Constructing bootstrap confidence intervals for principal component loadings in the presence of missing data: a multiple-imputation approach

Earlier research has shown that bootstrap confidence intervals from principal component loadings give a good coverage of the population loadings. However, this only applies to complete data. When data are incomplete, missing data have to be handled before analysing the data. Multiple imputation may be used for this purpose. The question is how bootstrap confidence intervals for principal component loadings should be corrected for multiply imputed data. In this paper, several solutions are proposed. Simulations show that the proposed corrections for multiply imputed data give a good coverage of the population loadings in various situations.     

Moving faces, looking places: validation of the Amsterdam Dynamic Facial Expression Set (ADFES)

We report two studies validating a new standardized set of filmed emotion expressions, the Amsterdam Dynamic Facial Expression Set (ADFES). The ADFES is distinct from existing datasets in that it includes a face-forward version and two different head-turning versions (faces turning toward and away from viewers), North-European as well as Mediterranean models (male and female), and nine discrete emotions (joy, anger, fear, sadness, surprise, disgust, contempt, pride, and embarrassment). Study 1 showed that the ADFES received excellent recognition scores. Recognition was affected by social categorization of the model: displays of North-European models were better recognized by Dutch participants, suggesting an ingroup advantage. Head-turning did not affect recognition accuracy. Study 2 showed that participants more strongly perceived themselves to be the cause of the other's emotion when the model's face turned toward the respondents. The ADFES provides new avenues for research on emotion expression and is available for researchers upon request.     

The neurocognition of conduct disorder behaviors: specificity to physical aggression and theft after controlling for ADHD symptoms

There is growing evidence that among the different conduct disorder (CD) behaviors, physical aggression, but not theft, links to low neurocognitive abilities. Specifically, physical aggression has consistently been found to be negatively related to neurocognitive abilities, whereas theft has been shown to be either positively or not related to neurocognition. The specificity of these links needs further examination because attention deficit hyperactivity disorder (ADHD) links to both physical aggression and neurocognitive variation. The development of self-reported physical aggression and theft, from age 11 to 17 years, was studied in a prospective at-risk male cohort via a dual process latent growth curve model. Seven neurocognitive tests at age 20 were regressed on the growth parameters of physical aggression and theft. The links between neurocognition and the growth parameters of physical aggression and theft were adjusted for ADHD symptoms at ages 11 and 15 (parent, child and teacher reports). Results indicated that verbal abilities were negatively related to physical aggression while they were positively associated with theft. However, inductive reasoning was negatively associated with increases in theft across adolescence. Symptoms of ADHD accounted for part of the neurocognitive test links with physical aggression but did not account for the associations with theft. These differences emphasize the importance of examining specific CD behaviors to better understand their neurodevelopmental mechanisms. They also suggest that youth who engage in different levels of physical aggression or theft behaviors may require different preventive and corrective interventions.     

How to Assess a Model's Testability and Identifiability

Formal definitions are given of the following intuitive concepts: (a) A model is quantitatively testable if its predictions are highly precise and narrow. (b) A model is identifiable if the values of its parameters can be ascertained from empirical observations. (c) A model is redundant if the values of some parameters can be deduced from others or if the values of some observables can be deduced from others. Various rules of thumb for nonredundant models are examined. The Counting Rule states that a model is quantitatively testable if and only if it has fewer parameters than observables. This rule can be safely applied only to identifiable models. If a model is unidentifiable, one must apply a generalization of the Counting Rule known as the Jacobian Rule. This rule states that a model is quantitatively testable if and only if the maximum rank (i.e., the number of linearly independent columns) of its Jacobian matrix (i.e., the matrix of partial derivatives of the function that maps parameter values to the predicted values of observables) is smaller than the number of observables. The Identifiability Rule states that a model is identifiable if and only if the maximum rank of its Jacobian matrix equals the number of parameters. The conclusions provided by these rules are only presumptive. To reach definitive conclusions, additional analyses must be performed. To illustrate the foregoing, the quantitative testability and identifiability of linear models and of discrete-state models are analyzed. Copyright 2000 Academic Press.     

Attributions of responsibility and affective reactions to decision outcomes

Immediate affective reactions to outcomes are more intense following decisions to act than following decisions not to act. This finding holds for both positive and negative outcomes. We relate this "actor-effect" to attribution theory and argue that decision makers are seen as more responsible for outcomes when these are the result of a decision to act as compared to a decision not to act. Experiment 1 (N = 80) tests the main assumption underlying our reasoning and shows that affective reactions to decision outcomes are indeed more intense when the decision maker is seen as more responsible. Experiment 2 (N = 40) tests whether the actor effect can be predicted on the basis of differential attributions following action and inaction. Participants read vignettes in which active and passive actors obtained a positive or negative outcome. Action resulted in more intense affect than inaction, and positive outcomes resulted in more intense affect than negative outcomes. Experiment 2 further shows that responsibility attributions and affective reactions to outcomes are highly correlated; that is, more extreme affective reactions are associated with more internal attributions. We discuss the implications for research on post-decisional reactions.     

