Flexible Bayesian modelling in dichotomous item response theory using mixtures of skewed item curves

Most item response theory (IRT) models for dichotomous responses are based on probit or logit link functions which assume a symmetric relationship between the probability of a correct response and the latent traits of individuals taking a test. This assumption restricts the use of those models to the case in which all items behave symmetrically. On the other hand, asymmetric models proposed in the literature impose that all the items in a test behave asymmetrically. This assumption is inappropriate for great majority of tests which are, in general, composed of both symmetric and asymmetric items. Furthermore, a straightforward extension of the existing models in the literature would require a prior selection of the items' symmetry/asymmetry status. This paper proposes a Bayesian IRT model that accounts for symmetric and asymmetric items in a flexible but parsimonious way. That is achieved by assigning a finite mixture prior to the skewness parameter, with one of the mixture components being a point mass at zero. This allows for analyses under both model selection and model averaging approaches. Asymmetric item curves are designed through the centred skew normal distribution, which has a particularly appealing parametrization in terms of parameter interpretation and computational efficiency. An efficient Markov chain Monte Carlo algorithm is proposed to perform Bayesian inference and its performance is investigated in some simulated examples. Finally, the proposed methodology is applied to a data set from a large-scale educational exam in Brazil.     

Reading, hearing, understanding]

The relationship between reading comprehension, listening comprehension, and two indicators of intelligence (verbal reasoning, speed of information processing) is analyzed on the basis of a hierarchical monistic model. Two tests (reading comprehension, listening comprehension) were administered to 221 4th graders in classroom context at two sessions. Order of administration was balanced. Additionally, verbal reasoning and speed of information processing were assessed, marks in German were collected. On the whole, performance in listening comprehension exceeds reading comprehension as expected for children at that age. In spite of this mean difference a high correlation between the variables was found. In accordance with theory, the relationship between reading and listening comprehension is stronger when the influence of reading specific abilities is lower and reading material is less complex. Listening comprehension appears to be of more relevance to the prediction of reading comprehension than verbal intelligence, speed of information processing, and marks in German, even when listening comprehension is introduced as the last predictor in multiple regression analysis. It is suggested to emphasize the role of listening comprehension in the assessment and prognosis of reading disabilities.     

Self-motion perception influences number processing: evidence from a parity task

We investigated the role of horizontal body motion on the processing of numbers. We hypothesized that leftward self-motion leads to shifts in spatial attention and therefore facilitates the processing of small numbers, and vice versa, we expected that rightward self-motion facilitates the processing of large numbers. Participants were displaced by means of a motion platform during a parity judgment task. We found a systematic influence of self-motion direction on number processing, suggesting that the processing of numbers is intertwined with the processing of self-motion perception. The results differed from known spatial numerical compatibility effects in that self-motion exerted a differential influence on inner and outer numbers of the given interval. The results highlight the involvement of sensory body motion information in higher-order spatial cognition.     

Performing gender justice: the 2005 woman-led prayer in New York

On March 18, 2005, a group of American Muslim women and men participated in a Friday prayer led by Dr. Amina Wadud, who also gave the Friday sermon. Widely publicized in various media and debated among Muslims around the world, this event was hailed as a turning point in Muslim gender discourses by the organizers and many media representatives. This article describes the prayer as a performance and argues that the organizers, participants, and media representatives all participated in the production of meaning embodied by the prayer. According to the organizers, the achievement of Qur'anic gender justice required changes in Muslim communities, and various forms of media were of vital importance for the discussion and realization of this goal. As such, the prayer was an act of symbolic significance, which despite its discursive, spatial, and temporal limitations, became much more than an act of Islamic worship.     

A Process Model of the Formation of Spatial Presence Experiences

In order to bridge interdisciplinary differences in Presence research and to establish connections between Presence and “older” concepts of psychology and communication, a theoretical model of the formation of Spatial Presence is proposed. It is applicable to the exposure to different media and intended to unify the existing efforts to develop a theory of Presence. The model includes assumptions about attention allocation, mental models, and involvement, and considers the role of media factors and user characteristics as well, thus incorporating much previous work. It is argued that a commonly accepted model of Spatial Presence is the only solution to secure further progress within the international, interdisciplinary and multiple-paradigm community of Presence research.     

Who’s Afraid of Nagelian Reduction?

We reconsider the Nagelian theory of reduction and argue that, contrary to a widely held view, it is the right analysis of intertheoretic reduction. The alleged difficulties of the theory either vanish upon closer inspection or turn out to be substantive philosophical questions rather than knock-down arguments.     

Crime Scene Investigation: The Chief Inspectors’ Display Rules

Television as one factor in the “cycle of role division” (Eagly 1987; Shields 2002) can aid to perpetuate traditional role attitudes as well as set new norms. The aim of the study is to examine gender differences in facial expression of emotion on TV as well as changes of these differences over time. A content analysis of 12 episodes of a prominent German crime series from two time samples (1979–1981 / 2005) was done by employing the Emotional Facial Action Coding System (EmFACS, Friesen and Ekman 1983). Results show that there are gender differences in stereotypically male emotions: Male actors express these emotions significantly more frequently than female actors, while the latter show more “social smiles”. These differences are reduced over time.