Remarks on the identifiability of thurstonian paired comparison models under multiple judgment

It is well-known that the representations of the Thurstonian models for difference judgment data are not unique. It has been shown that equivalence classes can be formed to provide a more meaningful partition of the covariance structures of the Thurstonian ranking models. In this paper, we examine the equivalence relations between Thurstonian covariance structure models for paired comparison data obtained under multiple judgment and discuss their implications on the general identification constraints and methods to check for parameter identifiability in restricted models.The author is indebted to Ulf Böckenholt and Albert Maydeu-Olivares for their significant comments and suggestions which led to considerable improvement in this article.     

Global and local covert visual attention: Evidence from a bayesian hidden markov model

Psychological, psychophysical and physiological research indicates that people switch between two covert attention states, local and global attention, while visually exploring complex scenes. The focus in the local attention state is on specific aspects and details of the scene, and on examining its content with greater visual detail. The focus in the global attention state is on exploring the informative and perceptually salient areas of the scene, and possibly on integrating the information contained therein. The existence of these two visual attention states, their relative prevalence and sequence in time has remained empirically untested to date. To fill this gap, we develop a psychometric model of visual covert attention that extends recent work on hidden Markov models, and we test it using eye-movement data. The model aims to describe the observed time series of saccades typically collected in eye-movement research by assuming a latent Markov process, indicative of the brain switching between global and local covert attention. We allow subjects to be in either state while exploring a stimulus visually, and to switch between them an arbitrary number of times. We relax the no-memory-property of the Markov chain. The model that we develop is estimated with MCMC methodology and calibrated on eye-movement data collected in a study of consumers' attention to print advertisements in magazines.We thank Dominique Claessens of Verify International for making the data available to us.     

What do computer models of cognition explain: a reply to Gobet

The differences between Gobet’s views and ours call attention to some points concerning the argumentative status of computational models. If we have two fundamentally different models which reasonably accurately simulate a phenomenon, we must ask, what is the argumentative status of the models in psychological terms. Moreover, if it is possible to present different models of same phenomena, what is the general argumentative power of models in psychology? As the kind of differences between our views and the ones of Gobet’s are common in modelling, we briefly call attention to these foundational issues in our paper.     

Psychoanalysis and Diplomacy: Part III. Potentials for and Obstacles Against Collaboration

Given the pervasive influence of Realpolitik over government and the study of international relations, and some inherent difficulties within the field of psychoanalysis, it is not surprising that political science and psychoanalysis remain distant cousins. Part III in this series on diplomacy and psychoanalysis discusses obstacles against collaboration between these two disciplines, but also points to areas where collaboration is possible and can be useful.     

A local model of concurrent performance

Concurrent procedures may be conceptualized as consisting of two pairs of schedules with only one pair operating at a time. One schedule of each pair arranges reinforcers for staying in the current alternative, and the other schedule arranges reinforcers for switching to the other alternative. These pairs alternate operation as the animal switches between choices. This analysis of the contingencies suggests that variables operating within an alternative produce behavior that conforms to the generalized matching law. Rats were exposed to one pair of stay and switch schedules in each condition, and the probabilities of reinforcement varied across conditions. Both run length and visit duration were power functions of the ratio of the probabilities of reinforcement for staying and switching. The local model, a model of performance on concurrent procedures, was derived from this power function. Performance on concurrent schedules was synthesized from the performances on the separate pairs. Both the generalized matching law and the local model fitted the synthesized concurrent performances. These results are consistent with the view that the contingencies in the alternative, the probability of stay and switch reinforcement, are responsible for performance consistent with the generalized matching law. These results are compatible with momentary maximizing and molar maximizing accounts of concurrent performance. Models of concurrent performance that posit comparisons among the alternatives are not easily applied to these results.     

Bayesian estimation and testing of structural equation models

The Gibbs sampler can be used to obtain samples of arbitrary size from the posterior distribution over the parameters of a structural equation model (SEM) given covariance data and a prior distribution over the parameters. Point estimates, standard deviations and interval estimates for the parameters can be computed from these samples. If the prior distribution over the parameters is uninformative, the posterior is proportional to the likelihood, and asymptotically the inferences based on the Gibbs sample are the same as those based on the maximum likelihood solution, for example, output from LISREL or EQS. In small samples, however, the likelihood surface is not Gaussian and in some cases contains local maxima. Nevertheless, the Gibbs sample comes from the correct posterior distribution over the parameters regardless of the sample size and the shape of the likelihood surface. With an informative prior distribution over the parameters, the posterior can be used to make inferences about the parameters underidentified models, as we illustrate on a simple errors-in-variables model.We thank David Spiegelhalter for suggesting applying the Gibbs sampler to structural equation models to the first author at a 1994 workshop in Wiesbaden. We thank Ulf Böckenholt, Chris Meek, Marijtje van Duijn, Clark Glymour, Ivo Molenaar, Steve Klepper, Thomas Richardson, Teddy Seidenfeld, and Tom Snijders for helpful discussions, mathematical advice, and critiques of earlier drafts of this paper.     

