Marginal maximum likelihood estimation of item parameters: Application of an EM algorithm

Maximum likelihood estimation of item parameters in the marginal distribution, integrating over the distribution of ability, becomes practical when computing procedures based on an EM algorithm are used. By characterizing the ability distribution empirically, arbitrary assumptions about its form are avoided. The Em procedure is shown to apply to general item-response models lacking simple sufficient statistics for ability. This includes models with more than one latent dimension.Supported in part by NSF grant BNS 7912417 to the University of Chicago and by SSRC (UK) grant HR6132 to the University of Lancaster.We are indebted to Mark Reiser and Robert Gibbons for computer programming. David Thissen clarified a number of points in an earlier draft.     

The statistical analysis of general processing tree models with the EM algorithm

Multinomial processing tree models assume that an observed behavior category can arise from one or more processing sequences represented as branches in a tree. These models form a subclass of parametric, multinomial models, and they provide a substantively motivated alternative to loglinear models. We consider the usual case where branch probabilities are products of nonnegative integer powers in the parameters, 0_s1, and their complements, 1 - _s. A version of the EM algorithm is constructed that has very strong properties. First, the E-step and the M-step are both analytic and computationally easy; therefore, a fast PC program can be constructed for obtaining MLEs for large numbers of parameters. Second, a closed form expression for the observed Fisher information matrix is obtained for the entire class. Third, it is proved that the algorithm necessarily converges to a local maximum, and this is a stronger result than for the exponential family as a whole. Fourth, we show how the algorithm can handle quite general hypothesis tests concerning restrictions on the model parameters. Fifth, we extend the algorithm to handle the Read and Cressie power divergence family of goodness-of-fit statistics. The paper includes an example to illustrate some of these results.This research was supported by National Science Foundation Grant BNS-8910552 to William H. Batchelder and David M. Riefer. We are grateful to David Riefer for his useful comments, and to the Institute for Mathematical Behavior Sciences for its support.     

一种高效的CD-CAT在线标定新方法：基于熵的信息增益与EM视角

项目增补(Item Replenishing)对认知诊断计算机自适应测验(CD-CAT)题库的维护有着至关重要的作用, 而在线标定是一种重要的项目增补方式。基于数据挖掘中特征选择(Feature Selection)的思路, 提出一种高效的基于熵的信息增益的在线标定方法(记为IGEOCM), 该方法利用被试在新旧题上的作答联合估计新题的Q矩阵和项目参数。研究采用Monte Carlo模拟实验验证所开发新方法的效果, 并同时与已有的在线标定方法SIE、SIE-R-BIC和RMSEA-N进行比较。结果表明：新开发的IGEOCM在各实验条件下均具有较好的项目标定精度和项目估计效率, 且整体上优于已有的SIE等方法; 同时, IGEOCM标定新题所需的时间低于SIE等方法。总之, 研究为CD-CAT题库中项目的增补提供了一种更为高效、准确的方法。     

Method and methodology in medical ethics: Inaugurating another new section

This essay announces the inauguration of a section ofTheoretical Medicine and invites submissions on the topic “Method and Methodology in Medical Ethics.” It offers some sketches of plausible meanings of “method” and of “methodology” and their relationships as these might apply to work in biomedical ethics. It suggests a broad range of issues, dilemmas or conflicts that may be addressed for help via method and/or methodology.     

Testing a SEM Model of Two Religious Concepts and Experiential Spirituality

Guided by Atchley’s Continuity Theory of the Spiritual Self as presented in Aging, spirituality, and religion, Fortress Press, Minneapolis, MN (1995), this study tested the validity of two dimensions of religiosity and one dimension of spirituality. It then examined the extent to which each dimension of religiosity influenced having spiritual experiences for 221 chronically ill older adults. Mean age of the sample was 80 years. Structural equation modeling was used to test a conceptual model. Substantive findings were that private religiosity (prayer and coping), but not public religiosity (participation and other church involvement) may influence reporting spiritual experiences by the older adults in the study. Findings revealed a good model fit to the data and strong factor loadings revealed sound construct validity for the latent variables (i.e., public and private religiosities, and experiential spirituality) in the model.     

