The Local Minima Problem in Hierarchical Classes Analysis: An Evaluation of a Simulated Annealing Algorithm and Various Multistart Procedures

Hierarchical classes models are quasi-order retaining Boolean decomposition models for N-way N-mode binary data. To fit these models to data, rationally started alternating least squares (or, equivalently, alternating least absolute deviations) algorithms have been proposed. Extensive simulation studies showed that these algorithms succeed quite well in recovering the underlying truth but frequently end in a local minimum. In this paper we evaluate whether or not this local minimum problem can be mitigated by means of two common strategies for avoiding local minima in combinatorial data analysis: simulated annealing (SA) and use of a multistart procedure. In particular, we propose a generic SA algorithm for hierarchical classes analysis and three different types of random starts. The effectiveness of the SA algorithm and the random starts is evaluated by reanalyzing data sets of previous simulation studies. The reported results support the use of the proposed SA algorithm in combination with a random multistart procedure, regardless of the properties of the data set under study. Eva Ceulemans is a post-doctoral fellow of the Fund for Scientific Research Flanders (Belgium). Iwin Leenen is a post-doctoral researcher of the Spanish Ministerio de Educación y Ciencia (programa Ramón y Cajal). The research reported in this paper was partially supported by the Research Council of K.U. Leuven (GOA/05/04).     

Hierarchical Classes Modeling of Rating Data

Hierarchical classes (HICLAS) models constitute a distinct family of structural models for N-way N-mode data. All members of the family include N simultaneous and linked classifications of the elements of the N modes implied by the data; those classifications are organized in terms of hierarchical, if–then-type relations. Moreover, the models are accompanied by comprehensive, insightful graphical representations. Up to now, the hierarchical classes family has been limited to dichotomous or dichotomized data. In the present paper we propose a novel extension of the family to two-way two-mode rating data (HICLAS-R). The HICLAS-R model preserves the representation of simultaneous and linked classifications as well as of generalized if–then-type relations, and keeps being accompanied by a comprehensive graphical representation. It is shown to bear interesting relationships with classical real-valued two-way component analysis and with methods of optimal scaling. The research reported in this paper was supported by the Research Fund of the University of Leuven (GOA/00/02 and GOA/05/04) and by the Fund for Scientific Research-Flanders (project G.0146.06). Eva Ceulemans is a Post-doctoral Researcher supported by the Fund for Scientific Research, Flanders. The authors gratefully acknowledge the help of Gert Quintiens and Kaatje Bollaerts in collecting the data used in Section 4 and of Jan Schepers in additional analyses of these data.     

Retrospective reports of dream characteristics and preferences for organic vs. junk foods

The authors investigated correlations between retrospective dream characteristics, food preferences, and eating attitudes. Graduate students (7 men, 42 women) at Santa Clara University were administered the MEGA food scale and the KJP Dream Inventory. High intake of organic food was positively correlated with reports of multiple dream factors. Conversely, high scores on preferences for fast food, potato chips, and carbohydrates were negatively correlated with several factors. Findings are discussed in terms of the hypothesis that certain foods may influence dreaming.     

Exercise motivation in university community members: a behavioural intervention

The purpose of this study was to examine how exercise level, exercise motives, and barriers changed from the baseline phase to the follow-up phase after a behavioural and cognitive intervention aimed at increasing exercise. Seventy-five members of our university community (43 subjects in the control group and 32 in the experimental group), all of whom received cognitive feedback, agreed to complete the baseline phase. Only the experimental group received behavioural feedback and a free-access gym ticket with personal training in order to facilitate their adherence to exercise. The results suggest that a combination of behavioural and psychological techniques is an efficient strategy for increasing exercise level. In addition, the results showed that extrinsic motivation predominates the early stages of change-of-exercise behaviour, and that intrinsic motivation is important for progression towards maintenance. Subjects who decreased their exercise level increased their extrinsic exercise motivation and subjects who increased their exercise level decreased the barriers related to intrinsic motivation. These findings indicate that, in order to facilitate exercise adherence, feedback about motives for undertaking exercise is needed, combined with advice about how to improve physical condition. This combination could help eliminate certain barriers that hinder engaging in an active and healthy life-style.     

