On the Relationships between Sum Score Based Estimation and Joint Maximum Likelihood Estimation

This paper analyzes the sum score based (SSB) formulation of the Rasch model, where items and sum scores of persons are considered as factors in a logit model. After reviewing the evolution leading to the equality between their maximum likelihood estimates, the SSB model is then discussed from the point of view of pseudo-likelihood and of misspecified models. This is then employed to provide new insights into the origin of the known inconsistency of the difficulty parameter estimates in the Rasch model. The main results consist of exact relationships between the estimated standard errors for both models; and, for the ability parameters, an upper bound for the estimated standard errors of the Rasch model in terms of those for the SSB model, which are more easily available. The authors acknowledge partial financial support from the FONDECYT Project No. 1060722 from the Chilean Government, and the BIL05/03 grant to P. De Boeck, E. Lesaffre and G. Molenberghs (Flanders) for a collaboration with G. del Pino, E. San Martín, F. Quintana and J. Manzi (Chile).     

The Assumption of Proportional Components when Candecomp is Applied to Symmetric Matrices in the Context of Indscal

The use of Candecomp to fit scalar products in the context of INDSCAL is based on the assumption that the symmetry of the data matrices involved causes the component matrices to be equal when Candecomp converges. Ten Berge and Kiers gave examples where this assumption is violated for Gramian data matrices. These examples are believed to be local minima. It is now shown that, in the single-component case, the assumption can only be violated at saddle points. Chances of Candecomp converging to a saddle point are small but still nonzero.     

Female degus (Octodon degus) monitor their environment while foraging socially

Vigilance or scanning involves interruptions in foraging behavior when individuals lift their heads and conduct visual monitoring of the environment. Theoretical considerations assume that foraging with the "head down", and scanning ("head up") are mutually exclusive activities, such that foraging precludes vigilance. We tested this generalization in a socially foraging, small mammal model, the diurnal Chilean degu (Octodon degus). We studied spontaneous bouts of scanning of captive degus when foraging in pairs of female sibs and non-sibs. We examined the extent to which foraging (head down postures) and scanning (head up postures) were mutually exclusive in subjects exposed to none, partial, and complete lateral visual obstruction of their partners. In addition, we monitored the orientation of their bodies to examine the target of attention while foraging and scanning. Lastly, we examined the temporal occurrence of scanning events to assess the extent of scanning coordination, and whether this coordination is kin-biased. Visual obstruction had a significant influence on degu vigilance. Focal degus increased their quadrupedal and semi-erect scanning when foraging under a partially obstructed view of their partners. Degus oriented their bodies toward partners when foraging and scanning. Despite this, degus did not coordinate scanning bouts; instead, they scanned independently from one another. Relatedness among cage mates did not influence any aspect of degu behavior. Contrary to theoretical expectations, these results indicate that foraging and vigilance are not mutually exclusive, and that kinship per se does not influence scanning behavior and coordination.     

False recognition of facial expressions of emotion: causes and implications

This article examines the importance of semantic processes in the recognition of emotional expressions, through a series of three studies on false recognition. The first study found a high frequency of false recognition of prototypical expressions of emotion when participants viewed slides and video clips of nonprototypical fearful and happy expressions. The second study tested whether semantic processes caused false recognition. The authors found that participants made significantly higher error rates when asked to detect expressions that corresponded to semantic labels than when asked to detect visual stimuli. Finally, given that previous research reported that false memories are less prevalent in younger children, the third study tested whether false recognition of prototypical expressions increased with age. The authors found that 67% of eight- to nine-year-old children reported nonpresent prototypical expressions of fear in a fearful context, but only 40% of 6- to 7-year-old children did so. Taken together, these three studies demonstrate the importance of semantic processes in the detection and categorization of prototypical emotional expressions.     

External validation of the computerized, group administrable adaptation of the “operation span task”

One of the most widely used tasks for measuring working memory capacity is the operation span task (OSPAN; Turner & Engle, 1989). This task has almost always been applied individually, and stimuli presentation is controlled by the experimenter. Recently, De Neys, d'Ydewalle, Schaeken, and Vos (2002) improved the administration procedure by designing an automated, group-administrable version of the task (GOSPAN). They found GOSPAN to be reliable, and they also provided evidence on its validity (a significant positive correlation between GOSPAN and OSPAN scores). However, an external test of GOSPAN validity is still lacking. In this work, we present such a validation for the automated version, when the task is administered both individually (Experiment 1) and to groups (Experiment 2). There are abundant previous data on the relation between working memory capacity and reading comprehension. In this work, this relation is studied using an automated OSPAN version to measure working memory capacity. Given that our results are similar to those found using the original OSPAN, our data support the external validity of the automated version of the task. We also tested the reliability of the task and found high internal consistency in both experiments.     

Validation of a Portuguese version of the multidimensional measure of employability

This study describes the validity and reliability evidence of the multidimensional measure of employability (MME) based on the internal structure and relations to career self-efficacy and career success. Two hundred forty seven Portuguese persons (75.7% women) aged from 21–73 years old (M = 39.9, SD = 10.9) participated. Confirmatory factor analysis suggested adequate fit in the correlational and hierarchical models. Measurement reliability was good for total score and each factor. Correlations with the additional measures provided evidence of validity. MME provides a tool for research and career counseling, enabling comprehensive employability assessment and personalized interventions, while recognising the interplay between employability dimensions.     

A challenging dissociation in masked identity priming with the lexical decision task

The masked priming technique has been used extensively to explore the early stages of visual-word recognition. One key phenomenon in masked priming lexical decision is that identity priming is robust for words, whereas it is small/unreliable for nonwords. This dissociation has usually been explained on the basis that masked priming effects are lexical in nature, and hence there should not be an identity prime facilitation for nonwords. We present two experiments whose results are at odds with the assumption made by models that postulate that identity priming is purely lexical, and also challenge the assumption that word and nonword responses are based on the same information. Our experiments revealed that for nonwords, but not for words, matched-case identity PRIME–TARGET pairs were responded to faster than mismatched-case identity prime–TARGET pairs, and this phenomenon was not modulated by the lowercase/uppercase feature similarity of the stimuli.