Continuous and discrete latent structure models for item response data

Relations are examined between latent trait and latent class models for item response data. Conditions are given for the two-latent class and two-parameter normal ogive models to agree, and relations between their item parameters are presented. Generalizationss are then made to continuous models with more than one latent trait and discrete models with more than two latent classes, and methods are presented for relating latent class models to factor models for dichotomized variables. Results are illustrated using data from the Law School Admission Test, previously analyzed by several authors.     

Identifying the Career-Interest Profiles of Junior-High-School Students Through Latent Profile Analysis

Exploring the career-interest profiles of students has both practical and theoretical significance; however, a minimal amount of research has been conducted to address this issue. The present study combined latent profile analysis and differentiation values to investigate the career-interest profiles of 13,853 junior-high-school students. The results indicate that while the students’ interests could be stratified into 25 profiles, 44.6% of students could be classified the as having low-differentiation profiles (such as like or dislike all types of vocational activities) and 24.9% of students could be classified the as having the artistic-social (like both artistic and social types of activities) profile. In addition, the proportions of females and males differed significantly among the profiles, but different grades did not. The proportion of males was higher for all three low-differentiation groups than of female proportions. Implications for career practices and future research are proposed.     

Clustering colors

Regier, Kay, and Khetarpal report the results of computer simulations that cluster color stimuli on the basis of their coordinates in CIELAB space, one of two commonly used perceptual color spaces. Regier and coauthors find partitions of those stimuli that are strikingly similar to the way actual color lexicons partition color space. They do not argue for the custom-made clustering method used in their simulations, nor for the assumption of CIELAB space. The present paper aims to answer the question to what extent their computational results depend on these assumptions. It does this by applying a great variety of known clustering methods to Regier et al.’s stimuli, and by assuming not only CIELAB space but also CIELUV space, the other main color space.     

Frontal-Lobe Involvement in Spatial Memory: Evidence from PET,fMRI, and Lesion Studies

Many studies have identified the prefrontal cortex as the brain area that is critical for spatial memory, both in humans and in other primates. Other studies, however, have failed to establish this relation. Therefore, the aim of this paper was to review the literature regarding the role of the human prefrontal lobe in spatial memory. This was done by examining the evidence obtained from neuropsychological patients and from studies using brain-imaging techniques (PET and fMRI). Evidence supporting the notion that the prefrontal cortex is extensively involved in spatial working memory was found. The majority of these studies, however, suggests that frontal-lobe involvement is not related to the type of material that is being processed (e.g., spatial vs. nonspatial), but to process-specific functions, such as encoding and retrieval. Theoretically, these functions could be linked to the central executive within Baddeley's working-memory model, or to recent theories that emphasize the various processes that play a role in working memory. Also, methodological issues were discussed. Further research is needed to enhance our understanding of the precise interaction of domain-specific and general processes.     

Semantic Shifts in Argumentative Processes: A Step Beyond the ‘Fallacy of Equivocation’

In naturally occuring argumentation, words which play a crucial role in the argument often acquire different meanings on subsequent occasions of use. Traditionally, such semantic shifts have been dealt with by the fallacy of equivocation. In my paper, I would like to show that there is considerably more to semantic shifts during arguments than their potentially being fallacious. Based on an analysis of a debate on environmental policy, I will argue that shifts in meaning are produced by a principle I call local semantic elaboration. I will go on to show that semantic shifts in the meaning of a word, the position advocated by a party, and the questions that the parties raise during an argumentative process are neatly tailored to one another, but can be incommensurable to the opponent's views. Semantic shifts thus may have a dissociative impact on a critical discussion. By linking the structure of argumentation to its pragmatics, however, it may be revealed that there are two practices that account for a higher order of coherence of the debate. The first practice is a general preference for disagreeing with the opponent, the second practice is the interpretation of local speech acts in terms of an overall ideological stance that is attributed to the speaker. Because of these practices, parties do not criticize divergent semantic conceptions as disruptive, but they treat them as characteristic and sometimes even metonymic reflections of the parties' positions.