When are item response models consistent with observed data?

The problem of deciding whether a set of mental test data is consistent with any one of a large class of item response models is considered. The classical assumption of locla independence is weakened to a new condition, local nonnegative dependence (LND). Necessary and sufficient conditions are derived for a LND item response model to fit a set of data. This leads to a condition that a set of data must satisfy if it is to be representable by any item response model that assumes both local independence and monotone item characteristic curves. An example is given to show that LND is strictly weaker than local independence. Thus rejection of LND models implies rejection of all item response models that assume local independence for a given set of data.This research was supported in part by Grant NIE-G-78-0157 to ETS from the NIE, by the Program Statistics Research Project, and by TOEFL Program Research. I would like to thank Dr. Douglas Jones of ETS for stimulating discussions during the early stages of this research, Dr. Frederick Lord of ETS for his encouragement of this work and comments on earlier drafts of this paper and Professor Robert Berk of Rutgers University for pointing out that conditions (a), (b) and (c) of Theorem 2 were also sufficient for LND and Monotonicity. Dr. Donald Alderman of ETS provided financial support for the development of a computer program to apply these results to data from the TOEFL program.     

Local homogeneity in latent trait models. A characterization of the homogeneous monotone irt model

The stochastic subject formulation of latent trait models contends that, within a given subject, the event of obtaining a certain response pattern may be probabilistic. Ordinary latent trait models do not imply that these within-subject probabilities are identical to the conditional probabilities specified by the model. The latter condition is called local homogeneity. It is shown that local homgeneity is equivalent to subpopulation invariance of the model. In case of the monotone IRT model, local homogeneity implies absence of item bias, absence of item specific traits, and the possibility to join overlapping subtests. The following characterization theorem is proved: the homogeneous monotone IRT model holds for a finite or countable item pool if and only if the pool is experimentally independent and pairwise nonnegative association holds in every positive subpopulation.This research was supported by the Dutch Interuniversity Graduate School of Psychometrics and Sociometrics. The authors wish to thank two reviewers for their thorough comments.     

EFFECTS OF CALORIC LEVEL ON RUMINATING

A series of recent studies has shown that a number of dietary variables affect ruminative behavior in institutionalized retarded persons. This experiment extends an earlier study that examined the influence of the caloric level of the diet on the frequency of ruminating. Subjects consumed regular portions of food that varied between phases from normal to high caloric levels. The data show a clear but modest inverse relation between the caloric value of the diet and the rates of postmeal ruminating.     

Impact of artificial fissioning and social networks on levels of aggression and affiliation in primates

Levels of aggression may be affected by stability of social relationships or by population density. A number of studies of nonhuman primates have indicated that spatial density influences agonistic activity levels less than does social density. Artificial fissioning of a captive troop of rhesus macaques was undertaken and the resultant differences in patterns of aggression and affiliation were examined. If population density has a major effect on levels of aggression, then fissioning will result in a decrease in aggression; if social stability has a major effect on levels of aggression, then fissioning is likely to be accompanied by an increase in aggression. An increase in rates of both aggressive and affiliative behavior resulted from artificial troop fissioning. These findings concur with other studies that have concluded that social stability is a more important determinant of primate aggression than is population density. Nonhuman primates use affiliative mechanisms to adjust their behavior when population density increases such that potentially adverse consequences of crowding are avoided.     

Initial excitatory conditioning with the truly random control procedure in rats: The effects of density of the conditioned stimulus

The present experiments were designed to test whether initial excitatory conditioning to a stimulus was obtained, using a within-subject design of the truly random control (TRC) procedure, and to examine the effects of the density of the conditioned stimulus on it. In Experiment 1, the effect of the three levels of CS density (50%, 25%, 20%) was assessed at six different stages of training, using the conditioned suppression of licking in rats. Although all of the groups given the TRC procedure showed evidence of initial excitatory conditioning, it was more marked in the group with the highest CS density than in the other groups. Experiment 2 confirmed the results of Experiment 1, using a between-subject design. The findings are in line with predictions from the Rescorla-Wagner model, and are discussed with reference to other contemporary theories of associative learning.     

New approaches to the ‘crucial’ test of the causation and selection hypotheses in a Northern Irish sample

This paper examines the relationship between minority/majority status and psychological adjustment, as measured by the GHQ‐12. Rather than using religious labels in Northern Ireland to define minority/majority status, the authors hypothesized that such status is more contingent upon the local area context. Using a purer operationalization of minority/majority status, the authors found no evidence of an ‘ethnic density effect’. Implications for the questionable validity of the ‘crucial test’ of the selection and causation hypotheses are discussed. Copyright © 2002 John Wiley & Sons, Ltd.     

高创造力个体的群体差异性研究

高创造力群体的界定是创造力研究的重要前提,但迄今极少有研究关注以往研究中高创造力群体间的同质性问题。本研究以创造力问题提出能力测验调查了两所高校（一所地方高校和一所教育部直属高校）的975名大学生的创造力,通过极端组方法（extreme groups approach, EGA）为大学生创造力水平分组,考察不同创造力分组之间的差别。研究发现：地方高校和部属高校的高创造力大学生被试,在创造力的流畅性、变通性和独特性三个维度上,均存在显著差异。本研究结果提示,大学生高创造力组间可能存在质的差别,因此相关研究在外推结果时需要采取谨慎态度;研究者在实验过程中和讨论文献结果的可比性时一定要关注样本的同质性问题。     

Prediction of psychological reactions to bone density screening for osteoporosis using a cognitive-behavioral model of health anxiety

Pre-screening measures derived from a cognitive-behavioral theory of health anxiety were significant predictors of individual differences in post-screening reactions to a health screening procedure, bone densitometry. Predictors included specific illness beliefs (vulnerability, severity/consequences, coping and treatment) and general health anxiety measures. Three months after a low bone mineral density (BMD) result, women with high levels of pre-existing general health anxiety gave higher ratings of anxiety about osteoporosis and perceived likelihood of developing osteoporosis than women with low levels of preexisting health anxiety, even though the two groups' initial ratings had not differed significantly. Women with a low BMD result generally showed "minimization" of the seriousness of low BMD but women with very high levels of pre-existing health anxiety did not. After a high BMD result, highly health anxious women were only temporarily reassured. The results were consistent with the cognitive-behavioral analysis of health anxiety.     

Safe periods both explain and need explaining.

Dinsmoor's (2001) stress on the response‐produced safe period as a reinforcer for avoidance behavior is a positive contribution, even though several questions about such safe periods remain to be answered.     

文本信息的激活与整合：阅读优生与差生的比较

探讨阅读优生与差生文本阅读过程中文本信息的激活与整合模式,包括3个实验。实验一通过运用不一致实验范式（inconsistent paradigm）考察阅读优生与阅读差生能否形成整体连贯性与局部连贯性。结果发现,阅读差生难以形成整体连贯性。实验二运用探测－核证范式（probe-verification paradigm）通过比较在三个位置后（人物特征描述、填充段落、目标句）的探测句的反应时间,探讨阅读差生不能形成整体连贯性的原因是由于不能激活先前的信息,还是整合信息时出现了问题。结果发现阅读差生与优生一样都可以激活先前的信息,说明阅读差生不能形成整体连贯性的原因可能是整合的问题。实验三进一步验证了阅读差生不能形成整体连贯性的原因是由于不能把已经激活的信息很好地加以整合所致。