Wisconsin Card Sorting in adolescents: analysis of performance, response times and heart rate

Forty-nine adolescents performed the Wisconsin Card Sorting Test (WCST). A main PCA component of WCST performance was identified as 'efficiency of reasoning'. This factor was related to feedback processing. From the WCST, a perseveration score can be derived. Perseveration is the continued application of a rule, after it has been disconfirmed. We compared more and less perseverating subjects in relation to stimulus-response (SR) time, feedback inspection time and cardiac acceleration and deceleration. Less perseverating subjects responded faster, and had longer and more adaptive inspection times of error feedback. We examined the switch from rule application to rule search, and the difference between correct and error responses. A transient cardiac deceleration at the initiation of rule search was interpreted as a change in supervisory attention. An error-related deceleration to negative feedback was interpreted as a disturbance of higher control processing. Previous trial feedback influenced current processing time, feedback inspection time, and the cardiac acceleration and deceleration responses.     

Excessive breathlessness through emotional imagery in asthma

Breathlessness and negative emotions during asthma attacks interact in complex patterns. This study tested the influence of emotional imagery on breathlessness during voluntary breath holding. Adolescents with and without asthma (n = 36 + 36) were assigned to positive imagery, negative imagery, or no imagery. There were four trials with close to thresholds for breath holding combined with imagery. Breathlessness and quality of imagery were measured by the end of breath holding. Additional measures were lung function and anxiety. The results showed that positive and negative imagery were only influencing breathlessness in participants with asthma. Although threshold duration for the groups were not significantly different, participants with asthma reported more breathlessness. The intensity of imagery enhanced breathlessness but diminished the accuracy of symptom perception. Positive imagery diminished breathlessness in participants with asthma, but also the difference in breathlessness between 75% and 95% of threshold duration. Breathlessness did not correlate with lung function, anxiety or other variables. It was concluded that emotional imagery during asthma attacks distracts from accurate introspection or enhances breathlessness, irrespective of anxiety.     

Facial composite production: a comparison of mechanical and computer-driven systems

Computer-driven systems for constructing composite faces of suspects (E-fit; Mac-a-Mug) have largely replaced mechanical systems (Photofit; the Identikit) in police use, yet little is known of their comparative effectiveness in rendering an accurate likeness. Participants (N = 24) constructed 2 of 4 familiar or unfamiliar faces, for one of which they used Photofit and for the other, E-fit. A likeness of each face was made first under target-absent conditions and then with photographs of the target present. The accuracy of the resulting composites was assessed by familiarity ratings, names elicited, and matching accuracy. The computer-driven system showed consistent superiority only when a familiar face was constructed in the presence of photographs; when participants worked from memory, E-fit was no better than Photofit. The implications of these findings for theories of face retrieval and the operational use of composites are discussed.     

The role of causal discourse structure in narrative writing

All writers produce text content and ideally connect it together according to discourse conventions. We investigate whether a particularly strong discourse convention, the need for causal coherence in narratives, can predict the kind of text writers will produce. Causality has been found to be a significant discourse factor in reading comprehension and hence can be expected to determine also what writers produce during composition. In Experiment 1, writers composed short continuations at various points throughout a simple narrative, whereas in Experiment 2, writers composed continuations to complete several narratives. The results indicate that causality indeed plays a major role in composition. Writers tend to produce new text in such a way that it is causally connected to the prior text. Furthermore, writers favored causal relations of necessity or of necessity and sufficiency while largely avoiding relations of sufficiency alone, which suggests a general discourse constraint to be maximally informative (e.g., Grice, 1975).     

Velocity constancy in a virtual reality environment

During everyday life the brain is continuously integrating multiple perceptual cues in order to allow us to make decisions and to guide our actions. In this study we have used a simulated (virtual reality--VR) visual environment to investigate how cues to speed judgments are integrated. There are two sources that could be used to provide signals for velocity constancy: temporal-frequency or distance cues. However, evidence from most psychophysical studies favours temporal-frequency cues. Here we report that two depth cues that provide a relative object--object distance--disparity and motion parallax--can provide a significant input to velocity-constancy judgments, particularly when combined. This result indicates that the second mechanism can also play a significant role in generating velocity constancy. Furthermore, we show that cognitive factors, such as familiar size, can influence the perception of object speed. The results suggest that both low-level cues to spatiotemporal structure and depth, and high-level cues, such as object familiarity, are integrated by the brain during velocity estimation in real-world viewing.