Two new illusions of the tongue

New illusions resulting from failures in proprioception are described. The Forked Tongue illusion results from weaving the tongue among the prongs of a fork, or from using the prongs of a fork to distort skin on other parts of the body-in these cases, the prongs feel misaligned even though the fork has not bent. The Tongue Twister illusion results from turning the tongue upside down and probing it with a finger or foreign object-the object can be felt to be in the wrong spatial location, opposite to where it actually is on the tongue.     

Human stigmergy: Theoretical developments and new applications

This paper contextualizes and introduces this special issue.     

The memory of another past: Bergson,Deleuze and a new theory of time

Through the philosophies of Bergson and Deleuze, my paper explores a different theory of time. I reconstitute Deleuze’s paradoxes of the past in Difference and Repetition and Bergsonism to reveal a theory of time in which the relation between past and present is one of coexistence rather than succession. The theory of memory implied here is a non-representational one. To elaborate this theory, I ask: what is the role of the “virtual image” in Bergson’s Matter and Memory? Far from representing the simple afterimage of a present perception, the “virtual image” carries multiple senses. Contracting the immediate past for the present, or expanding virtually to hold the whole of memory (and even the whole of the universe), the virtual image can form a bridge between the present and the non-representational past. This non-representational account of memory sheds light not only on the structure of time for Bergson, but also on his concepts of pure memory and virtuality. The rereading of memory also opens the way for Bergsonian intuition to play an intersubjective role; intuition becomes a means for navigating the resonances and dissonances that can be felt between different rhythms of becoming or planes of memory, which constitute different subjects.     

A note on the geometric interpretation of the EM algorithm in estimating item characteristics and student abilities

This note uses the EM-algorithm in an item response model as an illustration of a general method of parameter estimation, which geometrically can be described as an alternating projection method. The research was initiated by a series of lectures on alternating projection methods given by Imre Csiszar in 1993 at Stanford University where the first author was a graduate student.     

Overcoming a child's resistance to late adoption: how one new attachment can facilitate another

The paper describes the difficulty which late-adopted children may have in forming attachments to their new parents. It considers the nature of the disorganized attachment pattern which many of these deprived, abused children display and the origin of this pattern in experiences of 'fright without solution'. The psychotherapy of a 9-year-old, late-adopted boy is used to illustrate long-standing resistance to new attachments on account of defences on which security depends, and the persistence of loyalty to prior internal attachment representations. Change becomes possible through psychotherapy in which earlier negative attachment models are externalized together with their associated feelings of 'fright without solution'. For this boy, a long period of rejection of the therapist gave way to a new capacity to play together; this was associated with the development of positive attachments to the boy's adoptive parents.     

Acquired flavour preferences: contextual control of adaptation-level effects

This experiment investigated the role of context in the expression of conditioned flavour preferences. Rats were trained on a mixture of almond and sucrose and were then given intermixed exposures to almond in one context (Context A) and to sucrose in a second context (Context S). Finally, choice tests were given in both contexts, with one group given almond-versus-water tests and the other almond + sucrose-versus-sucrose tests. Preference for almond over water was greater in Context A than in Context S. Conversely, preference for almond + sucrose over sucrose was greater in Context S than in Context A. These results suggest that the perceived sweetness of a flavour depends on the context in which it is presented and confirm that expression of a flavour preference depends on the type of test employed.     

Acquired flavour preferences: Contextual control of adaptation-level effects

This experiment investigated the role of context in the expression of conditioned flavour preferences. Rats were trained on a mixture of almond and sucrose and were then given intermixed exposures to almond in one context (Context A) and to sucrose in a second context (Context S). Finally, choice tests were given in both contexts, with one group given almond-versus-water tests and the other almond + sucrose-versus-sucrose tests. Preference for almond over water was greater in Context A than in Context S. Conversely, preference for almond + sucrose over sucrose was greater in Context S than in Context A. These results suggest that the perceived sweetness of a flavour depends on the context in which it is presented and confirm that expression of a flavour preference depends on the type of test employed.     