Facial dynamics as indicators of trustworthiness and cooperative behavior

Detecting cooperative partners in situations that have financial stakes is crucial to successful social exchange. The authors tested whether humans are sensitive to subtle facial dynamics of counterparts when deciding whether to trust and cooperate. Participants played a 2-person trust game before which the facial dynamics of the other player were manipulated using brief (<6 s) but highly realistic facial animations. Results showed that facial dynamics significantly influenced participants' (a) choice of with whom to play the game and (b) decisions to cooperate. It was also found that inferences about the other player's trustworthiness mediated these effects of facial dynamics on cooperative behavior.     

The Relationship Between Agentic and Communal Personality Traits and Psychosocial Adjustment to Breast Cancer

Agency, communion, unmitigated agency (UA), and unmitigated communion (UC) are related to psychosocial health outcomes in nonclinical and medical populations. This study examined the relationship between these personality traits and emotional and interpersonal well-being, as up to 50% of women experience difficulties in psychosocial adjustment after being diagnosed with breast cancer. Seventy-four women newly diagnosed with breast cancer completed baseline assessment measures within 2 weeks prior to their first chemotherapy treatment or at the beginning of their hormonal therapy. Findings indicate that (1) agency and UA are important correlates of emotional and interpersonal adjustment and should be considered when attempting to identify women at high risk for psychosocial distress, and (2) UC deserves increased attention in behavioral medicine research, given its strong relationship with emotional distress in a breast cancer population. Thus, evidence continues to accumulate regarding the important relationship of these personality traits to psychosocial outcomes in medical populations.     

The Effects of Weight Loss Attempts, Exercise Initiation, and Dietary Practices on Health Related Quality of Life

This study (N = 98) randomly placed participants in either a higher protein or American Heart Association diet group with each group initiating an aerobic exercise program. Body composition (BC) was measured using four different methodologies (DEXA, BIA, skinfold, BMI) along with height and weight, while Health-Related Quality of Life (HRQOL) changes were measured using the Medical Outcomes Short Form 36 (SF-36). There were no significant time/diet interactions in HRQOL scores, body fat measures, and weight with the exception of Role-Physical scores (p = .006) with posttest scores higher in participants in Diet 1. Role-Physical scores changed significantly in participants in Diet 1 (p = .0001) and Diet 2 (p = .026) with higher posttest scores in each group. Social functioning had a significant main effect for time in both groups with pretest scores in both diet groups lower than their respective posttest scores (p = .015). HRQOL pretest scores were not significantly different between groups at baseline (p = .56). ANOVA revealed no significant differences in average calories between groups (p = .88). Analysis revealed no differences in exercise in minutes (p = .66) nor statistically significant changes in BC or weight (p = .65). Conclusions: Improvements in HRQOL were demonstrated in two subscales related to physiological and psychological functioning. These novel findings add to literature suggesting that HRQOL, at least concerning social functioning, work and other daily activities (Role-Physical) may improve by initiating an exercise and dietary program even when weight loss or BC improvements have been unsuccessful.     

When congruence breeds preference: the influence of selective attention processes on evaluative conditioning

We investigated in two experiments whether selective attention processes modulate evaluative conditioning (EC). Based on the fact that the typical stimuli in an EC paradigm involve an affect-laden unconditioned stimulus (US) and a neutral conditioned stimulus (CS), we started from the assumption that learning might depend in part upon selective attention to the US. Attention to the US was manipulated by including a variant of the Eriksen flanker task in the EC paradigm. Similarly to the original Flanker paradigm, we implemented a target-distracter logic by introducing the CS as the task-relevant stimulus (i.e. the target) to which the participants had to respond and the US as a task-irrelevant distracter. Experiment 1 showed that CS–US congruence modulated EC if the CS had to be selected against the US. Specifically, EC was more pronounced for congruent CS–US pairs as compared to incongruent CS–US pairs. Experiment 2 disentangled CS–US congruence and CS–US compatibility and suggested that it is indeed CS–US stimulus congruence rather than CS–US response compatibility that modulates EC.     

Memory for Textual Conflicts Predicts Sourcing When Adolescents Read Multiple Expository Texts

This study investigated whether memory for conflicting information predicted mental representation of source-content links (i.e., who said what) in a sample of 86 Norwegian adolescent readers. Participants read four texts presenting conflicting claims about sun exposure and health. With differences in gender, prior knowledge, and interest controlled for, and with self-reported critical reading strategies also included in a multiple regression analysis, it was found that the better participants remembered that the texts presented conflicting claims on the issue, the more likely they were to include source-content links in their mental representations of the texts.