The role of posttraumatic fear and social support in the relationship between trauma severity and posttraumatic growth among adolescent survivors of the Yaan earthquake

Middle school students in Lushan county (N = 315) were assessed 6 months after the Yaan earthquake using a trauma severity questionnaire, a posttraumatic fear questionnaire, a social support questionnaire and a posttraumatic growth inventory to examine the effects of posttraumatic fear and social support in the relationship between trauma severity and posttraumatic growth (PTG). The results showed that posttraumatic fear mediated the relationship between trauma severity and PTG, and social support moderated the relationship between posttraumatic fear and PTG. These findings suggested that trauma severity could be positively associated with PTG in a direct way or in an indirect way through posttraumatic fear. Moreover, posttraumatic fear had a positive relation to PTG under the condition of high social support level, whereas the relation was non‐significant when the level of social support was low. These results were discussed in terms of their implications for adolescents after trauma.     

Wisdom at the end of life: Hospice patients’ reflections on the meaning of life and death

The processes of aging and confronting mortality are often accompanied by unique psychological challenges. From the perspective of positive psychology, such challenges can yield opportunities for growth, including increased wisdom. This qualitative study explored 15 terminally ill hospice patients’ perspectives on wisdom, the dying process, and the meaning of life using consensual qualitative research methods. Most participants cited humility as a key component of wisdom, emphasizing that “Wisdom is when we realize ‘I don’t really know much’.” Other components of wisdom included self-knowledge, rationality, experiential learning, listening to and learning from others, and sharing knowledge with others. Participants also suggested that the process of facing illness and death presents opportunities for positive growth, including changing priorities and learning to appreciate life more fully in the present moment. In considering the sources of meaning in their lives, participants emphasized relational connections, personal growth, spirituality, vocational fulfilment, and living a full life. Participants also shared their reflections on important past experiences and regrets. Lastly, participants offered advice to others based on their experiences facing illness and mortality. Implications for psychological care of the dying and future research are discussed.     

Predicting elections from the most important issue: A test of the take‐the‐best heuristic

We used the take‐the‐best heuristic to develop a model to forecast the popular two‐party vote shares in U.S. presidential elections. The model draws upon information about how voters expect the candidates to deal with the most important issue facing the country. We used cross‐validation to calculate a total of 1000 out‐of‐sample forecasts, one for each of the last 100 days of the ten U.S. presidential elections from 1972 to 2008. Ninety‐seven per cent of forecasts correctly predicted the winner of the popular vote. The model forecasts were competitive compared to forecasts from methods that incorporate substantially more information (e.g., econometric models and the Iowa Electronic Markets). The purpose of the model is to provide fast advice on which issues candidates should stress in their campaign. Copyright © 2010 John Wiley & Sons, Ltd.     

Chinese college students' general and relationship‐specific representations of adult attachment: Variable‐centred and person‐centred analysis

Formerly, researchers often treated adult attachment as a trait‐like construct with consistency across relationship contexts. However, recent studies have shown that people possess multiple relationship‐specific attachment representations, and inter‐correlations among them are only in a small‐to‐medium range. The aim of this study is to test whether these variable‐centred results could be replicated in China and further supplement them with a person‐centred analysis focusing on identifying prototypical patterns of multiple working models across relationships. We administrated measurements of general and four relationship‐specific (mother/father/best friend/romantic partner) working models and indicators of psychological adjustment upon 302 Chinese college students. Results from variable‐centred analysis demonstrated the cross‐relationship variability in working models. Furthermore, global indicators of psychological adjustment were better predicted by general models, while relationship‐specific indicators were better predicted by corresponding relationship‐specific models. These results largely replicate previous Western studies, supporting the existence of multiple attachment representations in China. In person‐centred analysis, a latent profile analysis identified four typical classes of working model profiles: all‐average, all‐secure, romantic‐insecure and peer‐secure. These classes differed not only in the cross‐relationship variability of their working models, but also in their levels of psychological adjustment. These interesting patterns may have theoretical implications and are worthy of further examination.