1991, 1997) conjectures that the models are equivalent if and only ifF(x)=G(x) is an extreme value distribution. This paper presents a proof for this conjecture. 相似文献
106.
107.
Although there has been a proliferation of models of supervision in the marriage and family therapy literature recently, most tend to focus on methods rather than on the process of supervision. The model presented here is grounded in developmental concepts and focuses on student learning through a dialectical process of cognitive and emotional growth and incorporates three stages: 1) developing relationships; 2) breaking impasses, and 3) orchestrating changes. Students discover that supervision becomes isomorphic with relationship issues that arise in their therapy sessions. Dialectical in nature in that each stage is characterized by the resolution of contradictory emotions, the supervision process helps supervisees experience emotional shifts in their interactions with others, referred to as emotional restructuring. 相似文献
108.
Ken Cheng 《Animal cognition》1999,2(2):73-78
Honeybees were trained to find sugar water in the middle of an array of two landmarks of different colours. Unrewarded tests
compared searching on the training array with searching on rotated arrays. On rotated tests, a system using the angles between
landmarks would continue to search in the middle. A system using vectors to individual elements would search at locations
outside the rotated array at which the distances and compass directions to a subset of landmarks matched. Results indicated
that bees used both elements and interlandmark angles, but they relied most on one favourite landmark element. Results support
the template model of landmark use in honeybees, with the minor parametric modification that weights given to different elements
may be unequal.
Received:6 July 1998 / Accepted after revision:7 December 1998 相似文献
109.
Effects of practice and task constraints on stiffness and friction functions in biological movements
A dynamical model of the movements of the platform of a ski-simulator was derived from experimental data, using the graphical and statistical methods developed by Beek and Beek (Beek, P. J., & Beek, W. J. (1988). Human Movement Science, 7, 301–342). The data were collected in an experiment in which both amplitude and practice were manipulated. The data were filtered and further reduced to normalised cycles that were averaged within and across subjects. Graphical methods were applied to these averaged normalised cycles to determine the stiffness and friction terms to be included in the model. The relative contribution of each term was assessed by means of multiple regression. The model, which included cubic and quintic Duffing terms and one or two dissipative Van der Pol terms, accounted on average for 99.2% of the variance. The exact parameter setting of the model differed considerably across subjects. For one subject, a qualitatively different model, including Rayleigh instead of Van der Pol terms, provided a better account of the data. Systematic changes of the coefficients in the model, related to amplitude and the duration of practice, were evident. 相似文献
110.
基于等级反应模型的规则空间方法 总被引:1,自引:0,他引:1
本研究基于Tatsuoka的规则空间方法, 对理想反应模式与异常反应指标进行了扩展, 推导了多级评分项目下规则空间方法的算法公式。在4种属性层级结构(发散型、收敛型、线型与无结构型)×4种“失误”作答概率(2%、5%、10%与15%)测验情境下, 以属性模式判准率、被试属性判准率、敏感性与特异性为指标, 检验了多级评分项目下规则空间方法的分类准确性。结果表明:(1) 基于多级评分项目构建的异常反应指标, 能有效地对被试进行分类与解释, 且0-1评分项目下异常反应指标及其性质都是多级评分下的特例; (2) 随着“失误”作答概率的增加, 4种属性层级结构的分类准确性都会降低; (3) 线型和收敛型的分类准确性明显好于发散型与无结构型; (4) 纯规则点的分布对规则空间方法的分类准确性有显著影响。 相似文献