Beyond the treatment of epilepsy: new applications of vagus nerve stimulation in psychiatry

Vagus nerve stimulation (VNS) in humans generally refers to stimulation of the left vagus nerve at the cervical level VNS is an established treatment largely devoid of severe side effect for medically refractory partial onset seizures and has been used in more than 16,000 patients. Over the past 5 years, applications in other neuropsychiatric disorders have been investigated with a special emphasis on depression. Recent data from an open-label, multi-center pilot study involving 60 patients suggest a potential clinical usefulness in the acute and maintenance treatment of drug-resistant depressive disorder. The perspective of VNS as along-term treatment with the advantage of assured compliance makes it an interesting technique to potentially treat drug-resistant depression. However, definite therapeutic effects of clinical significance remain to be confirmed in large placebo-controlled trial. Results of clinical pilot studies involving patients suffering from obesity and Alzheimer's disease indicate that VNS might induce weight loss and improve cognition. Besides its clinical usefulness, VNS can be used as a research tool, allowing neurophysiologic investigations of the parasympathetic system and its interactions with other parts of the central nervous system.     

Psychological applications on the internet: A discipline on the threshold of a new millennium

The rapid developments in computers and information technology over the past decade has had an impact on psychology, which has moved in this context from local computer applications to network applications that take advantage of the Internet. This article critically reviews various psychological applications in use on the Internet, with special emphasis given to their promises and advantages as well as to their shortcomings and problems. Specifically, 10 types of psychological Internet applications are reviewed: information resources on psychological concepts and issues; self-help guides; psychological testing and assessment; help in deciding to undergo therapy; information about specific psychological services; single-session psychological advice through e-mail or c-bulletin boards; ongoing personal counseling and therapy through e-mail; real-time counseling through chat, web telephony, and videoconferencing; synchronous and asynchronous support groups, discussion groups, and group counseling; and psychological and social research. Following a discussion of ethical and related concerns, a call is voiced for intensive research and international brainstorming.     

Kant and Hegel on freedom: Two new interpretations

Can Kant's theory of freedom be defended in contemporary ‘incompatibilist’ terms, as Henry Allison believes, or is it vulnerable to Hegelian criticisms of the ‘compatibilist’ sort that Allen Wood presents? I argue that the answer to both of these questions is negative, and that there is a third option, namely that Kant's real theory of freedom is not as well off as Allison contends, nor as weak as Wood claims. Allison tries to save Kant's theory of freedom from both what he takes to be traditional and improper interpretations ‐ notably including Hegel's and Wood's ‐ of what that theory means, as well as from traditional and improper objections to its defensibility. I argue in part with Wood (and Hegel) against Allison on the issue of the meaning of Kant's theory, and in part with Allison against Wood (and Hegel) on the issue of the defensibility of Kant's theory.     

Seasonal variations in the birth of left-handers: another look

An attempt was made to replicate a reported seasonal variation in the birth of left-handed females. The observed number of births per month (as well as season) did not depart from the number expected by chance. This is the second failure to observe the reported overrepresentation of November births.     

Malicious pleasure: schadenfreude at the suffering of another group

Two studies examined intergroup schadenfreude--malicious pleasure at an out-group's misfortune. Study 1 showed that schadenfreude regarding a German loss in soccer was increased by interest in soccer and threats of Dutch inferiority. The effect of inferiority threat was especially strong for participants less interested in soccer; the more interested showed relatively high schadenfreude. Study 2 replicated these effects by showing a similar pattern of schadenfreude regarding losses by Germany and Italy in another setting. However, schadenfreude toward legitimately superior Italy was lower when a norm of honest and direct expression was made salient to participants lower in soccer interest. These results establish schadenfreude as an emotion that is moderated by the salient dimensions of particular intergroup relations.